Voice over time: long-term effects of therapy in muscle tension dysphonia with a 24-month follow-up.

OBJECTIVE

Muscle tension dysphonia (MTD) is the most common functional voice disorder worldwide, yet evidence on the long-term effectiveness of voice therapy remains scarce. This study aimed to evaluate the sustainability of therapeutic outcomes in patients with MTD over a treatment-free period of at least 24 months.

METHODS

Fifty-five participants were included: 25 patients with MTD and 30 healthy controls. All patients with MTD underwent an eight-week structured voice therapy program consisting of vocal hygiene education, relaxation techniques, resonant voice therapy, and laryngeal manual therapy. Assessments included videolaryngoscopic examination, acoustic analysis (F0, jitter, shimmer, NHR, VTI, SPI), and self-reported measures (Voice Handicap Index-10, Vocal Tract Discomfort Scale). Evaluations were conducted pre-therapy, post-therapy, and at least 24 months after treatment completion. Statistical analyses were performed using independent samples t-tests, Mann-Whitney U, Wilcoxon signed ranks, and chi-square tests.

RESULTS

At baseline, patients with MTD reported significantly higher VHI and VTDS scores compared to controls (p < 0.001), although acoustic parameters showed no significant differences. Following therapy, significant improvements were observed in jitter, shimmer, NHR, VTI, and all self-reported outcomes (p < 0.05). At the 24-month follow-up, most therapeutic gains were maintained, with no significant deterioration in acoustic parameters and sustained reductions in VHI and VTDS scores compared to baseline (p < 0.001). A subgroup of seven patients demonstrated resistance to therapy, with limited improvement in both early and long-term follow-up.

CONCLUSION

Voice therapy yields significant and durable improvements in both acoustic and self-reported outcomes in MTD, with benefits sustained for at least 24 months after treatment. Early recognition of resistant cases is critical, as these individuals may require booster sessions or adjunctive therapeutic approaches.