Effects of Subthalamic Nucleus Deep Brain Stimulation Surgery on Voice and Formant Frequencies of Vowels in Turkish.

Abstract

To investigate the effects of deep brain stimulation (DBS) of the subthalamic nucleus (STN) on acoustic characteristics of voice production in Turkish patients with Parkinson's disease (PD). This study recruited 20 patients diagnosed with PD. Voice samples were recorded under the "stimulation on" and "stimulation off" conditions of STN-DBS. Acoustic recordings of the patients were made during the production of vowels /a/, /o/, and /i/ and repetition of the syllables /pa/-/ta/-/ka/. Acoustic analyses were performed using Praat. A significant difference in the parameters was observed among groups for vowels. A positive significant difference was observed between preoperative med-on and postoperative med-on/stim-on groups for /a/ and the postoperative med-on/ stim-on and postoperative med-on/stim-off groups for /o/ and /i/ for frequency perturbation (jitter) and noise-to-harmonics ratio. No significant difference was noted between the preoperative med-on and postoperative med-on/stim-off groups for any vowels. STN-DBS surgery has an acute positive effect on voice. Studies on formant frequency analysis in STN-DBS may be expanded with both articulation and intelligibility tests to enable us to combine patient abilities in various perspectives and to obtain precise results.