[Development or worsening of myoclonus associated with gabapentin therapy].

To evaluate the development or worsening of myoclonus in patients receiving gabapentin (GBP). Clinical charts of 162 patients treated with GBP were reviewed concerning development or worsening of myoclonus. We found 3 cases (1.9%) of myoclonus. Two patients had preexisting myoclonus and generalized tonic-clonic seizures, while the other one had generalized tonic-clonic seizures only. All patients experienced development or worsening of myoclonus within 2 weeks after starting GBP. Dose at the onset of development or worsening of myoclonus varied from 600 mg to 1,800 mg. Two patients developed multifocal myoclonus. Discontinuation of GBP or clonazepam add-on resulted in cessation of myoclonus with no serious sequela. GBP may increase the risk of development of de novo myoclonus or worsening of myoclonus in patients with preexistent myoclonus. According to the result of this study and the treatment guidelines, GBP should be avoided when a patient has preexistent myoclonus.