Comparison of high-speed digital imaging with stroboscopy for laryngeal imaging of glottal disorders

Objectives: High-speed digital imaging (HSDI), unlike stroboscopy, is a frequency-independent visualization technique that provides detailed biomechanical assessment of vocal physiology due to increased temporal resolution. The purpose of this study was to investigate the clinical value of HSDI compared to that of stroboscopy across 3 disorder groups classified as epithelial, subepithelial, and neurologic disorders. Methods: Judgments of vibratory features of vocal fold edge, glottal closure, phase closure, vertical level, vibratory amplitude, mucosal wave, phase symmetry, tissue pliability, and glottal cycle periodicity from 252 participants were performed by 3 experienced raters. Results: The results revealed that 63% of the data set was noninterpretable for assessment of vibratory function on stroboscopic analysis because of the severity of the voice disorder (100% of participants with severe voice disorders and 64% of participants with moderate voice disorders), whereas HSDI resulted in analysis of 100% of the data. The neuromuscular group (74%) was the most difficult to analyze with stroboscopy, followed by the epithelial (58%) and subepithelial groups (53%), secondary to the severity of hoarseness. Conclusions: Because it is desirable in clinical examination to observe vocal fold vibrations, which cannot be done in cases of severe dysphonia, HSDI may aid in clinical decision-making when patients exhibit values exceeding 0.87% jitter, 4.4% shimmer, and a signal-to-noise ratio of less than 15.4 dB on acoustic analysis. These measures could serve as minimal indications for use of HSDI. The data suggest that HSDI can be viewed as augmentative to stroboscopy, particularly in cases of moderate to severe aperiodicity, in which HSDI may aid clinical decision-making.