Nonconvulsive Seizures in Electroconvulsive Therapy

In recent years, attention has been focused on the role of electrode placement in determining efficacy and cognitive side effects of electroconvulsive therapy (ECT). In particular, interest in bifrontal electrode placement has increased. Some evidence indicates differential therapeutic, cognitive, and neurophysiological aspects of bifrontal versus bitemporal ECT. Occasionally in ECT practice, electroencephalographic seizure activity is manifested in the absence of motor convulsive activity, a phenomenon termed nonconvulsive seizures. This probably indicates isolated prefrontal seizure activity in the absence of motor strip involvement. We reviewed our records and found that bifrontally treated patients had a significantly higher incidence of nonconvulsive seizures in ECT than did bitemporally treated patients. Seizure threshold was also higher among the bifrontal patients. We hypothesize that this provides further evidence of differential neurophysiology of seizures induced with these 2 electrode placements.