Classification
Epilepsies are classified in five ways:
1. By their first cause (or etiology).
2. By the observable manifestations of the seizures, known as semiology.
3. By the location in the brain where the seizures originate.
4. As a part of discrete, identifiable medical syndromes.
5. By the event that triggers the seizures, as in primary reading epilepsy
or musicogenic epilepsy.
In
1981, the International League Against Epilepsy (ILAE) proposed a classification
scheme for individual seizures that remains in common use. This classification
is based on observation (clinical and EEG) rather than the underlying
pathophysiology or anatomy and is outlined later on in this article.
In 1989, the ILAE proposed a classification scheme for epilepsies and
epileptic syndromes. This can be broadly described as a two-axis scheme
having the cause on one axis and the extent of localisation within the
brain on the other. Since 1997, the ILAE have been working on a new
scheme that has five axes: ictal phenomenon, seizure type, syndrome,
etiology and impairment.