, Volume 54, Issue 9, pp 1007–1013

Lateralized petrous internal carotid artery: imaging features and distinction from the aberrant internal carotid artery

  • Christine M. Glastonbury
  • H. Ric Harnsberger
  • Patricia A. Hudgins
  • Karen L. Salzman
Head and Neck Radiology

DOI: 10.1007/s00234-012-1034-8

Cite this article as:
Glastonbury, C.M., Harnsberger, H.R., Hudgins, P.A. et al. Neuroradiology (2012) 54: 1007. doi:10.1007/s00234-012-1034-8



This study aimed to describe the lateralized petrous internal carotid artery (ICA), a rare variant of the intratemporal course of the ICA, and distinguish it from aberrant ICA.


A retrospective multi-institutional review of all patients diagnosed over a 10-year period with lateralized ICA was completed. Medical records were reviewed for demographic data as well as clinical information in all patients. Computerized tomography (CT) studies were reviewed in all patients. Magnetic resonance studies in this patient group were reviewed when available. In order to obtain normative data for the ICA, the intratemporal course of the ICA was evaluated on 50 consecutive high-resolution sinus CT scans.


Sixteen cases of lateralized ICA were identified on CT scans in 12 patients. In each of these, the ICA entered the skull base in a position more lateral to the cochlea than normal and protruded into the anterior mesotympanum with dehiscent or thinned overlying bone. Magnetic resonance angiography was available in 5 of 12 patients and catheter angiography in 1 of 12.


Lateralized petrous ICA can be identified on CT by its more posterolateral entrance to the skull base and protrusion into the anterior mesotympanum. It can be distinguished from the aberrant ICA which enters the posterior hypotympanum through an enlarged inferior tympanic canaliculus, then courses across the inferior cochlear promontory to connect with the normal horizontal petrous ICA. Lateralized ICA is best considered an incidental petrous ICA variant. Awareness of this entity is important in the presurgical evaluation of the temporal bone to avoid vascular injury and confusion with the congenital diagnosis of aberrant ICA.


Lateralized internal carotid arteryAberrant internal carotid arteryTemporal bone



Internal carotid artery


Computerized tomography


Magnetic resonance


Magnetic resonance angiography


Multiplanar image projection

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • Christine M. Glastonbury
    • 1
  • H. Ric Harnsberger
    • 3
  • Patricia A. Hudgins
    • 2
  • Karen L. Salzman
    • 3
  1. 1.Neuroradiology Section, Department of RadiologyUniversity of California, San FranciscoSan FranciscoUSA
  2. 2.Neuroradiology Section, Department of RadiologyEmory University School of MedicineAtlantaUSA
  3. 3.Neuroradiology Section, Department of RadiologyUniversity of Utah School of MedicineSalt Lake CityUSA