Finite element modeling of vocal fold vibration in normal phonation and hyperfunctional dysphonia: implications for the pathogenesis of vocal nodules.

A computer model of the vocal fold was developed using finite element modeling technology for studying mechanical stress distribution over vibrating vocal fold tissue. In a simulated normal phonation mode, mechanical stress was found to be lowest at the midpoint of the vocal fold and highest at tendon attachments. However, when other modes predominated, high mechanical stress could occur at the midpoint of the vocal folds. When a vocal fold mass was modeled, high shearing stress occurred at the base of the modeled vocal fold mass, suggesting that the presence of a vocal nodule or polyp is associated with high mechanical stress at the margins of the mass. This finding supports a hypothesis that mechanical intraepithelial stress plays an important role in the development of vocal nodules, polyps, and other lesions that are usually ascribed to hyperfunctional dysphonia.