[Aberrant internal carotid artery in the middle ear: a case report].

Aberrant course of the internal carotid artery within the middle ear is a rare condition. Surgical interventions following clinical or radiological misinterpretations may lead to fatal complications. A 23-year-old female patient presented with a hearing impairment of 10-month duration. On otoscopic examination, the left tympanic membrane was intact, but there was a pulsatile lesion in the tympanic cavity, synchronous with the heartbeats. Pure-tone audiometric examination of the left ear showed a unilateral mixed hearing loss, especially in low frequencies. Computed tomography showed protrusion of the internal carotid artery into the middle ear from the lateral and superior aspects of the cochlea. Magnetic resonance imaging and MR-angiography showed a left-sided deviation of the left internal carotid artery near the cochlea, associated with a filling defect. The caliber of the left internal carotid artery was narrower than the right one in the middle ear, and its proximal part was thinner. A diagnosis of aberrant internal carotid artery was made.