Abstract
Deep brain stimulation of the subthalamic nucleus (STN-DBS) in patients with Parkinson’s disease (PD) affects speech in small, inconsistent ways. However, voice intensity generally increases. Recently the caudal zona inserta (cZi) has been investigated as an alternate target in DBS treatment of PD. The effects of cZi-DBS on voice intensity have not yet been investigated. The aim of this study was to compare the voice intensity effects of cZi-DBS and STN-DBS in PD patients. Voice intensity during reading and intensity decay during rapid syllable repetition were measured for eight STN-DBS and eight cZi-DBS patients in a pre-surgical baseline and then on- and off-stimulation 12 months after surgery. Voice intensity on-stimulation was larger than off-stimulation for the STN-DBS patients, but smaller for the cZi-DBS patients. There were no significant changes in intensity decay. The results suggest that cZi and STN are involved differently in neuromuscular control of the speech respiratory subsystem.