Aberrant ICA in the middle ear.

An aberrant internal carotid artery (a-ICA) in the middle ear is rare, but it may be injured during routine otological procedures. This review examines 48 publications on its embryological basis, clinical presentation, imaging diagnosis, and management. The a-ICA results from agenesis of the first embryonic segment of the internal carotid artery, with collateralisation through the inferior tympanic artery. Presentation is often non-specific; hearing loss (47.7%) and pulsatile tinnitus (30.0%) are the most frequent symptoms. Otoscopy may show a pulsatile retrotympanic mass in the anteroinferior quadrant. High-resolution computed tomography is central to diagnosis; relevant features include absence of the normal vertical carotid canal and its exocranial opening, and enlargement of the inferior tympanic canaliculus. The a-ICA must be distinguished from the more common lateralised petrous ICA variant, which retains a normal proximal calibre and enters the anterior mesotympanum without involving the inferior tympanic canaliculus. In iatrogenic injury, immediate packing is followed by definitive treatment in most reported cases; endovascular approaches have fewer complications than surgical ligation. Preoperative recognition remains one of the main safeguards against severe haemorrhage and neurological sequelae.