The general aim of the study was to provide evidence for the usability and feasibility of applying vibro-tactile stimulation (VTS) at home as a non-invasive form of neuromodulation to improve speech in people with spasmodic dysphonia (laryngeal dystonia). This work addresses a clinical need to develop alternative or auxiliary treatments for a rare voice disorder with limited treatment options.
Participants with either adductor or abductor-type of spasmodic dysphonia applied VTS at home for a period of 2 months. During the first four weeks they gradually increased their weekly dosage from 3 to 6 days per week. Each application per day lasted 20 minutes.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
TREATMENT
Masking
NONE
Enrollment
40
Participants received vibro-tactile stimulation (VTS) as a non-invasive treatment option. Stimulators were a pair of light-weight encapsulated cylindrical vibrators applied to both sides of the larynx (voice box). The vibration frequency for VTS was set be to 100Hz. During VTS, participants feel a mild tingling or vibrating sensation at their larynx. They applied VTS at home over a period of 8 weeks with a daily dosage of 20 minutes. During weeks 1-4, the weekly dosage of VTS was gradually increased (week 1: 3 days/wk; week 2: 4 days/wk; week 3: 5 days/wk; week 4: 6 days/wk). During weeks 5-8, participants applied VTS on self-selected days as needed, not exceeding 6 times a week.
University of Minnesota
Minneapolis, Minnesota, United States
Perceived Speech Effort (PSE) at Week 4
Perceived Speech Effort was self-rated by participants on a 0-10 scale (0 = no effort, 10 = maximum effort) while reading standardized sentences at habitual pitch and loudness. Ratings were collected immediately before and after each vibro-tactile stimulation session. The PSE value reported here reflects the group mean at week 4.
Time frame: Week 4
Perceived Speech Effort (PSE) at Week 8
Perceived Speech Effort was self-rated by participants on a 0-10 scale (0 = no effort, 10 = maximum effort) while reading standardized sentences at habitual pitch and loudness. Ratings were collected immediately before and after each vibro-tactile stimulation session. The PSE value reported here reflects the group mean at week 8.
Time frame: Week 8
Voice Quality Change (VQC) at Week 1
Voice Quality Change (VQC) was self-assessed using a 5-point Likert scale (1 = very unnoticeable, 5 = very noticeable; 3 = neutral). Ratings were recorded at the end of each VTS session. VQC at week 1 represents a baseline measure of symptom severity. It was computed as the mean of the first three sessions of VTS of the study.
Time frame: Week 1
Voice Quality Change (VQC) at Week 8
Voice Quality Change (VQC) was self-assessed using a 5-point Likert scale (1 = very unnoticeable, 5 = very noticeable; 3 = neutral). Ratings were recorded at the end of each VTS session. The score reflects the overall longitudinal change in symptoms experienced after treatment end. VQC at week 8 was computed as the mean of the last three sessions of the study.
Time frame: Week 8
Relative Change in Perceived Speech Effort (rPSE) for VTS Application Method
Relative change in PSE (rPSE) was calculated as \[(Post - Pre) / Pre\] × 100. The between-group difference in mean rPSE comparing VTS received during direct skin contact vs. VTS collar was assessed over the total study period of 8 weeks to understand if the VTS applied directly to the skin was more effective in reducing speech effort than VTS applied via the collar.
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Time frame: 8 weeks
Adherence Rate (Feasibility)
Number of participants who completed at least 80% of prescribed VTS sessions during the intervention period.
Time frame: Week 1-4