Seizure threshold in ECT: I. Initial seizure threshold.

Seizure threshold determination is of crucial importance in optimizing electrical stimulus dosage during administering electroconvulsive therapy (ECT). We measured initial seizure threshold by means of Srinakharinwirot University titration schedule in 150 psychotic patients. Initial seizure threshold was approximately 104 millicoulombs on average, but varied widely (12-fold) across patients. Motor seizure duration was inversely related to initial seizure threshold. Seizure threshold could be strongly predicted by age. The results may have important clinical implications for stimulus dosing strategy in ECT.