Objective: High-speed video laryngoscopy (HSV) captures asynchronous vibrations and diplophonia in paralysis and paresis that are difficult to resolve with stroboscopy. This study characterizes vibratory patterns of paralysis and paresis using high-speed video laryngoscopy (HSV) and digital kymography (DKG) and compares them with stroboscopy.

Methods/Design: Two laryngologists rated HSV and stroboscopy findings in patients with paralysis and paresis. A standard set of seven ratings was used for each examination, including periodicity, amplitude, phase shift, multiple oscillators, and the presence of diplophonia. The HSV was analyzed using a multi-slice DKG.

Results: Twenty one patients with paralysis (N=10) and paresis (N=11) were recorded. The lateral/medial phase shift and greater amplitude of the affected vocal fold were observed in paralysis and paresis. This anomaly was detected on both stroboscopy and HSV. Diplophonia was present in both paralysis and paresis patients, although more consistently observed in paralysis. Vibrogram analysis shows typical diplophonia vibration patterns in paralysis with vocal fold vibrating at different frequencies coming in and out of phase, creating sub-harmonics in vibration heard as diplophonia. Multiple oscillation frequencies were generated in cases of vocal fold paralysis but not paresis. Subharmonics to the fundamental frequency and chaotic and asymmetric vibration during voice onset and offset can be visualized by HSV alone.

Conclusions: HSV recording and analysis provide additional information about vibratory abnormalities in paralysis and paresis. Chaotic vibration at voice onset can only be resolved with HSV. HSV can resolve vibratory anomaly due to diplophonia and voice onset delay in patients suspected of paresis.