Effects of deep brain stimulation on vocal fold immobility in Parkinson's disease

BACKGROUND: Vocal fold (VF) immobility is a rare, potentially fatal complication of advanced Parkinson's disease (PD). Previous reports suggest that subthalamic nucleus deep brain stimulation (STN-DBS) may influence laryngeal function, yet the role of STN-DBS on VF immobility remains unexplored. CASE DESCRIPTION: We report a case of a patient with advanced PD and bilateral VF immobility ultimately requiring a tracheostomy. To assess the effects of STN-DBS on vocal cord function and to correlate these effects with peripheral motor symptoms at different stimulation settings, the patient was evaluated before and after initiation of bilateral STN-DBS. Measures included direct observation of VF mobility via transnasal laryngoscopy, levodopa equivalent dose of anti-PD medication, and motor scores. High frequency (150 Hz) STN-DBS resulted in improved motor scores, reduced medication requirement, and modestly improved right VF abduction although insufficient for safe decannulation. Low frequency (60 Hz) stimulation resulted in lower motor scores, but without worsening VF abduction. CONCLUSIONS: STN-DBS may play an important role in the neuromodulation of PD-induced laryngeal dysfunction, including VF mobility. Characterization of these axial symptoms is important when programming and evaluating responsiveness to DBS.