The major recent enhancements to ECT technique are:
- Right Unilateral electrode placement. The cognitive side-effects of ECT such as retrograde and anterograde amnesia are significantly less compared to Bilateral electrode placement.
- Brief pulse stimulus currents. The characteristics of the electrical stimulus affect the effectiveness and cognitive outcomes of the seizure. Sine wave stimuli have been replaced with rectangular pulses on modern ECT devices, leading to a substantial decrease in cognitive effects
- Improved anesthesia techniques makes it possible to regulate the cardiac output during ECT when necessary
- The “dose titration” technique to individualize treatment stimulus dosing
- The discovery of the dose-response relationship between electrical stimulus dosing and antidepressant outcome with RUL electrode placement
- Pulse width. Several studies conclude that right unilateral (RUL) electroconvulsive therapy (ECT) given with ultrabrief pulse-width stimulus packages causes less cognitive impairment than other techniques
Contemporary ECT devices can be set to deliver pulse-widths between 0.25 and 2.0 milliseconds. Stimuli between 0.5 and 2.0 milliseconds are called “brief,” and those less than 0.5 millisecond are called “ultrabrief.”
A recent study from Sackeim and colleagues was published about ultrabrief puls width and efficcay and cognitiev side-effects. Those participating in this trial were assessed for depressive symptoms and cognition at baseline, during and after the acute course of ECT, and at 2 and 6 month time points. Responders were monitored for 1 year. Reported remission rates were 73% for ultrabrief RUL, 65% for brief pulse BL, 59% for brief pulse RUL, and 35% for ultrabrief BL. Ultrabrief pulse RUL produced less severe cognitive effects than the other 3 treatment groups, both acutely and long-term, on multiple measures in several cognitive domains, including subjective assessment of memory function. Relapse in the year following acute ECT was unrelated to treatment group. These authors concluded, “the use of an ultrabrief stimulus coupled with high-dosage RUL stimulation is a strategy that appears to retain the therapeutic properties of ECT, although substantially reducing its potential for adverse cognitive side effects.”
The big problem is that ultrabrief bilateral treatment is less efficacious in this trial than Right unilateral electrode placement. Normally bilateral ECT is the most efficacious form of ECT. Is this a real difference or is this another strange finding from the Columbia University Group comparable to their results with medication resistant depressed patients. According to their research patients with “medication resistance” as defined by arbitrary (ATHF) criteria were less responsive to ECT. Other researchers couldn’t find any influence of medication resistance on efficacy of subsequent ECT. It seems that medication resistance is irrelevant in the decision for a trial of ECT in patients with severe depressive illness, whether psychotic or non-psychotic.
Does pulse width influence efficacy of bilateral ECT? Opinion from another expert, Charles H Kellner:
Fortunately, the nature of ECT is such that if, after several RUL treatments with ultrabrief pulse stimuli, the patient is not responding adequately, the treatment technique can be switched, either to a different waveform or electrode placement, or both.
We did a retrospective study comparing bilateral ultrabrief pulse width compared to brief pulse width for depressive disorder. We couldn’t find a significant difference. Is to be continued.
SACKEIM, H., PRUDIC, J., NOBLER, M., FITZSIMONS, L., LISANBY, S., PAYNE, N., BERMAN, R., BRAKEMEIER, E., PERERA, T., & DEVANAND, D. (2008). Effects of pulse width and electrode placement on the efficacy and cognitive effects of electroconvulsive therapy Brain Stimulation, 1 (2), 71-83 DOI: 10.1016/j.brs.2008.03.001