Objective: Laryngeal dystonia (LD) is a task-specific focal dystonia characterized by involuntary spasms of the laryngeal musculature that impairs speech and communication. Prior research demonstrated that a one-time application of vibrotactile stimulation (VTS) improved voice and speech quality in 69% of LD patients (Khosravani et al. 2019). This study investigated the usability and feasibility of prolonged use of laryngeal VTS at home as a symptomatic treatment for LD.
Method: 32 LD patients (mean age: 62.3 ± 15.2 years; 21 females, 11 males) applied VTS over the thyroid cartilage for an 8-week period at home. Daily VTS dosage was 20 minutes. Participants progressively increased the number of VTS sessions from 3 days in week 1 to 6 days in week 4, followed by four weeks of self-selected VTS dosage to find an optimal dosage for effective symptom management. Participants administered VTS at 100Hz during the first four weeks and could change the frequency between 100-150Hz in the second four weeks. The first cohort (n = 15) secured the vibrators on the skin using double-sided tape, while the second cohort (n = 17) used a wearable custom-designed fabric collar with inserted vibrators worn around the neck. Outcome measures were perceived speech effort (PSE; scale 1-10, 10 = maximum effort) and relative change in PSE.
Results: Within a session, VTS reduced mean PSE across all participants by 13.5% (range: -9 to 44%) in the first 4 weeks. Across sessions, 63% of participants reported reduced speech effort after VTS. Compared to direct skin contact VTS, the use of the collar induced a similar relative PSE change (Tape: M = 14.9%; Collar: M = 12.6%; p > 0.05). In 67% of participants, single-session VTS effects lasted from 30 minutes to more than 1 day. 70% of participants considered using VTS in the future as adjuvant or as a supplement to Botox therapy.
Conclusion: VTS could reduce speech effort in people with LD with lasting effects and high patient acceptance. The collar was easier to use than applying tape to the skin. Results document that laryngeal VTS is a feasible, non-invasive in-home treatment option for LD.