Lingual Artery-Retromandibular Vein Fistula Four Years after an Uncomplicated Carotid Endarterectomy: Case Report and Review of Possible Etiologies and Treatment Options.

The external carotid artery's lingual branch to retromandibular venous fistula following a carotid endarterectomy has not been reported earlier in literature. We report a unique case of an 87-year-old man who had a right-sided carotid endarterectomy in 2009 and presented four years later with complaints of fullness and discomfort in the area of right parotid gland with associated pulsatile tinnitus. A computed tomography (CT) scan of the neck revealed a deep portion of the right parotid gland having abnormal aneurysmal dilatation of a vascular structure, which appeared to be an arteriovenous fistula between branches of right external carotid artery and the retromandibular vein. Conventional catheter angiogram showed a complex arteriovenous fistula seen with the right retromandibular vein receiving multiple small arterial feeders from the right external carotid artery via its lingual artery branch. Slight reflux was noted into the right pterygoid plexus, right maxillary, and right submental veins as well. Surgical treatment was deferred due to high risk of inadvertent facial nerve injury from extensive parotid dissection involved in the procedure. Transarterial embolization of five discrete arterial branches from the right external carotid artery supplying the fistula was performed using particles with resultant remarkable slowing of the venous drainage into the retromandibular vein. After the procedure, his tinnitus and ear fullness resolved completely. The presence of arteriovenous fistula after carotid endarterectomy is a rare yet serious complication and therefore should be diagnosed early and treated promptly. The article highlights the relevant literature on arteriovenous fistula formation in the setting of arterial patch, intraoperative shunting, and surgical-site infections.