Brain stimulation device-device interactions

Currently, there are few data in the literature on the use of transcranial brain stimulation in the presence of implanted stimulation systems. Many clinical and research studies list implanted metallic hardware as an absolution contraindication to transcranial brain stimulation, since the safety of the dual-device usage has not been established. The strong magnetic field emitted by TMS/MST coils and the electrical current from ECT may induce large voltages in nearby wires and electronic devices, interfering with their function and potentially damaging the implanted system components. Further, interactions between the stimulation devices may result in significant, undesirable stimulation effects, and even in neural injury. As more patients receive electronic implants for a variety of neural disorders, and as the use of transcranial brain stimulation devices grows, it is of great importance to evaluate the safety of the interactions between intracranial devices and transcranially applied electric and magnetic stimulators. Safety concerns currently limit the access of subjects with intracranial electronic devices to therapies involving transcranial stimulation technology, which may preclude them from obtaining appropriate medical treatments. Gaining better understanding of the interactions between transcranial and implanted stimulation devices will demarcate significant safety risks from benign interactions, and will provide recommendations for reducing risk, thus enhancing the patient’s therapeutic options. Further, if transcranial brain stimulation can be safely applied in patients with intracranial implants, this may lead to novel synergistic dual-device therapies. The objective of this study is to systemically investigate, both computationally and experimentally, the safety of transcranial brain stimulation techniques (TMS, MST, ECT) in patients with an FDA-approved intracranially implanted stimulation device and propose safety guidelines for the dual-device therapy.