(p. 891) Seizures, epilepsy, and other episodic disorders in adults 

Epilepsy, or more correctly a seizure, is most easily defined in physiological terms, being ‘the name for occasional sudden, excessive, rapid, and local discharges of grey matter’ (Jackson 1873). It is more difficult to offer a comprehensive clinical definition of epileptic seizures and epilepsy because of the varied clinical manifestations produced by cerebral neuronal discharge. However, an epileptic seizure can be defined as an intermittent and stereotyped disturbance of consciousness, behaviour, emotion, motor function, or sensation that on clinical grounds is believed to result from cortical neuronal discharge. Epilepsy can then be defined as a condition in which seizures recur, usually spontaneously. The differential diagnosis of epilepsy is large because of the enormous range of symptoms that can occur during seizures. Inevitably, the differential diagnosis for tonic-clonic seizures is very different from that for simple partial seizures with autonomic symptoms. The most common clinical problem is the differential diagnosis from other causes of transient loss of consciousness associated with collapse, the commonest cause of which is syncope.