Epilepsy is a brain disorder characterized by recurrent seizures -- episodes of abnormal electrical activity in almost any part of the brain. The symptoms of a seizure can mimic different types of human behavior, depending on which part of the brain is affected. Generally, the term epilepsy (or seizure disorder) refers to relatively stereotyped attacks of involuntary behavior. The exact symptoms and severity may vary, and the seizures may occur infrequently or in rapid succession.
While every case of epilepsy is distinct, a standardized classification scheme has been developed to describe seizures. The attacks are divided into two main types:
Within these categories, seizures are further identified according to the pattern of the attack. The two most common forms of seizure are both of the generalized type:
Absence (petit mal) seizures
Tonic/clonic (grand mal) seizures
Among the partial types are "simple" seizures (without impairment of consciousness), such as motor or Jacksonian seizures, and "complex" seizures (with impairment of consciousness), such as temporal lobe seizures.
The first signs of epilepsy are usually seen in childhood or adolescence. Approximately one in 11 Americans will have a seizure during their lifetime, but only 1% of the population develops recurrent seizures, or epilepsy. Epilepsy may also begin in the elderly and in that case may be the result of a stroke or a tumor.