Myoclonic seizures induced by antipsychotic drugs: A case series and literature review (eng)

Abstract

The true frequency of myoclonic seizures caused by antipsychotics is unknown. Myoclonus associated with clozapine and other antipsychotics has been shown less frequently than tonic-clonic seizures in the literature and the treatment protocol is controversial. In this study, we have compiled current literature data by presenting our clinical experiences in patients who developed myoclonic seizures with antipsychotic use. The patients were followed up in the inpatient service of Gazi University Hospital, Department of Psychiatry between 2014-2019. Demographic data, clinical variables, imaging methods and response to treatment of 10 patients with myoclonic seizures were analyzed. After clinical evaluation, psychiatric diagnoses were clarified according to DSM-5. Psychotropic drugs and doses, EEG, MRI examinations and follow-up data were recorded in these patients with myoclonic seizures. While 6 of the patients (60%) were receiving clozapine treatment, other patients using olanzapine, amisulpride and quetiapine were seen as 2 (20%), 1 (10%) and 1 (10%), respectively. The mean chlorpromazine dose-equivalent of the antipsychotics used by all 10 patients was 876.66 mg per day. In addition to antipsychotic change, valproic acid was used (most frequently) for the control of myoclonic seizures in 8 of the patients (80%), due to insufficient response. Myoclonic seizures may be misdiagnosed as sudden falls resulting from generalized tonic-clonic seizures, dyskinesia, and clozapine induced hypotension. In patients with myoclonic seizures, use of antipsychotic drugs should be kept in mind, especially in additional medical conditions such as renal failure, as well as direct central nervous system pathologies.

Keywords

• myoclonic seizures
• myoclonus
• antipsychotics
• schizophrenia
• atypical antipsychotics