Type:
Educational Exhibit
Keywords:
Ear / Nose / Throat, Head and neck, Mediastinum, CT, Localisation, Aneurysms, Neoplasia, Speech disorders
Authors:
A. Micolich Vergara, J. Capellades, F. Zuccarino
DOI:
10.26044/ecr2023/C-17377
Findings and procedure details
DIAGNOSTIC ASESSMENT
Once VCP is suspected, patients must undergo a clinical evaluation of the larynx followed by a thorough head and neck radiological evaluation.
Cross sectional imaging modality of choice is CECT. The study must include the upper mediastinum up to the aortopulmonary window and acquired during quiet respiration so the cords are in an abducted position.
Both the CN X and RLN cannot be directly visualized on CT, therefore, it is imperative for radiologists to recognize their expected courses so we dont miss out on pathologies that may have more significance than the VCP itself .
IMAGING FEATURES OF VCP
VCP can be reliably identified at CT due to characteristic findings although careful evaluation must be carried out by appropriately handling the scan planes of the glottis so we can avoid potential pitfalls and mimics.
The scan planes we must utilize when evaluating the glottis are:
- STRICT AXIAL PLANE = at the level of the anterior and posterior comissures.
- OBLIQUE AXIAL PLANE = at the level of true vocal cords (cricoarytenoid joints)
CT signs of VCP are all ipsilateral and the most specific ones are the first three:
- Dilated laryngeal ventricle: due to atrophy of thyroarytenoid muscle.
- “sail sign” (oblique axial plane) = unilateral dilation of laryngeal ventricle + medialisation of posterior margin of true vocal cords
- “mushroom sign” (strict axial plane) = unilateral dilation of laryngeal ventricle + medialisation of posterior margin of true vocal cords + contralateral anterior subglottic air
- Medial deviation and thickening of aryepiglottic fold = due to paralysis of the posterior cricoarytenoid muscle (only abductor muscle).
- Enlarged piriform sinus = due to medial deviation of aryepiglottic fold which forms the medial wall of the piriform sinus.
- Anteromedial rotation of arytenoid cartilage = this causes the affected vocal cord to sag inferiorly.
- Wide valleculae = probably due to the medially deviated aryepiglottic fold that generates some epiglottic displacement.
- “Pointing” of the atrophied cord (coronal view) = due to atrophy of thyroarytenoid muscle, the paralysed cord looses its globular medial edge resulting in a sharp medial margin.
- Subglottic fullness = the anteromedial rotation of arytenoid cartilage provokes the inferior sagging of the paralysed cord resulting in fullness of the subglottic area.
- Paramedian position of affected true vocal cord = the less reliable sign because of the multiple positions the cord can take on CT.
- Flattening of subglottic arch (coronal view) = the subglottic arch forms a 90º degrees angle and this angulation is lost on the affected side.
DIFFERENTIAL DIAGNOSIS OF VCP BY LOCATION
LARYNX
- Laryngocele
- Polyps, cysts
- Squamous cell carcinoma
- Papillomatosis
- Amyloidosis
BRAINSTEM
SKULL BASE
- Meningioma
- Metastases
- Glomus jugulare
CAROTID SHEATH
- Glomus vagale
- Schwannoma
- Trauma
- Extrinsic compression: ostheoarthritis
UPPER MEDIASTINUM
- Neoplastic :
- Vascular etiologies:
- Ortner's syndrome
- aortic aneurysm
- Inflammatory
- Miscellaneus:
- medial bullae
- esophageal diverticulum