Hypothesis: Adduction arytenopexy (AP) with thyroplasty provides improved physiologic placement of the vocal fold and therefore provides improved acoustic, aerodynamic, and vibratory function as compared with arytenoid adduction (AA) with thyroplasty.
Methods: Five cadaveric human larynges were prepared by removing supraglottic tissues and fixing the nontest vocal fold medially on the cricoid facet with a needle in a physiologic phonating position. Each test vocal fold was then sequentially tested using an excised larynx phonation system, first with AA with silastic medialization and then converted to AP without changing the contralateral fold position or silastic wedge. The excised larynx setup allowed for simultaneous collection of data, specifically subglottic pressure (including measurement of phonation threshold pressure [PTP]), mean airflow, acoustic output, and full-frame high-speed digital video.
Results: Aerodynamic evaluation was similar for each group with similar subglottic pressure versus output curves. Conditions involving AP typically had PTP values that were 80% of that for comparable AA conditions. Acoustic evaluation revealed differences between the two groups. Each AA was found to be vibrating with two dominant frequencies with their associated harmonics. Each AP vibrated at a single dominant frequency with its harmonics.
Conclusion: AP provides improved vocal outcomes by decreasing system noise and decreasing PTP, which may lead to a stronger glottal signal with decreased vocal effort.