Deep-brain stimulation of the subthalamic nucleus or the pars interna of the globus pallidus in Parkinson's disease.

Background: Increased neuronal activity in the subthalamic nucleus and the pars interna of the globus pallidus is thought to account for motor dysfunc tion in patients with Parkinson's disease. Although creating lesions in the se structures improves motor function in monkeys with induced parkinsonism and patients with Parkinson's disease, such lesions are associated with neu rologic deficits, particularly when they are created bilaterally. Deep-brai n stimulation simulates the effects of a lesion without destroying brain ti ssue. Methods: We performed a prospective, double-blind, crossover study in patie nts with advanced Parkinson's disease, in whom electrodes were implanted in the subthalamic nucleus or pars interna of the globus pallidus and who the n underwent bilateral high-frequency deep-brain stimulation. We compared sc ores on the motor portion of the Unified Parkinson's Disease Rating Scale w hen the stimulation was randomly assigned to be turned on or off. We perfor med unblinded evaluations of motor function preoperatively and one, three, and six months postoperatively. Results: Electrodes were implanted bilaterally in 96 patients in the subtha lamic-nucleus group and 38 patients in the globus-pallidus group. Three mon ths after the procedures were performed, double-blind, crossover evaluation s demonstrated that stimulation of the subthalamic nucleus was associated w ith a median improvement in the motor score (as compared with no stimulatio n) of 49 percent, and stimulation of the pars interna of the globus pallidu s with a median improvement of 37 percent (P<0.001 for both comparisons). B etween the preoperative and six-month visits, the percentage of time during the day that patients had good mobility without involuntary movements incr eased from 27 percent to 74 percent (P<0.001) with subthalamic stimulation and from 28 percent to 64 percent (P<0.001) with pallidal stimulation. Adve rse events included intracranial hemorrhage in seven patients and infection necessitating removal of the leads in two. Conclusions: Bilateral stimulation of the subthalamic nucleus or pars inter na of the globus pallidus is associated with significant improvement in mot or function in patients with Parkinson's disease whose condition cannot be further improved with medical therapy. (N Engl J Med 2001;345:956-63.) Copy right (C) 2001 Massachusetts Medical Society.