Relationship Between 3D Behavior of the Unilaterally Paralyzed Larynx and Aerodynamic Vocal Function

Abstract

Objective—We used multi-slice helical computerized tomography (MSHCT) to evaluate the 3D characteristics of the laryngeal structures in patients with unilateral vocal fold paralysis (UVFP) during phonation, and compared the results with those obtained using an aerodynamic vocal function test. Material and methods—The subjects were 37 patients with UVFP. The region over the larynx was scanned during quiet phonation and again during inspiration using MSHCT, and 3D endoscopic and coronal reconstruction images were produced. Maximum phonation time (MPT) and mean airflow rate (MFR) during phonation were measured. Results—During phonation, the affected fold was thinner than the healthy fold in 30 subjects and located at a higher position than the healthy fold in 21 subjects. Abduction or thinning of the affected fold during phonation (paradoxical movement) was seen in seven subjects. MFR was significantly greater when the affected fold was thinner than the healthy fold during phonation, and MPT was significantly shorter when the affected fold showed paradoxical movement. Over-adduction of the healthy fold during phonation was present in 15 subjects. There were no significant differences in MPT or MFR between subjects with and without over-adduction. Conclusion—The combination of MSHCT endoscopic and coronal reconstruction images enables the 3D characteristics of the unilaterally paralyzed larynx to be visualized during phonation, and some of these characteristics are significantly correlated with vocal function in patients with UVFP.