Weight Gain following Pallidal Deep Brain Stimulation: A PET Study

Area of Science:

• Neuroscience
• Metabolic Research
• Neurosurgery

Background:

• Weight gain is a known side effect of deep brain stimulation (DBS) for Parkinson's disease (PD), but mechanisms vary by surgical target (subthalamic nucleus [STN] or globus pallidus internus [GPi]).
• Potential causes include reduced energy expenditure from motor improvement or alterations in behavior and metabolism.

Purpose of the Study:

• To investigate the relationship between changes in brain metabolism and weight gain in PD patients undergoing GPi-DBS.
• To determine if metabolic shifts or motor improvements are primary drivers of weight gain after GPi-DBS.

Main Methods:

• 19 PD patients had their Body Mass Index (BMI) measured before and after GPi-DBS.
• Brain metabolism was assessed using 2-deoxy-2[18F]fluoro-D-glucose Positron Emission Tomography (PET) scans pre- and post-surgery.
• Dopaminergic medication effects on metabolism were controlled for.

Main Results:

• A significant increase in BMI (0.66 ± 1.3 kg/m2) was observed post-GPi-DBS (p = 0.040).
• Weight gain correlated with metabolic changes in premotor and somatosensory areas (BA 6, 8, 7, 9, 46).
• No correlation was found between weight gain and metabolic changes in limbic/associative areas; a trend suggested reduced dyskinesia correlated with weight gain (p=0.067).

Conclusions:

• Motor improvement, rather than metabolic alterations, appears to be the primary driver of weight gain following GPi-DBS in PD patients.
• These findings support the motor-selective effects of GPi-DBS, distinguishing it from STN-DBS regarding weight changes.