Magnetic seizure therapy for the treatment of depression
Cognitive side effects limit the clinical utility of electroconvulsive therapy (ECT), the most effective and rapidly acting treatment for severe depression. Studies suggest that prefrontal cortical involvement may be important to preserving the efficacy of ECT, while seizure spread to the medial temporal lobes may be related to its amnestic side effects. However, the scalp and skull shunt the flow of electricity, limiting control over current spread with ECT. Magnetic fields enter the brain unimpeded, allowing enhanced control over the site of stimulation and seizure initiation compared to ECT. Magnetic seizure therapy (MST) involves the induction of a seizure under general anesthesia using high-frequency repetitive transcranial magnetic stimulation. MST was developed to reduce the cognitive side effect burden of convulsive therapy through focal seizure induction in the prefrontal cortex. Work to date supports the feasibility of MST in the nonhuman primate and in patients with depression. Preliminary results indicate that seizures induced with MST are more focal, result in less involvement of hippocampal and deep brain structures, and have a better acute side effect profile than those induced with ECT. Future directions for the clinical development of MST technology are discussed. Copyright © 2007 S. Karger AG, Basel.