Clinical features, EEG findings and diagnostic pitfalls in juvenile myoclonic epilepsy: a series of 63 patients

Juvenile myoclonic epilepsy (JME) is a common idiopathic generalized epilep tic syndrome distinctively characterized by myoclonic jerks often associate d to generalized tonic-clonic seizures (GTCS) and typical absence seizures. In spite of typical clinical and EEG profiles, JME is widely underdiagnose d. In the present study we retrospectively revised clinical and EEG data of JME patients referring to our Epilepsy Service. A diagnosis of JME could b e made in 63 patients, that is 5.7% of all the epileptic patients referring to our Service and 25.9% of those suffering from an idiopathic generalized epilepsy. General features as well as modality of onset and course of the syndrome of our JME subjects were in accordance with literature. Regarding EEG findings, asymmetries were detected in 38.1% of cases. At referral to o ur Service only 31.7% of JME patients were correctly diagnosed. Main factor s responsible for misdiagnosis were failure in eliciting a history of myocl onic jerks and misinterpretation of myoclonic jerks as simple partial seizu res. EEG asymmetries were misleading in 13 patients. In conclusion, a corre ct JME diagnosis is strictly dependent on the knowledge of the syndrome lea ding the interviewer to look for and correctly interpret myoclonic jerks wh ereas EEG is just an ancillary diagnostic tool. (C) 2001 Elsevier Science B .V. All rights reserved.