Comparison of electric field strength and spatial distribution of electroconvulsive therapy and magnetic seizure therapy in a realistic human head model.
This study examines the strength and spatial distribution of the electric field induced in the brain by electroconvulsive therapy (ECT) and magnetic seizure therapy (MST).



The electric field induced by standard (bilateral, right unilateral, and bifrontal) and experimental (focal electrically administered seizure therapy and frontomedial) ECT electrode configurations as well as a circular MST coil configuration was simulated in an anatomically realistic finite element model of the human head. Maps of the electric field strength relative to an estimated neural activation threshold were used to evaluate the stimulation strength and focality in specific brain regions of interest for these ECT and MST paradigms and various stimulus current amplitudes.



The standard ECT configurations and current amplitude of 800-900mA produced the strongest overall stimulation with median of 1.8-2.9 times neural activation threshold and more than 94% of the brain volume stimulated at suprathreshold level. All standard ECT electrode placements exposed the hippocampi to suprathreshold electric field, although there were differences across modalities with bilateral and right unilateral producing respectively the strongest and weakest hippocampal stimulation. MST stimulation is up to 9 times weaker compared to conventional ECT, resulting in direct activation of only 21% of the brain. Reducing the stimulus current amplitude can make ECT as focal as MST.



The relative differences in electric field strength may be a contributing factor for the cognitive sparing observed with right unilateral compared to bilateral ECT, and MST compared to right unilateral ECT. These simulations could help understand the mechanisms of seizure therapies and develop interventions with superior risk/benefit ratio.
Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
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Lee
Department of Psychiatry and Behavioral Sciences, Duke University, Durham, NC 27710, USA; Department of Psychology & Neuroscience, Duke University, Durham, NC 27708, USA; Department of Psychiatry, Columbia University, New York, NY 10032, USA; National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA.
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Lisanby
Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA.
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Laine
Department of Psychiatry and Behavioral Sciences, Duke University, Durham, NC 27710, USA; Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA; Department of Electrical and Computer Engineering, Duke University, Durham, NC 27708, USA. Electronic address: angel.peterchev@duke.edu.
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Peterchev
D001921:Brain / Q000502:physiology; D004558:Electric Stimulation; D004565:Electroconvulsive Therapy / Q000379:methods*; D004566:Electrodes; D006257:Head; D006624:Hippocampus; D006801:Humans; D008297:Male; D008953:Models, Anatomic; D012640:Seizures / Q000628:therapy*
ECT; MRI; Mania and bipolar disorder; Transcranial magnetic stimulation (TMS); Unipolar depression