Unilateral sudden hearing loss as a result of anomalous carotid anatomy.

The term sudden hearing loss refers to hearing losses of sensorineural origin that evolve over a short period of time and are often of unknown origin. Common causes include damage to the cochleovestibular nerve by viral infection, autoimmune disease, vascular insult, and labyrinthine membrane rupture. A 70-year-old man had a history of recent diplopia, dysarthria, syncopal episodes, dysequilibrium, and the sudden onset of deafness in his right ear. Angiography demonstrated severe ulcerative stenosis of the right internal carotid origin and an anomalous vessel (probable remnant of hypoglossal artery) originating from the distal right internal carotid artery that perfused the entire distal vertebral and basilar artery circulation. Arch angiograms confirmed the absence of a proximal right vertebral artery and revealed a small left vertebral artery that ended in the cervical region without reaching the posterior fossa. Standard right carotid endarterectomy with patch angioplasty resolved all neurologic symptoms except for persistent unilateral deafness at 9 months' follow-up. Presumed embolization through this anomalous vessel to the internal auditory artery and subsequent cochlear and vestibular branches represents the first reported case of sudden hearing loss as a result of anterior circulatory ulcerative disease.