[A clinical and electroencephalographic study of juvenile myoclonic epilepsy: its pathophysiological considerations based on the findings obtained from neuropsychological EEG activation].

Juvenile myoclonic epilepsy (JME) is one of the idiopathic generalized epilepsies with age-related onset. Myoclonic seizures of JME often occur on awakening. On the other hand, patients with reflex epilepsy, whose seizures are particularly induced by activating higher cognitive functions, are thought to belong to the same category. As to the seizure precipitating factors of these patients with JME, however, few studies have ever been made. In this study, clinical and electroencephalographic findings of 25 patients with JME, on whom "neuropsychological EEG activation" (NPA) was performed, were carefully analyzed. After a routine EEG examination, NPA was carried out; this is a special method for EEG activation that requires the patients to speak, read, write, calculate and perform constructive acts (drawing figures and doing a block design test); in addition to EEG recording, simultaneous video-EEG monitoring was also made during these tasks. In the patients with JME, the sex ratio was about equal (11 males and 14 females). Eight patients (32%) had a family history of epilepsy but none of the patients had a positive past history responsible for epilepsy. The age at the onset of myoclonic seizures ranged between 10 and 20 years (mean: 15.3 years). A total of 18 patients (72%) had another type of seizures; 3 had absence seizures, 9 had generalized tonic-clonic seizures and 6 had both absence and generalized tonic-clonic seizures. Myoclonic seizures often occurred in the morning on awakening in 17 (68%) of 25 patients. As for EEG findings (all but one patient were receiving antiepileptic drugs when EEG was examined), paroxysmal discharges in a resting state were found in 12 patients (48%); most of them were either very brief generalized spike and wave complexes or bursts of generalized 3-5 Hz spike and wave complexes lasting for 1-3 seconds; generalized multiple spikes were observed only in 5 patients. These clinical and EEG findings were in accordance with those reported previously. Careful investigation of the histories obtained from the patients disclosed the following: Myoclonic seizures were induced (1) by mental activity associated with the use of hands in 20 patients (80%), (2) in a situation with psychic tension in 12 (48%), and (3) by decision making in 3 (12%). Interestingly, these findings could be confirmed by NPA with simultaneous video-EEG monitoring.(ABSTRACT TRUNCATED AT 400 WORDS)