Objective: To evaluate the short-term efficacy of a wearable vibrotactile stimulation (VTS) device in patients with laryngeal dystonia (LD) prior to botulinum toxin (BoNT) injection, using the voice breaks/maximum phonation time (MPT) ratio and perceived speaking effort (PSE) as outcomes, and to assess persistence after device removal.

Background: Laryngeal dystonia (LD) is a focal dystonia characterized by involuntary laryngeal spasms causing voice breaks and increased speaking effort. Vibrotactile stimulation (VTS) may modulate abnormal sensorimotor activity and has been proposed as a non-invasive adjunct to botulinum toxin (BoNT) injection [1],[2].

Method: This within-subject, single-blind study with a sham condition included patients with laryngeal dystonia scheduled for BoNT injection. The fixed sequence comprised baseline, 5 minutes device OFF (sham), 5 minutes device ON, continued stimulation to 20 minutes total ON, and reassessment 15 minutes after deactivation. At each timepoint, participants sustained /a/ for 10 seconds. Voice breaks and maximum phonation time (MPT) were recorded, with the voice breaks/MPT ratio as the primary acoustic endpoint. Perceived speaking effort (PSE, 0–10) was rated after sentence repetition.

Results: Twenty-six patients were included (25 female; mean age 59.6±13.5 years; disease duration 4.69±3.39 years; baseline VHI 73.35±24.16, first vs repeat injection: 9 vs 17). PSE improved during sham wearing (6.77±2.10 to 5.62±2.12; Δ −1.154, p<0.0001) and showed further improvement with active stimulation versus sham (4.73±2.05 vs 5.62±2.12; Δ −0.885, 95%CI −1.252 to −0.517; paired t p=0.000041; Wilcoxon p=0.000478; dz=−0.973). Improvement persisted 15 minutes after removal (Δ −2.08 vs baseline; p=1.46×10⁻⁷; 84.6% responders; Δ −0.92 vs sham; p=0.0010).

The voice breaks/MPT ratio did not differ between active and sham (Δ +0.225; p=0.381; Wilcoxon p=0.745) and showed no sustained effect (p=0.856). MPT increased during sham (+1.69 s; p=0.058) without additional active benefit (Δ −0.42 s; p=0.343)

Conclusion: In this sham-controlled study, VTS significantly and persistently reduced speaking effort in LD prior to BoNT injection. Although acoustic measures did not differ from sham, the controlled design clarifies the symptomatic profile of VTS and suggests a perceptual–sensorimotor effect requiring further investigation.

References: [1] Konczak J, Bhaskaran D, Elangovan N, Oh J, Goding GS, Watson PJ. Effects of an 11-week vibro-tactile stimulation treatment on voice symptoms in laryngeal dystonia. Front Neurol. 2024;15:1403050. Published 2024 May 30. doi:10.3389/fneur.2024.1403050
[2] Mahnan A, Xu J, Oh J, et al. Laryngeal Vibration to Treat Abductor-Type Laryngeal Dystonia: Effectiveness and Cortical Response. Laryngoscope. 2026;136(1):368-376. doi:10.1002/lary.70020

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MDS Abstracts - https://www.mdsabstracts.org/abstract/short-term-effects-of-wearable-vibrotactile-stimulation-in-laryngeal-dystonia/