Extracranial internal carotid artery pseudoaneurysm

Case contributed by Bruno Di Muzio


This patient has presented with a non-traumatic subarachnoid hemorrhage.

Patient Data

Age: 40 years
Gender: Male

CTA (presentation)


Large saccular (10.5 mm maximal dimension) left distal ICA (likely PComm) aneurysm.

A left posterior communicating artery aneurysm is demonstrated with multiple lobules. This aneurysm measures 7.7 mm from dome - to - neck, 11.4 mm across the waist, with a neck of 4mm. No additional aneurysm is identified. The aneurysm was coilled under the standard technique. 

MRI (3 months followup)


There is a residual filling of the left PCom aneurysm neck measuring approximately 5.0 x 5.6 mm (depth x width). There is a new saccular aneurysm in the C2 extracranial segment of the left internal carotid artery, cranially oriented, measuring approximately 5.2 x 5.7 mm (depth x width). The remainder of the circle of Willis MRA has normal flow signal, with no high-grade stenosis, vascular malformations, or other aneurysms. No intra or extraaxial masses, collections, or regions of restricted diffusion are identified.

Conclusion: There is a new extracranial left internal carotid artery false aneurysm. Residual filling at the neck of the coiled left PCom aneurysm.

Case Discussion

This case shows the diagnosis and endovascular treatment of a posterior communicating artery aneurysm.  The post coiling baseline MRA has demonstrated a new extracranial left internal carotid artery false aneurysm, likely related to the endovascular treatment.  

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