Deep Brain Stimulation (DBS) and Motor Evoked Potentials (MEP)

MEP onset latencies from the hand muscle using two different stimulus methods will be compared from each study participant. Conventional MEP data will be collected prior to skin incision. Following the DBS insertion hand muscle evoked responses will be generated via the DBS electrode. A hand held DBS programmer will be connected to the proximal end of the implanted DBS for delivery of electrical stimuli. Stimulus intensity will be adjusted until a hand muscle evoked potential is registered from the same recording electrodes used for the conventional MEP acquisition. A STN-implanted electrode can produce hand muscle responses due to it's close proximity to the motor fibres of the internal capsule. When the conventional and DBS-induced hand muscle responses have been acquired the study data objectives have been met. Data will be analyzed off-line.