Observations on juvenile myoclonic epilepsy amongst ethnic Bengalees in West Bengal--an Eastern Indian State.

BACKGROUND: Juvenile myoclonic epilepsy (JME) is not too uncommonly encountered in Indian neurological practice. A number of reports from different parts of India have documented the clinical phenomenology and EEG characteristics of this genetically determined epileptic syndrome. However, no study has yet been reported from the Eastern part of India and none done so far in patients in a specific ethnic group. Furthermore therapy response and follow up data are not available in detail in the Indian studies. OBJECTIVE: To study disease expression, EEG characteristics and therapy response of JME patients in ethnic Bengalees in West Bengal, an Eastern Indian State, in a clinic based study. MATERIAL AND METHODS: 200 patients with JME attending the Neurology Department of the Institute have been followed up for 5 years and different parameters of disease expression as outlined above have been studied. RESULTS: Overall clinical disease expression has been found to be similar in this clinic based study in ethnic Bengalees as compared to other reports from India and elsewhere. About 16% of patients showed a relative resistance to Valproate therapy. Hundred percent of patients in whom therapy withdrawal was attempted, relapsed within<1-2 years. Amongst female patients (132), 16 developed features of polycystic ovarian syndrome while on Valproate therapy. In over half of them, the symptoms regressed after successful switch over from Valproate to Clobazam. 12/132 female patients became pregnant during follow up and while on Valproate; teratogenic effect was evident in only one such patient. CONCLUSIONS: Phenotypic variations in disease expression including therapy response have been noted within a single ethnic group of patients attending the clinic and might account for genetic heterogeneity noted in molecular genetic studies. JME cannot really be called a very 'benign' epileptic syndrome; recurrence after therapy withdrawal almost invariably occurs.