Update on magnetic seizure therapy: a novel form of convulsive therapy.

Magnetic seizure therapy (MST) refers to the use of transcranial magnetic stimulation to induce a seizure for therapeutic purposes. MST is under investigation as a means of improving the safety profile of electroconvulsive therapy (ECT). Although both MST and ECT induce seizures through electrical stimulation of the brain, the electric field induced by MST is more focal and limited than that induced by ECT. Because magnetic fields pass through tissue unimpeded, there is greater control over the site and extent of stimulation with MST than can be achieved with ECT. This enhanced control represents a means of focusing the treatment on target cortical structures thought to be essential to antidepressant response and of reducing spread to medial temporal regions implicated in the cognitive side effects of ECT. MST is currently at an early stage of development. This article reviews the experience with MST in animal models and initial human investigations. Preliminary results have demonstrated the feasibility of performing MST in the clinical setting, and there are suggestions that MST may have advantages over ECT in terms of subjective side effects and some measures of acute cognitive functioning. The antidepressant efficacy of MST is not yet known, but studies designed to address that critical issue are underway. As with all attempts to refine convulsive therapy techniques (such as modifications in stimulation parameter configurations and electrode placement), the ultimate clinical value of MST will need to be established through controlled clinical trials.