Background and purpose: Persistent developmental stuttering is a frequent speech fluency disorder that can considerably reduce quality of life. Because available therapies do not always provide satisfying results, new therapeutic approaches are needed. The anomalous cerebral speech network in persons who stutter provides substrate for neuromodulation. We report here the effectiveness of deep brain stimulation (DBS) used for the first time to treat stuttering.
Methods: A 24-year-old male who stuttered severely since childhood received chronic left ventral intermediate thalamic nucleus electrical stimulation following a patient- and examiners-blinded two-year stimulation protocol. Stuttering frequency was determined as percent stuttered syllables and stuttering severity using the Stuttering Severity Instrument - 4th edition (SSI-4). The Overall Assessment of the Speaker's Experience of Stuttering - Adults (OASES-A) questionnaire quantified the patient's self-evaluated experience of stuttering and quality of life.
Results: The average stuttering frequency decreased by 46 % postoperatively and the stuttering severity by 29 %. The maximal achieved reduction of stuttering frequency was 62 % and of stuttering severity 39 %; self-assessment of stuttering improved by 38 %. Stuttering frequency was negatively associated with DBS stimulation frequency, demonstrating a biological stimulation effect beyond any potential placebo effects. Stuttering responded to stimulation parameter changes with a lag of several weeks, pointing to a rather slow modulatory than direct suppressive effect of deep brain stimulation on stuttering.
Conclusion: These results suggest deep brain stimulation as a new treatment option for severe stuttering and warrant further systematic exploration in a series of people who stutter.
Keywords: DBS; Dysfluency; Left ventral intermediate thalamic nucleus; Neurosurgery; Speech production; VIM.
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