Efficacy of Manual Circumlaryngeal Therapy in Patients with Muscle Tension Dysphonia

Objectives: The aim of this study was to evaluate the effects of manual circumlaryngeal therapy after one session of treatment on the voice of patients with muscle tension dysphonia. Methods: A total of 20 patients with muscle tension dysphonia were evaluated by recording vowel /a/ phonation and extracting fundamental frequency (F0), first formant frequency (F1), jitter, shimmer, and harmonics-to-noise ratio (HNR). One session of manual circumlaryngeal therapy was held for these patients. Immediately after treatment, acoustic assessments were replicated. Results: Following manual circumlaryngeal therapy, jitter and shimmer showed a significant reduction (P < 0.009), while HNR improved significantly versus pretreatment (P < 0.001). The mean changes in F0 were not significant, whereas a significant reduction was observed in F1 parameter (P < 0.009). Conclusions: The reduction in jitter and shimmer and increase in HNR after therapy resulted in the patients’ vocal improvement. Reduction of F1 after treatment suggests elongation of vocal tube and elimination of vocal tract shortness in response to the descent of larynx from its high-tension status. The insignificant change of F0 was attributed to the lack of change in vibrational characteristics, as well as stretching of vocal cords.