1367 Enigmas of the Supraclinoid Internal Carotid Artery: Bypass Versus Non-Bypass Microsurgical Techniques for Blood-Like Blister Aneurysms

INTRODUCTION: Blister aneurysms (BAs) of the internal carotid artery (ICA) have high associated mortality and are challenging owing to their friable wall and poorly defined neck. Microsurgical treatment options have been suggested, including bypass of the parent vessel to exclude the aneurysm. METHODS: Three databases were queried for relevant studies published between 2000 and 2023. The following primary data points were extracted from each study: specific therapy employed, complications, and postoperative functional status (favorable versus unfavorable modified Rankin Score [mRS]). Ultimately, relevant data were pooled for meta-analysis using the Mantel-Haenszel method with random-effects modeling. RESULTS: Among the 519 cases of BAs of the ICA reported across 26 studies, 182 (32.6%) were surgical, while 337 (67.4%) involved endovascular treatment. The cohort's mean age was 47.0 years, and 248 (47.8%) patients were female. Among the seven studies comparing bypass to non-bypass microsurgery, rates of intra- and post-operative bleeding, ischemic infarct, vasospasm, recurrence, favorable outcomes rate, and mortality were comparable for both bypass (n=52 patients; 37.1%) and non-bypass groups (n= 88 patients; 62.9%). CONCLUSIONS: Blister aneurysms of the internal carotid artery are rare intracranial aneurysms that are difficult to treat with microsurgical and endovascular techniques. Considering only patients treated with open surgery, there appears to be no significant difference in complication profile or functional outcomes between patients undergoing bypass or alternative microsurgical techniques. However, it must be noted that the complex nature of bypass procedures means much of the data granularity is lost on meta-analysis, suggesting additional investigations comparing bypass to other open microsurgical techniques may be merited. Similarly, further studies should seek to determine the limitations of DAPT in endovascular therapy and the efficacy of different numbers and types of stents (+/-coil embolization) and other flow-diverting devices.