Electronic Theses and Dissertations

Date of Award


Document Type


Degree Name

M.S. in Communication Sciences and Disorders


Communication Sciences and Disorders

First Advisor

Myriam Kornisch

Second Advisor

Toshikazu Ikuta

Third Advisor

Hyejin Park

Relational Format



Purpose: Speech fluency changes following deep brain stimulation are one aspect that is crucial to consider when exploring treatments for Parkinson’s disease. Deep brain stimulation, specifically of the subthalamic nucleus, has been linked to a decrease in speech fluency despite improved bodily motor control. This acquired dysfluency is referred to as “neurogenic stuttering.” The purpose of the current study is to determine the incidence and severity of speech fluency decline following deep brain stimulation in patients with Parkinson’s disease. A meta-analysis was conducted with 7 studies (239 subjects) that recorded changes in speech fluency. All studies used a quantitative assessment, and included the levodopa equivalent dose (LED) for recording motor speech symptoms and pharmacological management among Parkinson’s disease patients. The results show that speech fluency decreases in patients who have deep brain stimulation in the “on” state, regardless of their baseline fluency levels with deep brain stimulation “off.” The overall effect size of deep brain stimulation on speech fluency was -0.61, which indicates a medium or moderately negative effect.

Available for download on Thursday, August 15, 2024