EPILEPSY

Epilepsy, chronic brain disorder characterized by repeated convulsions or seizures. The seizures can occur as a result of underlying brain damage, a structural brain lesion, as part of a systemic medical illness, or may be idiopathic (no organic cause). Epileptic seizures differ with the type of condition and may consist of loss of consciousness, convulsive jerking of parts of the body, emotional explosions, or periods of mental confusion. Studies show that although epilepsy is not inherited, predisposition to the disorder is a hereditary trait responsible for some of the idiopathic cases.

In individuals suffering from epilepsy, the brain waves, which are manifestations of electrical activity in the cerebral cortex, have a characteristically abnormal rhythm produced by excessive and synchronous nerve-cell discharges. Furthermore, the wave patterns differ markedly according to type. Recordings of the brain waves are therefore important in the diagnosis and study of the disease, and are obtained by means of a device called the electroencephalograph.

No specific cure for epilepsy exists, but seizures can be prevented or reduced in frequency in nearly 90 per cent of the patients by the administration of drugs. The anticonvulsant drugs employed include diphenylhydantoin (phenytoin), phenobarbital, carbamazepine, ethosuximide, and valproic acid.

Because epileptic seizures vary in intensity and in symptoms, epilepsy is divided into the following major types: focal seizures (including psychomotor seizures) and generalized seizures (including grand-mal and petit-mal seizures).

The onset of an attack of grand-mal epilepsy is often signalled by an involuntary scream, caused by contraction of the respiratory muscles. As loss of consciousness sets in, the entire body is gripped by a spastic muscular contraction. The face becomes livid, the breathing is arrested, and the back arched. Subsequently, alternate contractions and relaxations of the muscles throw the body into such violent agitation that the patient is subject to serious injury. A folded handkerchief in the mouth may help prevent tongue and cheeks from being bitten during a seizure. After the convulsion subsides, the patient is exhausted and may sleep heavily. Fatigue and depression are often experienced upon awakening, and occasionally the patient has no memory of the seizure. Attacks occur at varying intervals, in some cases as seldom as once a year and in others as frequently as several times a day. Seizures may occur successively with no intervening period of consciousness; this condition, known as status epilepticus, affects approximately 8 per cent of those subject to grand-mal attacks and may be fatal unless treated promptly with diazepam or other drugs.

In petit-mal epilepsy the seizures are characterized by a sudden, momentary loss or impairment of consciousness. Overt symptoms are often as slight as an upward staring of the eyes, a staggering gait, or a twitching of the facial muscles. The patient often resumes activity without realizing that the seizure has occurred.

In psychomotor epilepsy the main symptom is amnesia. Duration of the seizures varies from a few minutes to several hours. Activity of the patient does not cease during the seizure, although behaviour is totally unrelated to environment. Also called temporal-lobe epilepsy, this form of seizure can be preceded by an aura (abdominal discomfort, dizziness, or strange odours and sensations). Some severe forms of temporal-lobe epilepsy are successfully treated by surgical removal of the damaged part of the brain.