Revisiting CT Signs of Unilateral Vocal Fold Paralysis: A Single, Blinded Study

Abstract

BACKGROUND AND PURPOSE: Several CT findings are thought to be indicative of vocal cord paralysis; however, these signs have never been validated in a blinded fashion. This study attempts to compare and validate these signs and determine their accuracy in predicting vocal cord paralysis. MATERIALS AND METHODS: A retrospective chart review was performed, and CT scans from patients with known unilateral vocal cord paralysis and known normal vocal cord movement were reviewed by 3 radiologists who were blinded to the status of the patients' laryngeal function. The scans were reviewed and scored for 8 accepted signs of vocal cord paralysis as well as for predicting a final diagnostic conclusion. Statistical analysis using odds ratios for signs and the Fleiss k for criterion agreement among the radiologists was performed for diagnostic accuracy. RESULTS: The presence of medial displacement of the posterior ipsilateral vocal fold margin and ipsilateral laryngeal ventricular dilation yielded the greatest positive predictive value. Other signs demonstrated high specificity, but interrater discrepancy was greater than expected and diminished the reliability of these signs in predicting vocal cord paralysis. Overall, sensitivity and negative predictive values were low. CONCLUSIONS: Predicting vocal cord paralysis on the basis of CT findings is not as accurate or straightforward in prospectively predicting vocal cord paralysis as implied in prior studies.