Surgical therapy for Parkinson's disease.

Surgical therapies for Parkinson's disease (PD) are now being performed with increasing frequency due to the limitations of conventional dopaminergic therapies, improvements in operative procedures, and increased information on the organization of the basal ganglia in normal and pathologic conditions. Ablation procedures have now been largely replaced with deep brain stimulation, which permits benefits to be obtained without the need to make a destructive brain lesion. Several studies now demonstrate the value of stimulating the subthalamic nucleus or the globus pallidus pars interna in patients with advanced PD. Nonetheless, there are limitations associated with these procedures and benefits do not exceed those obtained with levodopa, albeit with reduced motor complications. Fetal transplantation remains an experimental procedure that has shown limited benefits in a double-blind trial and is complicated by persistent dyskinesia. Stem cell, trophic factor, and gene therapy approaches are promising and are currently under intensive investigation.