Seizures induced by low-dose right unilateral and bifrontal electroconvulsive stimuli

The duration of electroconvulsive therapy (ECT) seizures of depressive patients has been found to be inversely related to titrated right unilateral (RUL) and bilateral (BL) seizure threshold (ST) levels. This inverse relationship is thought to reflect those neural processes determining seizure duration. The relation between seizure duration and titrated ST level in bifrontal (BF) ECT, which has not been previously studied, is examined here in addition to RUL ECT. We found an inverse relationship in RUL ECT but no relationship in BF ECT. Eighteen percent of RUL patients seized at the first stimulus level versus 40% of BF patients. Compared with previous studies, both our starting dose and the increments between stimuli were greater in BF ECT (50.4 mC) than in RUL ECT (25.2 mC). A relationship between stimulus dose and seizure length may have also been present in BF ECT had similar titration schedules been used for both electrode placements. Future studies using titration schedules with a lower initial dose and finer gradations between stimulus levels are needed to evaluate whether a relationship between stimulus dose and seizure duration exists in BF ECT.