Videostrobokymographic analysis of benign vocal fold lesions

Videostrobokymography (VSK) has recently been introduced. The aim of this study was to analyze vibratory patterns and objective parameters in various benign vocal fold lesions using VSK and to examine the efficacy of VSK in clinical applications.

Using VSK, we analyzed the vibration patterns of normal vocal folds, various benign lesions such as nodules, polyps, cysts and Reinke's edema and cases of unilateral vocal fold paralysis. We also calculated the objective parameters open quotient and asymmetric index and compared them with their mean values in normal controls.

In nodules, polyps and cysts, the open quotient at the site of the lesion was similar to the mean value in the normal controls; however, on the other parts of the vocal folds, it was much larger than the normal mean value. In Reinke's edema, irregular and asymmetric vibrations were observed. The posterior area of the vocal folds showed larger open quotients than the anterior area. In unilateral vocal fold paralysis, irregular vocal fold vibration and incomplete closure of the vocal folds were documented. Much larger asymmetric indices were calculated for unilateral vocal fold paralysis than in normal controls or for other lesions. The asymmetric index may be a good quantitative parameter of vibration in patients with vocal fold paralysis.

This study demonstrated that VSK could generate clear quantitative documentation of fine vibrations of vocal folds in many different types of benign lesion. VSK has the potential to be an effective tool for the quantitative analysis of vibratory patterns of vocal folds in clinical settings.