Aneurysm of the petrous portion of the internal carotid artery at the foramen lacerum: anatomic, imaging, and otologic findings.

Aneurysms of the petrous portion of the internal carotid artery (ICA) are rare. Their etiology is usually congenital, traumatic, or mycotic. Depending on the size and location of the aneurysm, the direction of its growth, and the specific adjacent structures involved, patients may or may not present with signs and symptoms. When signs and symptoms do manifest, they may include headaches, epistaxis, a vascular retrotympanic mass with hemotympanum and/or otorrhagia, pulsatile tinnitus, hearing loss, vertigo, and Horner syndrome or Raeder paratrigeminal neuralgia. We describe the imaging aspects of the case of a 27-year-old man who presented with a 5-day history of unilateral symptoms secondary to a lesion located in the area of the right foramen lacerum. The lesion proved to be an aneurysm of the petrous portion of the ICA. We discuss the anatomic, imaging, and otologic aspects of ICA aneurysms in this location.