Clozapine lnduced EEG Changes

Abstract

Background: Clozapine has been used with increasing frequency over the last decadein our country. lt's known to induce epileptic seizures and cause various EEG changes.Objective: In this retrospective study we included patients (n=37) followed in thePsychiatry Department of our hospital in the last decade due to psychosis or bipolaraffective disorder, who were taking clozapine and had at least one EEG recorded. We reviewed the EEG changes in detail and investigated how they were influencedby the clinical characteristics of the patients. Material and Methods: Mean clozapine dosage of the patients (79 F, 18 M; mean age 31.2 years) was 550 (200-900 mg) mg/day.Findings: While being treated with clozapine 7.1 % of the patients had seizures(generalized tonic clonic and/or myoclonic) that were controlled by reduction in dose of clozapine and/or addition of valproate. Hundred EEGs were reviewed. Eighty-six were recorded during therapy and only 14 % of these were normal. The most common finding in pathological EEGs was generalized slowing in background activity (60.5 %). Epileptic abnormalities were detected in 1/3 of the tracings. Epileptic discharges were seen during photic stimulation in 4 (10.8 %) patients. EEGs recorded during high doses (>400 mg/day) of treatment tended to be more pathological (p<0.05). Pathological EEGs did not predict seizure occurrence, however they were correlated with remission in the psychiatric disorder (p=0.032). Conclusion: Clozapine leads to EEG changes depending on dosage. Pathological EEGs do not predict seizure occurrence, but are correlated with remission in the psychiatric disorder. Epileptic seizures can occur during clozapine treatment, but they are easily controlled by reduction in dose or addition of valproate.