Long Term Follow up of Weight Changes in STN and GPi Deep Brain Stimulation

Congratulations to Drs. Shah, Almeida, Okun, and Wagle-Shukla on the publication of “Long Term Follow up of Weight Changes in STN and GPi Deep Brain Stimulation,” in the April 23rd edition of Neurology.


Objective: To determine the impact of deep brain stimulation (DBS) in long term followup of post-operative weight changes in Parkinson’s disease (PD)

Background: Patients have been observed to experience weight gain following DBS, however specific phenotypes of predisposed patients, specific target associations, and long term followup has not been widely reported

Design/Methods: A retrospective chart review of PD DBS patients implanted at the University of Florida targeting subthalamic (STN) or globus pallidus interna (GPi) was conducted and included the period between January 2005 and December 2014. Clinical, demographic, and weight change data was recorded at baseline (pre-surgery) and at 6,12,24 and 36 months postoperatively. A repeated measures analysis of variance (ANOVA) was performed to evaluate changes in mean weight at each of the targets across different time points, assuming a p=0.05 for statistical significance.

Results: Preliminary results revealed that 91 patients had unilateral DBS (52 GPi and 39 STN) and 78% were male. There was a mean age of 64±8.9 and 63.1±9.6 years for GPi and STN subgroups. Forty-two patients (21 GPi and 21 STN) completed 3-years of follow-up. Both GPi and STN groups gained weight during the first 6 months post-surgery (1.7% and 2.2% increase for GPi and STN, respectively). However, subsequent visits revealed at 3-year follow-up a gradual average weight gain for the STN group (additional 1.5% weight gain), contrasting with a gradual weight loss in the GPi group (3.8% weight loss) (p=0.169).

Conclusions: These preliminary data suggests that DBS though leading to weight gain initially in both targets, may be associated with weight loss in GPi target at longer term followup. It is possible that during interdisciplinary screening GPi targets were inadvertently selected for patients prone to lose weight secondary to a disease phenotype or due to comorbidities. Future studies will be needed to further clarify the mechanisms and to test with a better randomization of targets.