Brain function in spasmodic dysphonia: A functional MRI study

• DOI: 10.1121/1.425983
• Publication Date: 2002-07-26T14:21:02Z
• Authors: Masanobu Kumada; Einar Mencl; Kenneth R. Pugh; R. Todd Constable; Fredericka Bell-B...; Douglas N. Honorof; Vincent L. Gracco

The symptoms of spasmodic dysphonia (SD) are caused by the hyperadduction or hyperabduction of the vocal folds, but its mechanism is unknown. The purpose of this study is to locate dysfunctional regions in the brains of SD patients by functional MRI (fMRI) and to identify the mechanism of this disorder. The extrapyramidal system works normally as a stabilizer of muscle activities. This hypothesis is that its dysfunction (especially in the basal ganglia and brainstem) causes instability of the activity of the vocalis muscle which induces symptoms (voice break, etc.). The data for four normal subjects have been obtained, and sessions for four SD patients are planned. The tasks are: isolated phonations of /a/ in chest register (Ch); isolated phonations of /a/ in falsetto register (Fa); and breathing naturally for baseline (Br). Subjects phonate in Ch and Fa to visual cues given every 2 s. Each scan consists of nine 20-second blocks of tasks (2 Chs, 2 Fas, 5 Brs), and is repeated four times with counterbalanced task order. Imaginary phonation scans for Ch and Fa, in which subjects just imagine phonation without actually setting the vocal cords into vibration, are also repeated four times.