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Bilateral subthalamic (STN) deep brain stimulation (DBS) is generally effective in improving the cardinal motor signs of advanced Parkinson's disease (PD). However, in many cases postural instability is refractory to STN DBS. The goal of this project was to determine if postural instability could be improved with STN DBS by avoiding current spread to the non-motor territories of the STN. Stimulation parameters that maximized activation of a theoretically defined target region were determined via patient-specific computer models created in Cicerone. Postural stability was assessed under three conditions: Off DBS, Clinical DBS, and Model DBS. Clinical settings were the patients' DBS settings determined via traditional clinical practice and were considered optimized and stable for at least 6 months prior to study enrollment. Blinded and randomized evaluations were performed in five patients. Postural sway was significantly less during Model DBS compared to Clinical DBS. These results support the hypothesis that minimizing spread of current to non-motor territories of the STN can improve PD related instability with DBS.

Bilateral subthalamic (STN) deep brain stimulation (DBS) is effective in improving the cardinal motor signs of advanced Parkinson's disease (PD); however declines in cognitive function have been associated with this procedure. The aim of this study was to assess cognitive-motor performance of 10 PD patients implanted with STN DBS systems during either clinically determined stimulation settings or settings derived from a computational model. Cicerone DBS software was used to define the model parameters such that current spread to non-motor areas of the STN was minimized. Clinically determined and model defined parameters were equally effective in improving motor scores on the traditional clinical rating scale (UPDRS-III). Under modest dual-task conditions, cognitive-motor performance was worse with clinically determined compared to model derived parameters. In addition, the model parameters provided a 66% reduction in power consumption. These results indicate that the cognitive-motor declines associated with bilateral STN can be mitigated, without compromising motor benefits, utilizing stimulation parameters that minimize current spread into non-motor regions of the STN.