[Weight gain after functional surgery for Parkinsons disease]

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.

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.

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.

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.