Aberrant Internal Carotid Artery in the Temporal Bone

Abstract

To describe the clinical and radiological features of the vascular anomaly aberrant internal carotid artery (ICA) in the temporal bone and to discuss management strategies. Retrospective study. Sixteen cases of aberrant ICA were diagnosed between 1982 and 2003. Of 16 cases, 11 were recognized by imaging assessment, 4 were recognized during middle ear surgery, and 1 was recognized clinically. Among the 11 cases, 8 malformations were diagnosed because of otologic symptoms related to the abnormal ICA or chronic otitis, while the other 3 were identified incidentally because of an underlying accompanying disease. In 4 cases, the diagnosis was made during surgery related to chronic otitis media (n = 2) or conductive hearing loss (n = 2). In these 4 cases, massive bleeding resulted from surgical injury to the vessel. Packing the external auditory canal and the middle ear first controlled the bleeding. Endovascular procedure was required in 2 cases to exclude an aneurysm or to control bleeding but was followed by anterior cerebral stroke in 1 case. The aberrant ICA could be identified on computed tomographic scan by the following features: intratympanic mass, enlarged inferior tympanic canaliculus, absence of the vertical segment of the ICA canal, and absence of bone covering the tympanic portion of the ICA. Conventional angiography was mandatory when intervention was planned to control bleeding or aneurysm. This study highlights that aberrant ICA has to be identified before any middle ear surgery because misdiagnosis may lead to dramatic surgical complications, whereas diagnosis with computed tomographic scan is easy. Bleeding is a minor complication compared with the putative neurologic deficit due to endovascular occlusion.