The effect of bilateral subthalamic nucleus deep brain stimulation (STN-DBS) on the acoustic and prosodic features in patients with Parkinson's disease: A study protocol for the first trial on Iranian patients.

The effect of subthalamic nucleus deep brain stimulation (STN-DBS) on the voice features in Parkinson's disease (PD) is controversial. No study has evaluated the voice features of PD underwent STN-DBS by the acoustic, perceptual, and patientbased assessments comprehensively. Furthermore, there is no study to investigate prosodic features before and after DBS in PD. The current study aimed to assess the efficacy of STN-DBS on the voice and prosodic features by acoustic, perceptual and self-reported evaluations in PD. An experimental prospective cohort pretest-posttest group has been designed to survey patients with PD candidates for STN-DBS surgery. All participants will be evaluated by a speech and language pathologist before and after surgery in four different conditions as follow: pre-surgery: Medication On/ Medication Off; post-surgery: Stimulation On/ Stimulation Off. To compare pre-surgery and post-surgery conditions paired- samples T Test or Wilcoxon signed-rank test will be used. A 95% confidence interval (p value of <0.05) will be considered to be statistically significant. This study protocol is approved by the Ethical Committee of Teheran University of Medical Sciences, and the results of the study will be published in a peer-reviewed journal and presented at national congresses.