Hyolaryngeal Kinematics in Primary Muscle Tension Dysphonia Determined by Ultrasound

The purpose of this study was to determine hyolaryngeal kinematics during voicing in people with primary muscle tension dysphonia (pMTD) compared with healthy speakers, and to investigate the relationships between hyolaryngeal displacement and self-perceived vocal function.

Twenty-six participants, 13 with pMTD and 13 healthy speakers, were assessed using sonography during sustained vowel phonation and rest. Displacement of the hyoid bone and thyroid cartilage was measured from still frames extracted from ultrasound video recordings, with measures normalized to reflect change from rest during voicing for each participant. Vocal function was determined for all participants through self-perceived speaking effort and the Voice Handicap Index-10.

Normalized displacement of the hyoid bone and thyroid cartilage was significantly greater during voicing for participants with pMTD than for the healthy speakers. Weak-to-moderate, nonsignificant relationships between hyoid displacement and vocal function measures were evidenced, whereas moderate-to-strong, significant relationships were found for thyroid displacement and vocal function measures.

Displacement of the hyoid and elevation of the larynx during phonation appear to be prominent features of pMTD that differentiate the disorder from healthy phonatory kinematics. Ultrasound imaging provides a sensitive, reliable, noninvasive, and feasible method for objectively determining hyolaryngeal kinematics and may be useful for differential diagnosis and determination of treatment outcomes in pMTD.