Subthalamic nucleus deep brain stimulation improves deglutition in Parkinson's disease

Relatively little is known about the role of the basal ganglia in human deglutition. Deep brain stimulation (DBS) affords us a model for examining deglutition in humans with known impairment of the basal ganglia. The purpose of this study was to examine the effects of subthalamic nuclei (STN) DBS on the oral and pharyngeal stages of deglutition in individuals with Parkinson's Disease (PD). It was hypothesized that DBS would be associated with improved deglutition. Within participant, comparisons were made between DBS in the ON and OFF conditions using the dependent variables: pharyngeal transit time, maximal hyoid bone excursion, oral total composite score, and pharyngeal total composite score. Significant improvement occurred for the pharyngeal composite score and pharyngeal transit time in the DBS ON condition compared with DBS OFF. Stimulation of the STN may excite thalamocortical or brainstem targets to sufficiently overcome the bradykinesia/hypokinesia associated with PD and return some pharyngeal stage motor patterns to performance levels approximating those of "normal" deglutition. However, the degree of hyoid bone excursion and oral stage measures did not improve, suggesting that these motor acts may be under the control of different sensorimotor pathways within the basal ganglia.