Myoclonus in patients treated with clozapine: a case series.

BACKGROUND

Various types of movement disorder have been reported to occur rarely in patients treated with clozapine. This paper describes five cases in which these phenomena appeared to be clearly associated with clozapine medication and discusses possible pharmacologic mechanisms and treatment options.

METHOD

Inpatients receiving clozapine were investigated for the presence of movement disorders. We present five patients with clozapine-induced myoclonus, describe their patterns, and compare clinical features.

RESULTS

Five patients treated with clozapine developed a similar pattern of movement disorder that can be described as myoclonus. The neurologic symptoms improved after the treatment was discontinued, the clozapine dose reduced, or concomitant carbamazepine administered.

CONCLUSION

Clozapine can induce dose-dependent myoclonus. However, these symptoms can be relieved by reducing the dose of clozapine or giving carbamazepine so that discontinuation of clozapine treatment can be avoided.