Abstracts

Chronic myoclonus is often associated with severe functional disability and it frequently results intractable to currently used antiepileptic drugs (AEDs). Levetiracetam (Keppra , LEV) is a new AED with broad-spectrum activity including strong efficacy against myoclonus. We present data from an open-labeled treatment trial of LEV aimed to evaluate the clinical effect and the tolerability of orally administrated LEV in patients with chronic cortical myoclonus of various etiology. In addition, we attempted to determine if treatment with LEV modifies electrophysiological findings in these patients. Patients affected with refractory chronic (i.e., present without remission for at least one year) myoclonus of cortical origin were enrolled. Each subject underwent a detailed electrophysiological study jerk-locked averaging, median nerve SEP and Long Latency Reflex I. Only patients showing myoclonus of cortical origin entered the study. Unified Myoclonus Rating Scale (UMRS) was used to assess severity of myoclonus. LEV was orally administered at a starting dose of 500 mg bid for one week followed by increments of 500 mg bid each week. In all patients, daily doses were increased up to 1500-2000 mg bid. Dosage of concomitant AEDs remained unchanged. Each subject was either clinically and electrophysiologically re-evaluated 4-5 weeks after having achieved the target dose. Sixteen patients (10 M, 6 F), aged 19 to 72 years, and affected with chronic myoclonus were enrolled. Five had the diagnosis of Unverricht-Lundborg disease; 2 had Lafora disease; nine patients received diagnosis of Benign Adult Familial Myoclonic Epilepsy. Enhanced SEP were found before LVT trial in 9 cases. All patients but one completed the trial. Add-on with LEV to the baseline therapy clinically improved myoclonus in 12/16 cases, as showed by lower UMRS scores after treatment. Follow-up electrophysiological study showed reduction of SEP amplitude in 4/9 patients. This study confirms the antimyoclonic properties of LEV when added to existing treatment. LEV was very well tolerated. electrophysiological study showed that LEV tended to decrease N20-P25 as well as P25-N30 SEP amplitudes but not latencies in four cases. These results suggest that the electrophysiological approach may supply quantifiable data of the drug effect as well as help to understand the LEV mechanism of action.