Can Maximum Phonation Time Predict Voice Outcome after Thyroplasty Type I?

Background: Thyroplasty type I, as introduced by Isshiki and colleagues almost 30 years ago, has become the gold standard of improving glottal incompetence caused by unilateral vocal fold paralysis. Intraoperative assessment of the adequacy of glottal closure is subjective and based on the perceptual judgment of vocal quality and degree of improvement in glottal gap size. Objective/Hypotheses: The primary purpose of this study was to investigate whether the intraoperative measurement of maximum phonation time (MPT) is an adequate predictor of voice outcome after thyroplasty type I. To assess this possibility, it was necessary to evaluate the effect of body posture (seated vs. supine) and anesthesia (none vs. light sedation) on the measure of MPT. Study Design: A prospective study of 20 individuals with unilateral vocal fold paralysis was undertaken. Methods: Subjects were assessed at three time points: pre‐, intra‐, and postoperatively across parameters of breathiness rating, glottal gap size, glottal flow rate, and MPT. Results: Results indicated that MPT was significantly lower in the supine versus seated position. In addition, light sedation resulted in a trend toward lower MPT that was not statistically significant. Finally, the intraoperative measurement of MPT, although lower than a 1‐month postoperative measurement, was significantly predictive of the outcome. Conclusions: The intraoperative measure of MPT appears to be an adequate predictor of the postoperative outcome.