Dynamic CT Study on the Morphology and the Motor Ability of Unilateral Vocal Fold Paralysis.

OBJECTIVE: To investigate the morphological changes and motor functions of the larynx in unilateral vocal fold paralysis by using dynamic three-dimensional CT, and to explore the differences between vocal fold paralysis with different nerves involved.

METHODS: Twenty-five patients with unilateral vocal fold paralysis and 10 healthy subjects were selected as the paralytic group and the normal group, respectively. Ten dynamic sequence images of laryngeal movement from inhalation to phonation were reviewed, and the glottic morphology at the coronal position, the minimum glottic area at the horizontal position, and the overall activity of the two groups were compared. The 25 patients with unilateral vocal fold paralysis were divided into the thyroarytenoid (TA) muscle group, the TA and posterior cricoarytenoid (PCA) (TA + PCA) muscle group, and the PCA muscle group. The coronal and horizontal parameters of the three types were compared as noted above and the dynamic parameter changes were also compared between the groups.

RESULTS: The height and thickness of bilateral vocal cords, the minimum glottic area, and the whole glottic activity were different in the paralysis group and were significantly different from those of the normal group (P < 0.05). The value of the glottic gap ratio and its decrease rate in the TA + PCA group was smaller than those in the TA and PCA group, and the glottic gap ratio was the largest in the PCA group.

CONCLUSION: Dynamic CT can provide a qualitative evaluation of laryngeal morphology and quantitative evaluation of motor function in vocal fold paralysis.