Stimulation of the Thalamus to Ameliorate Persistent Disfluency

Suitable participants are referred by speech pathology centers, after having failed an intensive speech therapy program. Referred participants are contacted by the Neurosurgery DBS Clinic, and assessed for suitability and willingness to participate. These potential participants will be contacted by the DBS Clinic at Vancouver General Hospital to discuss the scope of the study, and educate them about deep brain stimulation. Those who wish to be included in the study will attend a face-to-face appointment at the DBS Clinic. At the initial appointment, informed consent will take place. Baseline assessments will be undertaken, including the Overall Assessment of the Speaker's Experience of Stuttering (OASES), Voice-related Quality of Life (VRQoL), and "The One Page Stuttering Assessment". The participants will be referred for a functional MRI for mapping of speech and language laterality. The participants will then undergo surgery for implantation of a bilateral thalamic DBS system. They will stay overnight in the hospital, and have a post-operative CT scan on the first post-operative day. This scan will be used to assess accuracy of electrode placement, as per usual technique. 4 weeks post-operatively, the participants will attend the DBS Clinic for programming of their devices. 4 weeks after device programming, the participants will attend the DBS clinic for 1-page stutter assessment with bilateral electrodes on, bilateral electrodes off, left electrode on, and right electrode on, as well as OASES and VRQoL. The scores from the 1-page stutter assessment, as well as pre- and post-operative OASES and VRQoL, will be compared via the Wilcoxan rank sum test for nonparametric repeated measures.