The Effects of Deep Brain Stimulation on Deglutition in Parkinson Disease

Abstract

Relatively little is known about the role of the basal ganglia and their pathways in human deglutition. Deep Brain Stimulation (DBS) is a treatment for Parkinson Disease (PD) that stimulates the subthalamic nuclei and 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 DBS in the ON versus Off conditions on the oral and pharyngeal stages of deglutition in participants with PD. It was hypothesized that DBS in the ON condition would yield improvement in the following dependent variables: oral total composite score, pharyngeal total composite score, pharyngeal transit time, and maximal hyoid bone excursion. Statistically significant differences (improvement) were found for the pharyngeal composite score and pharyngeal transit time in the DBS ON condition. Findings of this study demonstrated that DBS in the ON condition helps to alleviate some of the bradykinesia and hypokinesia associated with PD on the pharyngeal stage of deglutition, but not the oral stage. These findings suggest that Parkinsonian swallowing dysfunction is not solely related to nigrostriatal dopamine deficiency which is purported to be the primary means of DBS alleviation of motor signs. Rather, it may be due to an additional non-dopamine related system of deglutition found in the brainstem.