Assessment of Multidetector Computed Tomography Signs of Unilateral Vocal Cord Palsy: Do We Really Need to Evaluate Coronal Reformatted Images?

Abstract

Introduction: Vocal Cord Palsy (VCP) is a common clinical presentation and must be considered as a sign of underlying disease, rather than simply a diagnosis unto itself. Despite of idiopathic causes in nearly half of the cases, imaging studies are still indispensible for evaluating the varied aetiologies. Most of the signs of VCP are clearly demonstrable on axial Computed Tomography (CT) sections except one i.e., flattening of ipsilateral subglottic arch which needs specific evaluation only on coronal reformatted images. The diagnostic value of this sign is still debatable. Aim: To evaluate any additional advantage offered by coronal reformatted images in cases of unilateral VCP especially those with confusing/equivocal findings and to find out most reliable signs of unilateral VCP on axial CT sections. Materials and Methods: This retrospective study comprised of patients with clinical suspicion of VCP who were referred for CT neck and thorax in Department of Radiology at tertiary care hospital in the previous 36 months (July 2014 to June 2017). Only the cases with laryngoscopically confirmed unilateral VCP were included. The cases with laryngeal malignancy were excluded. Various imaging signs of unilateral VCP were evaluated on both axial and coronal reformatted images. Spearman’s rho (ρ) correlation coefficient was calculated to assess correlation between most frequent signs of unilateral VCP individually and also with flattening of ipsilateral subglottic arch (evaluated on coronal reformatted images). Results: Thickening and medialisation of ipsilateral aryepiglottic fold was uniformly present in all the cases of unilateral VCP. Two other most frequent signs which correlated strongly with unilateral VCP were dilatation of ipsilateral laryngeal ventricle (n=29, 93.5%) and dilatation of ipsilateral pyriform sinus (n=27, 87%). Flattening of ipsilateral subglottic arch on coronal reformatted images was seen in only 26% patients. This sign was absent in all four cases with equivocal and contralateral findings in present study. Conclusion: The coronal reformatted images failed to demonstrate any additional advantage over axial sections in diagnosing unilateral VCP even in equivocal or difficult cases. The thickening and medialisation of ipsilateral aryepiglottic fold on routine axial CT images is probably the most reliable and consistent sign for diagnosing unilateral VCP with dilatation of ipsilateral laryngeal ventricle and ipsilateral pyriform sinus as two other major supportive signs.

Keywords

• aryepiglottic fold
• laryngeal malignancy
• recurrent laryngeal nerve