epilepsy

n.

a disorder of brain function characterized by recurrent seizures that have a sudden onset. The term idiopathic is used to describe epilepsy that is not associated with structural damage to the brain. Seizures may be generalized or partial. Generalized epilepsy may take the form of tonic-clonic or absence seizures. In tonic-clonic (or major) seizures (formerly called grand mal), the patient falls to the ground unconscious with the muscles in a state of spasm. The lack of any respiratory movement may result in a bluish discoloration of the skin and lips (cyanosis). This – the tonic phase – is replaced by convulsive movements (the clonic phase) when the tongue may be bitten and urinary incontinence may occur. Movements gradually cease and the patient may rouse in a state of confusion, complaining of headache, or may fall asleep. Absence seizures (formerly called petit mal in children) consist of brief spells of unconsciousness lasting for a few seconds, during which posture and balance are maintained. The eyes stare blankly and there may be fluttering movements of the lids and momentary twitching of the fingers and mouth. The electroencephalogram characteristically shows bisynchronous spike and wave discharges (3 per second) during the seizures and at other times. Attacks are sometimes provoked by overbreathing or intermittent photic stimulation. As the stream of thought is completely interrupted, children with frequent seizures may have learning difficulties. This form of epilepsy seldom appears before the age of three or after adolescence. It often subsides spontaneously in adult life, but it may be followed by the onset of major or partial epilepsy.

In partial (or focal) seizures, the nature of the seizure depends upon the location of the damage in the brain. For example, a simple partial motor seizure consists of convulsive movements that might spread from the thumb to the hand, arm, and face (this spread of symptoms is called the Jacksonian march). Complex partial seizures are commonly caused by damage to the cortex of the temporal lobe or the adjacent parietal lobe of the brain: this form of epilepsy is often called temporal lobe (or psychomotor) epilepsy. Symptoms may include hallucinations of smell, taste, sight, and hearing, paroxysmal disorders of memory, and automatism. Throughout an attack the patient is in a state of clouded awareness and afterwards may have no recollection of the event (see also déjà vu, jamais vu). A number of these symptoms are due to scarring and atrophy (mesial temporal sclerosis) affecting the temporal lobe.

The different forms of epilepsy can be controlled by the use of antiepileptic drugs (see anticonvulsant). Surgical resection of focal epileptogenic lesions in the brain is appropriate in a strictly limited number of cases.

Derivatives:

epileptic adj., n.