The effect of breathing exercises combined with manual therapy on muscle tension dysphonia in traditional singers: a blinded randomized controlled trial

Background Muscle tension dysphonia (MTD) is common in traditional singers and can lead to serious complications, but there is inconclusive evidence about how MTD should be treated in singers as professional voice users. This study was conducted to investigate the effects of breathing exercises combined with manual therapy versus breathing exercises and manual therapy on voice quality in traditional singers suffering from MTD. Methods In this blinded randomized clinical trial, 60 patients with MTD were randomly allocated to four groups: (1) breathing exercises, (2) manual therapy, (3) combined intervention (CI) and (4) control. Patients received treatments for 13 sessions, once per week. Treatment effects were assessed in terms of primary outcome measures: (1) breathing performance, measured by maximum phonation time (MPT) and (2) laryngeal function, measured by Stroboscopy Evaluation Rating Form (SERF). Secondary outcome measure was patient’s self-perceived voice handicap, measured by Persian version of Singing Voice Handicap Index (SVHIp). All outcome variables were measured before and after treatment. The between group comparisons on MPT and SVHIp score were investigated using analysis of covariance (ANCOVA). The Kruskal–Wallis non-parametric test was used for between group comparisons of SERF items. Results Three treatment groups had improved regarding breathing performance, laryngeal function and voice handicap over the time ( P < 0.01). The improvements achieved in all outcomes were significantly greater in the CI group than those of the breathing exercises, manual therapy and control groups. Conclusions This randomized controlled trial showed that th e combination of breathing exercises and manual therapy significantly improved the laryngeal function, breathing performance and voice handicap in traditional singers suffering from MTD. Trial registration: IRCT2015102524686N1.