March 2016
An 80-year-old woman with several months of bilaterial otalgia. No otoscopic findings or inflammatory signs present.
Bilateral Intrapetrous Internal Carotid Artery Aneurysms
- Background:
- Petrous ICA segment aneurysms are rare, and bilateral aneurysms rarer.
- Origin may be traumatic, postinfectious, or congenital. When congenital, it is thought to be secondary to weak areas in the arterial wall at the origin of embryonic vessels.
- Clinical Presentation:
- Typically, petrous ICA segment aneurysms are asymptomatic and diagnosed incidentally.
- When symptomatic, can present with headache, pulsatile tinnitus, hearing loss or cranial nerve palsies.
- When rupture occurs, otorrhagia, epistaxis, or neurologic deficit may occur, with the entire triad present in 25%.
- Key Diagnostic Features:
- Unenhanced bone CT may show carotid canal dilatation with smooth and scalloped margins, occasionally with bone erosions.
- CT angiography (CTA) demonstrates enhancement of the aneurysm lumen during arterial acquisition, and may depict a mural thrombus if present.
- On MRI lesions can have heterogeneous, complex signal intensities on T1WI and T2WI, arranged in a “swirl” pattern with central flow void of the patent lumen.
- Contrast-enhanced MRA can be diagnostic by delineating the size, extent, and patency of the aneurysm.
- Differential Diagnosis:
- Schwannoma of the sympathetic plexus of the carotid canal
- Treatment:
- Asymptomatic small aneurysms may not require any treatment besides imaging follow-up
- Symptomatic or progressively growing aneurysms should be treated by endovascular interventions or surgical trapping procedures.
