Weight gain after deep brain stimulation tied to electrode location in subthalamic nucleus

Key takeaways:

• Medial-lateral electrode position in the right subthalamic nucleus correlated with weight gain, with greater gains from medial to lateral.
• Location in the left STN was not associated with weight change.

CHICAGO — Active electrode placement in the right subthalamic nucleus in deep brain stimulation was associated with weight gain in patients with Parkinson’s disease, with lesser gain reported with medially placed electrodes.

“We know that there is weight gain after [deep brain stimulation] surgery, but it’s currently unknown exactly why that happens,” Amelia L. Heston, MD, clinical instructor in the department of neurology at Michigan Medicine, told Healio at the International Association of Parkinsonism and Related Disorders World Congress.

Heston and colleagues examined the relationship between electrode contact location in deep brain stimulation (DBS) and subsequent weight gain, as current data linking electrode location to postprocedural weight gain are inconsistent.

They conducted a retrospective study of 83 individuals (mean age, 62.7 years; 69.8% men) who underwent subthalamic nucleus stimulation in the University of Michigan Surgical Therapies Improving Movement program between 2009 and 2019. Participants were weighed before and at 6 and 12 months after the procedure, which entailed DBS electrodes implanted into each subthalamic nucleus (STN) with the tip of the lead placed near the ventral border of the STN. Two weeks after the procedure, participants underwent a head CT scan.

Researchers defined the location of the active electrode contact as the distance to the STN midpoint — between the STN rostral and caudal poles — and identified six variables along X, Y and Z axes in the left and right STNs. They used an ordinary least squares regression model to evaluate the role of contact location on patient weight at follow-ups controlling for baseline weight.

According to results, mean weight increased by 12.4 pounds from baseline after DBS (175.9 vs. 188.3 pounds), with 72 participants gaining weight and 11 losing weight. Baseline weight for men was 47.9 pounds more than women, but weight change between sexes after the procedure was not statistically significant.

Researchers reported that although electrode contact locations in the left STN were not associated with weight change, medial-lateral placement in the right STN did correlate with weight gain, with greater gain from medial to lateral STN.

Additionally, age and disease duration were associated with lower weight at baseline and follow-up and change in levodopa equivalent dosing was inversely linked with weight gain.

Although researchers acknowledged these findings are not likely to affect current practices on electrode placement, Heston noted, “We might help counsel patients whether or not they could expect weight gain depending on the location and active electrode contact.”