giovedì 12 agosto 2010

Aneurysm of the right cervical internal carotid artery causing vocal cord paralysis


CT imaging through the neck demonstrates findings suggestive of right vocal cord paralysis.
Figure 1 shows dilation of the right pyriform sinus.
Figure 2 shows thickening and medial positioning of right aryepiglottic fold.
Figure 3 shows dilation of the laryngeal ventricle.
Figure 4: CT through the skull base reveals a rounded well defined brightly enhancing mass in the right carotid space displacing the carotid and internal jugular vein.
Figure 5: MR images demonstrate flow void on T2 weighted images.
Conventional angiography confirms an aneurysm of right internal carotid artery.

Diagnosis: Aneurysm of the right cervical internal carotid artery causing vocal cord paralysis

Unilateral vocal fold paralysis (UVFP) occurs from a dysfunction of the recurrent laryngeal or vagus nerve innervating the larynx. Clinical presentation includes characteristic hoarseness often accompanied by swallowing disabilty, weak cough, and sometimes shortness of breath. Its is important to note that a high vagal lesion results in both a recurrent laryngeal nerve and superior laryngeal nerve palsy with the latter resulting in significant anesthesia of the pharynx and increasing the risk for aspiration

CT scanning or MRI should be performed as part of a workup for a unilateral vocal fold paralysis (UVFP) of unknown etiology. The imaging should include the entire path of the vagus/recurrent laryngeal nerve involved. For left unilateral vocal fold paralysis (UVFP), imaging should extend from the base of skull to the mid chest (arch of the aorta) with right sided vocal fold paralysis including the base of the skull to the clavicle.

Unilateral vocal cord paralysis can be reliably identified on cross sectional imaging. Characteristic findings include:
1. Medial positioning and thickening of the ipsilateral aryepiglottic fold.
2. Ipsilateral pyriform sinus dilatation.
3. Ipsilateral laryngeal ventricle dilatation.
4. Fullness of the ipsilateral true vocal cord.
5. Anteromedial positioning of the ipsilateral arytenoid cartilage.

Causes of vocal cord paralysis are varied with nearly 25% classified as toxic or idopathic. Post-surgical cord paralysis is another important consideration often without specific imaging findings. Identifiable causes include mass compression and or malignant invasion. Although rare, aneurysm or pseudoaneurysm of the cervical internal carotid artery should be considered in the differential diagnosis of a carotid space mass. Because of the intimate proximity of structures within the carotid space, it is sometimes difficult to definitively determine the epicenter of an enhancing lesion. However, as the resolution of cross-sectional imaging improves, preoperative characterization is increasingly possible. A demonstrable arterial connection, arterial enhancement, peripheral calcification, and flow void on MR imaging is suggestive of the diagnosis.

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