Multicenter study report: electrophysiological monitoring procedures for subthalamic deep brain stimulation surgery in Parkinson's disease.

Despite the wide diffusion of subthalamic deep brain stimulation (STN-DBS) for Parkinson's disease, systematic practical recommendations for intraoperative electrophysiological monitoring are still lacking. In this paper, a shared protocol for intraoperative electrophysiological monitoring arising from the meetings of a panel of neurophysiologists of the DBS Study Group of the Italian Neurological Society is proposed. Intraoperative monitoring is composed by microrecordings and functional stimulation. In microrecordings, it is recommended to use at least 2-3 electrodes, descending with steps of 0.5-1 mm and waiting at least 60 s before changing the position. Functional stimulation is used to assess the clinical efficacy and the side effects induced by STN-DBS at different positions. Based on the therapeutic window, an algorithm to find the optimal target is proposed. The procedures for intraoperative monitoring for STN-DBS proposed here are safe, relatively cheap, take approximately 30-40 min per side and could offer valuable additional information to the surgeon.