Lesion Trapping with High-Flow Bypass for Ruptured Internal Carotid Artery Blood Blister–Like Aneurysm Has Little Impact on the Anterior Choroidal Artery Flow: Case Series and Literature Review

-OBJECTIVE: To examine the relationship between trap location and cerebral infarction in the anterior choroidal artery (AChA) region and associated risks in ruptured in-ternal carotid artery blood blister -like aneurysm (BLA) treatment with high-flow bypass and lesion trapping. -METHODS: We included 26 patients diagnosed with BLAs and treated with high-flow bypass and trapping. We examined clinical characteristics including age, aneurysm trap location, final prognosis, cerebral infarction on post -operative magnetic resonance imaging, and modified Rankin Scale score at discharge. We also searched the literature for similar studies. -RESULTS: The modified Rankin Scale score at discharge was 0-2 in 20 patients, 3-5 in 2 patients, and 6 in 2 pa-tients. In 19/26 patients (73.1%), the trapped segment was between the posterior communicating (PcomA) and the ophthalmic arteries. In 2 patients (7.7%), the trapped segment included the PcomA and the AChA; in 4 patients (15.4%), the trapped segment was within the PcomA. In these patients, the PcomA was occluded, and blood from the high-flow bypass flowed out to the AChA alone. No patient showed cerebral infarction. Our systematic review identified 70 patients. Of all 96 patients, 12 had AChA cerebral infarction; however, the infarction affected the prognosis of only 2 patients. -CONCLUSIONS: When treating BLAs with high-flow bypass and lesion trapping, the frequency of AChA cere-bral infarction is low even when the PcomA is occluded, leaving the AChA as the only outflow vessel during high-flow bypass. However, PcomA occlusion may be associ-ated with risks when treating patients with advanced arteriosclerosis near C1-2.