Classification and the need to classify epilepsy.

ABSTRACT

Epilepsies are a diverse group of disorders with both shared and distinct features. Classification allows a coherent, systematic approach and serves as a 'universal language' between neurologists all over the world. There are two systems of classifications of epilepsies in use today. The International League Against Epilepsy (ILAE) Classification of Epileptic Seizures 1981 divides seizures into 3 morphologic types--generalised, partial and unclassifiable, with subtypes of each. This system has the advantage that seizures can be classified relatively easily and choice of antiepileptic is dictated by seizure type. However, the same patient may have more than one type of seizure either together or sequentially and many patients show a distinct evolution of their illness. This paved the way for another system of classification--the ILAE Classification of Epilepsies & Epileptic Syndromes 1989, which is meant to supplement the previous classification. An epileptic syndrome is defined as an epileptic disorder characterised by a cluster of signs and symptoms occurring together. According to this system, epilepsies are divided into 4 broad groups--localisation related and generalised, undetermined whether localised or generalised and special syndromes. Within the generalised and localised groups, there are further subdivisions into idiopathic, cryptogenic or symptomatic. This classification is complex and many syndromes are not adequately defined. At initial presentation, it may not be possible to identify the syndrome. Only a small proportion of patients fit into specific syndromes and a large proportion fall into non specific categories. For the present then, classification of epilepsy is still being refined. A brief description of major childhood epileptic syndromes according to age at onset is presented.