Background: The origin of weight gain after functional surgery for Parkinson's disease (PD) is incompletely known. We have done a prospective study to determine the possible causes of weight gain after pallidal and subthalamic surgery.
Patients and method: Twenty-seven patients were studied (9 unilateral pallidotomy, 9 bilateral deep brain stimulation (DBS) of palidum, and 9 bilateral DBS of suthalamic nucleus) with a follow-up of 12 months. The relationship between weight gain and changes in motor situation, levodopa dosage, dyskinesias, dysphagia and mood state were analyzed. The patients filled a questionnaire about the severity and etiology of weight gain.
Results: Weight gain was noted in 26 patients (mean of 4.7 kg at 12 months). It was found a significant correlation between weight gain and improvement of dyskinesias (AIMS) (r = 0.461; p = 0.023), the scores of the UPDRS part III, (r = 0.479; p = 0.028), and a significant inverse correlation with the pre-operative weight of the patient (r = 0.399; p = 0.050). Weight gain was most pronounced with bilateral than unilateral pallidal surgery (p = 0.021). The majority of patients referred weight gain as an slight adverse event and secondary to the improvement of dyskinesias.
Conclusion: Functional surgery for PD, independently of the surgical target, provokes weight gain which is benign in the majority of cases. Reduction of energy expenditure with respect to the pre-operative situation would be the responsible of that phenomenon.