Paragangliomas are neuroendocrine tumors that arise from glomus bodies (paraganglia), which are derived from neural crest cells and are associated with the sympathetic nervous system. As such, these cells are capable of secreting catecholamines. In the head and neck, the four most common sites for paragangliomas to occur, in decreasing frequency, are the carotid body, middle ear (tympanicum paraganglioma), jugular bulb (jugular paraganglioma), and the nodose ganglion of the vagus nerve (vagal paraganglioma). Paragangliomas have been associated with the MEN syndromes and thyroid carcinoma.
Patients with head and neck paragangliomas usually present with a painless, pulsatile, unilateral neck mass. These lesions are highly vascular and, if large enough, an audible bruit may be present. Vagal paragangliomas frequently cause cranial nerve dysfunction and Horner syndrome. The vagus nerve is the most commonly affected, producing hoarseness, vocal cord paralysis, and dysphagia. Palsies of IX, XI, and XII have also been reported. Rarely will paragangliomas secrete enough catecholamines to reach clinically significant levels, at which point patients present with a pheochromocytoma-like picture.
Imaging is an important part of the diagnostic evaluation of these tumors. CT of vagal paragangliomas demonstrates an ovoid mass in the nasopharyngeal carotid space. This mass is isodense to muscle on noncontrast studies and shows avid enhancement on contrast studies. These tumors displace the ICA anteriorly without splaying the carotid bifurcation, a key distinction from a carotid body paraganglioma. MR findings characteristic of large vagal paragangliomas include prominent flow voids (â€śpepperâ€ť appearance), marked enhancement throughout the lesion on post-contrast images, and hyperintensity of the mass compared to muscle on T2 and STIR. CTA/MRA demonstrate ICA displacement and the capillary bed of the tumor. Angiography typically demonstrates enlarged, tortuous ECA feeding vessels with an intense, prolonged vascular blush. Arteriovenous shunting is apparent on angiography by early visualization of draining veins, as is the characteristic anterior displacement of the ICA without splaying of the carotid bifurcation.
Treatment involves surgical resection of the tumor. As these lesions are highly vascular, preoperative embolization can reduce bleeding risk and facilitate tumor removal. The rare catecholamine-secreting (3%-5%) tumors are managed medically with alpha and beta adrenergic antagonists prior to embolization/resection. Poor surgical candidates may elect to undergo radiation therapy, as it has been shown to be useful in improving symptoms.