Diseases of the spinal cord

The spinal cord is subject to numerous pathological processes that can arise within (intramedullary) and/or extrinsic to the cord (extramedullary lesions).

Clinical features

Symptoms and signs suggestive of spinal cord disease include (1) motor—weakness and alteration in tone; acute cord lesions produce flaccidity (‘spinal shock’) and chronic processes spasticity, with hyper-reflexia, clonus, and upgoing plantar responses; pathological processes targeting lower motor neurons in the anterior horns typically produce early muscle wasting and fasciculation; (2) sensory—including numbness, loss of sensation, tingling, sensory ataxia; the demonstration of a sensory level and analysis of specific sensory deficit patterns are of particular importance in localizing the site, and therefore the likely cause, of any lesion; and (3) autonomic—sphincter dysfunction, most commonly affecting bladder function.

Other clinical features may give clues to the cause of spinal cord disease, e.g. multiple sclerosis, systemic lupus erythematosus (SLE), neurofibromatosis.

Investigation

Intramedullary and extramedullary pathologies may produce distinguishable symptom profiles, but the clinical distinction can only ever be probabilistic. If there is acute onset of myelopathy, and/or structural disease is suspected, imaging of the cord is mandatory, with MRI the investigation of choice. Once structural lesions are excluded, further investigation depends on suspected cause (e.g. neurogenetic testing for some hereditary spastic paraplegias and spinocerebellar ataxias), and on geographical location or travel history (e.g. schistosome ova in faeces). Examination of the cerebrospinal fluid may be required.

Particular conditions affecting the spinal cord

Many diseases can affect the spinal cord. Those of particular note include (1) spondylotic myelopathy—the most common cause of progressive myelopathy due to cord compression; (2) multiple sclerosis—may present as an isolated cord syndrome, usually partial rather than complete; (3) transverse myelitis—most commonly affects the thoracic cord; there may be a preceding history of infection, and cerebrospinal fluid analysis may disclose an infective agent; (4) subacute combined degeneration of the cord—demyelination of the posterior and lateral columns due to vitamin B₁₂ deficiency; may occur in the absence of haematological abnormality; (5) genetic disorders—hereditary spastic paraplegia is usually an autosomal dominant disorder; causative mutations have been described in several genes; (6) vascular disorders—anterior spinal artery occlusion can infarct whole or part of the anterior two-thirds of the cord; (7) syringomyelia; (8) injury/trauma—see Chapter 24.13.1; (9) motor neuron disease—see Chapter 24.15.

Treatment and prognosis

Specific medical and surgical treatments are determined by the particular cause of myelopathy. These may arrest progression, but function that has been lost does not usually recover. Prognosis of acute cord compression is directly related to the time delay between symptom onset and relief of compression. Chronic disability as a consequence of spinal cord disease requires intensive neurorehabilitation.