Epilepsy: A Brief History

Diagnosing and characterizing epilepsy in an individual is a multi-step process. First, one must confirm that the patient does, in fact, have epileptic seizures. Second, once the diagnosis of epilepsy is established, the patient's seizure type(s) is characterized. Third, the clinician determines whether the patient's seizure disorder conforms to a particular type of epilepsy or epileptic syndrome. Fourth, a clinical investigation targeting the cause of the epilepsy is conducted. Finally, based on this and other information, the most appropriate therapy is selected.

Epilepsy is characterized by repeated seizures caused by recurrent, abnormal, and excessive synchronous discharges from cerebral neurons. This basic pathophysiological understanding of epileptic seizures was deduced by the 19th-century physician John Hughlings Jackson based solely on clinical observations. His contributions to the field of epilepsy continue to be recognized by modern medical sciences.

Jackson, like many before and after him, recognized that epileptic seizures take many forms and have many causes. The first known description of epilepsy appears in the Hippocratic text of 350 B.C., and epilepsy has been called the "Hippocratic disease."

Many prominent physicians in addition to Jackson have attempted to classify the epilepsies. In 1861, J. Russell Reynolds labeled convulsions associated with a structural disorder of the nervous system symptomatic epilepsy. He called convulsions associated with structural conditions outside the central nervous system (renal failure, for example) sympathetic epilepsy. And he categorized seizures associated with no structural abnormalities inside or outside the nervous system as idiopathic, or true, epilepsy. In 1881, Sir William Gowers classified epilepsy as grand mal, petit mal, and hysteroid. Some of these early terms persist in current diagnostic jargon.

In addition, several features of these older classifications have persisted into contemporary classifications of seizures and types of epilepsy. Some earlier classification schemes were based on various combinations of anatomic substrate, etiology, patient age and genetic factors. Some of these schema mixed types of seizures and types of epilepsy with confusing results. Synonyms for epilepsy include convulsive disorders and seizure disorders. Additional distinctions among types of epilepsy use terms such as secondary or acquired epilepsy and primary or idiopathic epilepsy. The latter terms are used to describe seizure disorders typified by generalized seizures with no detectable cause. These distinctions are valid and can be valuable when educating and counseling patients.

But a lack of universally understood diagnostic terms for seizures and epilepsy syndromes prevented direct comparisons of findings and therapeutic interventions and impeded the exchange of information. To improve this situation, the International League Against Epilepsy (ILAE) in 1969 proposed a new classification of seizure types based on the clinical and electroencephalographic (EEG) manifestations of epileptic seizures. In 1980, the International Classification was revised, and some seizure types were subdivided and reclassified. These refinements were possible primarily because of increasingly sophisticated technology. In particular, intensive, simultaneous video and EEG monitoring has permitted more precise clinical and electroencephalographic definition of epileptic seizures.

Although differences of opinion about some seizure types persist, given its benefits, the classification system has been universally accepted. All persons who treat or assist individuals with epilepsy are encouraged to use it. In 1985, the ILAE established a Classification of the Epilepsies and Epileptic Syndromes. Both classification systems provide a framework for diagnosis while further improvements are made.