The Return of LART?
Out on PubMed, from Colleen Loo's group in Sydney, Australia, is this study:
Electrode placement in electroconvulsive therapy (ECT) has a major impact on treatment efficacy and cognitive side effects. Left Anterior Right Temporal (LART) is a lesser utilised bilateral montage which may produce more optimal clinical outcomes relative to standard bitemporal ECT. In this study we used computational modelling to explore how stimulation effects from LART and two novel variants (LART - F3 and LART - Frontal) compared to the more common bilateral placements of bitemporal and bifrontal ECT. High resolution finite element human head models were generated from MRI scans of three subjects with Major Depressive Disorder. Differences in regional stimulation were examined through parametric tests for regions of interest and subtraction maps. Compared to bitemporal ECT, LART - Original resulted in significantly greater stimulation of the left cingulate gyrus (hypothesised to be associated with treatment efficacy), and relatively reduced stimulation of the bilateral hippocampi (potentially associated with cognitive side effects). No additional clinical benefit was suggested with the novel LART placements compared to the original LART. The original LART placement is a promising montage for further clinical investigation.
Keywords: Cognition; Computational modelling; Depression; Efficacy; Electroconvulsive therapy (ECT).
This is a complex and sophisticated experiment, modelling electrical fields in 5 ECT electrode placements (original LART, two minor variants in which the left electrode is moved a bit laterally or superiorly, BF and BT, but no RUL). The results summarized above, if you believe that the correct brain regions for antidepressant efficacy (subgenual anterior cingulate (ACC) and cognitive effects (hippocampus) have been identified, argue for LART being an optimal placement. These authors have previously investigated RUL in this paradigm; it would have been informative to comment in this paper on how LART compares to RUL.
When the CORE group did its electrode placement comparison study (Bifrontal, bitemporal and right unilateral electrode placement in ECT: randomised trial, Br J Psychiatry, 2010, Mar), the NIMH intimated that it would be the last such study ever funded by the NIMH. Perhaps we should have included LART, but we decided that the sample size needed for an additional arm would have been prohibitive. It is unclear how an adequately powered comparison trial including LART will be funded in the future.
So, just when you thought LART was of only historical interest, here is this compelling plea for its revival. Conrad Swartz, the inventor of LART, must be pleased. Perhaps the original LART manuscript will one day appear in "Classics in ECT"...
Thanks for bringing this important study to my attention Charlie.
ReplyDeleteClinical considerations led to me to construct the left-anterior right temporal (LART) electrode placement (Swartz 1994). Symmetrical disruption of brain function amplifies adverse cognitive effects (as in the Klüver–Bucy syndrome) but both bitemporal and bifrontal placement are fully symmetrical. The asymmetry of R-unilateral placement presumably underlies its diminished cognitive side-effects. Starting with bifrontal placement and sliding the two electrodes to the right about an inch--while slicked with jelly in a rubber headstrap--produces LART. The right electrode is in the same location as for bitemporal ECT and the resulting left electrode position is at the left edge of the forehead.
My LART patients had no noticeable side-effects and looked so improved that other inpatients on the same ward noticed and asked their psychiatrists for the same treatment. Can you imagine inpatients asking for ECT? The psychiatrists in private practice there quickly adopted LART. One, David Manly MD, collaborated with me on several reports. I published about half a dozen papers on LART, and described it in my two ECT books and several review articles.
When minimizing cognitive side-effects of ECT appears essential I consider using the propofol interruption method (Warnell et al., 2010). In this, cognitive side effects are diminished by infusing propofol very soon after the stimulus to assure that seizure ends promptly, and not leaving seizure ending to happenstance. Seizure activity can continue in the absence of observable activity on EEG monitoring electrodes and produce or exacerbate cognitive side effects.
References:
Swartz CM. Asymmetric bilateral right frontotemporal left frontal stimulus electrode polacement. Neuropsychobiology 1994; 29:174-8.
Warnell RL, Swartz CM, Thomson A. Propofol interruption of ECT seizure to reduce side-effects. Psychiatry Research 2010; 175:184-5.