Controllable pulse parameter TMS

We are developing a new class of efficient transcranial magnetic stimulation (TMS) devices that allow adjustment of the magnetic stimulus parameters over a wide range, which had not been possible with existing technology. Pulse shaping is accomplished through the use of high power insulated-gate bipolar transistors (IGBTs), high energy storage capacitors, and requisite snubber and control circuits, enabling switching of currents up to 7 kA with pulse widths from microseconds to hundreds of microseconds. These controllable pulse TMS (cTMS) devices could enable research and clinical applications not previously possible due to technological limitations. For instance, the cTMS machine can be used to non-invasively characterize changes in neuronal membrane properties associated with brain pathology or pharmacological interventions. In addition, cTMS can produce briefer magnetic pulses than conventional TMS, which could reduce unpleasant scalp sensation. This has the advantage of both making the treatment more tolerable, and providing more effective blinding for randomized clinical trials. Further, cTMS can generate high frequency trains of unipolar pulses which may have more potent therapeutic effect, but have not been feasible with existing devices. Finally, cTMS generates near-rectangular pulse shapes that use less electrical energy and cause as much as four times less heating of the stimulating coil compared to conventional devices.

This work is supported by the NIH, Columbia University Office of Technology Ventures, New York State Office of Science, Technology and Academic Research (NYSTAR), Coulter Foundation, and Rogue Research. The patents on cTMS technology were licensed by Rogue Research who are now producing prototype devices. Through the partnership with Rogue Research, cTMS devices are now placed in the labs of Prof. John Rothwell at University College London, UK and Prof. Yohikazu Ugawa at Fukushima Medical University, Japan.