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

AIM: 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). MATERIAL and METHODS: 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.RESULTS: 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. CONCLUSION: 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.