Spectrum of EEG abnormalities during clozapine treatment.
Clozapine is a novel antipsychotic agent effective in treating refractory schizophrenia. Clozapine produces fewer extrapyramidal effects than other neuroleptics, although agranulocytosis and seizures are significant adverse effects. To characterize the spectrum of clozapine-related electroencephalographic abnormalities, we identified 10 patients who had electroencephalograms (EEGs) performed before and during clozapine treatment. These 10 patients represented a subset of individuals participating in an investigational trial. During clozapine treatment, five developed myoclonus and one experienced a generalized tonic-clonic seizure. Records were retrospectively reviewed by an electroencephalographer blinded to the patient's history and medications. All patients had normal EEGs before clozapine treatment. While receiving clozapine (250-900 mg daily), all patients developed background slowing in the theta and often delta ranges. Additionally, 7 patients exhibited bilateral spike, polyspike and slow wave discharges, one with a photoparoxysmal response. Follow-up EEGs performed in 4 of these 7 patients after a decrease in clozapine dosage and/or addition in valproic acid showed diminished epileptiform activity.
Malow
B A
BA
EEG Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892.
Reese
K B
KB
Sato
S
S
Bogard
P J
PJ
Malhotra
A K
AK
Su
T P
TP
Pickar
D
D
D000328:Adult; D003024:Clozapine / Q000009:adverse effects* / Q000627:therapeutic use; D004569:Electroencephalography / Q000187:drug effects*; D004827:Epilepsy / Q000139:chemically induced* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D009207:Myoclonus / Q000139:chemically induced* / Q000503:physiopathology; D012189:Retrospective Studies; D012559:Schizophrenia / Q000188:drug therapy*
D003024:Clozapine