Focal prefrontal seizures induced by bilateral ECT

INTRODUCTION: It has been proposed that the greater efficacy of bilateral (BL) over right unilateral (RUL) electroconvulsive therapy (ECT) at low stimulus intensity is due to differences in site of seizure initiation. We hypothesized that focal prefrontal seizures are more common with BL than RUL administration. METHOD: Records were reviewed of the 1,007 ECT treatments of 84 consecutive patients randomized to RUL or BL electrode placement. RESULTS: Eight events were identified in which there was an electroencephalographic seizure without motor manifestation. All of these events occurred at titration sessions and with BL stimuli (p = 0.002). These events were more likely to occur later in the course of treatment. DISCUSSION: We suggest that BL ECT may induce focal seizures in prefrontal areas and that these seizures are more likely to occur later in the treatment course.