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Neurological emergencies 

Neurological emergencies
Chapter:
Neurological emergencies
Author(s):

Punit S. Ramrakha

, Kevin P. Moore

, and Amir H. Sam

DOI:
10.1093/med/9780198797425.003.0006
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date: 04 August 2020

Coma: assessment

Presentation

Coma is a ‘state of unarousable unresponsiveness’.

  • No evidence of arousal: there is no spontaneous eye opening, comprehensible speech, or voluntary limb movement.

  • Unresponsive to external stimuli and surrounding environment, although abnormal postures may be adopted, eyes may open, or grunts may be elicited in response to pain.

  • Involuntary movements, e.g. seizures or myoclonic jerks, may occur.

  • GCS (Neurological emergencies Glasgow Coma Scale (GCS), p. [link]) is a useful way of assessing and monitoring level of consciousness.

  • Signs of brain shift (Neurological emergencies Examination of brainstem function 3, pp. [link][link]) may accompany a decreasing level of consciousness.

Causes

For practical purposes, it is best to divide these into:

  • Metabolic.

  • Toxic.

  • Infective.

  • Structural lesions.

With or without:

  • Focal brainstem signs.

  • Lateralizing cerebral signs.

  • Meningeal irritation.

In general, toxic and metabolic causes usually do not produce focal signs (except rarely with hypoglycaemia or liver or renal failure), whereas infections and structural lesions do. Meningism offers a very useful clue about the cause of coma (see Neurological emergencies Coma with meningism, p. [link]).

Coma without focal/lateralizing neurological signs

  • Anoxia/hypoperfusion.

  • Metabolic, e.g. hypo-/hyperglycaemia, acidosis/alkalosis, hypo- or hypernatraemia, hypercalcaemia, hepatic or renal failure.

  • Intoxications, e.g. alcohol, opiates, benzodiazepines, tricyclics, neuroleptics, lithium, barbiturates, carbon monoxide.

  • Endocrine: hypothyroidism.

  • Hypo- or hyperthermia.

  • Epilepsy.

  • Hypertensive encephalopathy.

Coma with focal/lateralizing neurological signs (due to brainstem or bihemispheric cerebral dysfunction)

  • Vascular: cerebral haemorrhage or infarction (e.g. large-territory infarct or basilar artery thrombosis).

  • Supra- or infratentorial space-occupying lesion (SOL): tumour, haematoma, abscess. In order to produce coma, these either have to be within the brainstem or compress it by producing a brain shift (Neurological emergencies Examination of brainstem function 3, pp. [link][link]).

Coma with meningism

  • Meningitis, encephalitis.

  • SAH.

Assessment of severity

  • GCS (Neurological emergencies Glasgow Coma Scale (GCS), p. [link]).

  • Signs of brain shift (Neurological emergencies Examination of brainstem function 3, pp. [link][link]) and/or brainstem compromise.

  • Precipitating lesion or injury.

  • Length of time in comatose state.

  • Comorbidities.

Coma: immediate management

Priorities

  1. 1. Stabilize the patient (airway, breathing, circulation). Give O2.

  2. 2. Consider giving thiamine, glucose, naloxone, or flumazenil.

  3. 3. Examine the patient. Is there meningism? Establish the GCS score. Is there evidence of brainstem failure? Are there focal or lateralizing signs?

  4. 4. Plan for further investigations.

  5. 5. Observe for signs of deterioration, and attempt to reverse them.

For treatments to be considered in coma, see Box 6.1.

Stabilize the patient

  • Open the airway by laying the patient on their side. Note the pattern of breathing (Neurological emergencies Examination of brainstem function 2, p. [link]). If there is apnoea or laboured or disturbed breathing, intubation and ventilation should be considered. Measure ABGs.

  • Support the circulation. Correct hypotension with fluids and/or inotropes. If prolonged therapy is required, both require careful and frequent monitoring of CVP and/or pulmonary artery wedge pressure (PAWP). Search for any occult source of bleeding, e.g. intra-abdominal.

  • Treat seizures with usual drugs (Neurological emergencies Status epilepticus (tonic–clonic) 1, pp. [link][link]), but beware of over-sedation and hypotension.

  • Take blood for glucose, U&Es, Ca2+, liver enzymes, albumin, clotting screen, FBC, and toxicology (including urgent paracetamol and salicylate levels). Urine should be saved for toxicology screen.

Give thiamine, glucose, naloxone, or flumazenil

  • Check blood glucose. There is a good argument for giving 50mL of 50% glucose immediately for presumed hypoglycaemia because this will usually not cause any harm.

  • The only concern is that glucose may precipitate Wernicke’s encephalopathy (WE) in malnourished individuals. Some clinicians therefore favour giving a bolus of thiamine 100–200mg IV beforehand.

  • Naloxone should only be given if opiate intoxication is likely (small pupils) and the patient is in a coma or has a markedly reduced RR. In adults, naloxone 0.8–2.0mg IV should be given at intervals of 2–3min to a maximum of 10mg.

  • Flumazenil should only be administered if benzodiazepine intoxication is likely; it is contraindicated in epileptics who have received prolonged benzodiazepine therapy. In adults, flumazenil 200 micrograms should be given over 15s; further 100-microgram boluses may be given at 1-min intervals (usual dose is 300–600 micrograms, maximum total dose outside intensive care setting is 1mg).

  • Both naloxone and flumazenil may be given as IVIs if drowsiness recurs, but intensive care monitoring is advisable.

Coma: clues from examination

History

If available, this will often be the most useful source of assessment. Even if the history is not extensive, a witness is vital to establish whether coma commenced suddenly (suggestive of a vascular event) or whether there was a gradual decline in level of consciousness over hours or days and for relevant premorbid history (e.g. previous generalized seizures, use of drugs, etc.). Individuals known to suffer from specific diseases may be wearing a MedicAlert bracelet or carrying their regular medication. An enormous amount may be learnt from a rapid, but thorough, examination.

General examination

This should establish the following:1,2

  • Core temperature: fever usually indicates an infection but sometimes results from diencephalic lesions. Hypothermia is often forgotten as a cause for coma; the possibility of myxoedema should be considered. Ideally, prognosis should be based on normothermic state.

  • HR and rhythm: may indicate a dysrhythmia as the reason for poor cerebral perfusion.

  • BP: prolonged hypotension of any cause will lead to anoxia and ischaemia. Apart from a cardiac cause, occult bleeding, a cause of sepsis, and drug intoxication need to be considered.

  • Respiratory pattern: shallow, slow breathing should alert the examiner to the possibility of drug intoxication, e.g. opiates. Deep, rapid Kussmaul breathing suggests acidosis. Brainstem compromise can cause distinctive patterns of breathing (see Fig. 6.4).

  • Breath: alcohol, ketones, hepatic or uraemic fetor?

  • Skin: there may be signs of trauma to the head. Bruising over the scalp or mastoids and blood in the nostrils or external auditory meatus raise the possibility of a basal skull fracture. A rash suggests the possibility of meningitis. Look for signs of chronic liver disease or sallow discoloration of uraemia. IV drug abuse suggested by needle tracks.

  • Heart: occasionally bacterial endocarditis or vasculitides associated with heart murmurs present with coma.

  • Abdomen: look for enlargement of organs which may give clues to the cause of coma. It is important not to miss an acute intra-abdominal event such as perforation of a viscus or a leaking aortic aneurysm.

  • Fundi: papilloedema indicates raised ICP, but its absence does not exclude that possibility. Subhyaloid haemorrhages are pathognomonic of SAH but are rare. Changes of diabetic or hypertensive retinopathy suggest the possibility of encephalopathy secondary to these conditions.

Fig. 6.4 Abnormal respiratory patterns associated with pathologic lesions (shaded areas) at various levels of the brain. (A) Cheyne–Stokes respiration. (B) Central neurogenic hyperventilation. (C) Apneusis. (D) Cluster breathing. (E) Ataxic breathing.

Fig. 6.4 Abnormal respiratory patterns associated with pathologic lesions (shaded areas) at various levels of the brain. (A) Cheyne–Stokes respiration. (B) Central neurogenic hyperventilation. (C) Apneusis. (D) Cluster breathing. (E) Ataxic breathing.

Republished with permission of Oxford University Press, from The Diagnosis of Stupor and Coma, 3rd edn, Plum F and Posner JB. Copyright © 1982; permission conveyed through Copyright Clearance Center, Inc.

Is there meningism?

Neck stiffness should be assessed only if it is certain that there has been no trauma to the cervical spine. Stiffness suggests meningeal irritation, either because of inflammation or infiltrative processes affecting the meninges or because of the presence of blood. Meningism raises the possibility of meningitis, meningoencephalitis, or SAH. Start antibiotics immediately if meningitis is suspected.

Assess the GCS

This may reveal brainstem dysfunction or lateralizing signs. When testing the motor response, decorticate or decerebrate posturing may become evident (Neurological emergencies Examination of brainstem function 1, pp. [link][link]). If there is a change in these signs, it may indicate a brain shift (Neurological emergencies Examination of brainstem function 3, pp. [link][link]).

Look for evidence of brainstem dysfunction

See Neurological emergencies Examination of brainstem function 1, pp. [link][link] for details.

  • Test and observe:

    • Pupillary response.

    • Corneal reflex.

    • Resting position of the eyes.

    • Spontaneous eye movements.

    • Oculocephalic response/doll’s head manoeuvre (if no C-spine injury).

    • Oculovestibular response/caloric stimulation.

    • Swallowing.

    • If intubated: cough and gag to suction.

    • Respiratory pattern.

    • If intubated: ventilator dependency.

  • There will be evidence of brainstem failure either because there is structural damage (intrinsic lesion or extrinsic compression due to brain shift; see Neurological emergencies Examination of brainstem function 3, pp. [link][link]) or because of metabolic coma such as drug intoxication with diffuse, usually reversible, dysfunction.

  • If there is focal brainstem dysfunction, the cause is most likely structural or intrinsic brainstem disease.

  • If there is rostro-caudal progression of brainstem signs, consider a herniation syndrome (Neurological emergencies Examination of brainstem function 3, pp. [link][link]).

  • If there appears to be diffuse brainstem dysfunction, it may not be easy to distinguish between structural and metabolic aetiologies. The most important clue is that in metabolic coma, irrespective of their size, the pupils continue to react, except in very few exceptional cases (atropine, hyoscine, or glutethimide intoxication will depress brainstem function and produce pupillary abnormalities).

Are there lateralizing signs?

Testing of brainstem reflexes, assessing the GCS score, and general examination may reveal facial asymmetry and differences in muscle tone, clonus, reflexes, and plantar responses between the two sides. All these features point towards the possibility of a structural lesion, although occasionally metabolic coma is associated with focal neurological signs.

References

1. Posner JB, Saper CB, Schiff ND, Plum F (2007). Plum and Posner’s Diagnosis of Stupor and Coma (Contemporary Neurology Series), 4th edn. Oxford University Press, New York, NY.Find this resource:

2. Bates D. The management of medical coma. J Neurol Neurosurg Psychiat. 1993;56:589–98.Find this resource:

Coma: management

Plan for further investigations

The history, physical examination, and/or laboratory studies may help make the diagnosis. Often, however, a diagnosis cannot be reached so rapidly. The practical approach is to divide patients according to the following scheme.

Brainstem function intact

Urgent CT head scan. This will reveal one of the following:

  • Operable lesions (e.g. subdural, subarachnoid, or intracerebral haemorrhage): refer to neurosurgery as appropriate.

  • Inoperable lesions: treatment is supportive.

  • Normal CT: an LP should be performed. Measure the opening pressure. CSF analysis may suggest an infective process (e.g. meningitis, encephalitis) (Neurological emergencies Acute bacterial meningitis: assessment, p. [link]). If the CSF is normal, the most likely diagnosis is a metabolic coma.

Brainstem function not intact

  • Consider whether there are signs of brain shift (Neurological emergencies Examination of brainstem function 3, pp. [link][link]).

  • If a herniation syndrome appears to be progressing rapidly, mannitol should be given, hyperventilation commenced, and a neurosurgeon contacted urgently (Neurological emergencies Raised intracranial pressure, pp. [link][link]).

  • If the tempo of events is not so rapid, mannitol may be given and an urgent CT scan arranged.

  • Even if the brainstem signs appear to be non-progressive, a CT scan should be arranged to exclude the possibility of an operable posterior fossa mass or haemorrhage (e.g. cerebellar haemorrhage).

  • If the CT is normal, an LP should be performed to exclude infection. If this too is normal, the diagnostic possibilities are intrinsic brainstem disease not detected by CT, metabolic coma, paraneoplasia, and parainfectious or possibly infection, e.g. encephalitis, without leucocytic response.

  • MRI is more sensitive in detecting intrinsic brainstem pathology, but fluid attenuation inversion recovery (FLAIR) sequences are limited in sensitivity in this part of the brain. Additionally, standard 5-mm slices may be too thick for some discrete pathologies.

  • LP should be repeated the next day if there is no improvement in the patient’s condition. Treatment is supportive.

Monitoring progress

  • Regular observations of vital signs and neurological state (and GCS score).

  • An important cause of deterioration in structural brain lesions is brain shift leading to herniation syndromes (Neurological emergencies Examination of brainstem function 3, pp. [link][link]). The emergency treatment of raised ICP is discussed under Neurological emergencies Raised ICP: further management, p. [link].

  • Other reasons for deterioration are electrolyte or metabolic changes, hypovolaemia, or fluid overload. Monitor regularly.

Prognosis

In coma due to head injury, prognosis is clearly related to the GCS score. Patients scoring 8 or less have a poor prognosis. In non-traumatic coma, the GCS score alone is not a very good predictor. Patients with drug intoxications may have low scores on admission but, in general, have good outcomes. Prognosis in non-traumatic coma is gauged by simple features of the examination. (e.g. if after 24h, pupillary responses, corneal reflexes, and oculovestibular response remain absent, survival is extremely unlikely).3 Early myoclonus (within 24h) after hypoxic–ischamic brain injury is a poor prognostic marker. Prognosis requires assessment at least 3 days subsequent to rewarming (if therapeutically cooled or patient presented in hypothermic coma).

References

3. Levy DE, Bates D, Caronna JJ, et al. Prognosis in nontraumatic coma. Arch Int Med. 1981;94: 293–301.Find this resource:

Limb weakness: assessment

History

The history should establish if there has been:

  • Sudden onset or gradual progression.

  • Weakness or incoordination.

  • Upper limb or facial weakness.

  • Asymmetrical or symmetrical weakness.

  • Associated sensory symptoms, e.g. paraesthesiae or numbness.

  • Difficulty with swallowing, speech, micturition, or defecation.

  • Back or neck pain.

  • Lhermitte’s phenomenon (flexion of the neck causing sensory symptoms radiating down the limbs) suggests cervical cord inflammation, radiation-induced myelopathy, or vitamin B12-deficient subacute degeneration of the cord.

  • Systemic symptoms, e.g. malaise, fever, diarrhoea and vomiting, arthralgia.

  • Recent trauma.

  • Previous medical history, e.g. hypertension, IHD, stroke, DM, connective tissue diseases, immunosuppression.

  • Drug history, e.g. phenytoin, isoniazid, vincristine, metronidazole.

  • Social history, e.g. smoker (cord infarct), vegan (vitamin B12 deficiency), travel history (infectious, e.g. TB, parasitic), sexual history (e.g. HIV).

Examination

  • What is the pattern of weakness? Some common patterns, together with associated features, are illustrated under Neurological emergencies Limb weakness: localizing the lesion, p. [link]. This should help to localize the level of the lesion in the nervous system.

  • Is the weakness upper (UMN) or lower motor neuron (LMN)/combination?

  • If UMN, is it pyramidal? That is, extensor more than flexor weakness in the upper limbs, and flexor greater than extensor weakness in the lower limbs.

  • Is there fatiguable weakness with repetitive effort? As in myasthenia.

  • Are there any involuntary movements? Tremor [e.g. multiple sclerosis (MS)], myoclonic jerks, or fits (e.g. venous sinus thrombosis) may be noted.

  • What is the gait like? This is important to test, if at all possible. It may demonstrate, for example, a hemiplegic gait, ataxia (cerebellar or sensory), a waddling (myopathic) gait, steppage (LMN) gait, or festinating movements of the parkinsonian patient.

  • Is there any sensory loss? Where? Is there a ‘sensory level’? Sensory changes are often the most difficult to elicit. Do not forget to test all modalities or to test the back of the legs up to the anal sphincter.

  • What modalities of sensation are lost? Dorsal column loss produces a ‘discriminatory’ loss with impaired two-point discrimination, joint position and vibration loss, and sensory ataxia. Spinothalamic loss usually produces a lack of awareness of pain and temperature.

The history and examination should help to localize the lesion and, together with the patient’s age, give an indication of the likely pathological process involved.4

Investigations

The initial investigation of choice depends upon the likely diagnosis. Investigations to consider are given in Box 6.2.

Diagnoses not to miss

  • Spinal cord compression (Neurological emergencies Spinal cord compression: assessment, p. [link]).

  • GBS (Neurological emergencies Guillain–Barré syndrome, pp. [link][link]).

  • Subdural haematoma (Neurological emergencies Subdural haematoma, pp. [link][link]).

  • Stroke (Neurological emergencies Stroke: overview, pp. [link][link]).

Diagnoses to consider

  • Demyelination (MS, neuromyelitis, post-infectious, etc.).

  • Malignancy (malignant meningitis, intracranial mass).

  • Syringomyelia.

  • Motor neuron disease.

  • Vitamin deficiency (subacute combined degeneration—vitamin B12).

  • Peripheral neuropathy (toxic, DM, autoimmune, amyloid, etc.).

  • TB, syphilis.

References

4. Adapted from Lindsay KW, Bone I, Fuller G (2010). General approach to history and examination: In: Lindsay KW, Bone I, Callender R. Neurology and Neurosurgery Illustrated, 5th edn, pp. 1–2. Churchill Livingstone, London.Find this resource:

Limb weakness: localizing the lesion

For patterns of limb weakness, see Table 6.1.

Table 6.1 Patterns of limb weakness

Monoplegia

Lesion site

Other features

Arm ± face

Neurological emergencies

Contralateral cortex (e.g. stroke, tumour, or inflammation)

  • Visual field defect

  • Dysphasia (dominant hemisphere lesion)

  • Cortical sensory loss (JPS and 2-point discrimination)

Leg only

Neurological emergencies

Contralateral cortex (e.g. anterior cerebral artery territory)

  • With ipsilateral sensory deficit

Ipsilateral spinal lesion (e.g. inflammation, injury, or tumour)

  • Contralateral pain and temperature loss

  • JPS lost on same side

Hemiplegia

Lesion site

Other features

Face + arm + leg

Neurological emergencies

Contralateral hemisphere (e.g. stroke, tumour, or inflammation)

  • UMN CN VII involvement

  • Impaired consciousness

  • Visual field defect

  • Dysphasia (if dominant hemisphere lesion)

Contralateral internal capsule

  • UMN CN VII involvement

  • Alert

  • No dysphasia (even with a dominant hemisphere lesion)

Contralateral midbrain lesion (e.g. stroke, inflammation, tumour)

  • Contralateral CN III palsy

  • Impaired upgaze

Arm (± face) or leg alone

Neurological emergencies

Contralateral cortex

  • CN VII unaffected

  • Visual field defect

  • Dysphasia (if dominant hemisphere lesion)

  • Cortical sensory loss (Neurological emergencies JPS and 2-point discrimination)

Contralateral medullary

  • Ipsilateral pain and temperature loss

  • Contralateral Horner’s syndrome

  • Contralateral palatal and tongue weakness

Ipsilateral spinal lesion

  • Pain and temperature loss in contralateral leg

  • Ipsilateral loss of JPS

  • Ipsilateral Horner’s

Arm, leg, and opposite face

Neurological emergencies

Contralateral pons

  • LMN face involvement on opposite side to weak limbs

  • Conjugate gaze deviation towards weak side

Arm and opposite leg

Neurological emergencies

Medullary lesion

  • Palatal and tongue weakness on side of arm weakness

Paraplegia

Lesion site

Other features

Neurological emergencies

Midline cortical lesion

  • Cortical sensory loss (JPS and 2-point discrimination)

  • ‘Frontal’ incontinence

  • Normal pain and temperature

Thoracic spine

  • ‘Sensory level’

  • Acute urinary retention or hesitancy of micturition

Tetraplegia

Lesion site

Other features

Face and all four limbs involved

Neurological emergencies

Pontine lesion

  • ‘Locked-in’ syndrome: only vertical eye movements possible

Face spared

Neurological emergencies

Cervical spine lesion

  • No CN lesion

  • High lesions (C1–3) require ventilation

  • Lesions at C4 have intact diaphragmatic breathing

Medullary lesion

  • No palatal or tongue movement or speech, but intact facial movements

Combined UMN and LMN signs

Neurological emergencies

  • LMN signs point to level of lesion

  • Two lesions (e.g. cervical and lumbar spondylosis) may produce mixed signs in limbs

LMN limb weakness (unilateral or bilateral)

Neurological emergencies

  • Nerve root distribution?

  • Plexopathy (suggested by involvement of contiguous nerve roots on one side)?

  • Peripheral nerve distribution (mono- versus polyneuropathy)

  • Presence of reflexes and normal sensation suggests myopathy (cf. neuropathy)

  • Fatiguability suggests neuromuscular junction disease

CN, cranial nerve; JPS, joint position sense; LMN, lower motor neuron; UMN, upper motor neuron.

Acute dizziness: assessment

History

Determine whether:

  • There is true vertigo, i.e. a sensation that either the patient or their environment is rotating. Distinguish this from ‘light-headedness’ more likely related to pre-syncope.

  • Symptoms started acutely are progressively worsening or are transient (see ‘vertebrobasilar TIAs’ under Neurological emergencies Transient ischaemic attacks, pp. [link][link]). Vestibular neuritis typically begins over a period of a few hours, peaks in the first day, and then improves within days. Infarction causes a vestibular syndrome that typically has an abrupt onset. TIAs often last for <30min. Abrupt onset of vertigo for seconds after a change in head position is characteristic of benign paroxysmal positional vertigo.5

  • Symptoms worse with certain postures: vertigo is worse with certain head positions in benign positional vertigo and some cases of central nystagmus (see Box 6.3). Postural hypotension is frequently caused by drugs and can be caused by acute blood loss; uncommonly, it is due to autonomic failure.

  • There is associated tinnitus (as in Ménière’s disease).

  • Hearing loss is present in Ménière’s disease, cerebellopontine angle lesions, e.g. acoustic neuroma (Vth, VIIth, and VIIIth nerves + ataxia).

  • Ear discharge may occur with middle ear disease.

  • Associated focal neurological symptoms, e.g. unilateral weakness, clumsiness, paraesthesiae, or numbness.

  • Headache: sudden onset in intracerebral haemorrhage; progressive with features of Neurological emergencies ICP in mass lesions (e.g. acoustic neuroma). History of migraine (suggesting migrainous vertigo).

  • Any recent head injury?

  • Systemic symptoms, e.g. weakness and lethargy in anaemia.

  • Previous medical/psychiatric history, e.g. hypertension, IHD, DM, risk factors for stroke or TIAs (Neurological emergencies Transient ischaemic attacks, pp. [link][link]), episodes of neurological disturbance, panic attacks, and anxiety.

  • Drug history is pertinent to both true vertigo (e.g. phenytoin, gentamicin, furosemide) and dizziness (e.g. antihypertensives, antidepressants, drugs for Parkinson’s disease, hypoglycaemics).

Examination

  • Ear: is there a discharge? Is the tympanic membrane normal?

  • Neurological examination: should discover whether there are any focal signs due to brainstem or cerebellar disease (Neurological emergencies Examination of brainstem function 1, pp. [link][link]). Non-contiguous brainstem pathology may be due to patchy demyelination. Do not forget to assess the corneal reflex, the absence of which is one of the earliest signs of an ipsilateral acoustic neuroma. Observe the gait, if possible; it may be ataxic. Examine extraocular eye movements. Is there intranuclear ophthalmoplegia (vascular/demyelinating brainstem disease)? Examine carefully for nystagmus (see Box 6.3). Hallpike manoeuvre involves positioning the patient’s head over one side of the bed and watching for nystagmus. Benign positional vertigo: nystagmus develops after a brief delay, but it fatigues and, with repetition, adapts. Central nystagmus: no initial delay, fatiguability, or adaptation. Head impulse test involves the examiner holding the patient’s head while the patient fixates on the examiner’s nose; rapid, small left and right rotations of the head should not displace the patient’s gaze from the examiner’s nose; if it does, with a corrective ‘catch-up’ saccade, peripheral vestibular disturbance is likely on the side towards which the head was turned. Fundoscopy may reveal papilloedema (suggestive of an intracranial SOL) or optic atrophy (which occurs with previous demyelination in MS).

  • General examination: measure BP lying and then after 3 and 5min of standing (including pulse). Postural hypotension is a common cause of dizziness.

References

5. Hotson JR, Baloh RW. Acute vestibular syndrome. N Engl J Med. 1998;339:680–5.Find this resource:

Acute dizziness: management

Investigations

These depend upon the likely diagnosis.

  • Cerebellopontine angle lesions, such as acoustic neuroma, may be imaged by CT with contrast, but in general, posterior fossa and brainstem disease is better appraised by MRI scanning.

  • Pure tone audiometry is a sensitive way of detecting sensorineural loss.

  • Measure blood sugar and FBC, if indicated.

For management, see Tables 6.2 and 6.3.

Table 6.2 Approach to true vertigo

Type of vertigo

Management

Acute vestibular neuritis

Bed rest, then vestibular rehabilitation

Consider cyclizine or prochlorperazine (avoid prolonged use)

Benign positional vertigo

Avoid precipitating position

Epley or Sermont manoeuvre

Ménière’s disease (sensorineural deafness and tinnitus)

Bed rest

Consider cyclizine or prochlorperazine

Pure tone audiometry

ENT referral

Middle ear disease

ENT referral

Brainstem/cerebellar disease (stroke, see Neurological emergencies Stroke: overview, pp. [link][link]; demyelination; vertebrobasilar insufficiency; migraine; vasculitis)

Consider CT/MRI

Cerebellopontine angle lesions (e.g. acoustic neuroma)

Pure tone audiometry

MRI scan of internal auditory meati

Table 6.3 Dizziness but no true vertigo

Type of dizziness

Management

Hypotension

Postural, cardiac, volume loss, or autonomic failure

Anaemia

FBC, blood film, other investigations as necessary

Hypoglycaemia

Diabetic on hypoglycaemics or insulin, insulinoma

Hyperventilation

Attempt to reproduce symptoms; explain

Carotid sinus hypersensitivity

See Neurological emergencies Sinus bradycardia or junctional rhythm, p. [link]

Acute loss of vision

History

Determine whether:

  • Visual loss is or was monocular or binocular, complete or incomplete, e.g. hemianopia, central or peripheral loss, haziness or complete obscuration of vision.

  • Loss of acuity occurred instantly (‘like a curtain’), as in amaurosis fugax.

  • Period for which it lasted.

  • There were any other associated visual symptoms, e.g. scintillations (‘flashing lights and shapes’) occur in migraine.

  • The eye is painful and red.

  • Headache or facial pain: unilateral or bilateral; migrainous features.

  • Associated focal neurological symptoms, e.g. unilateral weakness, clumsiness, paraesthesiae, or numbness.

  • Any recent trauma?

  • Systemic symptoms, e.g. malaise, aches, and pains.

  • Previous medical history, e.g. hypertension, IHD, DM, other risk factors for stroke or TIAs (Neurological emergencies Transient ischaemic attacks, pp. [link][link]), migraine, connective tissue diseases.

Examination

  • External appearance of the eye: is it red (Neurological emergencies Painful red eye: assessment, pp. [link][link])? Is there corneal clouding?

  • Visual acuity: should be measured for each eye with a Snellen chart. Near vision should be tested (with newsprint, if necessary). If none of these are possible, the patient’s acuity for counting the number of fingers or perceiving hand movement or light should be noted. Correct with glasses/contact lenses or pinhole. Ideally, colour vision should also be examined with Ishihara plates.

  • Plot the visual fields: often careful bedside examination is sufficient; perimetry available in ophthalmological departments is more sensitive and should be done to document the defect and recovery. Loss of vision may be incomplete.

  • Is there an afferent pupillary defect? (Swinging torch test.)

  • Fundoscopy: may reveal a retinal embolus, changes of central/branch retinal artery occlusion, swollen or pale optic nerve head, papilloedema, or hypertensive changes.

  • Is the temporal artery tender? It need not be in temporal arteritis.

  • Complete neurological examination: is necessary to discover if there are any other associated signs (e.g. spasticity in MS).

  • Listen for carotid bruits: although they may not be present in patients with symptomatic carotid stenosis.

  • Assess heart rhythm (including ECG) and cardiovascular system: for a possible cardiogenic source of embolus.

  • Measure BP lying and then after 3 and 5min of standing (including pulse) and blood sugar: hypotension in the presence of arteriosclerosis can lead to occipital lobe ischaemia. Hypertension and DM are risk factors for TIAs.

Investigations

See Neurological emergencies Stroke: other investigations, p. [link].

NB An ESR and CRP should be performed in any patient aged >50 years who presents with monocular blindness and unilateral headache. It is rarely normal in temporal arteritis. If the ESR is elevated and the presentation is compatible with temporal arteritis, high-dose corticosteroid therapy should be considered (initially 60mg/day PO) because the other eye is also at risk of anterior ischaemic optic neuropathy.

Approach to acute/subacute visual loss

Monocular transient loss without prominent unilateral headache

  • Amaurosis fugax (Neurological emergencies Transient ischaemic attacks, pp. [link][link]): in the elderly, this may be due to embolism. In some younger patients, it is probably due to vasospasm (a diagnosis of exclusion).

  • Hyperviscosity syndrome (e.g. polycythaemia, myeloma, sickle-cell anaemia), hypercoagulable state, vasculitis: blood film, protein electrophoresis, autoimmune screen, other haematological investigations as required (Neurological emergencies Hyperviscosity syndrome, p. [link]).

  • Postural hypotension (may exacerbate vertebrobasilar ischaemia): stop any exacerbating drugs. Exclude autonomic neuropathy.

Monocular transient loss with prominent headache

  • Migraine (usually there are symptoms such as nausea, sensory sensitivity, movement aggravation of headache, and positive visual phenomena, e.g. scintillations): observe, give analgesics/ergot derivative. Arrange neurological consultation.

  • Giant cell arteritis [temporal artery tenderness, non-pulsatile, jaw claudication, fever, symptoms of polymyalgia rheumatica (PMR), raised ESR]. Start steroids and refer for urgent biopsy.

Monocular sustained loss with red eye

  • Acute glaucoma (dilated pupil and corneal clouding): urgent ophthalmology referral.

  • Acute uveitis (inflammation of the iris and ciliary body, with small pupil), keratitis (corneal inflammation), endophthalmitis (involvement of the vitreous, uvea, and retina, with cellular debris/pus in the anterior chamber), or ocular trauma: urgent ophthalmic referral.

Monocular sustained loss without red eye

Central scotoma with relative afferent pupillary defect

  • Optic neuritis (orbital pain exacerbated by eye movement, reduced acuity and colour vision, inflamed disc unless retro-orbital) : the most common cause is demyelination, but consider the possibility of mass lesions compressing the optic nerve (consider evoked potentials, axial MRI orbit). Anterior ischaemic optic neuropathy (acutely inflamed optic disc) due to presumed atherosclerosis of posterior ciliary arteries or to temporal arteritis (temporal artery tenderness, non-pulsatile, jaw claudication, fever, symptoms of PMR, raised ESR): start steroids and refer for urgent biopsy.

Central scotoma without relative afferent pupillary defect

  • Vitreous haemorrhage.

  • Macular disorder: macular degeneration, haemorrhage, or exudate.

  • Branch or central retinal vein/artery occlusion (see Fig. 6.1).

Fig. 6.1 Central retinal vein occlusion with assorted closure of the arterial circulation above the macula ( Approach to acute/subacute visual loss, pp. Approach to acute/subacute visual loss366–Approach to acute/subacute visual loss367).

Fig. 6.1 Central retinal vein occlusion with assorted closure of the arterial circulation above the macula ( Approach to acute/subacute visual loss, pp. [link][link]).

Reproduced from Easty D, et al. Oxford Textbook of Ophthalmology, 1999, with permission from Oxford University Press.

Peripheral visual field loss

  • Retinal detachment.

  • Chorioretinitis.

  • Intraocular tumour.

  • Retinal vascular occlusion.

Binocular sustained loss

  • Field loss, e.g. quadrantanopia (stroke, tumour, inflammation), hemianopia, bitemporal (pituitary lesions): initially CT scan.

  • Hypotension (e.g. cardiac failure).

  • Basilar artery thrombosis : dysrhythmias or vertebrobasilar insufficiency may produce transient episodes of binocular visual loss. CT scan.

  • Posterior reversible encephalopathy syndrome (PRES) with headaches, confusion, seizures, and visual loss: triggered by hypertension, renal failure, eclampsia, and immunosuppressants. Improves over days or weeks. MRI brain required.

  • Toxic optic neuropathies (e.g. tobacco, alcohol, methanol).

  • Genetic (e.g. Leber’s hereditary optic neuropathy).

Painful red eye: assessment

For a differential diagnosis of the ‘red eye’, see Table 6.4.

Table 6.4 Differential diagnosis of the ‘red eye’*

Conjunctiva

Iris

Pupil

Cornea

Anterior chamber

Intraocular pressure

Appearance

Acute glaucoma

Both ciliary and conjunctival vessels injected. Entire eye is red

Injected

Dilated, fixed, oval

Steamy, hazy

Very slow

Very high

Neurological emergencies

Iritis

Redness most marked around cornea

Colour does not blanch on pressure

Injected

Small, fixed

Normal

Turgid

Normal

Neurological emergencies

Conjunctivitis

Conjunctival vessels injected, greatest towards fornices

Blanch on pressure

Mobile over sclera

Normal

Normal

Normal

Normal

Normal

Neurological emergencies

Subconjunctival haemorrhage

Bright red sclera with white rim around limbus

Normal

Normal

Normal

Normal

Normal

Neurological emergencies

* Reproduced with permission from Judge RD et al. (1989). Clinical Diagnosis, 5th edn.

History

This should establish if there has been:

  • Ocular trauma or foreign body (including contact lens) in the eye.

  • Sudden or gradual onset of symptoms, and nature and location of pain: irritation, soreness, or gritty sensations may occur with conjunctivitis, but the pain is severe in acute glaucoma.

  • Diminution of visual acuity: occurs with conditions affecting the cornea (variable reduction), iris (mild reduction), and glaucoma (severe reduction of acuity).

  • Discharge (not simply lacrimation) from eyes: may be mucopurulent with bacterial or chlamydial conjunctivitis. It may be mucid and stringy with allergic conditions or dry eyes.

  • Headache or facial pain: is common with orbital cellulitis. It may precede cavernous sinus thrombosis (IIIrd, IVth, V1, V2, VIth nerves) or herpes zoster ophthalmicus.

  • Photophobia: suggests corneal involvement or iritis.

  • Systemic symptoms, e.g. malaise/fever: occurs with orbital cellulitis and cavernous sinus thrombosis; vomiting is a feature of acute glaucoma, arthralgias + urethral discharge suggests Reiter’s or chlamydial infection.

  • Previous history: recurrent red eyes may occur with episcleritis, iritis, and herpes simplex corneal ulcer. Ask specifically about BP, heart disease, DM, connective tissue diseases, and atopy.

Examination

  • What is red? The conjunctiva, iris, sclera or episclera (which lies just beneath the conjunctiva and next to the sclera), eyelid, skin around the orbit? Is there visible haemorrhage, either subconjuctival or in the anterior chamber (hyphaema)? In conjunctivitis, there is ‘injection’, or filling of existing light red vessels, with individual branches distinctly visible; the vessels can be moved with the conjunctiva over the sclera. Ciliary or circumcorneal injection refers to a blue–red discoloration, most conspicuous at the limbus (cornea–scleral border) and occurs in anterior uveitis or iritis and keratitis (corneal inflammation). Mixed injection (conjunctival + ciliary) also occurs in uveitis.

  • Is there proptosis? Suggests a retro-orbital/intraorbital mass or cavernous sinus thrombosis, in which it may become bilateral.

  • Is it pulsatile? As in a carotid–cavernous fistula, with an audible bruit.

  • Is there ophthalmoplegia? (Mass lesion or cavenous sinus thrombosis.)

  • Is visual acuity diminished? A Snellen chart should be used and near vision tested (with newsprint, if necessary). In acute glaucoma, there is marked reduction in acuity; in acute iritis or keratitis, acuity is only modestly diminished; in conjunctivitis, it is normal. Orbital apex lesions (anterior to the cavernous sinus) may present similarly to cavernous sinus pathology, with additional acuity loss).

  • What is the size of the pupil? Fixed and dilated in acute glaucoma; small with reduced reaction to light in iritis; normal in conjunctivitis.

  • Is the red reflex normal? If it is, does the cornea appear normal? The red reflex may be impaired in keratitis, central corneal ulcer or oedema, anterior chamber hyphaema (blood in the anterior chamber after blunt trauma), anterior uveitis, glaucoma, or endophthalmitis (involvement of the vitreous, uvea, and retina, with cellular debris/pus in the anterior chamber). Fundoscopy may not be possible as with the corneal clouding of acute glaucoma.

  • Are there any anterior chamber abnormalities? In acute anterior uveitis, there are exudates in the anterior chamber.

  • Is there a rash or vesicles on the face, nose, or eyelid? Herpes zoster can lead to conjunctivitis, iritis, corneal ulceration, and secondary glaucoma.

Painful red eye: management

With a careful history and examination, the diagnosis may become clear. Unless you are absolutely sure of the diagnosis, discuss the patient with an ophthalmologist.

Diagnosis of painful red eye in non-traumatic cases

With prominent ocular discharge

  • Viral/bacterial conjunctivitis (watery/mucopurulent discharge, normal red reflex, normal pupil).

  • Bacterial/fungal keratitis (mucopurulent discharge, opaque cornea with impaired red reflex, normal or slightly reduced pupil).

  • Keratoconjunctivitis sicca or atopic response (dry eye, mucoid strands).

Without prominent discharge and normal red reflex

Normal cornea

  • Episcleritis, scleritis, or subconjunctival haemorrhage.

  • Orbital cellulitis (skin around the orbit is erythematous and tender).

  • Carotid–cavernous fistula (dilated conjunctival vessels, forehead veins, and choroidal vessels because of ‘arterialization’, reduced acuity because of optic nerve ischaemia, pulsatile proptosis, and bruit).

  • Cavernous sinus thrombosis (fever, acute onset, painful ophthalmoplegia, conjunctival oedema and congestion, proptosis, oedema over mastoid (emissary vein), may progress to meningitis).

Abnormal cornea

Corneal abrasion or ulcer (NB herpes simplex and herpes zoster).

Without prominent discharge and impaired red reflex

  • Acute glaucoma (severe pain, markedly reduced acuity, cloudy cornea, purple congestion at limbus, fixed dilated pupil, rock-hard globe).

  • Acute anterior uveitis (malaise, clear cornea, blue–red congestion at limbus, anterior chamber exudate, iris muddy and injected, small pupil with reduced response to light).

  • Endophthalmitis (reduced acuity, eyelid swelling, conjunctival injection, anterior chamber cellular debris, vitreous clouding, retinal haemorrhages).

  • Keratitis (red congestion at limbus, pupil normal or reduced in size, cornea opaque).

  • Central corneal ulcer.

Acute bacterial meningitis: assessment

Presentation

  • Headache, fever, neck stiffness (absent in some patients),6 photophobia (often over hours to days).

  • Rash: meningococcal meningitis is most commonly associated with a macular rash progressing to petechiae or purpura (Neurological emergencies Meningococcal infection: assessment, pp. [link][link]), but other organisms may also cause a rash.

  • Confusion, psychiatric disturbance (e.g. mania) or altered level of consciousness: in the elderly (especially those with DM or cardiopulmonary disease) and the immunocompromised or neutropenic, there may be little other than confusion.

  • Focal neurological signs: complicate meningitis in at least 15% of cases. These can suggest cerebral damage (e.g. hemiparesis following venous infarction or arteritis) or indicate cranial nerve and brainstem involvement by basal exudation and inflammation (e.g. in Listeria monocytogenes meningitis). They can also indicate brain shift secondary to raised ICP (Neurological emergencies Examination of brainstem function 3, pp. [link][link]). Consider the possibility of brain abscess or encephalitis if focal signs or seizures are prominent. Papilloedema is uncommon (<1%) and should suggest an alternative diagnosis.

  • Seizures: are the presenting feature in up to 30%.

Predisposing factors

Usually none, but acute otitis media, mastoiditis, pneumonia, head injury, sickle-cell disease, alcoholism, previous influenza infection, and immunocompromised states are all associated.

Causes in adults

Common

  • Neisseria meningitides.

  • Streptococcus pneumoniae.

Rarer

  • Gram-negative bacilli (in elderly).

  • Listeria (in elderly).

Assessment of severity

Mortality Neurological emergencies as consciousness Neurological emergencies (~55% for adults in coma). However, meningitis can proceed with alarming rapidity, even in the most alert patients.

Management

  1. 1 Stabilize the patient (Airway, Breathing, Circulation); give O2.

  2. 2 Commence antibiotics. It is not necessary to await CSF analysis.

  3. 3 CT scan prior to LP (this is the safest option).

  4. 4 Make a definitive diagnosis with LP.

  5. 5 Reconsider antibiotic regimen after CSF analysis. Consider adjunctive corticosteroid therapy.

  6. 6 Arrange for contacts (including medical/nursing staff) to have prophylaxis. Notify the public health service.

  7. 7 Observe for and, if necessary, treat complications.

References

6. Brouwer MC, Thwaites GE, Tunkel AR, van de Beek D. Dilemmas in the diagnosis of acute community-acquired bacterial meningitis. Lancet 2012;380:1684–92.Find this resource:

Acute bacterial meningitis: immediate management

For management of bacterial meningitis, see Box 6.4.

Antibiotic therapy: follow your hospital guidelines if available

  • Adults aged between 18 and 50 should receive cefotaxime 2g qds or ceftriaxone 2g every 12h. For adults aged over 55 without a rash, consider the addition of 2g ampicillin every 6h to cefotaxime or ceftriaxone as above (to cover Listeria). If the patient comes from an area of the world where penicillin and cephalosporin-resistant pneumococci are common (e.g. Mediterranean countries), then add IV vancomycin 500mg every 6h (± rifampicin). If the individual is allergic to penicillin, consider IV chloramphenicol 25mg/kg every 6h with vancomycin 500mg every 6h. Additional co-trimoxazole should be given in those over 50. Discuss the case with your microbiologist.

  • Blood cultures should be taken, but it is dangerous to withhold IV antibiotics until these are taken or an LP is performed. Most organisms will be diagnosed from blood cultures.

  • Meningococcal infections are discussed under Neurological emergencies Meningococcal infection: assessment, pp. [link][link].

CT scan

Our policy is that all patients should have a CT scan prior to LP. Others suggest this needs be performed only if there is Neurological emergencies level of consciousness, focal signs, papilloedema, or signs suggesting impending cerebral herniation (Neurological emergencies Examination of brainstem function 3, pp. [link][link]). You should discuss the patient with a senior member of your team.

Lumbar puncture

  • Measure opening pressure: CSF pressure is often raised (>20cm CSF) in meningitis, and there are only a few reports of cerebral herniation (coning) following the procedure. If the pressure is raised, the patient must be observed closely at no less than 15-min intervals. A CT scan is required to exclude a complication of meningitis or an SOL, e.g. cerebral abscess.

  • Analysis of CSF (see Table 6.5):

    • CSF WCC: bacterial meningitis characteristically demonstrates a high (usually >1000/mm3) WCC with predominance of neutrophils. A low CSF WCC (0–20/mm3) with a high bacterial count on Gram stain is associated with a poor prognosis.

    • CSF glucose: usually reduced (CSF:blood glucose ratio <0.3 in 70%) but may be normal.

    • CSF protein: usually elevated (>1.0g/L).

    • Gram stain: is positive in 60–90% but may not be if there has been a delay between starting antibiotics and LP. Also the yield of CSF culture falls to <50% from 70–85%.

Table 6.5 CSF composition in meningitis

Bacterial

Viral

TB meningitis

Appearance

Turbid

Clear

Clear

Cells (per mm3)

5–2000

5–500

5–1000

Main cell type

Neutrophil

Lymphocyte

Lymphocyte

Glucose (mmol/L)

Very low

Normal

Low

Protein (g/L)

Often >1.0

0.5–0.9

Often >1.0

Other tests

Gram stain

Bacterial antigen

PCR

ZN

Fluorescence test

PCR

See Neurological emergencies Lumbar puncture 2, p. [link] for reference intervals for CSF analysis.

This CSF profile may also occur with viral and TB meningitis in the early phase, but repeat CSF analysis shows transformation to a lymphocytic predominance. Patients with a CSF profile characteristic of bacterial meningitis should be treated as if they have this condition until proven otherwise.

Acute bacterial meningitis: continuing therapy

Reconsider antibiotics? Adjunctive steroids?

  • CSF lymphocytosis: if the CSF pleocytosis is predominantly lymphocytic, the diagnosis is unlikely to be bacterial meningitis. This is discussed further under Neurological emergencies Meningitis with lymphocytic CSF, pp. [link][link].

  • CSF polymorphs >50 000/mm3: suggests possibility of cerebral abscess. A CT brain scan should be performed.

  • CSF Gram stain: if Gram –ve diplococci are visible, continue with 2.4g benzylpenicillin IV every 4h or 2g ampicillin IV 4-hourly. Discuss the case with your microbiologist. If Gram +ve diplococci are visible, give 2g cefotaxime IV 6-hourly and consider adding vancomycin 500mg IV 6-hourly. If Gram +ve cocco-bacilli suggestive of L. monocytogenes are visible, give ampicillin 2g 4-hourly IV and gentamicin 5mg/kg/24h IV as a single daily dose or divided into 8-hourly doses.

  • Adjunctive corticosteroid therapy: has been shown to reduce the incidence of neurological sequelae in adults and children, especially in pneumococcal meningitis,8 and many neurologists now favour its use to reduce inflammation. In patients with raised ICP, stupor, or impaired mental status, give 10mg dexamethasone IV loading dose, followed by 4–6mg PO qds.

Prophylaxis for contacts should be given immediately

  • Public health services should be notified of any case of bacterial meningitis. They will be able to give advice on current prophylactic treatment and vaccination (possible with some strains of meningococcus); they will also assist in contact tracing. Patients with meningococcus are infectious and can spread organisms to others. Liaise with your local microbiologists.

  • Prophylaxis should be given as soon as the diagnosis of bacterial meningitis is suspected. In the UK, for adult contacts, rifampicin 600mg bd for 2 days is recommended. An alternative for adults is ciprofloxacin 750mg as a single dose (for children older than 1 year: 10mg/kg bd for 2 days; for children 3 months–1 year: 5mg/kg bd for 2 days).

References

8. Brouwer MC, Thwaites GE, Tunkel AR, van de Beek D. Dilemmas in the diagnosis of acute community-acquired bacterial meningitis. Lancet 2012;380:1684–92.Find this resource:

Acute bacterial meningitis: complications and their treatment

  • Raised ICP may respond to steroids and, as discussed earlier, some neurologists give this routinely to reduce inflammatory reaction. In the acute situation, if there is clinical evidence of brain shift or impending transtentorial herniation (Neurological emergencies Examination of brainstem function 3, pp. [link][link]), mannitol should be given 1g/kg over 10–15min (~250mL of 20% solution for an average adult) and the head of the bed elevated to 30° (Neurological emergencies Measures to reduce ICP, p. [link]). A preference of hypertonic 3% normal saline may be used to maintain Na+ >145 or serum Osm >290.

  • Hydrocephalus (diagnosed by CT) may require an intraventricular shunt and should be discussed urgently with neurosurgeons. It can occur because of thickened meninges obstructing CSF flow or because of adherence of the inflamed lining of the aqueduct of Sylvius or fourth ventricular outflow. Papilloedema may not be present.

  • Seizures should be treated as for seizures of any other aetiology (Neurological emergencies Status epilepticus (tonic–clonic) 1, pp. [link][link]).

  • Persistent pyrexia suggests that there may be an occult source of infection. The patient should be carefully re-examined (including oral cavity and ears).

  • Focal neurological deficit may occur because of arteritis or venous infarction or an SOL, e.g. subdural empyema. Basal meningitis may lead to cranial nerve palsies. A CT scan should be requested if it has not already been performed.

  • Subdural empyema is a rare complication. Focal signs, seizures, and papilloedema suggest the diagnosis. It requires urgent surgical drainage.

  • DIC is an ominous sign. Platelet and FFP may be required. The use of heparin should be discussed with a haematologist and neurologist.

  • Syndrome of inappropriate antidiuretic hormone secretion (SIADH) may occur. Fluid balance and electrolytes need to be checked regularly.

Meningitis with lymphocytic CSF

Presentation

  • Viral meningitis may be indistinguishable on clinical grounds from acute early bacterial meningitis, but it is usually self-limiting.

  • TB meningitis is usually preceded by a history of malaise and systemic illness for days to weeks before meningeal features develop. However, it may present very acutely. TB meningitis may be associated with basal arachnoiditis, vasculitis, and infarction, leading to focal neurological signs, e.g. cranial nerve palsies, obstructive hydrocephalus with papilloedema.

  • Cryptococcal or syphilitic meningitis in the immunocompromised present with features indistinguishable from TB meningitis.

  • Malignant meningitis (including metastases and lymphoma) may present with constitutional features. CSF cytology in large volumes and often repeated samples are needed for diagnosis.

Causes

Viral

  • Coxsackie.

  • Echo.

  • Mumps.

  • Herpes simplex type 1.

  • Varicella-zoster.

  • HIV.

  • Lymphocytic choriomeningitis virus.

Non-viral

  • TB.

  • Cryptococcus.

  • Leptospirosis.

  • Lyme disease.

  • Syphilis.

  • Brucellosis.

  • Parameningeal infection with a CSF reaction.

CSF findings

The CSF usually demonstrates lymphocytosis. but the CSF in viral meningitis may initially demonstrate predominantly neutrophils. It is important not to dismiss the possibility of TB meningitis if CSF glucose is normal; the tuberculin test may also be negative initially. Mycobacterium tuberculosis is seen in the initial CSF of ~40% of patients with TB meningitis. Send CSF for viral and TB PCR (the latter is specific, but not sensitive enough to rule out if not present when clinically likely).

Treatment regimens

  • Viral meningitis: usually supportive treatment only. Treat with aciclovir only if encephalitic features (e.g. confusion, seizures).

  • TB meningitis: for 2 months—rifampicin (450mg/day if weight <50kg or 600mg/day if weight >50kg; many clinicians give up to 2–3 times the dose), ethambutol (15mg/kg/day), pyrazinamide (1.5g/day if weight <50kg; 2g/day if weight >50kg), and isoniazid 300mg/day (double if severely unwell). Then continue rifampicin and isoniazid alone for further 7–10 months. Give treatment IV if any concern about absorption PO/NG. Give pyridoxine 10mg daily as prophylaxis against isoniazid neuropathy. Adjunctive prednisolone from start (2.5mg/kg/day IV, then PO) for 4 weeks (then 4-week taper), regardless of severity. Consult your local respiratory/ID specialists for advice. Test HIV status.

  • Cryptococcal meningitis: several regimens are used. Amphotericin 0.7–1.0mg/kg/day alone (divided into four daily doses). Ensure good hydration and monitor renal function. Fluconazole (1200mg/day initially) is an alternative if amphotericin is not available.

Further reading

Thwaites GE, van Toorn R, Schoeman J. Tuberculous meningitis: more questions, still too few answers. Lancet Neurol 2013;12:999–1010.Find this resource:

Acute viral encephalitis

Presentation

  • Change in personality.

  • Confusion, psychiatric disturbance, or altered level of consciousness.

  • Headache, fever, and some neck stiffness: meningism is usually not prominent—some individuals have meningoencephalitis.

  • Focal neurological signs: hemiparesis or memory loss (usually indicative of temporal lobe involvement) is not uncommon.

  • Seizures: are common; some are complex partial in nature.

  • Raised ICP and signs of brain shift (Neurological emergencies Examination of brainstem function 3, pp. [link][link]).

  • Predisposing factors: immunocompromised patient.

For autoimmune and paraneoplastic encephalitis, see Box 6.5.

Management

(See Box 6.6.)

1. Antibiotic therapy

If there is any suspicion that the illness is meningitis, start antibiotics (Neurological emergencies Acute bacterial meningitis: immediate management, pp. [link][link]). It is not necessary to await CSF analysis.

2. Specific antiviral therapies

Aciclovir has dramatically reduced mortality and morbidity in HSV encephalitis. Most clinicians therefore give it in suspected encephalitis, without waiting for confirmation that the pathogen is herpes simplex.

  • Aciclovir 10mg/kg IV (infused over 60min) every 8h (reduced dose in renal insufficiency) is given for 10–14 days.

  • Ganciclovir 2.5–5.0mg/kg IV (infused over 60min) every 8h should be given if CMV is a possible pathogen (more likely in renal transplant patients or those with AIDS). Treatment is usually for 14–28 days, depending upon the response.

3. CT scan: scan all patients prior to LP

In a patient with focal neurological signs, focal seizures, or signs of brain shift, a CT scan must be arranged urgently. CT may not demonstrate any abnormalities. In herpes simplex encephalitis, there may be low-attenuation areas, particularly in the temporal lobes, with surrounding oedema. MRI is more sensitive to these changes.

4. Lumbar puncture

  • Measure opening pressure. CSF pressure may be raised (>20cm CSF), in which case the patient must be observed closely at 15-min intervals.

  • Analysis of CSF usually reveals lymphocytic leucocytosis (usually 5–500/mm3) in viral encephalitis, but it may be entirely normal. The red cell count is usually elevated. PCR on CSF is sensitive and specific. CSF protein is only mildly elevated, and glucose is normal.

5. Further investigations

  • Serology: save serum for viral titres (IgM and IgG). If infectious mononucleosis is suspected (see Fig. 6.2), a monospot test should be performed.

  • EEG: should be arranged, even in those without seizures. There may be generalized slowing, and in herpes simplex encephalitis, there may be bursts of periodic high-voltage slow-wave complexes over the temporal cortex.

Fig. 6.2 Acute papilloedema (e.g. DM;  Chapter Chapter 9 Diabetes and endocrine emergencies9).

Fig. 6.2 Acute papilloedema (e.g. DM; Chapter 9).

Reproduced from Easty D, et al. Oxford Textbook of Ophthalmology, 1999, with permission from Oxford University Press.

Complications

Neurological observations should be made regularly. Two complications may require urgent treatment.

  • Raised ICP due to cerebral oedema may require treatment with dexamethasone (Neurological emergencies Intracranial space-occupying lesion, pp. [link][link]). In the acute situation, if there is evidence of brain shift, mannitol may be used (Neurological emergencies Measures to reduce ICP, p. [link]). Another cause of raised ICP is haemorrhage within necrotic tissue. Perform a CT scan if there is any deterioration in the patient, and discuss with neurosurgeons.

  • Seizures may be difficult to control but are treated as seizures of any other aetiology.

Causes in the UK

  • Herpes simplex.

  • Varicella-zoster.

  • Coxsackie.

  • CMV (in immunocompromised).

  • Mumps.

  • EBV.

  • Echovirus.

Head injury: presentation

For symptoms following a head injury, see Box 6.7.

  • Varies from transient ‘stunning’ for a few seconds to coma.

  • A fraction of patients who attend A&E need to be admitted for observation (indications for admission are given in Box 6.12).

In the alert patient, determine the following.

  • Circumstances surrounding injury. Was it caused by endogenous factors, e.g. loss of consciousness while driving? Or exogenous factors, e.g. another driver? Was there extracranial trauma?

  • Period of loss of consciousness. This relates to the severity of diffuse brain damage.

  • Period of post-traumatic amnesia. The period of permanent memory loss after injury also reflects the degree of damage. (NB The period of retrograde amnesia or memory loss for events prior to injury does not correlate with the severity of brain damage.)

  • Headache/vomiting. Common after a head injury, but if they persist, raised ICP should be considered (Neurological emergencies Raised intracranial pressure, pp. [link][link]).

  • GCS score.

  • Skull fracture present?

  • Neurological signs. Are there any focal neurological signs?

  • Extracranial injury. Is there evidence of occult blood loss?

The drowsy or unconscious patient needs the following:

  • Urgent assistance from senior A&E staff and anaesthetists.

  • Protection of airway: the patient who has deteriorating level of consciousness or is in coma should be intubated because hypocarbia and adequate oxygenation are effective means of reducing ICP rapidly. If the patient is neurologically stable and protecting their airway, intubation may not be necessary. Assume there is a cervical spine injury until an X-ray (of all seven cervical vertebrae) demonstrates otherwise.

  • Hyperventilation: the pattern of breathing should be noted (Neurological emergencies Examination of brainstem function 2, p. [link]). Hyperventilation of intubated patients with the aim of lowering PaCO2 is controversial—consult an intensivist.

  • Support of circulation: hypotension should be treated initially with colloid. If persistent or severe, exclude a cardiac cause (ECG) and occult haemorrhage (e.g. intra-abdominal).

  • Treatment of seizures: diazepam 5–10mg IV/PR, which may be repeated to a maximum of 20mg. If seizures continue, consider IV phenytoin (Neurological emergencies Status epilepticus (tonic–clonic) 1, pp. [link][link]).

  • Rapid survey of the chest, abdomen, and limbs: looking for a flail segment or haemo-/pneumothorax, possible intra-abdominal bleeding (if there are any doubts, peritoneal lavage may be required), limb lacerations, and long bone fractures.

  • Brief history: should be obtained from the ambulance crew or relatives. The patient may have lost consciousness just before the injury, e.g. due to SAH, seizure, or hypoglycaemia. The tempo of neurological deterioration should be established.

  • Guidelines for performing skull X-rays and CT head scans: see Neurological emergencies Head injury: assessment, p. [link].

Head injury: assessment

Examination

Rapid neurological assessment should take only a few minutes

  • The level of consciousness must be noted with the GCS score (Neurological emergencies Glasgow Coma Scale (GCS), p. [link]).

  • Note the size, shape, and reactions of the pupils to bright light.

  • Resting eye position and spontaneous eye movements should be observed. If the latter are not full and the patient is unresponsive, test oculocephalic and/or oculovestibular responses (Neurological emergencies Oculocephalic and oculovestibular responses, pp. [link][link]).

  • The doll’s head manoeuvre should not be attempted if cervical spine injury has not been excluded.

  • Test the corneal reflex [cranial nerves V (sensory) and VII (motor)].

  • Motor function should be assessed (Neurological emergencies Glasgow Coma Scale (GCS), p. [link]); any asymmetry should be noted.

  • Look for features suggesting brain shift and herniation (Neurological emergencies Examination of brainstem function 3, pp. [link][link]).

Head and spine assessment

  • The skull should be examined for a fracture. Extensive periorbital haematomas, bruising behind the ear (Battle’s sign), bleeding from the ear, and CSF rhinorrhoea/otorrhoea suggest a basal skull fracture. Look for facial (maxillary and mandibular) fractures.

  • Only 1% of patients will have a skull fracture. This greatly increases the chances of an intracranial haematoma (from 1:1000 to 1:30 in alert patients; from 1:100 to 1:4 in confused/comatose patients). NB Potentially fatal injuries are not always associated with skull fracture.

  • Consider the possibility of spinal cord trauma. ‘Log-roll’ the patient, and examine the back for tenderness over the spinous processes, paraspinal swelling, or a gap between the spinous processes. The limbs may have been found to be flaccid and unresponsive to pain during the neurological assessment. There may be painless retention of urine.

For indications for skull X-ray, see Box 6.8.

Do not use plain X-rays of the skull to diagnose significant brain injury without prior discussion with a neuroscience unit. However, they are useful as part of the skeletal survey in children presenting with suspected non-accidental injury.

For definite indications for CT scan, see Box 6.9.

For things to look for on C-spine films, see Box 6.10.

References

11. National Institute for Health and Care Excellence (2014). Head injury: assessment and early management. Clinical guideline [CG176]. Neurological emergencies https://www.nice.org.uk/guidance/cg176

Head injury: immediate management

  • After resuscitation, take blood for FBC, G&S, U&Es, ABGs, and, if the circumstances of injury are not clear or there is a suspicion of drug intoxication, toxicology screen.

  • For indications for admission, see Box 6.11.

  • Subsequent management depends upon the pace of events and the clinical situation; >40% of comatose patients with head injury have intracranial haematomas, and it is not possible definitively to distinguish between these patients and those who have diffuse brain injury and swelling on clinical examination alone.

  • Urgent CT scan: this is the next step in most patients who have a depressed level of consciousness or focal signs (see Box 6.9). The speed with which this needs to be arranged depends upon the tempo of neurological deterioration (relative change in GCS score; Neurological emergencies Glasgow Coma Scale (GCS), p. [link]) and/or the absolute level of consciousness (GCS score <8). If CT scanning is not available at your hospital, you must discuss with your regional neurosurgical centre.

  • Treatment of raised ICP is discussed under Neurological emergencies Raised intracranial pressure, pp. [link][link]; corticosteroids have no proven benefit. Discuss with your neurosurgical centre. In a rapidly deteriorating situation, it may be necessary to proceed directly to surgery. It may be decided to hyperventilate and give mannitol (1g/kg over 10–15min), while obtaining an urgent CT scan.

  • Surgery may be indicated for extradural (Neurological emergencies Extradural haemorrhage, p. [link]), subdural (Neurological emergencies Subdural haematoma, pp. [link][link]), and possibly some intracerebral haemorrhage (Neurological emergencies Intracerebral haemorrhage, pp. [link][link]) and complex head wounds such as compound depressed skull fractures.

    • A general rule is that urgent evacuation is required of extradural haematomas which produce a midline shift of 5mm or more and/or 25mL in calculated volume.

    • If the extradural haemorrhage is considered too small to warrant surgery on a CT scan performed within 6h of injury, the scan should be repeated after a few hours, irrespective of whether there has been a deterioration in the patient’s condition.

  • Non-operative management: brain contusion may be evident as areas of Neurological emergencies or Neurological emergencies density, but CT is not a sensitive way to detect primary diffuse brain injury. Effacement of the cavity of the third ventricle and of the perimesencephalic cisterns suggests raised ICP, but the absence of these signs is not to be taken as an indicator of normal ICP. Many centres therefore proceed to ICP monitoring (Neurological emergencies Intracranial pressure monitoring, pp. [link][link]), although this is a controversial subject.

For points on patients being discharged, see Box 6.12.

Head injury: further management

The aim of subsequent management is to minimize secondary injury to the brain other than intracranial haematomas (see Box 6.13). Management may be better undertaken at a neurosurgical centre, and if this is arranged, the guidelines in Box 6.14 should be followed for transfer.

Source: data from Report of the Working Party on the Management of Patients with Head Injuries (1999). Royal College of Surgeons of England, London.

The principles of management are:

  • Regular and frequent neurological observation: if there is deterioration, consider whether there may be a secondary cause of brain injury contributing to this (see Box 6.13). If there are new signs of Neurological emergencies ICP, declining level of consciousness, or signs of transtentorial herniation (Neurological emergencies Examination of brainstem function 3, pp. [link][link]), the patient requires intubation and hyperventilation if this has not already been performed. Mannitol may be started or a repeat bolus may need to be given (Neurological emergencies Measures to reduce ICP, p. [link]) and repeat CT scanning may be necessary.

  • Regular monitoring of BP, blood gases, U&Es, urinary output: pre-emptive treatment of a decline in any of these may prevent neurological deterioration. Hypotension is commonly due to sedative agents and/or hypovolaemia. But fluid therapy needs to be conducted with care because overgenerous administration may exacerbate raised ICP. Monitor CVP.

  • Prompt treatment of seizures (Neurological emergencies Status epilepticus (tonic–clonic) 1, pp. [link][link]).

  • NG tube: to administer nutrition and drugs.

  • A bowel regimen of stool softeners might be started.

Before transfer to the neurosurgical unit

  • Assess clinically for respiratory insufficiency, shock, and internal injuries.

  • Perform CXR, ABG estimation, and cervical spine X-ray.

  • Appropriate treatment might be to:

    • Intubate (e.g. if airway obstructed or threatened).

    • Ventilate (e.g. cyanosis, PaO2 <7.9kPa, PaCO2 >5.9kPa).

    • Commence IV fluids carefully.

    • Give mannitol, after consultation with neurosurgeons.

    • Apply cervical collar or cervical traction.

  • The patient should be accompanied by personnel able to insert ETT, initiate or maintain ventilation, administer O2 and fluids, and use suction.12

References

12. Mendelow AD, Teasdale G (1991). Decisions and guidelines for the early management of head injury patients in the UK. In: Swash M, Oxbury J, eds. Clinical Neurology. Churchill Livingstone, London; pp. 698–9.Find this resource:

Raised intracranial pressure

Presentation

Normal ICP in adults is 0–10mmHg at rest. Treatment is required when it exceeds 15–20mmHg for >5min. Symptoms and signs suggestive of raised ICP include:

  • Headache and vomiting: worse in mornings; exacerbated by bending.

  • Focal neurological signs: may occur if there is an SOL and in some metabolic conditions (e.g. liver failure). But there may also be false localizing signs, e.g. cranial nerve VI palsy.

  • Seizures: may occur with SOLs, CNS infection, or metabolic encephalopathies associated with raised ICP.

  • Papilloedema (see Fig. 6.2): is present only if there is CSF obstruction.

  • Impaired level of consciousness: from mild confusion to coma.

  • Signs of brain shift:13 may accompany decreasing level of consciousness. They are discussed with examination of brainstem function (Neurological emergencies Look for evidence of brainstem dysfunction, p. [link]; Neurological emergencies Examination of brainstem function 2, p. [link]).

  • Late signs: bradycardia and hypertension.

Causes

  • Head injury with intracranial haematoma/brain swelling/contusion.

  • Stroke (haemorrhagic, major infarct, venous thrombosis).

  • Metabolic (hepatic or renal failure, DKA, hyponatraemia, etc.).

  • CNS infection (abscess, encephalitis, meningitis, malaria).

  • CNS tumour.

  • Status epilepticus.

  • Hydrocephalus (of any cause).

  • Idiopathic intracranial hypertension (IIH).

Assessment of severity

  • GCS score (Neurological emergencies Glasgow Coma Scale (GCS), p. [link]).

  • Signs of brain shift and brainstem compromise (Neurological emergencies Examination of brainstem function 3, pp. [link][link]).

Management

  1. 1 Stabilize the patient.

  2. 2 Consider active means of reducing the ICP.

  3. 3 Attempt to make a diagnosis.

  4. 4 Treat factors which may exacerbate raised ICP.

  5. 5 Observe for signs of deterioration, and attempt to reverse them.

  6. 6 Consider specific therapy.

What follows is the management for stabilizing a patient presenting acutely with raised ICP and may not be appropriate for many patients with a long progressive history of deterioration.13

Stabilize the patient

  • Open the airway by laying the patient on their side. Give O2. Measure ABGs. Intubation and mechanical ventilation may be necessary because of respiratory compromise. It may also be necessary to reduce ICP by hyperventilating the patient (Neurological emergencies Measures to reduce ICP, p. [link]) to keep PaCO2 between 3.3 and 4.0kPa (25–30mmHg).

  • Correct hypotension. Volume expansion with colloids or infusions of inotropes needs to be conducted with careful and frequent monitoring of CVP and/or PAWP. In general, patients with raised ICP should be fluid-restricted to 1.5–2.0L/day. So if volume expansion is required, it should be kept to the minimum required to restore BP.

  • Treat seizures (Neurological emergencies Status epilepticus (tonic–clonic) 1, pp. [link][link]).

  • Examine rapidly for signs of head injury (Neurological emergencies Head injury: presentation, p. [link]). If the patient is hypotensive, examine carefully for any occult site of bleeding. If there is a rash, consider the possibility of meningococcal meningitis; take blood cultures and give antibiotics (Neurological emergencies Acute bacterial meningitis: immediate management, pp. [link][link]).

  • Take blood for glucose (this may be raised in DKA or hyperosmolar non-ketotic states; it may be very low in liver failure), U&Es [biochemical assessment of dehydration and renal function, K+ for susceptibility to dysrhythmia, hyponatraemia from inappropriate antidiuretic hormone (ADH), or hypernatraemia from aggressive diuretic-induced dehydration], LFTs, albumin, clotting studies and ammonium (to assess liver function), FBC, and blood culture.

Measures to reduce ICP

The value of ICP monitoring is a controversial subject. Irrespective of whether or not your patient’s ICP is monitored, the following interventions should be considered.

  • Elevate the head of the bed to 30° (once cervical spine injury has been excluded) to promote venous drainage.

  • Hyperventilation, so that PaCO2 is kept between 3.7 and 3.9kPa, will promote cerebral vasoconstriction and lower cerebral blood volume—this requires intubation and paralysis. It will also lower the BP and may compromise cerebral circulation. In patients with liver failure, this is no longer recommended. Discuss with your local ITU.

  • Mannitol: 0.5–1g/kg over 10–15min (250mL of 20% solution for an average adult) reduces ICP within 20min, and its effects should last for 2–6h. If required, further boluses of smaller doses of mannitol (0.25–0.5g/kg) may be given every few hours. U&Es and serum osmolality should be monitored, as profound diuresis may result. Serum osmolality should not be allowed to rise over 320mOsm/kg.

  • Corticosteroids are of benefit in reducing oedema around SOLs (Neurological emergencies Intracranial space-occupying lesion, pp. [link][link]) but are not helpful in the treatment of stroke or head injury. Dexamethasone is given as a loading dose of 10mg IV. It may be followed by 4–6mg q6h PO/via NG tube.

  • Fluid restriction to 1.5–2.0L/day. U&Es must be checked frequently.

  • Cooling to 35°C reduces cerebral ischaemia.

  • Avoid/treat hyperglycaemia because it exacerbates ischaemia.

References

13. Posner JB, Saper CB, Schiff ND, Plum F (2007). Plum and Posner’s Diagnosis of Stupor and Coma (Contemporary Neurology Series), 4th edn. Oxford University Press, New York, NY.Find this resource:

Raised ICP: further management

Attempt to make a diagnosis

Often the history makes the diagnosis obvious, and usually a raised ICP is a secondary diagnosis. If a history is not available, focal neurological signs or focal seizures suggest an underlying structural cerebral lesion (although such signs may occur with hepatic or renal failure). Meningism raises the possibility of SAH or meningitis.

A CT scan should be performed in all patients suspected of having raised ICP before LP is considered.

(LP should be discussed with a senior colleague and/or neurologist.) Blood sent for analysis on admission may help to detect metabolic causes of raised ICP.

Treat factors which exacerbate raised ICP

  • Hypoxia/hypercapnia: ABGs need to be measured regularly.

  • Inadequate analgesia, sedation, or muscle relaxation and hypertension. NB Hypertension should not be treated aggressively. Pain, e.g. from urine retention, may be the cause. Rapid lowering of BP may lead to ‘watershed’/’border-zone’ cerebral infarcts.

  • Seizures are not always easy to identify in paralysed patients.

  • Pyrexia increases cerebral metabolism and, as a consequence, cerebral vasodilatation. It also appears to increase cerebral oedema. The cause of pyrexia should be sought, but paracetamol (given PR) and active cooling should be commenced.

  • Hypovolaemia.

  • Hyponatraemia is usually the result of fluid overload but may be caused by SIADH. Treat with desmopressin 1–4 micrograms IV daily (Neurological emergencies Hyponatraemia: causes, pp. [link][link]).14

Consider specific therapy

  • Once a diagnosis is established, it may be appropriate to consider surgery in order to decompress the brain or insert a ventricular shunt to drain the CSF.

  • Intracranial infections need to be treated with the most suitable antibiotics.

  • Hyperglycaemia (ketotic/non-ketotic) and liver or renal failure have their own specific management (see relevant sections).

  • Often, however, there may not be a specific intervention that is appropriate, e.g. contusion following head injury, and management is confined to optimizing a patient’s condition while awaiting recovery.

References

14. Pickard JD, Czosnyka M. Management of raised intracranial pressure. J Neurol Neurosurg Psychiat 1993;56:845–58.Find this resource:

Idiopathic intracranial hypertension

IIH is a syndrome of raised ICP in the absence of an intracranial mass lesion or hydrocephalus. Although rarely life-threatening, IIH can cause permanent visual loss due to optic nerve damage. This disorder affects 1 in 100,000 of the population overall, but this increases to 1:5000 obese women of child-bearing age. There is a predominance in women over men (4:1), aged 17–45 years.

Presentation

  • Constant, but variable, headaches.

  • Visual disturbances (including diplopia, transient visual obscurations, scotoma), nausea.

  • The presence of focal neurology, including epilepsy, does not occur in IIH.

  • Fundoscopy almost invariably shows papilloedema.

Associations

  • Obesity or recent gain in weight is typical.

  • Drugs (tetracycline, isotretinoin and etretinate, nalidixic acid, nitrofurantoin, and lithium).

  • OCP.

  • Steroid withdrawal.

Investigations

  • CT or MRI head with venography are necessary to rule out venous sinus thrombosis.

  • LP reveals an elevated CSF pressure (>30cm is unequivocally high; 20–30cmH2O is intermediate). Ensure the lateral position is used to obtain CSF (and not sat upright which would increase CSF pressure).

Treatments (seek advice)

  • Losing weight.

  • Identifying other causative factors such as drugs.

  • Acetazolamide (maintenance dose 500mg bd).

  • Surgical shunting (lumboperitoneal shunt).

  • Repeated therapeutic LPs are no longer a favoured approach to treatment.

Intracranial space-occupying lesion

Presentation

  • Symptoms of raised ICP: headache, nausea, and vomiting (Neurological emergencies Raised intracranial pressure, pp. [link][link]).

  • Papilloedema: is present in the minority of cases.

  • Focal neurological symptoms and signs: these depend upon the location of the lesion, its extent and that of surrounding cerebral oedema, and compression of long tract fibres or cranial nerves. Some lesions, particularly those in the frontal lobe, are relatively ‘silent’ and may produce no signs or simply a change in personality.

  • Seizures.

  • Impaired level of consciousness: ranging from confusion to coma.

  • Signs of brain shift (Neurological emergencies Examination of brainstem function 3, pp. [link][link]) may be present.

  • Fever: suggests an infection. There may be a recent history of earache/discharge, toothache, foreign travel, or immunocompromise.

  • Acute onset of symptoms: suggests the possibility of a vascular event, either an infarct or bleeding into another type of lesion, e.g. tumour.

For common causes of intracranial SOLs, see Box 6.15.

Management

(See Box 6.16.) Depends upon the diagnosis. In a comatose individual with known inoperable brain metastases, it is usually not appropriate to intervene. On the other hand, if a patient presents for the first time with signs suggestive of an SOL, the diagnosis needs to be established.

  • Assess severity:

    • If comatose, protect the airway and manage as described under Neurological emergencies Coma: immediate management, p. [link].

    • If there are signs of brain shift which suggest impending transtentorial herniation (Neurological emergencies Examination of brainstem function 3, pp. [link][link]), give dexamethasone [10mg IV (loading dose), followed by 4–6mg PO or NG q6h] and/or mannitol 0.5–1g/kg over 10–15min (100–250mL of 20% solution for an average adult), and hyperventilate to keep PaCO2 between 3.7 and 3.9kPa. This may be followed by smaller doses of mannitol every few hours (Neurological emergencies Measures to reduce ICP, p. [link]).

    • If the patient is alert and stable, it is best to await CT scan and, in the interim, make regular neurological observations.

  • If the patient is pyrexial or the history is suggestive of infection, blood, sputum, and urine cultures should be sent. An urgent CT scan should be arranged for these cases; CSF analysis may be necessary, but an LP should not be performed before the scan or discussion with neurologists/neurosurgeons.

  • If a vascular event is suspected, a CT scan should also be arranged urgently because decompression may be possible.

  • Seizures should be treated. If they are recurrent, the patient may require loading with IV phenytoin. Many neurosurgeons give oral phenytoin prophylactically to patients (300mg/day; therapeutic levels are not reached for at least 5 days).

  • Steroid therapy is given if it is thought that some of the symptoms/signs are due to tumour-related brain oedema. Give dexamethasone 10mg IV (loading dose), followed by 4–6mg PO or NG q6h. This is a large dose of steroid (NB dexamethasone 20mg/day equivalent to prednisolone 130mg/day), and urine/blood glucose should be monitored. Duration of therapy is guided by response to the steroid and the patient’s general condition.

  • Neurosurgery/radiotherapy may be of some benefit in some individuals—discuss with your regional neurosurgical centre.

Further reading

Hawkes C. Smart handles and red flags in neurological diagnosis. Hosp Med. 2002;63:732–42.Find this resource:

Extradural haemorrhage

Presentation

There are no specific diagnostic features. Consider the diagnosis in any head-injured patient who fails to improve or continues to deteriorate.

  • Head injury: is almost invariable.

  • Skull fracture: present in over 90% of adult cases.

  • Headache and vomiting: may occur.

  • Impaired level of consciousness: there may be an initial lucid interval following a head injury, but extradural haematomas may be present in patients who have been in a coma continuously after the injury. Uncommonly, if the cause is a dural venous sinus tear (rather than shearing of a meningeal artery), the lucid interval may extend for several days.

  • Seizures.

  • Contralateral hemiparesis and extensor plantar: may be elicited.

  • Signs of brain shift (Neurological emergencies Examination of brainstem function 3, pp. [link][link]).

Causes

Common

  • Head injury tearing of meningeal artery (commonly middle meningeal).

Rare

  • Head injury dural sinus tear.

  • Intracranial infection (sinuses, middle ear, orbit).

  • Anticoagulants/blood dyscrasia.

Assessment of severity

Bilateral extensor plantars or spasticity, extensor response to painful stimuli, and coma are severe effects of an extradural haemorrhage.

Management

Depends upon the tempo of presentation. Priorities are:

  • Stabilize the patient: protect the airway; give O2, and support breathing and circulation. Assume C-spine injury till excluded.

  • Treat seizures (Neurological emergencies Status epilepticus (tonic–clonic) 1, pp. [link][link]).

  • Urgent CT scan:

    • Haematomas with >5mm midline shift on CT and/or >25mL calculated volume require urgent evacuation.

    • If the extradural haemorrhage is considered too small to warrant surgery on a CT scan performed within 6h of injury, the scan should be repeated after a few hours, irrespective of whether there has been a deterioration in the patient’s condition.

  • Closely monitor the neurological state (including GCS score):

    • If the patient slips into coma and signs of tentorial herniation (Neurological emergencies Examination of brainstem function 3, pp. [link][link]) are progressing rapidly, give 1g/kg of 20% mannitol as a bolus and inform on-call surgeons.

    • If there is evidence of brain shift, discuss with neurosurgeons—ICP should be reduced with mannitol (0.5–1.0g/kg of 20% mannitol) and hyperventilation.

  • All patients must be discussed with neurosurgeons: neurological impairment is potentially reversible if the extradural haematoma is treated early.

Intracerebral haemorrhage

Presentation

  • Headache, nausea, and vomiting of sudden onset is common.

  • Focal neurological deficit: the nature of this depends upon the location of the haemorrhage. Putaminal haemorrhages (30% of cases) or lobar bleeds (30% of cases) may lead to contralateral hemiparesis and sensory loss, visual field disturbance, dysphasia (left hemisphere), or spatial neglect (more severe with right hemisphere lesions). In other words, they may present like a middle cerebral artery (MCA) infarct (Neurological emergencies Cerebral infarction syndromes, p. [link]), but often there is a greater alteration in the level of consciousness. Thalamic haemorrhages (10% cases) may result in eye signs (forced downgaze, upgaze paralysis, or skew deviation), as well as contralateral sensory loss and hemiparesis. Cerebellar haemorrhage is dealt with under Neurological emergencies Cerebellar stroke, pp. [link][link] and pontine bleeds under Neurological emergencies Brainstem stroke, p. [link].

  • Seizures may occur.

  • Global neurological deficit with a decreasing level of consciousness progressing to coma. There may be signs of brain shift (Neurological emergencies Examination of brainstem function 3, pp. [link][link]).

  • Hypertension.

Common predisposing factors

  • Hypertension (40–50%): more commonly deep brain bleeds.

  • Cerebral amyloid angiopathy: more superficial lobar bleeds.

  • Anticoagulants.

  • Metastatic neoplasm: bleeds may occur within the lesion.

  • Drug abuse (alcohol, cocaine, pseudoephedrine, amphetamines).

Assessment of severity

A low GCS score (<9), a large-volume haematoma, and the presence of ventricular blood on the initial CT are factors that are predictive of a high mortality rate.

Management

Priorities are (see Box 6.17):

  1. 1 Stabilize the patient: protect the airway; give O2 if required; support the circulation if necessary or appropriate; commence general measures for treating a comatose patient (Neurological emergencies Coma: immediate management, p. [link]) if necessary. If there is evidence of raised ICP, it should be reduced.

  2. 2 Correct bleeding tendency or effects of anticoagulants.

  3. 3 Make a definitive diagnosis with an urgent CT scan. Liaise with the regional neurosurgery unit early, as surgical intervention may be of benefit. Whether aggressive intervention is appropriate should be decided early.

  4. 4 If appropriate, intensive care/high dependency ward nursing observations are required for the drowsy or comatose patient if they are not transferred to a neurosurgical centre immediately.

  5. 5 Surgical decompression may be beneficial—usually for accessible bleeds within the posterior fossa (Neurological emergencies Cerebellar stroke, p. [link]), putamen, or thalamus.

  6. 6 Patients who have a seizure at the onset of the haemorrhage should receive IV anticonvulsants.

  7. 7 BP control: severe hypertension may worsen intracerebral haemorrhage by representing a continued force for haemorrhage and can cause hypertensive encephalopathy. Continuous IV infusion with labetalol or nicardipine may be given if the SBP is >200 mmHg. If the SBP is over 180mmHg, use either continuous or intermittent treatments. The target BP should be 160/90mmHg or slightly less. More pronounced drops in BP should be avoided (avoid lowering the SBP to <140mmHg, as this may cause ischaemia). Patients should be carefully monitored for signs of cerebral hypoperfusion induced by the fall in BP.

Further reading

Keep RF, Hua Y, Xi G. Intracerebral haemorrhage: mechanisms of injury and therapeutic targets. Lancet Neurol 2012;11:720–31.Find this resource:

Subdural haematoma

Presentation

  • This may present in one of two ways: acute or chronic. Both are usually the result of tearing of bridging veins (between the cortical surface and venous sinuses).

  • Acute haemorrhage into the subdural space follows head injury and can be impossible to distinguish on clinical grounds from extradural haemorrhage (Neurological emergencies Extradural haemorrhage, p. [link]).

  • A chronic haematoma is also preceded in most cases by head injury, but this is often so trivial that patients are unable to recollect it.

  • Both types of patient may present with:

    • Skull fracture (more common in acute cases).

    • Headache.

    • Impaired and fluctuating level of consciousness, ranging from mild confusion through cognitive decline (e.g. impaired memory) to coma. The diagnosis should be considered in any individual, particularly the elderly, who presents with intellectual deterioration or ‘dementia’ of relatively recent onset.

    • Focal neurological signs (hemiparesis, dysphasia, hemianopia, etc.).

    • Seizures occur in a minority of patients.

    • Signs of brain shift (Neurological emergencies Status epilepticus (tonic–clonic) 1, pp. [link][link]) or papilloedema.

Common predisposing factors

  • Head injury: in young or old.

  • Old age: cortical atrophy stretches bridging veins.

  • Long-standing alcohol abuse.

  • Anticoagulant use.

Assessment of severity

The following are severe effects of a subdural haemorrhage:

  • Bilateral extensor plantars or spasticity.

  • Extensor response to painful stimuli.

  • Coma.

Management

Depends upon the tempo of presentation.

  • In suspected chronic cases, a CT scan is required less urgently, unless there has been an acute deterioration on a background of a steady neurological decline. Chronic haematomas become isodense with the brain and are therefore sometimes difficult to distinguish; MRI may be better.

  • In acute cases, priorities are (see Box 6.18):

    • Protection of the airway, give O2, and support the breathing and circulation as necessary.

    • Liaison with the neurosurgical team early.

    • Close monitoring of the neurological state (GCS score).

    • Consider methods to reduce the ICP if raised; if the patient slips into coma and if signs of tentorial herniation (Neurological emergencies Examination of brainstem function 3, pp. [link][link]) are progressing rapidly, give 1g/kg of 20% mannitol as a bolus, inform the on-call surgeon, and arrange a very urgent CT scan.

    • Treat seizures (Neurological emergencies Status epilepticus (tonic–clonic) 1, pp. [link][link]).

Subarachnoid haemorrhage: assessment

Presentation

  • Headache: classically sudden and severe (‘thunderclap’), radiating behind the occiput, with associated neck stiffness. Often, the time from onset to peak of headache is only a few seconds, but less dramatic presentations are common. Consider the diagnosis in any unusually severe headache, especially if the patient does not have a previous history of headaches and is >40 years. Many aneurysmal bleeds occur at/after sexual intercourse, but most coital headaches are not SAHs; 10% of patients with subarachnoid bleeds are bending or lifting heavy objects at the onset of symptoms.

  • Nausea, vomiting, dizziness: may be transient or protracted.

  • Impaired level of consciousness: there may be an initial transient loss of consciousness, followed by variable impairment. Patients may present in coma.

  • Early focal neurological signs: may occur, especially if there has been a concomitant intracerebral haemorrhage. Third nerve palsy raises the possibility of a posterior communicating artery aneurysm.

  • Seizures: are uncommon, but SAH in a person known to have fits suggests an underlying AV malformation.

  • Sentinel bleed: between 20% and 50% of patients with documented SAH report a distinct, unusually severe headache in the days or weeks before the index bleed.16 These are often misdiagnosed as simple headaches or migraine, so a high degree of suspicion is required.

  • Patients may present with secondary head injury following collapse. Blood seen on CT scanning may be attributed to trauma.

Causes

Common

  • Aneurysm (70%).

  • AV malformation (5%).

  • No known cause in up to 20%.

Rare

  • Clotting disorder/anticoagulants.

  • Tumour.

  • Vasculitis.

  • Associated with polycystic kidney disease (berry aneurysm).

Assessment of severity (prognostic features)

  • The Hunt and Hess scale allows grading at presentation and thereafter:

    • Grade 1: asymptomatic or minimal headache + slight neck stiffness.

    • Grade 2: moderate or severe headache with neck stiffness, but no neurological deficit other than cranial nerve palsy.

    • Grade 3: drowsiness with confusion or mild focal neurology.

    • Grade 4: stupor with moderate to severe hemiparesis or mild decerebrate rigidity.

    • Grade 5: deeply comatose with severe decerebrate rigidity.

  • Prognosis is best in grade 1 (mortality <5%), worst in grade 5 (mortality 50–70%), and intermediate in between.

  • Neurological deterioration following presentation has a worse prognosis. Patients should be re-graded on the Hunt and Hess scale.

References

16. Edlow JA, Caplan LR. Avoiding pitfalls in the diagnosis of subarachnoid hemorrhage. N Engl J Med 2000;342:29–35.Find this resource:

17. Hawkes C. Smart handles and red flags in neurological diagnosis. Hosp Med 2002;63:732–42.Find this resource:

Subarachnoid haemorrhage: immediate management

Confirm the diagnosis

  • Urgent HRCT scanning is required. This will clinch the diagnosis in 95% of patients scanned within 24h. Furthermore, it gives valuable information regarding a possible location of the aneurysm and may even demonstrate AV malformation. It may also display concomitant intracerebral and/or intraventricular bleeds.

  • LP is not usually required, unless the CT scan is normal but the history is highly suggestive. It is important to examine the CSF for blood under these circumstances; the presenting event may be a ‘warning leak’. Blood in the CSF may result from a traumatic tap. If this is the case, there may be diminishing numbers of red cells in each successive tube of CSF (although this is not always reliable). If the blood has been present for >6h, the supernatant should be xanthochromic after centrifugation.

  • Once the diagnosis is confirmed, discuss with regional neurosurgeons.

  • Transfer grade 1 and 2 patients as soon as possible. Surgery will prevent re-bleeding, and although the optimal time for operation is debated (2 days versus 7–10 days post-bleed), outcome is probably improved by early transfer.

  • Surgery on poor-prognosis patients is unrewarding; they are usually managed conservatively. However, suitability for surgery should be reassessed if their condition improves.

Stabilize the patient

(See Box 6.19.)

  • Protect the airway by laying the drowsy patient in the recovery position. Give O2.

  • Consider measures to reduce ICP if signs suggest it is raised (Neurological emergencies Raised intracranial pressure, pp. [link][link]), but avoid dehydration and hypotension.

  • Treat seizures with usual drugs (Neurological emergencies Status epilepticus (tonic–clonic) 1, pp. [link][link]), but beware of over-sedation and hypotension.

  • Correct hypotension, if necessary, with colloid or inotropes.

  • To avoid hypertension, the patient should be nursed in a quiet room; sedatives may be required, and stool softeners should be given to avoid straining. Once the diagnosis is established, nimodipine is usually given to reduce vasospasm; it helps also to reduce BP.

  • ECG monitoring and treat dysrhythmias if they compromise BP or threaten thromboembolism. Rarely, SAH is associated with (neurogenic) pulmonary oedema.

  • Take blood for clotting screen (if bleeding diathesis suspected) and U&Es (biochemical assessment of dehydration, K+ for susceptibility to dysrhythmia, hyponatraemia from inappropriate ADH or from aggressive diuretic-induced dehydration).

Further reading

Burrows AM, Korumilli R, Lanzino G. How we do it: acute management of subarachnoid hemorrhage. Neurol Res 2013;35:111–16.Find this resource:

Subarachnoid haemorrhage: further management

Specific therapies

  • Nimodipine is a calcium channel blocker which works preferentially on cerebral vessels to reduce vasospasm (and consequent cerebral ischaemia).18 It has been shown to reduce morbidity and mortality following SAH. Give 60mg PO (or in the comatose patient) every 4h; IV therapy is costly and requires central venous access.

  • Antifibrinolytics were introduced to prevent lysis of clot and re-bleeding. They have been associated with thrombotic complications and are not advised at present.

  • Appropriate analgesia (codeine phosphate 30–60mg every 4–6h) and antiemetics should be given for awake patients.19

Observe for deterioration; attempt to reverse it

Neurological observations should be performed regularly. If there is a deterioration, e.g. lowering of the level of consciousness, a CT scan should be performed. There are several possible mechanisms for deterioration:

  • Cerebral ischaemia is usually insidious and multifocal. It may give rise to focal and/or global neurological deterioration. Volume expansion with colloid or induced hypertension with inotropes have been attempted, but these procedures have not been properly studied.

  • Re-bleeding may be immediately fatal or lead to apnoea. It is reported that assisted ventilation for 1h may be all that is necessary for spontaneous breathing to return to the majority of apnoeic individuals.20 Patients who re-bleed are at high risk of further bleeding and should be considered for emergency aneurysm clipping.

  • Acute hydrocephalus may be treated with ventricular drainage. This can lead to dramatic improvement in the patient’s condition.

Refer for definitive treatment

Unless the patient has a poor prognosis (see Hunt & Hess Scale in Neurological emergencies Subarachnoid haemorrhage: assessment, p. [link]), they should be cared for at a neurosurgical centre. The complications listed here should be managed by clinicians experienced in treating them.

References

18. Pickard JD, Murray GD, Illingworth R, et al. (1989). Effect of oral nimodipine on cerebral infarction and outcome after subarachnoid haemorrhage: British aneurysm nimodipine trial. BMJ 1989;298:636–42.Find this resource:

19. Kirkpatrick PJ. Subarachnoid haemorrhage and intracranial aneurysms: what neurologists need to know. J Neurol Neurosurg Psychiat 2002;73(Suppl 1):i28–33.Find this resource:

20. van Gijn J. Subarachnoid haemorrhage. Lancet 1992;339:653–5.Find this resource:

Status epilepticus (tonic–clonic) 1

Presentation

Generalized tonic–clonic status epilepticus21 is either continuous tonic–clonic convulsions (30min or longer, but treatment should usually begin well before this) or convulsions so frequent that each attack begins before the previous post-ictal period ends.

Causes

  • Cerebral tumour (primary/secondary).

  • Intracranial infection.

  • Hypoglycaemia.

  • Head injury.

  • Electrolyte disturbance (low Na+, Ca2+, or Mg2+).

  • Drug OD (e.g. tricyclics).

  • Drug withdrawal (e.g. alcohol).

  • Hypoxia (e.g. post-cardiac arrest).

  • Sequela of stroke.

  • Anti-epileptic non-compliance/withdrawal.

NB Most episodes of status do not occur in known epileptic patients. Most patients will thus need brain imaging once stabilized and safe to do so.

Management

(See Box 6.20.)

Priorities

  1. 1 Stabilize the patient. Give O2.

  2. 2 Anti-epileptic drug therapy.

  3. 3 Attempt to identify the aetiology.

  4. 4 Identify and treat medical complications.

  5. 5 Initiate long-term maintenance therapy, if appropriate.

Stabilize the patient

  • Open the airway by laying the patient on the side in a semi-prone position, with the head slightly lower to prevent aspiration. Usually an oral airway will suffice and ET intubation is rarely necessary.

  • Give O2.

  • Correct hypotension with colloid, if necessary. Obtain an ECG if the patient is hypotensive. CVP monitoring may be necessary.

  • Take blood for U&Es, glucose, Ca2+, Mg2+, liver enzymes, and FBC; if relevant, blood should also be sent for toxicology screen (if drug OD or abuse suspected) and anticonvulsant levels.

  • Thiamine 250mg IV should be given if alcoholism or other malnourished states appear likely.

  • If hypoglycaemia is suspected, 50mL of 50% glucose should be administered IV. Because glucose increases the risk of WE, thiamine 1–2mg/kg IV should be administered beforehand in any patient suspected of alcohol excess.

Anti-epileptic drug therapy

  • A number of agents may be used:22

    • Benzodiazepines (diazepam, lorazepam).

    • Phenytoin.

    • Fosphenytoin.

    • Miscellaneous (general anaesthesia).

  • Lorazepam 0.07mg/kg IV (usually 4mg bolus, which may be repeated once after 10min). Because lorazepam does not accumulate in lipid stores and has strong cerebral binding and a long duration of action, it has distinct advantages over diazepam in early status epilepticus.

  • Alternatively, diazepam 10–20mg IV or PR, repeated once 15min later if necessary. IV injection should not exceed 2–5mg/min. Diazepam is rapidly redistributed and therefore has a short duration of action. With repeated dosing, however, as peripheral lipid compartments become saturated, there is less redistribution and blood diazepam levels increase. When this happens, there is a risk of sudden central nervous and respiratory depression, as well as cardiorespiratory collapse.

  • With benzodiazepine, start an infusion of phenytoin 15–18mg/kg at a rate of 50mg/min (e.g. 1g over 20min). NB 5% glucose is not compatible with phenytoin. The patient should have ECG monitoring, because phenytoin may induce cardiac dysrhythmias; pulse, BP, and RR should also be monitored. IV phenytoin is relatively contraindicated in patients with known heart disease, particularly those with conduction abnormalities.

  • An alternative is fosphenytoin given as an infusion of 15mg PE (phenytoin equivalents) at a rate of 100mg PE/min (i.e. about 1000mg PE in an average adult over 10min).

  • In refractory status (seizures continuing for 60–90min after initial therapy), the patient should be transferred to intensive care.

    • General anaesthesia with either propofol or thiopental should be administered.

    • Treat raised ICP (Neurological emergencies Raised intracranial pressure, pp. [link][link]).

    • EEG monitoring should be commenced, if available.

    • The anaesthetic agent should be continued for 12–24h after the last clinical or electrographic seizure; the dose should then be tapered down.

If treatment is failing to control seizures, consider whether

  • Initial drug dose is adequate.

  • Maintenance therapy has been started and is adequate.

  • The underlying cause of status epilepticus has been correctly identified.

  • Complications of status adequately treated (Neurological emergencies Status epilepticus (tonic–clonic) 2, p. [link]; see Box 6.20).

  • Coexisting conditions have been identified (e.g. hepatic failure).

  • Epileptic patient’s usual medications are being administered.

  • There has been a misdiagnosis: is this ‘pseudo-status’?

References

21. Hocker S, Wijdicks EF, Rabinstein AA. Refractory status epilepticus: new insights in presentation, treatment, and outcome. Neurol Res 2013;35:163–8.Find this resource:

22. Shorvon SD. The management of status epilepticus. J Neurol Neurosurg Psychiat 2001;70 (Suppl 2):ii22–7.Find this resource:

Status epilepticus (tonic–clonic) 2

Attempt to identify the aetiology

  • A history of previous anticonvulsant use, drug abuse/withdrawal (including alcohol), DM, trauma, or recent surgery (e.g. hypocalcaemia post-thyroid or parathyroid surgery) is obviously helpful.

  • Examine the patient for signs of head trauma, meningism, focal neurological deficit (the seizures may also have some focal characteristics), needle tracks, or insulin injection sites.

  • Consider an urgent CT scan if head injury may be a precipitant; an LP may be necessary if CSF infection is likely.

  • Although hypoglycaemia and hypocalcaemia should be corrected promptly, hyponatraemia should be reversed cautiously because of the possibility of precipitating pontine myelinosis.

See Box 6.20 for key points in management.

Identify and treat medical complications of status

Treatment is required for:

  • Hypoxia.

  • Lactic acidosis.

  • Hypoglycaemia.

  • Dysrhythmias.

  • Electrolyte disturbance (especially hyponatraemia, hypo-/hyperkalaemia).

  • Rhabdomyolysis.

  • Hypo-/hypertension.

  • Raised ICP.

  • Hyperpyrexia.

  • Pulmonary oedema.

  • DIC.

These complications are managed as in other contexts.

Initiate long-term therapy (if appropriate)

Some disorders, e.g. hypoglycaemia in a diabetic taking insulin, do not require long-term anticonvulsant therapy, but rather correction of the underlying problem. Other conditions may need anticonvulsant treatment for a short while, e.g. alcohol withdrawal, posterior reversible encephalopathy syndrome, or indefinitely, e.g. repeated status epilepticus in multi-infarct dementia.

  • Sodium valproate is a reasonable first-choice treatment but avoid in women of child-bearing age.23 Initially, sodium valproate should be given 400–600mg/day PO in divided doses (IV therapy can also be given). It should be Neurological emergencies by 200mg/day at 3- to 6-day intervals; the maintenance dose is 20–30mg/kg/day (usual adult dose is 1–2g/day). Alternative monotherapies include lamotrigine and carbamazepine. Levetiracetam is being increasingly used in this setting, as it can be rapidly titrated and has a low interaction with other medications and does not require monitoring. Phenytoin may be continued after IV loading at daily dosages of 5mg/kg (about 300mg for an average adult) either PO or via an NG tube or slow IVI. Dosage should be guided by phenytoin level measurements. Plasma concentration for optimum response is 10–20mg/L (40–80micromol/L). Phenytoin is disadvantageous, because it requires monitoring and its side effects.

  • Driving advice (see Box 6.21).

References

23. Smith D, Chadwick D. The management of epilepsy. J Neurol Neurosurg Psychiat 2001;70(Suppl 2):ii15–21.Find this resource:

Stroke: overview

Presentation

  • Sudden-onset focal deficit of cerebral function is the most common presentation.

  • Alternative presentations can include apparent confusion (e.g. due to dysphasia or visuospatial impairment), seizures, declining levels of consciousness or global loss of brain function, and coma.

  • If symptoms last for >24h (or lead to death) and there is no apparent cause other than a vascular event, the diagnosis is most likely to be a stroke. If the symptoms last <24h and, after adequate investigation, are presumed to be due to thrombosis or embolism, the diagnosis is a TIA. TIAs tend, however, to last from minutes to 1–2h.

Causes

  • Thrombosis or embolism causing cerebral infarction (80% cases).

  • Primary intracerebral haemorrhage (15% cases).

  • SAH (5% cases).

  • Cerebral venous thrombosis (1%).

Risk factors

See Box 6.22.

Differential diagnosis

Many conditions may masquerade as a stroke:

  • Cerebral tumour (primary or secondary).

  • Brain abscess.

  • Demyelination.

  • Focal migraine.

  • Functional (psychogenic).

  • Subdural haematoma.

  • Todd’s paresis (post-seizure).

  • Hypoglycaemic attack.

  • Encephalitis.

An alternative diagnosis to stroke is more likely in:

  • Patients <45 years.

  • Presence of seizures.

  • Presence of papilloedema.

  • Prolonged and/or discontinuous evolution of symptoms.

  • Absence of risk factors.

  • Fluctuating levels of consciousness.

  • Pyrexia (at presentation).

In general, a stroke commences suddenly and the deficit is at its peak and established within 24h. If the evolution of symptoms is longer or progresses in a stuttering way over days or weeks, an SOL must be suspected. If there is a variable depression of consciousness, the diagnosis of a subdural haematoma should be entertained, and pyrexia at presentation should alert one to the possibility of a cerebral abscess.

Seizures occur in 5–10% of strokes at their onset, although they are frequent sequelae. Papilloedema would be extremely unusual in arterial strokes but may occur in cerebral venous sinus thrombosis. Consider this diagnosis, particularly in patients who may have become dehydrated and young women (particularly during the puerperium) with headache and seizures ± focal signs.

Dissection of the internal carotid or vertebral arteries should always be considered, particularly in younger patients who may have experienced only mild neck trauma. Often, however, there may be no clear history of preceding trauma. Carotid dissection may be accompanied by Horner’s syndrome; vertebral dissection presents with symptoms associated with brainstem stroke.

Stroke: haemorrhage or infarct?

Intracerebral haemorrhage can have an apoplectic onset with a combination of headache, neck stiffness, vomiting, and loss of consciousness of acute onset. Conscious level can be depressed for >24h; there may be bilateral extensor plantar responses, and the BP is more likely to be raised 24h after admission. But although features such as these have been integrated into scoring systems, it is not possible with certainty to differentiate an ischaemic from a haemorrhagic stroke on clinical grounds alone. A CT scan is required.

When to scan?

All patients suspected of having a stroke should be scanned as soon as possible, at least within 24h of onset. If onset within a few hours, imaging should occur immediately. CT is the investigation of choice in the majority of cases because it is better at detecting haemorrhage in the early stages, compared with standard MRI sequences, allowing triage for thrombolytic treatment, and is more readily available as an imaging modality. After the first 24h, and in cases where the stroke is suspected to involve the brainstem or cerebellum, MRI is superior. Where the CT scan is normal, diffusion-weighted MRI may reveal areas of cerebral ischaemia or infarction.

Urgent CT should be performed in the presence of

  • Depressed level of consciousness.

  • History of anticoagulant treatment or known coagulopathy.

  • No available history.

  • Features suggesting an alternative diagnosis requiring immediate action, in particular:

    • SAH (severe headache, depressed level of consciousness, neck stiffness).

    • Subdural haemorrhage (headache, history of minor trauma, progressive or fluctuating signs and symptoms).

    • SOL (depressed level of consciousness, progressive signs, papilloedema).

    • Cerebral infection (headache, fever, neck stiffness, cranial nerve palsies).

  • Indications for thrombolysis (see Box 6.23) or early anticoagulation.

Source: data from Report of the Quality Standards Subcommitee of the American Academy of Neurology (1996). ‘Practice advisory: thrombolytic therapy for acute ischemic stroke – summary statement.’ Neurology 47: 835–9; and Adams HP, et al. (2003). ‘Guidelines for the early management of patients with ischemic stroke: A scientific statement from the Stroke Council of the American Stroke Association.’ Stroke 34: 1056–83.

Brain imaging should always be undertaken before anticoagulant treatment is started.

Stroke: thrombolysis/thrombectomy

(See Boxes 6.23 and 6.24.)

Stroke: other investigations

Apart from a CT scan, there are some basic tests that most patients suspected of having a stroke should have:

  • FBC: to detect polycythaemia, thrombocythaemia, or thrombocytopenia.

  • ESR and CRP: to screen for vasculitis, endocarditis, hyperviscosity.

  • Electrolytes and Ca2+: a neurological defect may be non-vascular and caused by hyponatraemia, hypercalcaemia, or renal failure.

  • Glucose: to exclude hypoglycaemia and non-ketotic hyperglycaemia (which can mimic stroke) and DM (a risk factor).

  • Cholesterol.

  • PT/INR: if the patient is taking warfarin.

  • ECG: to determine cardiac rhythm and exclude acute MI.

  • Carotid Doppler ultrasound: to exclude high-grade (>70%) stenosis or dissection. This should be performed in patients who would be suitable for carotid endarterectomy or angioplasty. A bruit need not be present!

  • Cardiac echocardiography: may demonstrate the presence of valvular disease or intracardiac clot, or may detect some rare causes of stroke such as atrial myxoma or PFO. The yield of a clinically meaningful abnormality on standard TTE is low in unselected ischaemic stroke.

Young patients, or those without common risk factors for stroke (see Box 6.22), should be investigated further. Possible tests include:

  • Serum protein, electrophoresis, viscosity: in hyperviscosity syndromes, the ESR is usually raised, but not always.

  • Autoantibody screen: particularly for SLE).

  • Haemostatic profile: in haemorrhagic stroke not apparently secondary to hypertension, measurement of PT, APTT, bleeding time, and fibrin degradation products may be indicated. In cerebral infarcts, blood should be taken for proteins S and C, antithrombin III, and anticardiolipin antibodies. APTT may be prolonged in anticardiolipin syndrome. Consider testing for sickle-cell in black patients. The factor V Leiden mutation may be an important risk factor for the development of venous thrombosis.

  • Toxicology screen: on admission sample if drug abuse (e.g. cocaine, pseudoephedrine, or amphetamines) suspected.

  • Urine tests: may detect homocystinuria (without other clinical manifestations) or porphyria. If BP is labile, consider phaeochromocytoma and measure urinary catecholamines.

  • CSF analysis: may be necessary if the diagnosis of stroke is not well established, e.g. normal CT scan and no risk factors.

  • Cerebral angiography: is also reserved for cases where the diagnosis is not well established and in those in whom cerebral vasculitis or malformation is suspected.

  • MRI: is more sensitive at detecting small infarcts, cerebral venous thrombosis, and lesions in the posterior fossa. In expert hands, contrast-enhanced MRA may be comparable to conventional angiography.

Stroke: management

(See Box 6.25.)

* Indications for decompressive craniectomy: clinical deficits suggestive of an MCA territory infarction with a score on the NIHSS of >15; decrease in the level of consciousness to a score of ≥1 on item 1a of the NIHSS; signs on CT of an infarct of at least 50% of the MCA territory, or an infarct volume >143cm2, as shown on MRI with diffusion-weighted imaging. There are recent trial data to suggest benefit in those over 60 years, as well as those under 60 years.

Stroke: complications

Cerebral complications

Further neurological deterioration may be caused by the following:

  • Transtentorial herniation (Neurological emergencies Examination of brainstem function 3, pp. [link][link]) is the most common cause of death within the first week and carries a mortality of 80%. It is due to raised ICP (Neurological emergencies Raised intracranial pressure, pp. [link][link]) secondary to cerebral oedema and, in ischaemic stroke, is most common after large MCA infarcts. Corticosteroids do not improve outcome; mannitol and hyperventilation may be useful temporary measures (Neurological emergencies Raised intracranial pressure, pp. [link][link]); surgical decompression may be indicated in large haemorrhages, particularly cerebellar ones.

  • Haemorrhagic transformation occurs in 30% of ischaemic strokes (and up to 70% of cardioembolic strokes), usually 12h to 4 days after the event. Neurological deterioration is usually due to a mass effect.

  • Acute hydrocephalus due to compression of the aqueduct of Sylvius by oedema or blood may occur. Ventricular shunting may be of value.

  • Seizures complicate 10% of infarcts and are most common in large, haemorrhagic, and cortical strokes. They usually respond to monotherapy (e.g. phenytoin).

  • SIADH occurs in 10–15% of strokes. It may initiate or worsen cerebral oedema and is treated by fluid restriction.

  • Depression occurs in 50% and may require therapy if it persists.24

Systemic complications

  • Aspiration is common. Dysphagia occurs in at least half of all cases of stroke; the incidence is higher in those with brainstem involvement or pre-existing cerebrovascular disease. It is often undetected at bedside and usually leads to aspiration. Testing the gag reflex is not a sufficient assessment; swallowing must be observed, and if there is any suspicion, video-fluoroscopy may be used. Patients should generally be fed upright.25

  • Infection is a common cause of death following a stroke. Pneumonia (including aspiration) and UTIs are the usual problems.

  • Fever usually occurs as a result of infection or DVT. Occasionally, it is a direct result of cerebral damage.

  • VTE: the incidence of DVT following a stroke is comparable to that following hip or knee arthroplasty. PE accounts for up to 25% of early deaths following a stroke. Use of prophylactic anticoagulants reduces the incidence of VTE, but it is associated with an Neurological emergencies risk of haemorrhagic transformation which may outweigh any benefit. Many physicians use prophylactic LMWH, although the Royal College of Physicians (RCP) guidelines recommend compression stockings only. In the absence of intracranial haemorrhage, subclinical or overt proximal DVT should be treated with standard therapy. Below-knee DVT should be managed with compression stockings and serial USS monitoring for evidence of proximal extension.

  • Pressure sores occur easily, unless patients are regularly turned.

References

24. Oppenheimer S, Hachinski V. Complications of acute stroke. Lancet 1992;339:721–4.Find this resource:

25. Perry L, Love CP. Screening for dysphagia and aspiration in acute stroke: a systematic review. Dysphagia 2001 Winter;16:7–18.Find this resource:

Stroke: secondary prevention

  • Attempt to modify ‘risk factors’ (see Box 6.22): target BP should be below 140/85mmHg (lower in diabetics). There is little to choose between the different classes of drugs—all reduce the risk of further events. Consider statins, especially in those with coexisting IHD.26

  • Antiplatelet drugs: aspirin reduces the recurrence of stroke and death from other causes. In the absence of absolute contraindications, aspirin (300mg initially for 2 weeks and clopidogrel 75mg od thereafter) should be given immediately after the onset of stroke symptoms once haemorrhage has been ruled out. Patients should be treated chronically with clopidogrel 75mg daily.

  • Anticoagulants: to prevent recurrence of ischaemic stroke, warfarin is superior to aspirin in valvular, non-valvular, and paroxysmal AF, but it is associated with Neurological emergencies risk of major bleeding. The balance of benefit may depend on the patient group but generally favours warfarin, particularly in valvular AF. Aim for an INR of 2–3, provided there are no contraindications and regular checks of INR are practicable. Current practice is to delay warfarinization for 2 weeks after the event, and to repeat the scan where the infarct is very large or where there is clinical suspicion of haemorrhagic transformation. There is no place for either UFH or LMWH. In such cases, it is best to discuss the management with a senior colleague. IV heparinization should be commenced immediately in patients with proven cerebral venous thrombosis (regardless of the presence of haemorrhagic change on CT), and many neurologists would also do the same for carotid/vertebral dissection.

  • Carotid endarterectomy: should be considered in all patients with >70% of ipsilesional stenosis. The operation has an appreciable morbidity (including further stroke) and mortality but appears to improve overall prognosis in selected patients. In centres with experience of the procedure, carotid angioplasty may be an alternative, particularly in patients who are considered poor surgical candidates.

  • PFO: some advocate closure using an endovascular device, but there is only anecdotal evidence of its effectiveness. Current prospective evidence suggests that stroke patients with PFOs treated with aspirin or warfarin only do not have an Neurological emergencies risk of recurrent stroke or death, compared with controls.27

  • HRT and the OCP: combined HRT increases the risk of ischaemic stroke and should be stopped. The combined, but not the progestogen-only, OCP also appears to be associated with an Neurological emergencies risk of stroke. Switch to a progestogen-only formulation or alternative forms of contraception.

References

26. Marshall RS, Mohr JP. Current management of ischaemic stroke. J Neurol Neurosurg Psychiat 1993;56:6–16.Find this resource:

27. Homma S, Sacco RL, Di Tullio MR, et al.; PFO in Cryptogenic Stroke Study (PICSS) Investigators. Effect of medical treatment in stroke patients with patent foramen ovale: patent foramen ovale in Cryptogenic Stroke Study. Circulation 2002;105:2625–31.Find this resource:

Cerebral infarction syndromes

Anterior (carotid territory) circulation

Middle cerebral artery syndrome

  • Total occlusion of the MCA (usually embolic) leads to contralateral hemiplegia, hemianaesthesia, homonymous hemianopia, and deviation of the head and eyes towards the side of the lesion.

  • Left-sided lesions cause global dysphasia; right-sided ones are more likely to cause unilateral neglect of contralateral space.

  • Branch occlusions of the MCA are more common and cause incomplete syndromes, e.g. occlusion of upper branches cause Broca’s (‘non-fluent’ or expressive) dysphasia and contralateral lower face and arm weakness; lower branch occlusion, on the other hand, may cause Wernicke’s (‘fluent’ or receptive) dysphasia.

Anterior cerebral artery syndrome

Occlusion of this artery (often embolic) can lead to paralysis of the contralateral leg, gegenhalten rigidity, perseveration, alien limb syndrome, grasp reflex in the opposite hand, and urinary incontinence.

Posterior circulation

Posterior cerebral artery syndrome

Occlusion by thrombus or embolus may lead to combinations of contralateral homonymous hemianopia/upper quadrantanopia, mild contralateral hemiparesis and/or hemisensory loss, dyslexia, and memory impairment.

Lacunar infarction

Infarcts in small penetrating vessels, often the consequence of hypertension, cause a number of syndromes: pure motor stroke or pure sensory stroke, sensorimotor stroke, ataxic hemiparesis (combined cerebellar and pyramidal signs in the same limb), and dysarthria clumsy-hand syndrome.

Prognostic significance

Prognosis based on these criteria alone are no longer used in routine practice.

Brainstem stroke

Presentation

Sudden onset of:

  • Headache, nausea, vomiting, vertigo.

  • Weakness: bilateral or unilateral.

  • Sensory symptoms (e.g. paraesthesiae): may be confined to the face and, if unilateral, may be contralateral to weakness.

  • Ophthalmoplegia, gaze deviation, or dysconjugate eye movements: in unilateral pontine lesions, conjugate gaze deviation is directed away from the lesion and towards the side of the hemiparesis if there is one. The reverse applies for frontal cortical strokes.

  • Horner’s syndrome.

  • Ptosis: caused by a midbrain infarct in the absence of an accompanying third nerve palsy or Horner’s syndrome is bilateral due to the levator subnucleus of the IIIrd nerve being in the midline.

  • Nystagmus.

  • Hearing loss: caused by damage to the VIIth nerve nucleus or fascicle.

  • Dysarthria or dysphagia.

  • Ataxia: which may be uni- or bilateral due to dysfunction of cerebellar connections.

  • Impaired level of consciousness: ranges from transient loss of consciousness to coma.

  • Altered pattern of respiration.

Signs associated with brainstem dysfunction are explained under Neurological emergencies Examination of brainstem function 1, pp. [link][link], Neurological emergencies Examination of brainstem function 2, p. [link], and Neurological emergencies Examination of brainstem function 3, pp. [link][link]. They result because of damage either to the nuclei (including cranial nerve nuclei) within the brainstem, to the cranial nerves, or to the long tracts which traverse and/or decussate within the brainstem. ‘Crossed signs’ may occur in brainstem strokes, e.g. part of the lateral medullary/Wallenberg’s syndrome consists of loss of pain and temperature sensation from the contralateral trunk and limbs (crossed spinothalamic) and ipsilateral loss of the same sensory modalities from the face (uncrossed trigeminal tract). There are a large number of other eponymous syndromes associated with damage to particular zones within the brainstem. Learning these is not particularly rewarding; better to concentrate on the principles of brainstem anatomy.26

Causes

Thrombosis, embolism, haemorrhage, or vertebral artery dissection (especially following neck manipulation).

Assessment of severity

  • Reduced level of consciousness and coma carry worse prognosis.

  • Extent of brainstem dysfunction may be appreciated from systematic examination of brainstem function (Neurological emergencies Examination of brainstem function 1, pp. [link][link]; Neurological emergencies Examination of brainstem function 2, p. [link]; Neurological emergencies Examination of brainstem function 3, pp. [link][link]).

  • Basilar occlusion carries a very poor prognosis (80% mortality).

Management

Consult a neurologist. The imaging modality of choice is MRI; this should be performed urgently to rule out other diagnoses. Some centres may consider intra-arterial thrombolysis in patients with basilar occlusion if the patient is referred swiftly. Urgent intervention is required for:

  • Metabolic coma with brainstem depression, e.g. opiates (Neurological emergencies Opioids, p. [link]).

  • Transtentorial herniation causing progressive brainstem compression (Neurological emergencies Examination of brainstem function 3, pp. [link][link]).

  • Posterior fossa mass with tonsillar herniation causing brainstem compression.

  • Cerebellar haemorrhage with/without brainstem compression (Neurological emergencies Examination of brainstem function 3, pp. [link][link]).

References

26. Rowland L (1991). Clinical syndrome of the spinal cord and brainstem. In: Kandel ER, Schwartz JH, Jessell TM, eds. Principles of Neural Science, 3rd edn. Appleton & Lange, Norwalk, CT; pp. 711–30.Find this resource:

Cerebellar stroke

Presentation

The triad of headache, nausea/vomiting, and ataxia is the classical syndrome. But it occurs in <50% of cases and, of course, is common in a number of other conditions. Patients present with symptoms and signs which are often attributed to brainstem or labyrinthine causes.27,28 Always consider the possibility of a cerebellar stroke as a serious alternative diagnosis because surgical decompression can be lifesaving if there is a mass effect within the posterior fossa. If the diagnosis is a possibility, ask for an urgent CT scan, or better still, an MRI.

  • Headache, nausea/vomiting: sudden or progressive over hours to days. Location of headache varies widely.

  • Dizziness or true vertigo: occurs in 30% of cases.

  • Visual disturbance: diplopia, blurred vision, or oscillopsia.

  • Gait/limb ataxia: most alert patients report or demonstrate this.

  • Nystagmus or gaze palsy.

  • Speech disturbance: dysarthria or dysphonia in 50% of alert patients.

  • Loss of consciousness: may be transient, but many present in coma.

  • Hypertension.

Predisposing factors

  • Hypertension (>50%).

  • Greater proportion of embolic cause of stroke in cerebellar infarction.

  • Anticoagulants: there is a disproportionately higher risk of cerebellar haemorrhage (cf. intracerebral haemorrhage) in patients taking warfarin.

  • Metastatic neoplasm.

Assessment of severity

Patients who present in coma, or subsequently develop it, will die unless they receive surgical treatment. There is debate about the prognosis of those who remain alert.

Management

Make a definitive diagnosis with an urgent CT scan. (Is there a haemorrhage/infarct? Is there distortion of the fourth ventricle and aqueduct with dilatation of the lateral ventricles?) Liaise with the regional neurosurgery unit early.

Priorities

  1. 1 Stabilize the patient and protect the airway (Neurological emergencies Coma: assessment, pp. [link][link]).

  2. 2 Correct the bleeding tendency or effects of anticoagulants.

  3. 3 Intensive care/high dependency ward nursing observations if the patient is not transferred to a neurosurgical centre immediately.

  4. 4 Definitive surgical decompression, if necessary and possible.

References

27. Dunne JW, Chakera T, Kermode S. Cerebellar haemorrhage—diagnosis and treatment: a study of 75 consecutive cases. Q J Med 1987;64:739–54.Find this resource:

28. [No authors listed]. Cerebellar stroke. Lancet 1988;1:1031–2.Find this resource:

Transient ischaemic attacks

Presentation

Sudden-onset focal deficit of cerebral function or monocular blindness resolving within 24h, but usually between a few minutes to 2h. The symptoms should have developed within a few seconds, and if several parts of the body (e.g. face, arm, leg) are involved, they should have been affected simultaneously without any ‘march’ or progression.

  • Symptoms of carotid TIA: hemiparesis, dysphasia, or transient monocular blindness (amaurosis fugax) (Neurological emergencies Cerebral infarction syndromes, p. [link]).

  • Symptoms of posterior circulation/vertebrobasilar TIA: bilateral or alternating hemiplegia or sensory symptoms, crossed motor/sensory signs (ipsilateral face, contralateral arm, trunk or leg deficit), quadriplegia. Sudden bilateral blindness. Two or more of: vertigo, diplopia, dysphagia, ataxia, and drop attacks if they occur simultaneously.

  • Symptoms of uncertain arterial territory origin: hemianopia alone or dysarthria alone.

  • Symptoms very unlikely TIA: syncope, loss of consciousness or confusion, convulsion, incontinence of urine or faeces, dizziness, focal symptoms associated with migrainous headache, scintillating scotoma.

Causes

Thrombosis or embolism (see Box 6.22 for risk factors).

Differential diagnosis

Many conditions may appear at first to be a TIA, e.g.:

  • Cerebral tumour (primary or secondary).

  • Brain abscess.

  • Demyelination.

  • Focal migraine.

  • Subdural haematoma.

  • Todd’s paresis (post-seizure).

  • Hypoglycaemic attack.

  • Encephalitis.

Investigations

In patients with a suspected TIA in whom the vascular territory or pathology is uncertain, a diffusion-weighted MRI should be performed. If MRI is contraindicated (i.e. pacemaker, shrapnel, some brain aneurysm clips and heart valves, metal fragments in the eyes, and severe claustrophobia), CT scanning should be used.

Management

The objective is to prevent recurrence or a complete stroke. The risk of stroke must be assessed, using a validated scoring system such as the ABCD2*. For management of TIAs, see Box 6.26.

The ABCD2* is a prognostic score to identify people at high risk of stroke after a TIA. It is calculated based on:

  • A: age (≥60 years, 1 point).

  • B: BP at presentation (≥140/90mmHg, 1 point).

  • C: clinical features (unilateral weakness, 2 points; or speech disturbance without weakness, 1 point).

  • D: duration of symptoms (≥60min, 2 points; or 10–59min, 1 point).

The calculation of ABCD2 also includes the presence of DM (1 point). Total scores range from 0 (low risk) to 7 (high risk).

Further reading

Johnstone JC, Rothwell PM, Nguyen-Huynh MN, et al. Validation and refinement of scores to predict very early stroke risk after transient ischaemic attack. Lancet 2007;369:283–92.Find this resource:

Confusional states and delirium: assessment

Up to 10% of acute medical admissions are complicated by acute confusion or delirium. The hallmark of acute confusional states is disorientation in time and place, impaired short-term memory, and impaired consciousness level. Typically, the patient is drowsy, with poor attention span and slowed mentation. In delirium, there are, in addition, disorders of perception such as hallucinations or illusions (misinterpreting shadows seen or sounds heard), and these may produce restlessness, agitation, and hyperactivity.

The main priority is to identify the cause of any treatable or life-threatening condition. Only a small minority (<10%) of patients will have a primary neurological disorder, and commonly there are multiple factors that may apply; these patients carry a good prognosis.

Assessment

  • Assess the mental state: check for disorientation and memory impairment with the mini-mental test (see Box 6.27). An anxiety state can usually be distinguished by talking to the patient. Vivid hallucinations in the absence of a history of mental illness suggests alcohol withdrawal.

  • Review the patient’s notes, and try to obtain a history from friends/relatives of previous mental state or episodes of confusion. Patients with dementia are prone to confusion with intercurrent illness.

  • Review the drug chart: benzodiazepines and narcotics may cause acute confusion in the elderly. Other drugs that may be involved are steroids, NSAIDs, β‎-blockers, and psychotropic medications.

  • Assess the patient for acute illness: exclude faecal impaction and urinary retention. Relevant investigations are listed in Table 6.6.

  • Examine for any focal neurological signs (pupils, limb power, reflexes, and plantar responses).

  • In patients with prior high alcohol intake, examine for signs of liver disease, liver ‘flap’, and possible WE (nystagmus, ataxia, ophthalmoplegia).

Hodkinson, HM; Evaluation of a mental test score for assessment of mental impairment in the elderly, Age and Ageing 2012; 41 (suppl_3): iii35–iii40, doi.org/10.1093/ageing/afs148. Reprinted by permission of Oxford University Press on behalf of the British Geriatrics Society.

Table 6.6 Differential diagnosis and investigations

Differential diagnosis

Investigations

Systemic disorder

  • Sepsis

  • Alcohol withdrawal

  • Metabolic disorder:

    • Neurological emergencies or Neurological emergencies glucose, Na+, or Ca2+

    • Vitamin deficiency

    • Endocrine disease (thyroid, adrenal cortex)

  • Myocardial ischaemia

  • Organ failure (renal, respiratory, liver, cardiac)

  • Organ failure (renal, respiratory, liver, cardiac)

Check urine, blood cultures, WBC, CRP, CXR, U&Es, glucose, LFTs, Ca2+, ABGs, pH, ECG, cardiac enzymes

Consider Mg2+, amylase, porphyrins, thiamine, vitamin B12, folate, thyroid-stimulating hormone (TSH), free T4

Drug toxicity

Check prescribed medication, serum alcohol/drug screen

CNS disorder

  • Dementia

  • Cerebrovascular accident (CVA) (especially non-dominant parietal lobe)

  • Intracranial bleed (SAH, subdural)

  • Infection (encephalitis, meningitis)

  • Trauma

  • Malignancy (primary or secondary)

  • Post-ictal; non-convulsive status

  • Cerebral vasculitis (SLE, PAN)

Consider CT scan with contrast, LP, EEG, blood cultures, CRP, syphilis serology, Lyme serology

Malignancy

Check CXR ± CT chest, serum Ca2+, CT brain

Confusional states and delirium: management

Management

(See Box 6.28.)

  • Treat the cause. Nurse in a moderately lit room, with repeated reassurance. See if a family member can stay with the patient.

  • Avoid sedation unless: (1) to facilitate essential tests and treatment for the patient’s benefit; (2) the patient is a danger to themselves or others; and (3) relieving distress in a highly agitated or hallucinating patient.

  • Use lorazepam 0.5–1mg PO/IM or otherwise haloperidol 0.5–1mg bd PO (or 2.5mg IM). Observe the effect on the patient for 15–20min, and repeat if necessary. In patients with cardiac or respiratory failure, correcting hypoxia may calm the patient by itself. Clomethiazole is indicated for confusion due to alcohol withdrawal (Neurological emergencies Acute alcohol withdrawal, pp. [link][link]).

Acute alcohol withdrawal

Minor symptoms may be managed at home by the GP or a community drug and alcohol team, but in severe or complex cases, hospital admission is indicated. Acute alcohol withdrawal may also occur in hospital inpatients (where the alcohol history may have been missed initially), typically after 12–48h following admission, or as a comorbidity to an A&E presentation, e.g. GI bleed, falls. Indications for admission can be found in Chapter 13 on alcohol withdrawal (Neurological emergencies Acute alcohol withdrawal, pp. [link][link]).

Presentation

  • Initial symptoms include anxiety and tremor, hyperactivity, sweating, nausea and retching, tachycardia, hypertension, and mild pyrexia. These symptoms peak at 12–30h and subside by 48h.

  • Generalized tonic–clonic seizures may also occur during this period, but status epilepticus is unusual. Typically, these may not show the EEG characteristics of epilepsy and may be precipitated by flickering lights or other photic stimulation.

  • Delirium tremens (‘DTs’) occurs in <5% of individuals, usually after 3–4 days of cessation of alcohol intake. It is associated with an untreated mortality of 15%. Features include:

    • Coarse tremor, agitation, confusion, delusion, and hallucinations.

    • Fever (occasionally severe), sweating, tachycardia.

    • Rarely lactic acidosis or ketoacidosis.

    • Also look for hypoglycaemia, Wernicke–Korsakoff syndrome, subdural haematoma, and hepatic encephalopathy.

Management

General measures

  • Nurse in a well-lit room to prevent disorientation. Rehydrate (IV fluids, if necessary; avoid saline in patients with known chronic liver disease). Monitor urine output.

  • Vitamin supplements: in uncomplicated alcohol withdrawal, to prevent WE, use thiamine IM/IV therapy (e.g. Pabrinex® one pair of ampoules daily. IV slowly—watch for signs of anaphylaxis) for 3–5 days). In suspected WE cases, see treatment under Neurological emergencies Wernicke–Korsakoff syndrome, p. [link].

  • Monitor blood glucose for hypoglycaemia, and treat if necessary.

  • Severe hypophosphataemia may complicate alcohol withdrawal and should be treated with IV PO43– (polyfusor phosphates) if serum PO43– is <0.6mmol/L (Neurological emergencies Hypophosphataemia, p. [link]).

  • Exclude intercurrent infection (pneumonia, skin, urine).

Medically assisted alcohol withdrawal

  • Long-acting benzodiazepines, such as chlordiazepoxide or diazepam are commonly used; lorazepam is not metabolized by the liver and may be used in liver disease.

  • Carbamazepine is as effective as benzodiazepines, but side effects limit its use.

  • For DT, use lorazepam PO as first line, if parenteral medication is required, use lorazepam, but olanzapine and haloperidol (Neurological emergencies risk of seizure and cardiotoxicity) may be considered too, though ‘off label’.

Wernicke–Korsakoff syndrome

  • WE comprises the triad of ophthalmoplegia (nystagmus, VIth nerve palsy), ataxia (cerebellar type), and confusional state. In Korsakoff’s syndrome, confusion predominates, often with overt psychosis, amnesia (antegrade and retrograde), and confabulation. Withdrawal symptoms may also occur.

  • Diagnosis: reduced red cell transketolase activity (not usually available).

  • Treat with IV thiamine (Pabrinex®), two pairs of ampoules tds for 2 days; if no response, discontinue; if there is an improvement, continue one pair of ampoules IM/IV daily for 5 days or as long as improvement continues. Ongoing oral thiamine treatment should follow parenteral thiamine.

Seizures

  • Withdrawal seizures are typically self-limiting; if needed, use IV diazepam (Diazemuls®) 10mg over 5min (Neurological emergencies Status epilepticus (tonic–clonic) 1, pp. [link][link]).

  • The most important issue here is to prevent the occurrence of seizures in the first place. This is mainly achieved by treating the patient with an appropriate alcohol withdrawal regime, usually chlordiazepoxide or diazepam (see Box 6.29 and Table 6.7). Consider adding lorazepam to prevent further seizures.

  • Review the reducing withdrawal regime if the seizure occurred while already on a regime, as it may be suboptimal or reducing too quickly.

  • A carbamazepine regime may be used for treatment of alcohol withdrawal; however, evidence shows this is not superior to benzodiazepines in seizure prevention, and combining both conferred no added benefit.

  • Phenytoin is no longer recommended to treat alcohol withdrawal seizures.

Table 6.7 Titrated fixed-dose chlordiazepoxide protocol for treatment of alcohol withdrawal

Typical recent daily consumption

15–25 units

30–49 units

50–60 units

Severity of alcohol dependence

MODERATE SADQ score 15–25

SEVERE SADQ score 30–40

VERY SEVERE SADQ score 40–60

Starting doses of chlordiazepoxide

15–25mg qds

30–40mg qds

50mg qds

Day 1 (starting dose)

15 qds

25 qds

30 qds

40 qds*

50 qds*

Day 2

10 qds

20 qds

25 qds

35 qds

45 qds

Day 3

10 tds

15 qds

20 qds

30 qds

40 qds

Day 4

5 tds

10 qds

15 qds

25 qds

35 qds

Day 5

5 bd

10 tds

10 qds

20 qds

30 qds

Day 6

5 nocte

5 tds

10 tds

15 qds

25 qds

Day 7

5 bd

5 tds

10 qds

20 qds

Day 8

5 nocte

5 bd

10 tds

10 qds

Day 9

5 nocte

5 tds

10 qds

Day 10

5 bd

10 tds

Day 11

5 nocte

5 tds

Day 12

bd

Day 13

5 nocte

* Doses of chlordiazepoxide in excess of 30mg qds should only be prescribed in cases where severe withdrawal symptoms are expected, and the patient’s response to treatment should always be regularly and closely monitored. Doses in excess of 40mg qds should only be prescribed where there is clear evidence of very severe alcohol dependence. Such doses are rarely necessary in women and never in the elderly or where there is severe liver impairment.

Alcohol-Use Disorders: The NICE guideline on Diagnosis, Assessment and Management of Harmful Drinking and Dependence. National Clinical Practice Guideline 115. National Collaborating Centre for Mental Health.

Table reproduced from The Blue Book (2015), 17th Edition, Editor Dr Niruj Agrawal, South West London and St. Georges Mental Health NHS Trust.

Follow-up

Arrange a referral to an alcohol dependence clinic.

Neuromuscular respiratory failure: assessment

Presentation

A number of disorders of the peripheral nerve, neuromuscular junction, or muscle may present with hypercapnic (type 2) respiratory failure or impending failure. There are many differences between these conditions, but consider the diagnosis in the presence of the following features:

  • Limb weakness: progressing over hours or days with diminished/no reflexes but no UMN signs.

  • Neck flexion/extension weakness: typical for many causes. Often mirrors bulbar dysfunction.

  • Muscular tenderness or pain: may be a feature (e.g. back pain in GBS, limb pain in radiculitis/plexopathy or vasculitic neuropathy, muscle pain in inflammatory myopathy).

  • Facial weakness.

  • Ptosis (myasthenia, botulism, Lambert–Eaton, myopathy).

  • Bulbar dysfunction: is a particularly ominous sign because it may lead to improper clearance of secretions and aspiration.

  • Paradoxical abdominal movement: if the diaphragm is paralysed, it moves passively into the thorax, with a fall in intrapleural pressure produced by expansion of the ribcage in inspiration. As a result, the anterior abdominal wall also moves in (rather than out) during inspiration.

  • Dyspnoea or distress in supine position: if the diaphragm is paralysed, movement of abdominal contents towards the thorax is more prominent when the patient lies flat because gravity no longer acts to counteract this passive movement. As a result, the volume of air inspired is reduced. This is a rare, but important, cause of orthopnoea.

  • Sensory symptoms: may be present with or without glove-and-stocking sensory loss.

  • Autonomic instability: may be a prominent feature of GBS and may lead to cardiac arrest.

  • Pneumonia: in known neuromuscular disease.

  • Respiratory arrest: a common pitfall is to consider the degree of respiratory distress unimpressive. Peripheral weakness, in combination with an expressionless ‘myopathic’ facies, may lead to a false sense of well-being when the patient may, in fact, be confronting an impending respiratory arrest.

Assessment of severity

  • Measurement of forced vital capacity (FVC) is mandatory (measured with Wright respirometer available from an anaesthetic nurse or ICU). Note that O2 saturations, peak flow rate, and forced expiratory volume in 1s (FEV1) do not correlate with the degree of neuromuscular impairment.

    • FVC <30mL/kg causes impaired clearance of secretions.

    • FVC <15mL/kg suggests ventilatory failure and is an indication for immediate intubation and ventilation, regardless of other parameters of respiratory function.

  • ABGs: hypercapnia occurs relatively late.

  • CXR: to determine the extent of consolidation if there is concomitant aspiration or infective pneumonia. Subtle linear atelectasis is often seen as a direct result of reduced lung volume.

Neuromuscular respiratory failure: investigations and management

For investigations of neuromuscular respiratory failure, see Box 6.30.

Management

  • Assess severity and measure FVC frequently.

  • Consider intubation and ventilatory support if in adults FVC <1L or 15mL/kg (or there is a progressive decline). Do not use suxamethonium as a muscle relaxant. It may cause a sudden rise in K+ in patients with denervated muscles.

  • Liaise with the neurologist early. Consider transfer to a regional neurology unit if the patient is well and FVC >25mL/kg and stable. If the patient is unwell and FVC <15mL/kg or falling precipitously from a higher level, intubate electively and then consider transfer. All patients should be accompanied by an anaesthetist.

  • For investigations, see Table 6.8. Most of these conditions will not come into the differential, but it is advised that blood be taken for virology screen and autoimmune profile, and 20mL be saved for retrospective analysis if required.

  • ECG monitoring and frequent observation of BP and pulse are required if GBS is suspected, because there is a high incidence of autonomic instability.

  • Consider specific therapies (see Table 6.8) and:

    • GBS (Neurological emergencies Guillain–Barré syndrome, pp. [link][link]).

    • Myasthenia gravis (Neurological emergencies Myasthenic crises, pp. [link][link]).

    • Botulism (Neurological emergencies Botulism, pp. [link][link]).

    • Heavy metal intoxication (Neurological emergencies Drug overdoses and antidotes, pp. [link]).

    • Organophosphate exposure (Neurological emergencies Drug overdoses and antidotes, p. [link]).

    • Porphyria.

    • Rhabdomyolysis (Neurological emergencies Rhabdomyolysis, pp. [link][link]).

  • SC heparin prophylaxis for DVT.

  • Enteral nutrition should be considered early.

Table 6.8 Neuromuscular respiratory failure

Condition

Investigation

Specific treatments

Central nervous system disease

Brainstem disease

  • MRI scan

  • Reduce ICP

  • Decompress

Spinal cord disease

  • MRI scan

  • Decompress

Peripheral neuropathies

GBS (Neurological emergencies Guillain–Barré syndrome, pp. [link][link])

  • NCS

  • IV immunoglobulin (IVIG)

  • Plasma exchange

Organophosphates

  • Red cell cholinesterase

  • Plasma pseudo-cholinesterase

  • Atropine

  • Pralidoxime

Heavy metals: lead, thallium, gold, arsenic

  • Blood and urine levels

  • Specific antidote (Neurological emergencies Drug overdoses and antidotes, p. [link])

Drugs (e.g. vincristine)

  • Stop drug

Malignancy

  • Nerve biopsy

  • Cytotoxics

Vasculitis (e.g. SLE)

  • Nerve biopsy

  • Immunosuppressants

Metabolic (porphyria)

  • Urinary porphyrins

  • Avoid precipitants

  • IV glu/haematin

Diphtheria

  • Throat swab

  • Antitoxin

Neuromuscular junction disease

Myasthenia gravis

  • Anti-AChR Ab

  • Edrophonium test

  • Steroids

  • IVIG, plasma exchange

Anti-cholinesterase OD

  • −ve Edrophonium test

  • Stop drug

Hypermagnesaemia

  • Plasma Mg2+

  • IV Ca2+

Botulism (Neurological emergencies Botulism, pp. [link][link])

  • Antitoxin

Muscle disease

Hypokalaemia

  • Plasma K+

  • K+ replacement

Hypophosphataemia

  • Plasma PO43–

  • PO43– replacement

Polymyositis

  • EMG

  • Muscle biopsy

  • Steroids

Acute rhabdomyolysis (Neurological emergencies Rhabdomyolysis, pp. [link][link])

  • EMG

  • Muscle biopsy

  • IV hydration

  • Urine alkalinization

Myasthenic crises

Presentation

  • Generalized weakness: usually worse proximally, and classically painless and fatiguable. There may be ptosis and diplopia. Reflexes and sensation are normal. Patients with pure ocular myasthenia for >2 years rarely generalize.

  • Dyspnoea: the patient may not, at first glance, appear very distressed. An expressionless myopathic facies, together with weak muscles of respiration, may give a false sense of well-being.

  • Bulbar dysfunction: is potentially dangerous, as it may lead to impaired clearance of secretions and aspiration pneumonia.

  • Exhaustion and ventilatory failure: leading to coma.

  • History of penicillamine use: may cause a syndrome identical to idiopathic myasthenia gravis.29

Common predisposing factors

Infection, surgery, and drugs (see Box 6.31). NB Corticosteroids used to treat myasthenia can initially lead to an acute crisis (so start low and go slow).

Assessment of severity

  • Vital capacity is the most useful indicator. ABGs are not sensitive enough and demonstrate hypercarbia late.

  • Bulbar dysfunction.

Cholinergic crisis

It may not be possible on clinical evaluation to distinguish between worsening myasthenia and excessive anticholinesterase treatment (which leads to weakness by producing depolarization block). Consider withdrawing anticholinesterases only after consulting a neurologist. Note that cholinergic crisis is very rare, compared to myasthenic crisis.

Management

  • Stabilize the patient: protect the airway; intubate and ventilate if necessary. Ensure there are no electrolyte disturbances (Neurological emergencies K+, Neurological emergencies Ca2+, Neurological emergencies Mg2+) or drugs prescribed which exacerbate weakness.

  • Consider Tensilon® (edrophonium) test (Neurological emergencies Tensilon® (edrophonium) test, p. [link]). Anticholinesterase treatment may be helpful if cholinergic crisis is excluded. If there is no effect with Tensilon®, reconsider the diagnosis. Withhold all anticholinesterase medications for 72h. The Tensilon® test may be repeated at intervals.

  • Immunosuppression should be supervised by a neurologist: prednisolone 60–80mg/day produces improvement after 10–12 days but should be introduced with care (start low and go slow) because there may be initial worsening of weakness. High-dose steroids are given until remission occurs. Azathioprine (2.5mg/kg) has also been used for maintenance therapy but takes months to have an effect.

  • Plasmapheresis is used to remove circulating antibody. It usually involves exchange of 50mL/kg/day over several days. Most centres use IVIG therapy, instead of plasmapheresis.

  • Regular anticholinesterase inhibitor therapy should be directed by a neurologist. Therapy depends upon response, but one initial strategy is to commence with pyridostigmine 60mg q4h. This can be given by NG tube or, if necessary, IM neostigmine can be used instead (1mg neostigmine should be given for every 60mg pyridostigmine).

Tensilon® (edrophonium) test

  1. 1 A history of asthma or cardiac dysrhythmias are relative contraindi-cations. Atropine should be drawn up prior to the test, in case edrophonium (an inhibitor of acetylcholinesterase) produces a severe cholinergic reaction, e.g. symptomatic bradycardia.

  2. 2 Prepare and label two 1-mL syringes: one containing saline, the other 10mg of edrophonium.

  3. 3 Select a muscle to observe for the test, and ask a colleague to assess its strength prior to the test.

  4. 4 Inject, in stages, the contents of either syringe, keeping both patient and colleague blinded to the contents of each syringe. Ask the observer to reassess muscle strength after the contents of each syringe have been injected.

  5. 5 Edrophonium should first be given as a bolus of 2mg (0.2mL), and untoward cholinergic effects should be observed for. If it is tolerated, the remaining 0.8mL can be given 1min later.

  6. 6 Improvement in muscle strength following edrophonium suggests the patient is suffering a myasthenic, not cholinergic, crisis.

Ice test

  1. 1 The test consists of the application of ice to the eyes for 2–3min, ensuring that the ice is covered (e.g. in a bag) to prevent ice burns. Avoid prolonged exposure (cold burns and false negatives).

  2. 2 If positive, the patient’s ptosis improves.

  3. 3 The results of the test can be deemed positive with an improvement of the patient’s diplopia or a raise of 2mm of the palpebral fissure following the removal of the ice pack.30

References

29. Thomas CE, Mayer AS, Gungor Y, et al. Myasthenia gravis: clinical feature, mortality, complications, and risk factors for prolonged intuition. Neurology 1997;48:1253–60.Find this resource:

30. Sethi KD, Rivner MH, Swift TR. Ice pack test for myasthenia gravis. Neurology 1987;37:1383–5.Find this resource:

Spinal cord compression: assessment

Presentation

  • Back pain: is usually the first symptom. It often starts weeks before other features and becomes progressively unremitting, keeping the patient awake at night. There may also be thoracic dermatomal pain which is misinterpreted and leads to a long and unrewarding search for the cause of chest or abdominal pain.

  • Sensory symptoms: such as paraesthesiae or a sensation of limb heaviness or pulling, may then occur.

  • Sensory loss: may be apparent as a sensory level on testing. It is wise to test for pin-prick (spinothalamic function) and joint position sense/vibration sense (dorsal column function)—anterior or posterior portions of the cord may be selectively compressed. ‘Sacral sparing’ refers to preservation of sensation in (usually) S3–S5 dermatomes; it is a relatively reliable sign of an intramedullary lesion (see Box 6.32) which initially spares laterally placed spinothalamic tract fibres subserving sacral sensation. Note that a sensory level only indicates the lowest possible level of the lesion—it may well be several segments higher.

  • Weakness: is often first described as clumsiness but soon progresses to clear loss of power.

  • Autonomic dysfunction: if the sympathetic pathways are involved, especially in high thoracic or cervical lesions, hypotension, bradycardia, or sometimes cardiac arrest may occur. This may be triggered by noxious stimuli such as pain, UTI, or abdominal distension caused by constipation or bladder outflow obstruction.

  • Sphincter dysfunction: commences as hesitancy or urgency of micturition and may progress to painless urinary retention with overflow. Constipation is another consequence of cord compression.

  • Fever: should alert one to the possibility of an infectious cause.

  • Respiratory failure: occurs with high cervical cord compression and is one cause of acute neuromuscular respiratory paralysis (Neurological emergencies Neuromuscular respiratory failure: assessment, pp. [link][link]).

  • Conus medullaris lesions: compress the sacral segments of the cord and lead to relatively early disturbance of micturition and constipation, impotence, reduced perianal sensation and anal reflex; rectal and genital pain occurs later. Plantar responses are extensor.

  • Cauda equina lesion: lesions at or below the first lumbar vertebral body may compress the spinal nerves of the cauda equina, leading to a flaccid, flexic, and often asymmetric paraparesis. Lumbosacral pain occurs early; bladder and bowel dysfunction appears relatively late. A sensory level is found in a saddle distribution up to L1 (corresponding to roots carried in the cauda equina).

  • Combined conus and cauda lesions: produce a combination of LMN and UMN signs.

  • General examination: remember that a common cause is malignant compression from metastatic disease. Perform a careful examination, including the breasts, testicles, and thyroid if appropriate.

Assessment of severity

The degree of weakness, sensory loss, and sphincter dysfunction are useful indicators of severity.

Spinal cord compression: management

This depends on the diagnosis and condition of the patient. If the diagnosis is unknown, it is imperative to make it swiftly and discuss the case with the regional neurosurgical centre. If the patient is known to have neoplastic disease and malignant compression is very likely, urgent radiotherapy is the first-line therapy in most, but not all, cases. In some patients with disseminated disease, it may not be appropriate to make any intervention, apart from analgesia. Always consult a senior oncologist.

  • Plain X-rays of the spine are sometimes used as initial investigation but should not delay definitive imaging. These may show vertebral collapse, lytic lesions, or sclerosis. Perform a CXR to look for malignancy.

  • MRI is the investigation of choice. This should be arranged urgently. If facilities are not available locally, discuss with the regional neurosurgical centre.

  • The use of steroids is an important component of the initial management of epidural spinal cord compression. However, the optimal dose and schedule remain uncertain. Some experts recommend a bolus of dexamethasone 10mg IV, followed by 16mg/day PO in divided doses for patients with minimal neurologic symptoms. The dose is gradually reduced once definitive treatment is well under way. In patients with paraparesis/paraplegia, high-dose dexamethasone may be given (96mg IV, followed by 24mg qds for 3 days), and the dose can be tapered over 10 days (halve the dose every 3 days).

  • A PPI should be given for gastric protection.

  • If the cause of compression appears to be infective (fever, neutrophilia, raised CRP, etc.), blood, sputum, and urine cultures should be sent.

  • Monitor haemodynamics and watch for autonomic dysfunction. Control pain and act to prevent constipation.

  • If there is bladder dysfunction, urinary catheterization may be necessary. If immobile, start prophylactic SC heparin (5000U tds).

  • If there is high cervical compression or if ventilation appears to be compromised, FVC and ABGs should be measured. Indications for intubation (if this is appropriate) are discussed under Neurological emergencies Neuromuscular respiratory failure: assessment, pp. [link][link].

  • If a diagnosis is not apparent and immediate neurosurgical action is not indicated, discuss with radiology with a view to CT-guided biopsy.

See Box 6.33 for key points in management of spinal cord compression.

Guillain–Barré syndrome

Presentation

  • Progressive weakness of more than one limb: in an individual who may recently have experienced a mild respiratory or GI febrile illness. Weakness is as commonly proximal as distal. It is usually symmetrical but may be asymmetrical.

  • Diminished tendon reflexes/areflexia: is typical.

  • Sensory symptoms: paraesthesiae often precedes weakness. Sensory loss is not usually profound, although there may be a glove-and-stocking distribution impairment of two-point discrimination, joint position, and vibration sense. If there is a sensory level, spinal cord compression (Neurological emergencies Spinal cord compression: management, p. [link]) should be the diagnosis, until proven otherwise.

  • Limb or back pain: is a major symptom in 30%. Back pain can precede symptoms of weakness.

  • Cranial nerve dysfunction: occurs in 50%. Bulbar function and muscles of mastication are affected in 30%; ocular muscles in 10% of patients.

  • Ventilatory failure: see Neurological emergencies Neuromuscular respiratory failure: assessment, pp. [link][link].

  • Autonomic dysfunction: is common—sweating, tachycardia, sudden swings of BP, dysrhythmias, and cardiac arrest. Bladder or bowel dysfunction occurs, but if it is present from the outset or if it is persistent, reconsider the diagnosis.

  • Miller–Fisher variant: ophthalmoplegia (giving rise to diplopia), ataxia, and areflexia, without significant weakness or sensory signs. Associated with anti-GQ1b antibodies in the serum.

Causes

GBS probably represents an immune-mediated attack on peripheral nerves. Infections which may precede it include CMV, Campylobacter jejuni, EBV, hepatitis B, Mycoplasma, and HSV.

Assessment of severity

Poor prognostic features on presentation include:

  • Rapid onset.

  • Requirement for ventilation (bulbar compromise, reducing vital capacity, respiratory failure).

  • Age >40 years.

  • Reduced amplitude of compound muscle action potential (<10% of control) and extensive spontaneous fibrillation in distal muscles suggesting denervation (NB electrophysiological studies may be normal in early GBS).

  • Presence of autonomic dysfunction.

  • Axonal variant (often with preceding C. jejuni infection).

A grading system has been devised to follow a patient’s progress:

  • Grade 1: able to run.

  • Grade 2: able to walk 5m but not to run.

  • Grade 3: able to walk 5m with assistance.

  • Grade 4: chair-/bed-bound.

  • Grade 5: ventilated.

Management

It is important to appreciate that GBS is a diagnosis of exclusion, with an extensive differential. The pace at which alternative diagnoses need to be excluded depends upon the history and findings.

Management of a patient with GBS is that of any patient with neuromuscular paralysis, although there are a few important specific measures:

  • Monitor FVC twice daily.

  • Autonomic instability is a common feature, so ECG monitoring and frequent assessment of BP and pulse are advisable, particularly in any patient with bulbar or respiratory involvement (NB tracheal suction may lead to bradycardia or asystole).

  • CSF analysis may be required. CSF protein may be normal initially but characteristically rises markedly and peaks in 4–6 weeks. If CSF lymphocytes are prominent in number, consider HIV seroconversion.

  • Steroids are of no benefit in GBS and can worsen matters.

  • Plasma exchange is proven to be better than supportive treatment alone. IVIG (0.4g/kg for 5 days) is as effective as plasma exchange and is currently the standard treatment. Therapy should not be commenced without prior discussion with a neurologist.

  • DVT prophylaxis.

For key points in the management of GBS, see Box 6.34.

Prognosis

Around 65% are able to resume manual work; 8% die in the acute stage (usually from autonomic dysfunction or PE), and the remainder are left with residual disability. The prognosis is worse in those with more severe disease.

References

31. Winer JB. An update in Guillain-Barré syndrome. Autoimmune Dis 2014;2014:793024.Find this resource:

Botulism

Presentation

Botulism is caused by exotoxins of Clostridium botulinum. There are three syndromes: food-borne, SC drug users wound, and infantile. The latter two causes are rare and will not be discussed here. The most common form of botulism is food-borne, with outbreaks usually attributed to canned food. Patients present with symptoms usually within 18h of ingestion of the toxin (see Box 6.35):

  • Sore throat, fatigue, dizziness, blurred vision.

  • Nausea, vomiting, constipation.

  • Rapidly progressive weakness, often beginning in the extraocular and/or pharyngeal muscles and descending symmetrically in severe cases to give upper and lower limb paralysis and respiratory failure (Neurological emergencies Neuromuscular respiratory failure: assessment, pp. [link][link]; Neurological emergencies Neuromuscular respiratory failure: investigations and management, p. [link]).

  • Paraesthesiae may occur, but there are no sensory signs.

  • Parasympathetic dysfunction causes a dry mouth, ileus, and dilated non-reactive pupils in an alert patient. This pupillary response may help to distinguish botulism from other neuromuscular disorders; however, in most cases, the pupils remain reactive.

Wound botulism is similar, except GI upset does not occur.

Assessment of severity

Limb weakness and ventilatory failure are indicators of severe disease. Patients with these features have a worse prognosis, as do patients >20 years and those who have ingested type A toxin.

Management

  • Assess severity; measure FVC frequently, and attempt to exclude other important causes of neuromuscular failure (Neurological emergencies Neuromuscular respiratory failure: assessment, pp. [link][link]). In particular, a Tensilon® test should be performed to exclude myasthenia gravis (Neurological emergencies Tensilon® (edrophonium) test, p. [link]); nerve conduction should be normal, but it is important to exclude GBS (Neurological emergencies Guillain–Barré syndrome, pp. [link][link]); EMG is frequently abnormal in botulism (decrement of compound muscle action potential at slow rates of repetitive stimulation of 3s–1 and facilitation of motor response at rapid rates of 50s–1). Serum and stool should be assayed for toxin and C. botulinum.

  • General management is described elsewhere (Neurological emergencies Neuromuscular respiratory failure: assessment, pp. [link][link]; Neurological emergencies Neuromuscular respiratory failure: investigations and management, p. [link]).

  • Specific treatment: if botulism is suspected, 10 000U of trivalent (A, B, E) antitoxin should be administered IV immediately and at 4-hourly intervals. ~20% of patients have minor allergic reactions to this and require corticosteroid and antihistamines, as for anaphylaxis (for supplies outside normal working hours, contact Department of Health Duty Officer (UK), tel: 020 7210 3000).

  • Guanidine hydrochloride (an acetylcholine agonist) may be of benefit in some patients (35–40mg/kg/day PO in divided doses).

  • Gastric lavage, emetics, cathartics, and enemas may be used with caution to accelerate elimination of toxin from the GIT. The first two interventions are contraindicated if bulbar weakness is present; Mg2+-containing cathartics should not be used, as there is a risk that Mg2+ may enhance toxin activity.

Tetanus

Presentation

Tetanus is caused by the effects of exotoxins produced by Clostridium tetani. It occurs after C. tetani spores have gained access to tissues. The wound may be very trivial, and in 20% of cases, there is no history or evidence of injury. Incubation of spores may take weeks, but most patients present within 15 days with:

  • Pain and stiffness of the jaw.

  • Rigidity and difficulty in opening the mouth: trismus or ‘lockjaw’.

  • Generalized rigidity of facial muscles, leading to the classical risus sardonicus or clenched teeth expression.

  • Rigidity of body musculature, leading to neck retraction and spinal extension.

  • Reflex spasms are painful spasms elicited by stimuli such as pressure or noise. These usually occur 1–3 days after the initial symptoms and are potentially very dangerous, as they may endanger respiration and precipitate cardiorespiratory collapse.

  • Convulsive seizures.

  • Autonomic dysfunction with both sympathetic (sweating, hypertension, tachycardia, dysrhythmias, hyperpyrexia) and parasympathetic (bradycardia, asystole) involvement.

Causes

Exotoxin blocks inhibitory pathways within the CNS.

Assessment of severity

Rapidly progressing features and the onset of spasms signify worse disease and prognosis.

Management

  • Assess severity: in severe spasms/respiratory failure, ventilation will be required. Otherwise patients should be nursed in a quiet, dark room (to reduce reflex spasms) under close observation. Sedation with diazepam may be necessary, but beware of respiratory depression.

  • General management: as discussed under Neurological emergencies Neuromuscular respiratory failure: assessment, pp. [link][link].

  • Specific treatment: human hyperimmune globulin 3000–10 000U IV or IM should be given to neutralize the circulating toxin. This will not ameliorate existing symptoms but will prevent further binding of the toxin to CNS. Penicillin IV (1.2g qds), or alternatively tetracycline 500mg qds, should be prescribed to treat C. tetani.

  • Wound care and debridement as appropriate: swabs should be sent for culture but often do not grow the organism.

  • Prophylaxis in patients who have previously been immunized: for any wound, give a booster dose of tetanus toxoid if the patient has not received a booster in the last 10 years. If the wound appears dirty and infected, or the patient has never been immunized/cannot recall/unable to give a history, give human antitoxin (250U IM), in addition to the toxoid.

Glasgow Coma Scale (GCS)

Developed to assess the depth and duration of impaired consciousness in a standard fashion. The total is out of 15 (see Table 6.9); the worst possible score is 3 (which can even be compatible with death). The scale has a high rate of inter-observer agreement, and the GCS score is one useful way of monitoring conscious level.

Table 6.9 GCS*

Eye opening

Spontaneously

4

To speech

3

To painful stimulus

2

No response

1

Best verbal response

Orientated

5

Disorientated

4

Inappropriate words

3

Incomprehensible sounds

2

No response

1

Best motor response

Obeys verbal commands

6

Localizes painful stimuli

5

Withdrawal to pain

4

Flexion to pain

3

Extension to pain

2

No response

1

* Adapted from The Lancet, 304(7872), Graham Teasdale and Bryan Jennett, ‘Assessment of coma and impaired consciousness: a practical scale’, pp. 81–4, Copyright (1974), with permission from Elsevier.

Eye opening

  • If spontaneous, indicates brainstem arousal mechanisms are probably intact, but the patient need not be aware of their surroundings.

  • Eye opening to speech is not necessarily a response to a verbal command to open the eyes; any verbal approach, e.g. calling the name of the patient, may elicit this.

  • Eye opening to pain is best tested by using a stimulus in the limbs, because supraorbital or styloid process pressure can lead to grimacing with eye closure.

Verbal responsiveness

  • An orientated patient knows who they are, where they are, and why they are there; they can recollect the month and year.

  • A confused patient will converse, but their responses indicate varying degrees of disorientation and confusion.

  • An individual with inappropriate speech cannot sustain a conversation; their utterances are exclamatory or random and may consist of shouting or swearing.

  • Incomprehensible speech does not consist of any recognizable words but involves moaning and groaning.

Motor response

(See Fig. 6.3.)

  • Patients who obey commands show the best possible motor response, but be careful not to misinterpret postural adjustments or the grasp reflex.

  • If there is no response to command, a painful stimulus may be applied initially by applying pressure to the fingernail bed. If this elicits flexion at the elbow, pressure may be applied to the styloid process, supraorbital ridge, and trunk to see if there is localization.

  • If pain at the nail bed elicits a rapid withdrawal, with flexion of the elbow and abduction at the shoulder, it is scored 4.

  • If instead it produces a slower flexion of the elbow, with adduction at the shoulder, it is considered an abnormal flexion response (sometimes called decorticate posturing).

  • If pain elicits extension of the elbow, adduction, and internal rotation of the shoulder, with pronation of the forearm, this is noted as an extensor response (sometimes called decerebrate posturing).

Prognosis

The GCS is a valuable tool in predicting likely outcome from coma, but it has limitations and should not be the only factor used to assess prognosis. Patients with GCS scores of 3–8 generally have far worse prognoses than those with scores of >8. But the cause of coma is also an important predictor, e.g. metabolic coma (especially due to drug intoxication) generally has a better outlook than other causes, irrespective of the GCS score.

Examination of brainstem function 1

Assessment of brainstem function is vital to the management of coma (Neurological emergencies Coma: assessment, pp. [link][link]), raised ICP (Neurological emergencies Raised intracranial pressure, pp. [link][link]), brainstem strokes (Neurological emergencies Brainstem stroke, pp. [link][link]), and brain death (Neurological emergencies Brain death, p. [link]). It is not necessary to have a detailed knowledge of brainstem anatomy. Some simple observations reveal a great deal about function at different levels of the brainstem.

Examination of the eyes

  • Pupillary reactions: the size of the pupils and their reactions to bright light should be assessed. This tests the pathway from each eye (IInd cranial nerve) through the superior colliculus (midbrain), its connection to the nearby Edinger–Westphal IIIrd nerve nucleus (also in the midbrain), and the efferent parasympathetic outflow of the IIIrd nerve. The pupillary reflex is consensual, so light in one eye should elicit constriction of both pupils. Thus, observations of the pupillary response can interrogate brainstem function at the level of the midbrain.

  • Corneal reflex: tests the integrity of the afferent pathway (Vth nerve) through to the efferent pathway (VIIth nerve). The corneal reflex is also a consensual reflex. This reflex allows one to interrogate brainstem function at the level of the pons.

  • Resting eye position: may give a useful clue to asymmetric brainstem dysfunction. If the eyes are dysconjugate, there must be a disorder of the nuclei of the IIIrd, IVth, or VIth nerves, their connections, or the nerves themselves. Note the IIIrd and IVth nuclei are located in the midbrain, whereas the VIth nucleus is located in the pons.

  • Spontaneous eye movements: if there are spontaneous fast (saccadic) horizontal and vertical conjugate eye movements, the brainstem mechanism for generating saccades is intact and there is no need to test for the oculocephalic or oculovestibular response because:

    • Horizontal saccades require the integrity of the paramedian pontine reticular formation (pons), the IIIrd nerve nucleus, the VIth nerve nucleus, and the medial longitudinal fasciculus connecting these.

    • Vertical saccades require the dorsal midbrain to be intact.

    • Dysconjugate eye movements raise the possibility of unilateral damage to brainstem oculomotor nuclei, their connections, or cranial nerves innervating the extraocular muscles. In this case, the resting position of the eyes may also be dysconjugate.

    • A number of oculomotor signs associated with brainstem dysfunction have been identified; none are absolutely specific, but they may provide useful clues to site of lesion.32

  • Oculocephalic response: the ‘doll’s head manoeuvre’ (Neurological emergencies Oculocephalic and oculovestibular responses, pp. [link][link]) should be performed only if cervical injury has been excluded. Both it and caloric stimulation assess the integrity of the vestibulo-ocular reflex (VOR), which is a three-neuron arc from the semicircular canals via the vestibular nuclei to the IIIrd and VIth nerve nuclei.

  • Oculovestibular response: caloric stimulation (Neurological emergencies Oculocephalic and oculovestibular responses, pp. [link][link]).

References

32. Lewis SL, Topel JL (1992). Coma. In: Weiner WJ, ed. Emergent and Urgent Neurology. Lippincott, Philadelphia, PA; pp. 1–25.Find this resource:

Examination of brainstem function 2

The swallowing reflex

This may be tested by injecting 10mL of water in a syringe into the mouth of the patient. Reflex swallowing requires, among other things, that the swallowing centre in the reticular formation of the medulla, very close to the solitary nucleus, is intact. Not often tested.

Respiratory pattern

(See Fig. 6.4.)

  • This is sometimes useful in localization but often is not.

  • Central neurogenic hyperventilation, for example, has no localization value. It is rapid, regular deep continuous breathing at 25/min, which is not produced by acidosis or hypoxaemia. Its usefulness is that increasing the regularity of this pattern signifies increasing the depth of coma and worsening prognosis.

  • Apneustic breathing (prolonged inspiration, followed by a period of apnoea), on the other hand, implies damage to the pons, as does cluster breathing (closely grouped respirations, followed by a period of apnoea). Damage to the medullary respiratory centres is suggested by ataxic breathing and gasping breathing (Biot’s respirations). The former are characterized by a chaotic pattern of respiration; the latter consists of gasps, followed by apnoeic periods of variable duration. Both are usually soon followed by respiratory arrest.

  • Shallow, slow breathing may be due to medullary depression caused by drugs, e.g. opiates. Cheyne–Stokes respiration may be caused by bilateral deep hemispheric and basal ganglia damage but is more usually due to non-neural causes, e.g. primary cardiovascular or respiratory dysfunction.

  • Long tract signs: finally, structural damage to the brainstem may produce long tract signs with dysfunction of descending pyramidal/extrapyramidal tracts or ascending sensory pathways. There may be ‘crossed signs’ because of decussation of pathways within the brainstem.

Examination of brainstem function 3

Signs of brain shift

Raised ICP may produce a number of distinct progressive brainstem syndromes associated with brain shift:33

  1. 1 Central herniation syndrome.

  2. 2 Lateral (uncal) herniation syndrome.

  3. 3 False localizing signs.

  4. 4 Tonsillar herniation.

Assessment involves:

  • Observation of respiratory pattern.

  • Pupillary reaction.

  • Oculocephalic/oculovestibular response.

  • Motor response at rest or to pain (Neurological emergencies Glasgow Coma Scale (GCS), p. [link]).

Central herniation syndrome

  • Vertical displacement of the brainstem due to a supratentorial mass.

  • The first sign is not of brainstem, but rather diencephalic impairment. The patient becomes less alert and there may be Cheyne–Stokes breathing. The pupils are small (perhaps due to hypothalamic sympathetic dysfunction) but reactive. There may initially have been unilateral hemiplegia due to the supratentorial mass. Characteristically in the early diencephalic stage, paratonic resistance (gegenhalten) develops in the contralateral limbs and both plantar responses become extensor. Eventually there is a decorticate response to pain (Neurological emergencies Glasgow Coma Scale (GCS), p. [link]).

  • Midbrain–upper pontine dysfunction becomes evident with fluctuations in temperature, onset of central neurogenic hyperventilation, apneustic or cluster breathing (Neurological emergencies Examination of brainstem function 2, p. [link] ), unreactive pupils which are ‘mid-position’ and often irregular in shape, loss of vertical eye movements (which may be tested with the doll’s head manoeuvre), and increasing difficulty in eliciting horizontal oculocephalic and oculovestibular responses which may become dysconjugate (Neurological emergencies Oculocephalic and oculovestibular responses, pp. [link][link]). Motor responses progress from decorticate (flexor) rigidity to decerebrate (extensor) rigidity in response to pain (Neurological emergencies Glasgow Coma Scale (GCS), p. [link]).

  • Lower pontine–upper medullary compromise is revealed by often ataxic breathing, fixed mid-position pupils, and failure to elicit oculocephalic and oculovestibular responses. The patient is flaccid at rest; painful stimuli may not elicit any motor response, except occasional flexor responses in the lower limbs.

  • Medullary dysfunction is terminal. Breathing is ataxic or gasping. The pulse rate may decrease and BP increase (Cushing response). After a few gasps, breathing stops and pupils often dilate and become fixed.

Lateral (uncal) herniation syndrome

  • Due to lesions in the lateral middle fossa or temporal lobe pushing the medial edge of the uncus and hippocampal gyrus over the free lateral edge of the tentorium.

  • The first sign is a unilaterally dilating pupil (due to compression of the IIIrd nerve at the tentorial hiatus), which is initially sluggish in response to light. This may soon be followed by ptosis and complete IIIrd nerve palsy with a fixed, dilated pupil. Oculocephalic and oculovestibular responses initially reveal only the palsy but are otherwise intact.

  • Midbrain compression by the herniating uncus may follow rapidly (the diencephalic stage of central herniation is bypassed). The patient becomes progressively less alert and slips into coma. The oculocephalic and oculovestibular responses cannot be elicited. A hemiplegia ipsilateral to the expanding supratentorial lesion (due to the opposite cerebral peduncle being compressed at the tentorial edge) develops and soon progresses to bilateral extensor plantar responses. As compression continues, both pupils become fixed in mid-position and central neurogenic hyperventilation commences.

  • The rostrocaudal progression of signs associated with central herniation then follow with decerebrate/extensor rigidity, etc., as already described. Note decorticate/flexor response to pain is not usually seen in uncal herniation because the diencephalic stage is bypassed.

False localizing signs

As they expand, supratentorial lesions may distort intracranial structures and produce signs which appear to help in localizing the lesion but are, in fact, due to traction ‘at a distance’. The most common of these involve cranial nerves V–VIII.

Tonsillar herniation

Subtentorial expanding lesions cause herniation of the cerebellar tonsils through the foramen magnum and compress the pons and midbrain directly. A degree of upward herniation through the tentorial hiatus may also occur and lead to compression of the upper midbrain and diencephalon. It may be difficult to distinguish these effects from those produced by supratentorial lesions. One clue is that there is usually a lack of the rostrocaudal sequence of central herniation.

References

33. Posner JB, Saper CB, Schiff ND, Plum F (2007). Plum and Posner’s Diagnosis of Stupor and Coma (Contemporary Neurology Series), 4th edn. Oxford University Press, New York, NY.Find this resource:

Oculocephalic and oculovestibular responses

Background

Passive rotation of the head, with respect to the trunk, stimulates vestibular and neck receptors. In comatose patients with intact brainstems, this leads to reflexive slow conjugate eye movements in the direction opposite to head rotation. The contribution of neck proprioceptors (cervico-ocular reflex) is minimal; the most important reflex pathway in the brainstem extends from the semicircular canals to the oculomotor nuclei (VOR). Ice water irrigation of a semicircular canal ‘switches off’ its contribution to this pathway and leads to unopposed function of the contralateral semicircular canal. The eyes then deviate towards the irrigated semicircular canal. Both the doll’s head manoeuvre and caloric tests check the integrity of the VOR; the latter is more sensitive.

Oculocephalic/doll’s head response

  • The doll’s head manoeuvre should not be attempted if there is any possibility of cervical spine injury.

  • The patient’s head is first rotated laterally from one side to the other. Vertical movements may be elicited by flexion and extension of the head.

  • ‘Positive’ responses are noted if turning of the head elicits slow conjugate deviation of both eyes in the direction opposite to head movement (see Fig. 6.5).

  • Because there is much confusion about what constitutes positive or negative responses, it is best simply to describe what you see.

Oculovestibular/caloric response

  • Caloric testing should be performed when the oculocephalic response is abnormal or cannot be performed (e.g. spine fracture).

  • The head is then raised 30° above supine, and 100mL of ice water is injected into the external auditory meatus using a thin polyethylene catheter.

  • A ‘positive’ response occurs when both eyes move towards the irrigated ear (see Fig. 6.5). This may take up to a minute. Five minutes should elapse before the other ear is tested.

Significance of results

  • If the VOR is intact, major brainstem pathology is unlikely.

  • If the horizontal VOR is absent, but the vertical one is present, there may be a lesion at the level of the pons.

  • If both responses are absent, there is either a major structural brainstem lesion (see Fig. 6.5) or there is a metabolic disturbance depressing brainstem function (e.g. opiates). Check pupil size and response to light; symmetrically reactive pupils suggest metabolic coma. Only a few drugs, such as atropine, hyoscine, and glutethimide, depress brainstem function and produce pupillary abnormalities.

  • If dysconjugate eye movements are elicited, a brainstem lesion is likely. Check to see if there is an internuclear ophthalmoplegia.

  • It may not be possible to elicit a VOR using the doll’s head manoeuvre because the patient has fast, roving saccadic eye movements. These suggest an intact brainstem.

Brain death

This is irreversible loss of the capacity for consciousness combined with irreversible loss of the capacity to breathe. Without the brainstem, both these functions are lost. But patients with severe, irreversible brain damage who have no brainstem function may survive for weeks or months, provided they have a normal circulation and are mechanically ventilated. Criteria for brain death have therefore been developed. It has been shown that patients who fulfil these, even if they are ventilated, will eventually develop cardiovascular collapse.

Preconditions

  • There must be no doubt that the patient has irremediable structural brain damage which has been diagnosed with certainty. Usually, this is a head injury or an intracranial haemorrhage, but it may be anoxia post-cardiac arrest when it is not always possible immediately to be certain that brain damage is irremediable.

  • The patient must be in apnoeic coma (unresponsive to noxious stimuli and on a mechanical ventilator), with no spontaneous respiratory effort.

  • There must be no possibility of drug intoxication and no paralysing or anaesthetic drugs should have been administered recently. Hypothermia must be excluded as a cause of coma and the core temperature (rectal or external auditory meatus) should be >35°C.

  • There must be no significant metabolic, endocrine, or electrolyte disturbance, either causing or contributing to coma.

Tests for confirming brain death

All brainstem reflexes must be absent

  • Pupils fixed and unresponsive to bright light (they need not be dilated). Paralytic eye drops, ocular injury, and lesions of the IInd/IIIrd cranial nerves may pose problems in this assessment.

  • Absent corneal reflexes.

  • Absent VORs on irrigation of each ear, in turn, with 20mL of ice-cold water.

  • No motor response within the cranial nerve distribution (eye, face, head) elicited by stimulation of any somatic area (nail bed, supraorbital, and Achilles tendon pressure on each side). Purely spinal reflexes, e.g. deep tendon reflexes, may be retained.

  • No reflex response to touching the pharynx (gag reflex) nor to a suction catheter passed into the trachea (cough reflex).

Apnoea

  • No respiratory movements when the ventilator is disconnected and PaCO2 reaches 6.65kPa. (In order to avoid anoxia during this procedure, the patient should be ventilated with 100% O2 for 10min beforehand; during disconnection, 6L/min 100% O2 should be delivered via a tracheal catheter. If just prior to disconnection, PaCO2 is <3.5kPa, give 5% CO2 in O2 via the ventilator until this level is reached, usually within 5min.)

The tests must be performed by two experienced clinicians, and all the above should be repeated after an interval which depends upon the clinical context.

NB Consider the patient a potential organ donor. Discuss with relatives, and contact the transplant coordinator for your area. Alternatively, contact the duty officer for the UK Transplant Support Service (tel: 01179 757575).