Effect of Dorsal and Ventral Subthalamic Nucleus Deep Brain Stimulation on Actual and Perceived Sense of Postural Balance (P7.059)

OBJECTIVE:To investigate the effect of STN DBS localization on postural balance (sway) and perceived sense of balance in dynamic and static test conditions. BACKGROUND:The effect of STN DBS on postural balance remains controversial. The ability of PD patients to accurately perceive their risk of falling and whether STN DBS localization has any effect on this ability is unclear. DESIGN/METHODS:Six subjects with advanced idiopathic PD and bilateral STN DBS, with at least one dorsal and one ventral STN DBS contact bilaterally, were tested for postural balance (using a strain-gauge force platform) in a double-blind fashion during three DBS conditions (after overnight withdrawal of medication): bilateral DBS of either the dorsal or ventral STN and both stimulators off. Sway length (SL) and sway area (SA) were measured in static test conditions (EO, EC, FO, and FC) and dynamic test conditions (SLT-GL, SLT-PL, RBRT-GL, and RBRT-PL) designed to simulate daily living tasks. The Perceived Sense of Postural Sway and Instability (PSPSI) scale was administered immediately after each postural balance test to evaluate the PSPSI of each patient. RESULTS:DBS localization did not affect SL significantly during static conditions. However, SL was significantly greater with ventral in comparison to dorsal stimulation during SLT-GL. During EC, FO, and SLT-GL, SA was significantly greater with ventral DBS in comparison to dorsal and “off” DBS. PSPSI rating was significantly lower with ventral DBS in comparison to “off” DBS during FO and FC. In addition, PSPSI rating was lowest with ventral stimulation in every test condition, with the exception of RBRT-GL. Gait velocity was significantly improved by both ventral and dorsal DBS. CONCLUSIONS: The current study demonstrated that a mismatch between actual and perceived balance exists in PD patients. Stimulation of the ventral STN further increases this mismatch and may increase fall risk. Study Supported by: The Gardner Family Center Research Grant, the Davis Phinney Foundation, and the C incinnati Veterans Affairs Medical Center. Disclosure: Dr. Larsh has nothing to disclose. Dr. Eskenazi has nothing to disclose. Dr. Urrea Mendoza has nothing to disclose. Dr. Mani has nothing to disclose. Dr. Bhattacharya has received personal compensation for activities with OsteoDynamics, Inc., as a member of the Board of Directors. Dr. Bhattacharya holds stock and/or stock options in OsteoDynamics Inc., which sponsored research in which Dr. Bhattacharya was involved as an investigator. Dr. Bhattacharya holds stock and/or stock options in OsteoDynamics Inc. Dr. Bhattacharya has received research support from OsteoDynamics Inc. Dr. Duker has nothing to disclose. Dr. Cox has nothing to disclose. Dr. Gartner has nothing to disclose. Dr. Revilla has nothing to disclose.