Three patients had exceptionally high seizure threshold, as determined
by an empirical titration procedure. Initial seizure threshold was 89
6 mC in two of the patients. The third patient had an initial threshol
d of 336 mC that increased to 840 mC at the end of the course of elect
roconvulsive therapy (ECT), and remained elevated during a second cour
se of ECT. All three patients were elderly men with complicated medica
l histories and ongoing low-dose benzodiazepine use. Each patient had
an excellent response to ECT delivered with a custom modified device,
capable of delivering more than twice the charge of ECT devices presen
tly commercially available in the United States. Implications for the
administration of ECT in patients with exceptionally high seizure thre
shold and the limitations of current device output are discussed.