Introduction: Blister aneurysms (BA) are a rare entity associated with fragile vessel walls, poorly defined anatomy, and a high risk of rupture. Case reports and small case series have reported results of differing surgical techniques in the treatment of BAs, however there is no consensus towards a superior approach. Our objective was to assess the efficacy of extracranial-intracranial (EC-IC) bypass for the treatment of BA as compared to direct clipping and wrap-clipping techniques.

Methods: Outcomes of patients undergoing EC-IC bypass for the treatment of BA were incorporated into the study. Five previous studies, in addition to three cases presented by the authors, identified a total of 36 cases. In addition, reports of microsurgical clipping and wrap-clipping techniques for management of BA identified 34 and 18 cases, respectively.

Results: 36 patients with BA underwent EC-IC bypass. Postoperative infarction was noted in six (16.7%), delayed cerebral ischemia in four (11.1%), four experienced re-bleeding (11.1%) with two mortalities (5.6%). One patient in the author’s presented series developed vasospasm and hydrocephalus with an ultimate modified Rankin score (mRS) of 3. The remainder of the cases experienced excellent outcomes, described as mRS 0-1. Twelve cases (35.3%) of direct clipping ruptured intraoperatively, seven (20.5%) died within one postoperative week. The remainder of cases described outcomes of mRS 0-1. Four (22.2%) of the wrap-clipping cases ruptured intraoperatively, with ultimate mRS ranging from 1 (n=11), 2 (n=3), and 3 (n=1) of reported outcomes.

Conclusions: Preliminary analysis suggests EC-IC bypass can be successfully implemented in the surgical management of blister aneurysms. Our results, in conjunction with previous reports of EC-IC bypass for blister aneurysms suggests that surgical outcomes and complication rates are comparable, if not safer than other techniques and could provide a safe and effective option for surgical management of BA.

Patient Care: Blister aneurysms are friable with difficult anatomy for microsurgical clipping and have a high rupture rate with high levels of associated morbidity and mortality. ECIC bypass offers a surgical intervention that is comparable to, if not safer, than other options for surgical management.

Learning Objectives: Extracranial-intracranial bypass can be an effective technique in the surgical management of blister aneurysms

References: Mooney MA, Kalani MY, Nakaji P, Albuquerque FC, McDougall CG, Spetzler RF, Zabramski JM. Long-term Patient Outcomes After Microsurgical Treatment of Blister-Like Aneurysms of the Basilar Artery. Neurosurgery. 2015 Sep;11 Suppl 3:387-93 Kawashima A, Okada Y, Kawamata T, Onda H, Kubo O, Hori T. Successful treatment of a blood blister-like aneurysm of the internal carotid artery by trapping with a high-flow bypass. J Clin Neurosci. 2008 Baskaya MK, Ahmed AS, Ates O, Niemann D. Surgical treatment of blood blister-like aneurysms of the supraclinoid internal carotid artery with extracranial-intracranial bypass and trapping. Neurosurg Focus. 2008;24(2):E13. Kamijo K, Matsui T. Acute extracranial-intracranial bypass using a radial artery graft along with trapping of a ruptured blood blister–like aneurysm of the internal carotid artery. Clinical article. J Neurosurg. 2010 Oct;113(4):781-5. Kalani MY, Zabramski JM, Kim LJ, et al. Long-term follow-up of blister aneurysms of the internal carotid artery. Neurosurgery. 2013;73(6)