Effectiveness of Edge Therapy: A Randomized Clinical Trial for Muscle Tension Dysphonia.

Abstract

Objective: This study investigated the effectiveness of "Edge Therapy" (ET) for improving glottal closure in singers with primary muscle tension dysphonia (MTD-1).

Study design: Double-blind randomized clinical trial.

Methods: Forty adult male singers with MTD-1 were recruited using convenience sampling method from a university otolaryngology clinic. The participants were randomly assigned to either laryngeal manual therapy (LMT) plus sham therapy (control group, CG), or LMT plus ET (Edge Therapy Group, ETG). All participants received eight treatment sessions and were evaluated before, immediately after, and at 2-week follow-up using videolaryngostroboscopy, acoustic voice analysis, auditory-perceptual ratings, and the Persian Singing Voice Handicap Index (SVHI). Data from 31 participants (14 CG and 17 ETG) were available for analysis using repeated measures analysis of variance and the Friedman test, respectively, based on data normality.

Results: Although no significant differences were found between the groups for acoustic measures (F0, jitter, shimmer, and harmonics-to-noise ratio), auditory-perceptual ratings improved more in the ETG, with 94% of participants scoring 6 or higher compared with 72% in the CG (P < 0.001). Glottal closure also improved significantly in both groups, with greater improvements in the ETG. MTD type shifted toward reduced supraglottic involvement in both groups. SVHI scores decreased significantly post treatment and at follow-up, with more prominent improvements in the ETG (P < 0.001).

Conclusion: Both LMT and ET were effective in improving vocal quality, laryngeal function, and reducing self-perceived vocal handicap in singers with MTD-1. The addition of ET to LMT provided superior benefits, particularly in perceptual measures and glottal closure.