Parkinson's Disease : Pallidal vs Subthalamic Stimulation

an interesting study about Parkinson's disease management;comparison of Pallidal and Subthalamic stimulation published in New England Journal of Medicine.

Background:
Deep-brain stimulation is the surgical procedure of choice for patients with advanced Parkinson's disease.The globus pallidus interna and the subthalamic nucleus are accepted targets for this procedure .In this study the 24 month outcomes for two groups of patients undergone two procedures are comapred:patients who had undergone bilateral stimulation of the globus pallidus interna (pallidal stimulation) or subthalamic nucleus(subthalamic stimulation).


299 patients with idiopathic parkinson's disease were randomly assigned to undergo either pallidal stimulation(152) or subthalamic stimulation (147).The primary outcome ws the change in motor function,as blindly assessed on the Unified Parkinson's Disease Rating Scale,part III(UPDRS-III),while patients were recieving but not recieving antiparkinsonian medication.Secondary outcomes included self-reported function ,quality of life ,neurocognitive function,and adverse events.

Results:
Mean changes in the primary outcome did not differ significantly between the two study groups(P=0.50).There was also no significant difference in self-reported function.Patients undergoing subthalamic stimulation required a lower dose of dopaminergic agents than did  those undergoing pallidal stimulation(P=0.02).One component of processing speed(visumotor)declined more after subthalamic stimulation than after pallidal stimulation(P=0,03).The level of depression worsened after subthalamic stimulation and improved after pallidal stimulation(P=0.02).Serious adverse events occured in 51% of patients undergoing pallidal stimulation and in 56% of those undergoing subthalamic stimulation ,with no significant between-group differences at 24 months.

Conclusions:
patients with Parkinson' disease had similar improvement in motor function after either pallidal or subthalamic stimulation .Nonmotor factors may reasonably be included in the selection of surgical target for deep-brain stimulation .