Aberrant internal carotid artery in the middle ear with a deficiency in the origin of the anterior cerebral artery: a case report.

An aberrant internal carotid artery (ICA) in the middle ear is rare and difficult to diagnose, and may lead to severe complications. We present here a case of aberrant ICA with a deficiency in the origin of the anterior cerebral artery. The only symptom was aural fullness, and a nonpulsatile and white tympanic mass in the anteroinferior area was noted. Computed tomography (CT) and magnetic resonance angiography (MRA) are useful tools that provide excellent visualization of the temporal bone for the diagnosis of aberrant ICA 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. In addition, in this case, a deficiency in the origin of the anterior cerebral artery on the same side was identified by MRA, and cerebral arteriography and a carotid occlusion test were performed. Because of the deficiency in the origin of the anterior cerebral artery, the ICA compression revealed that there was almost no cross flow from the other ICA. Our experience illustrates that after confirmation of the diagnosis of aberrant ICA, localized treatment and/or surgical procedures should be considered carefully.