EEG photosensitivity and response to valproate segregate together in Indians with juvenile myoclonic epilepsy

Objectives and background: Juvenile myoclonic epilepsy (JME) has a similar clinical expression including excellent response to valproate (VPA) across different populations. We aimed to define the clinical and EEG features in patients and their relatives diagnosed to have JME whose seizures best responded to VPA alone versus those who required VPA and another anti-epileptic drugs (AED). Materials and Methods: Indian probands and their relatives diagnosed to have JME were divided into 2 groups depending upon the AED to which they finally responded: 1) VPA alone (n=267; 248 probands and 19 relatives), 2) VPA in combination with carbamazepine, diphenylhydantoin or phenobarbitone (n=40; 36 probands and 4 relatives). Results: The two groups were comparable with regards to sex distribution, age at seizure onset, seizure types, precipitating factors for myoclonic jerks, EEG being normal or abnormal, history of febrile convulsions and family history of seizures. EEG photosensitivity was observed in 27 probands and 1 relative with JME who responded to VPA alone (28 of 267; 10%) compared to none of the 40 with JME responding to VPA plus other AEDs. Conclusions: EEG photosensitivity and response to VPA appear to segregate together in Indians with JME supporting heterogeneity in JME. Responsiveness to VPA should be taken into account in future molecular genetic studies on JME.