Objectives To measure the vocal fold length (VFL) during inspiration and phonation and to determine the vertical difference of the vocal folds during phonation in patients with unilateral vocal fold immobility.
Design Prospective study.
Setting University hospital.
Patients Thirty patients with unilateral vocal fold immobility.
Interventions Each subject was asked to sustain the vowel /a/ and, after a short rest, to inhale slowly. The region over the larynx was scanned using multislice helical computed tomography during each maneuver; 3-dimensional endoscopic, coronal, and sagittal images were produced.
Main Outcome Measures The VFLs on each side and the vertical differences between the vocal folds were calculated.
Results The inspiratory VFL on both sides was significantly longer in men than in women. It was significantly longer on the healthy side than on the immobile side in both groups. On the healthy side, the inspiratory VFL was significantly longer than the phonatory VFL in men, but there was no significant difference in women. In contrast, on the immobile side, the phonatory VFL was significantly longer than the inspiratory VFL in women, but there was no significant difference in men. The VFLs of the healthy and immobile sides varied in tandem. The immobile vocal fold was situated lower than the healthy vocal fold during phonation in 3 patients.
Conclusions Multislice helical computed tomography is a novel method to measure the VFL and the vertical level difference between the vocal folds. Application of this method might facilitate further understanding of laryngeal behavior in patients with unilateral vocal fold immobility.
