The effect of deep brain stimulation randomized by site on balance in Parkinson’s disease

Background: The effect of the surgical site of DBS on balance and gait in Parkinson’s Disease (PD) is uncertain. This is the first double-blind study of subjects randomized to either the STN (N 5 14) or GPi (N 5 14) who were assessed on a range of clinical balance measures. Methods: Balance testing occurred before and 6 months postsurgery. A control PD group was tested over the same period without surgery (N 5 9). All subjects were tested on and off medication and DBS subjects were also tested on and off DBS. The Postural Instability and Gait Disability items of the UPDRS and additional functional tests, which we call the Balance and Gait scale, were assessed. Activities of Balance Confidence and Activities of Daily Living questionnaires were also recorded. Results: Balance was not different between the besttreated states before and after DBS surgery for both sites. Switching DBS on improved balance scores, and scores further improved with medication, compared to the off state. The GPi group showed improved performance in the postsurgery off state and better ratings of balance confidence after surgery, compared to the STN group.