Background and Purpose Flow diversion has been well established as a treatment for intracranial aneurysms, but its use for extracranial internal carotid artery (ICA) pseudoaneurysms has not been well described. Here we provide the largest single institution case series to evaluate the technical safety and effectiveness of flow redirection therapy for extracranial ICA pseudoaneurysms.

Materials and Methods A retrospective review of our single institution’s prospectively collected endovascular database revealed 5 cases of flow diverter placement for extracranial ICA pseudoaneurysms treated between 2015 and 2022.

Results We found 5 extracranial ICA pseudoaneurysms in four patients treated with flow-diverter stents. The underlying etiology of pseudoaneurysms was trauma in four aneurysms and iatrogenic in one. One patient was treated for bilateral ICA pseudoaneurysms. The average pseudoaneurysm size was 2.1cm x 1.0 cm. Pipeline Flex with shield technology was used in one pseudoaneurysm, Pipeline Flex was used in three pseudoaneurysms, and classical Pipeline was used in one pseudoaneurysm. One to two Pipelines were used for each pseudoaneurysm. Technical success, defined as proper flow-diverter placement across the lesion with good angiographic wall apposition, was achieved in 100% of cases. No adverse events were reported in the immediate postoperative period. All cases underwent angiographic follow-up ranging from 3 to 21 months post-placement. In one case, short-term angiographic follow-up exhibited endoleak due to pipeline foreshortening in the setting of pseudoaneurysm enlargement and required retreatment with a second flow diverter. Angiographic follow-up showed complete obliteration of pseudoaneurysm in 3/5 cases, and minimal pseudoaneurysm filling in 2/5. There were no cases of in-stent occlusion or retreatment during long-term follow-up.

Conclusion Our initial experience with the use of flow diversion for extracranial ICA pseudoaneurysms suggests this treatment is safe and effective. Further studies should further delineate when flow diverters may be appropriate for extracranial use.

Disclosures B. Eby: None. M. Khasawneh: None.