Ultrabrief (0.3 ms) or brief (0.5 ms) pulses for right unilateral electroconvulsive therapy: is there a difference in seizure thresholds?

Objectives: To compare the minimum charge to elicit a seizure using 2 different pulse widths, the brief pulse (0.5 milliseconds [ms]) and the ultrabrief pulse (0.3 ms).

Methods: We compared retrospectively the last 30 patients in our ECT unit whose seizure thresholds were titrated using a pulse width of 0.5 ms to the last 30 patients whose seizure thresholds were titrated using a pulse width of 0.3 ms. The former were regular clinical patients, and the latter were participating in a clinical trial on the use of ultrabrief pulse treatment. All titrations were performed with right unilateral electrode positioning. Most patients continued to use psychotropic medications.

Results: Initial seizure threshold (as measured in millicoulombs [mC]) for the brief pulse group (0.5 ms) was 16 (n = 1); 32 (n = 21), and 64 (n = 8); whereas for the ultrabrief pulse group (0.3 ms), it was 9.2 (n = 3), 38.4 (n = 21), 19.2 (n = 3), 76.8 (n = 2), and 307.2 (n = 1). Excluding the outlier, there was no statistical difference between mean seizure thresholds.

Conclusions: If we exclude the outlier from the ultrabrief group (seizure threshold [ST], 307 mC), we can observe that most of the patients in both groups had an ST between 30 and 40 mC. No patient in the brief pulse group showed a lower ST than 16 mC, probably because this was the first step of titration for this group. The data suggest that the difference between 0.3 and 0.5 ms may not be big, although randomized prospective studies with a more precise and similar steps used for titration are needed. Clinical efficacy was not compared in the present study.