Glossopharyngeal schwannoma of the suprahyoid carotid space: Case report and discussion of the relationship to the carotid artery

BACKGROUND: The distinction between lesions of the deep parotid space and those of the carotid space has been greatly facilitated by cross-sectional imaging, particularly magnetic resonance imaging (MRI), due to 1) good assessment of parapharyngeal fat displacement, and 2) reliable and consistent identification of the carotid artery. While masticator space masses consistently displace the carotid artery posteriorly, it is generally assumed that carotid space masses, particularly schwannomas, displace the carotid artery anteriorly. We report on a patient with a rare glossopharyngeal schwannoma of the carotid space that caused posterior displacement of the carotid artery. METHODS: A 38-year-old female presented with headaches and a pharyngeal sensation of a foreign body without dysgeusia and dysphagia. Computed tomography (CT) and MRI showed a left carotid space mass, suggestive of a schwannoma, although the internal carotid artery was displaced posteriorly. The mass was hypovascular at angiography. The patient underwent surgical excision of her lesion via a left cervical-parotid approach. RESULTS: In our patient with a carotid space mass, all imaging features suggested a schwannoma, except for posterior displacement of the carotid artery. A glossopharyngeal nerve schwannoma was found at surgery. Schwannomas of the glossopharyngeal nerve are uncommon, and those originating from the extracranial course of the nerve are extremely rare. CONCLUSIONS: Schwannomas of the suprahyoid carotid space most commonly arise from the vagus nerve and have a typical pattern, which includes anterior displacement of the carotid artery. A rare exception to this has been reported in schwannomas of the sympathetic nerve, which may displace the carotid artery posteromedially. Our patient had a schwannoma of the extracranial glossopharyngeal nerve, which caused posterolateral carotid displacement.