Vibratory characteristics of Teflon-injected and noninjected paralyzed vocal folds.

This study compared the vibratory characteristics of normal vocal folds, Teflon-injected paralyzed vocal folds, and noninjected paralyzed vocal folds. Laryngeal videostroboscopy under eight phonatory conditions showed that the Teflon-injected vocal folds were adynamic. The noninjected vocal folds, however, vibrated during each of the phonatory conditions although not necessarily like a normal vocal fold. In terms of vocal fold physiology, it appeared that the noninjected paralyzed vocal folds were too compliant, whereas the Teflon-injected vocal folds were too stiff. Because vocal fold paralysis is often treated in voice therapy with "digital manipulation" and "head turning," the effect of these techniques on vocal fold vibration was also studied. The results showed that digital manipulation was superior to head turning for improving glottal closure but that neither technique appeared to influence the periodicity, amplitude, or extent of vocal fold vibration for either the injected or noninjected vocal folds.