Articulatory Closure Proficiency in Patients With Parkinson's Disease Following Deep Brain Stimulation of the Subthalamic Nucleus and Caudal Zona Incerta

PURPOSE: The present study aimed at comparing the effects of deep brain stimulation (DBS) treatment of the subthalamic nucleus (STN) and the caudal zona incerta (cZi) on the proficiency in achieving oral closure and release during plosive production of people with Parkinson's disease. METHOD: Nineteen patients participated preoperatively and 12 months after DBS surgery. Nine patients had implantations in the STN, 7 bilaterally and 2 unilaterally (left). Ten had bilateral implantations in the cZi. Postoperative examinations were made off and on stimulation. All patients received simultaneous L-dopa treatment in all conditions. For a series of plosives extracted from a reading passage, absolute and relative measures of duration of frication and amplitude of plosive release were compared between conditions within each treatment group. RESULTS: Relative duration of frication increased in voiceless plosives in the on-stimulation condition in cZi patients. Similar trends were observed across the data set. Duration of prerelease frication and the release peak prominence increased in voiceless plosives on stimulation for both groups. CONCLUSION: The increased release prominence suggests that patients achieved a stronger closure gesture because of DBS but that the increased energy available resulted in increased frication.