Compensatory Movement of Contralateral Vocal Folds in Patients With Unilateral Vocal Fold Paralysis

Previous studies of subjects with unilateral vocal fold paralysis (UVFP) as observed in a positron emission tomography-computed tomography (PET-CT) examination have demonstrated false positive results in the contralateral cricoarytenoid, in which the metabolism may be higher. This area may also be the site of contralateral compensatory movement in these patients. In this study, we compared the adduction speed of the contralateral vocal folds in patients with UVFP and in healthy subjects as measured by the stroboscopic laryngoscope frame rate. This study aimed to explore the contralateral compensatory movement of the vocal folds in subjects with UVFP.

(1) We collected visual data from 14 patients with UVFP and 14 healthy subjects through a stroboscopic laryngoscope. These subjects were divided into a vocal fold paralysis group and a control group, and we analyzed the excessive adduction of the contralateral vocal folds in the vocal fold paralysis group by examining vocal fold movement speed (pixels/s) as featured in a stroboscopic laryngoscope video. (2) We analyzed the uptake of 18-FDG in the posterior vocal fold from positron emission tomography-computed tomography imaging from four subjects with UVFP and 12 healthy subjects. An independent sample t test and a χ² test were used to compare data.

Four subjects with UVFP had a higher metabolic rate in the contralateral cricoarytenoid joints, with a significant difference between the two groups, P < 0.05. Fifty percent of the cases of contralateral adduction of the vocal folds in the subjects with UVFP adducted past the midline, with a significant difference between the two groups, P < 0.05. The contralateral adduction of the vocal folds in subjects with UVFP had shorter video frames and higher adduction speed than the control group, and the difference was statistically significant, P < 0.05. There were fewer vocal fold abduction video frames and higher abduction speed of the healthy side of the vocal fold in subjects with UVFP than the control group, but there was no statistically significant difference, P > 0.05.

Subjects with UVFP exhibited faster adduction compensation in the contralateral vocal folds, and the contralateral cricoarytenoid joint's metabolism in subjects with UVFP was higher. These data may help clarify the diagnostic criteria for laryngeal nerve damage.