Three Cases of Aberrant Internal Carotid Arteries in the Middle Ear

Abstract

The internal carotid artery (ICA) that runs laterally to the lateral aspect of the vestibule is defined as an aberrant ICA. Aberrant ICAs in the middle ear are relatively rare, however, it is important for otolaryngologists to recognize the entity, since common procedures, such as myringotomy, can lead to serious complications. We report herein on three cases with an aberrant ICA in the middle ear.

In Case 1, a 49-year-old female presenting with hearing loss (HL) and pulsatile tinnitus (PT) in her left ear was referred to our hospital with an initial diagnosis of a glomus tumor. Otoscopic examination revealed a reddish pulsatile mass behind the anteroinferior quadrant (AIQ) of the tympanic membrane (TM). A pure-tone audiogram showed bilateral mild mixed HL. In Case 2, a 64-year-old male presented to our hospital with PT in his right ear. Otoscopic examination revealed a reddish mass behind the AIQ of the TM. Her audiogram showed sloping sensorineural HL in the right ear, which was considered to be presbycusis. In Case 3, a 31-year-old female presenting with bilateral HL and PT in her left ear was referred to our hospital. Otoscopic examination revealed a reddish pulsatile mass behind the AIQ of the TM. Her audiogram showed bilateral mixed HL. An auditory brainstem response test and Bekesy audiogram indicated the presence of functional deafness. In all cases, computed tomography (CT) scans of the temporal bone showed characteristic findings of an aberrant ICA: 1) absence of the vertical carotid canal; 2) enlargement of the inferior tympanic canaliculus; 3) an aberrant course of the artery through the hypotympanum and 4) dehiscence of the carotid plate through which the artery enters the horizontal carotid canal.

A careful otoscopic examination should be performed to evaluate patients with PT. CT scans of the temporal bone can provide a definitive diagnosis of an aberrant ICA in the middle ear.