Deep brain stimulation of the internal globus pallidus does not affect the limbic circuit in patients with Parkinson's disease: a PET study.

INTRODUCTION: Internal globus pallidus (GPi) deep brain stimulation (DBS) is a safe and effective alternative treatment in Parkinson's disease (PD) for patients with cognitive impairment. However, no study has yet investigated metabolic changes within a large series of patients undergoing GPi stimulation.

OBJECTIVE: We assessed motor, cognitive and psychiatric changes, as well as modifications in brain glucose metabolism measured with FDG-PET, before and after bilateral GPi-DBS.

METHODS: In the same week, 32 patients with PD underwent a motor, cognitive and psychiatric assessment and a resting-state FDG-PET scan, 4 months before and 4 months after GPi-DBS surgery. For the voxelwise metabolic change assessment, the p value was controlled for multiple comparisons using the family wise error rate.

RESULTS: After GPi-DBS surgery, patients showed a significant overall improvement in motor status. No cognitive or psychiatric changes were observed after surgery. Nor were any clusters with significantly relative metabolic changes found in the limbic circuit after surgery. Clusters with significantly relative metabolic changes were observed in the left and right Brodmann area (BA) 6, the right BA 9, the right and left BA 39 and the left BA 17.

CONCLUSION: The present study confirmed that GPi-DBS is an effective treatment in patients with advanced PD, owing to metabolic changes in the areas involved in motor execution. The absence of relative metabolic decrease in the limbic circuit and the few changes affecting the associative circuit could explain why GPi-DBS is cognitively safe.