LEFT-RIGHT DIFFERENCES IN MOTOR THRESHOLDS AFTER STIMULATION OF THE GLOBUS-PALLIDUS BEFORE PALLIDOTOMY

Left-right upper limb motor threshold differences were found after ele ctrical stimulation of the globus pallidus administered as a neuroprot ective measure to avoid lesioning of the internal capsule during stere otactic pallidotomy for treatment of Parkinson's disease. Left sided s timulation resulted in lower thresholds in right handed patients compa red with left handed patients. These differences were significant in w omen, but no significant differences were found in men. In patients un dergoing bilateral pallidotomy, the stimulation produced more signific ant left-right motor threshold differences. In the absence of known se x-related anatomical left-right corticospinal tract differences, the v ariability was the result of spinal excitability modulations most like ly related to handedness.