Efficacy of Voice Therapy Combined with Photobiomodulation in Women with Behavioral Dysphonia: A Triple-Blind Randomized Controlled Trial.

Abstract

To investigate whether active low-level laser therapy (LLLT) provides an incremental effect as an adjunct to a comprehensive voice therapy (VT) program, compared to VT combined with a placebo laser therapy (PLT), in women with dysphonia. This prospective, parallel-group, triple-blind, placebo-controlled clinical trial enrolled 46 women (18-60 years), with 39 completing the 8-week per-protocol analysis (VT-LLLT n = 22; VT-PLT n = 17). The experimental group received infrared LLLT (808 nm, 100 mW, 30 J) prior to VT, while the control group received a placebo laser. The primary outcome was the auditory-perceptual overall severity (OS) of dysphonia. Secondary outcomes included acoustic measures, vocal self-assessment, and laryngeal videostroboscopic parameters. Both groups demonstrated significant pre-to-post improvements across auditory-perceptual, self-assessment, and acoustic parameters, with no statistically significant Group × Time interaction for the primary outcome (OS) or any secondary functional variable. Conversely, laryngeal imaging evaluated via Generalized Linear Models (GLM) revealed a statistically significant Group × Time interaction for the recovery of the vocal fold edge contour (P = 0.005), indicating a localized morphological improvement in the VT-LLLT group. No adverse events were associated with the interventions. Although adjunctive active LLLT significantly accelerates the localized macroscopic restoration of the vocal fold edge contour, this structural change does not translate into superior functional, acoustic, or perceptual voice outcomes compared to placebo. Behavioral VT unequivocally remains the primary and dominant therapeutic driver for functional vocal recovery in women with dysphonia.