Effects and Differences of Voice Therapy on Spasmodic Dysphonia and Muscle tension dysphonia: A Retrospective Pilot Study

Objectives. Laryngeal and voice findings of adductor spasmodic dysphonia (AdSD) and muscle tension dysphonia (MTD) are similar, and it is difficult to distinguish between both disorders. The purpose of this study is to ascertain the effect of voice therapy on MTD and AdSD and clarify their difference. Methods. A total of 49 patients, including 22 patients with MTD (MTD group) and 27 patients with AdSD (SD group), were included in the study. The MTD scores were evaluated, and aerodynamic analysis (maximum phonation time [MPT], mean airflow rate [MFR], highest pitch, lowest pitch, and pitch range), perceptual evaluation (Strangulation, Interruption, and Tremor), acoustic analysis (PPQ, APQ, NHR, and DVB), and subjective assessment (voice handicap index -10 [VHI-10]) were performed before and after voice therapy. Results. The MTD score, highest pitch, pitch range, strangulation, PPQ, APQ, NHR, and VHI-10 showed significant improvement after treatment in the MTD groups. On the other hand, the effect of voice treatment on AdSD was poor despite the improvement in the MTD score. Conclusions. This study could serve as a basis for conducting prospective studies to verify the effects of voice therapy on MTD and AdSD.