Introduction: Gait abnormalities are particularly challenging to subjects with Parkinson’s disease (PD) due to increased fall risk. These risks may be increased under conditions of simultaneous cognitive loading. In fact, bilateral STN DBS has been shown to impair upper extremity function under cognitive loads. The aim of this study was to compare the effects of unilateral and bilateral STN DBS on gait with and without cognitive loading in advanced Parkinson’s disease.
Methods: Seventeen advanced PD subjects (ages 50 to 74 years) who had bilateral STN DBS surgery at least 6 months prior were studied, off medications. All data were collected while subjects were off their anti-parkinsonian medication for at least 12 hours. Quantitative gait information was collected with a pressure-sensor mat (GaitRite) during three stimulation states: left stimulation, right stimulation and bilateral stimulation. For each stimulation state, subjects performed three tasks: gait alone, gait while counting by 3s, and gait while naming alternate letters of the alphabet.
Results: As gait task complexity increased, there was a significant decline in performance for all stimulation states. Unilateral stimulation performance was comparable to bilateral stimulation performance for most gait parameters. However, bilateral stimulation surprisingly demonstrated improvement in step length and double leg support time, compared to unilateral stimulation, under conditions of cognitive loading.
Conclusions: These results underscore the efficacy of bilateral subthalamic nucleus stimulation over unilateral stimulation on gait under dual-task conditions. Our findings suggest that differential advantages of bilateral and unilateral stimulation may occur for upper and lower extremity tasks under cognitive loads.
Patient Care: Gait is an important consideration for STN DBS. This work indicates that bilateral STN DBS will not impair gait over unilateral stimulation under cognitive loading.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the major effects of Parkinsons Disease and cognitive loading on gait, 2) Understand the differential effects of unilateral and bilateral stimulation on gait