Objectives: Understanding the relationship between the stimulus parameters of electroconvulsive therapy (ECT) and the electric field characteristics could guide studies on improving risk/benefit ratio. We aimed to determine the effect of current amplitude and electrode size and spacing on the ECT electric field characteristics, compare ECT focality with magnetic seizure therapy (MST), and evaluate stimulus individualization by current amplitude adjustment.
Methods: Electroconvulsive therapy and double-cone-coil MST electric field was simulated in a 5-shell spherical human head model. A range of ECT electrode diameters (2–5 cm), spacing (1–25 cm), and current amplitudes (0–900 mA) was explored. The head model parameters were varied to examine the stimulus current adjustment required to compensate for interindividual anatomical differences.
Results: By reducing the electrode size, spacing, and current, the ECT electric field can be more focal and superficial without increasing scalp current density. By appropriately adjusting the electrode configuration and current, the ECT electric field characteristics can be made to approximate those of MST within 15%. Most electric field characteristics in ECT are more sensitive to head anatomy variation than in MST, especially for close electrode spacing. Nevertheless, ECT current amplitude adjustment of less than 70% can compensate for interindividual anatomical variability.
Conclusions: The strength and focality of ECT can be varied over a wide range by adjusting the electrode size, spacing, and current. If desirable, ECT can be made as focal as MST while using simpler stimulation equipment. Current amplitude individualization can compensate for interindividual anatomical variability.
From the *Department of Psychiatry and Behavioral Sciences, Duke University, Durham, NC; †Department of Electrical Engineering, Columbia University, New York, NY; ‡Departments of Psychology and Neuroscience, §Biomedical Engineering; and ║Electrical and Computer Engineering, Duke University, Durham, NC.
Received for publication March 5, 2013; accepted July 11, 2013.
Reprints: Angel V. Peterchev, PhD, Department of Psychiatry and Behavioral Sciences, Duke University, Box 3950 DUMC, Durham, NC 27710 (e-mail: firstname.lastname@example.org).
Dr Deng is an inventor on patent applications on TMS/MST technology assigned to Columbia. Dr Lisanby has served as a principal investigator on industry-sponsored research grants to Columbia/RFMH or Duke (Neuronetics [past], Brainsway, ANS/St Jude Medical, Cyberonics [past], and NeoSync); equipment loans to Columbia or Duke (Magstim and MagVenture); is a co-inventor on a patent application on TMS/MST technology; is supported by grants from National Institutes of Health (NIH; R01MH091083-01, 5U01MH084241-02, and 5R01MH060884-09), Stanley Medical Research Institute, and Brain & Behavior Research Foundation/NARSAD; and has no consultancies, speakers bureau memberships, board affiliations, or equity holdings in related device industries. Dr Peterchev is an inventor on patents and patent applications on TMS/MST technology assigned to Columbia and Duke, including technology licensed to Rogue Research; was a principal investigator on a research grant to Duke from Rogue Research and equipment donations to Columbia and Duke by Magstim, MagVenture, and ANS/St Jude Medical; and has received patent royalties from Rogue Research through Columbia for TMS technology. Dr Peterchev is supported by NIH grant R01MH091083 and Duke Institute for Brain Sciences Research Incubator Award. This work was supported in part by NIH grants R01MH60884 and R01MH091083.