The aim of our study was to evaluate the effectiveness of
ethosuximide in the treatment of epileptic negative
myoclonus, a motor disorder that can occur in childhood
partial epilepsy. We introduced
ethosuximide in nine patients with
partial epilepsy of varying etiology (idiopathic, cryptogenic, symptomatic) who presented with epileptic negative
myoclonus. The
drug was added to the patients' preexisting
antiepileptic drugs, which were maintained unchanged for the following 6 months. Epileptic negative
myoclonus disappeared in all patients 15 to 30 days after
ethosuximide was started. Plasma
ethosuximide levels ranged from 55 to 89 micrograms/mL. The clinical response was not influenced by the patients' preexisting treatment or by the etiology of the
epilepsy. No side effects were observed, and none of the patients presented a recurrence of epileptic negative
myoclonus during follow-up. Furthermore, in five patients we observed the disappearance of
partial seizures; in the remaining patients
seizures were reduced by more than 75%. Electroencephalograms showed a decrement or disappearance of focal paroxysmal abnormalities. Our results suggest that
ethosuximide is effective in the treatment of epileptic negative
myoclonus and that it should be considered as a first-choice
drug in the treatment of this motor disorder.