Vagal neuropathy: evaluation with CT and MR imaging.

Abstract

The vagus nerve, as a result of its protracted course from the brain stem to the abdomen, can present a difficult imaging problem when it is compromised by a clinically occult lesion. The clinical and radiologic records of 48 patients with suspected vagus nerve dysfunction were reviewed to derive an efficient and effective approach to imaging this patient population. An imaging algorithm is proposed in which vagal neuropathies are divided both clinically and radiologically into proximal and distal categories. Proximal vagal lesions are part of a cranial neuropathy complex and have associated oropharyngeal signs and symptoms (e.g., abnormal gag reflex, uvular deviation). Distal vagal lesions occur as an isolated paralysis of the vagus nerve with no symptoms or signs referable to the oropharynx. Either computed tomography (CT) or magnetic resonance imaging can be used to diagnose proximal or distal lesions. However, CT will be insensitive in the detection of the more cephalic proximal lesions, especially those in the brain stem, basal cisterns, and skull base.

Utility of Helical Computed Tomography in the Study of Arytenoid Dislocation and Arytenoid Subluxation

“…3 However, the final position of the involved vocal cord may vary, depending on the cause of disease and its site along the course of the vagus nerve or its recurrent branch. 9 The ary- tenoid, therefore, may be seen in fixed adduction or abduction and may be tilted anteromedially. 3 The spectrum of positions the arytenoid may take in AS or AD, and the overlapping appearances that are possible with RLN dysfunction, make the task of describing and assigning a cause for an asymmetric vocal process daunting.…”

Evaluation of Unilateral Vocal Fold Immobility

“…If a high vagal lesion is suspected, an MRI may be the most useful imaging modality for evaluation of the skull base [40]. True positive findings on CT or MRI will be more likely for patients who fall into a high-suspicion group on the basis of clinical history; the number of false positive findings will be greater for those in a low-suspicion group [41].…”

Denervation Atrophy of Motor Cranial Nerves

“…More inferiorly, imaging findings consist of those described in association with vocal cord paralysis: paramedian position of the vocal cord, anteromedial positioning of the arytenoid cartilage, ipsilateral laryngeal ventricle dilatation, denervation atrophy of the thyroarytenoid muscle, ipsilateral medial positioning and thickening of the aryepiglottic fold, ipsilateral dilatation of the pyriform sinus, ipsilateral subglottic fullness, and ipsilateral vallecular dilatation. 45,46 An additional indicator of recurrent laryngeal nerve paralysis is denervation atrophy of the posterior cricoarytenoid muscle (Figs. 26-28).…”