Comparison between thyroplasty type I andArytenoid rotation: a study of vocal fold vibration using excised human larynges

The purpose of this paper was to compare the vibration of the vocal fold submitted to Isshiki thyroplasty type I (TPI) to that of the contralateral one adducted by the arytenoid rotation (AR) technique. The vocal folds of ten human fresh excised larynges were medialized by TPI on one side and by rotation of the arytenoid on the contralateral side. Laryngeal vibration was artificially produced and was recorded by videostroboscopy. The images were subjectively and objectively analyzed. Subjective analysis included periodicity of vibratory cycles, features of the mucosal wave present on the TPI side, amplitude of vibration, and profile of free border of each vocal fold during the opening phase. Objective analyses were carried out on frame-by-frame digitalized images to determine amplitudes of vibrations and phase differences between the folds in three glottic regions (anterior, middle, and posterior). Subjective analysis revealed regular periodicity in 100% of the larynges, a decrease in the mucosal wave on the TPI side in 70%, reduction in amplitude in 30%, and a sigmoid profile of the free border on the TPI side in 80%. Objective analysis showed mean amplitude in the posterior glottic region on the TPI side significantly larger than that on the arytenoids rotation side and phase asymmetry in 90% of the larynges.