gms | German Medical Science

Objective: Blood blister-like aneurysms (BBLA) are rare and challenging. Whereas in the past outcome was fatal, recent retrospective studies reported excellent outcomes. We report our critically analyzed results of these challenging aneurysms. Additionally, risk factors for unfavorable outcome were identified.

Methods: Patient and aneurysm characteristics, clinical course and treatment results were collected prospectively and analyzed retrospectively including data from patient records and review of imaging findings. Aneurysm configuration was analyzed in detail and categorized to the four different subtypes of BBLA (Bojanowski et al. JNS 2015). In BBLA type I only a part of the artery’s wall is affected by the blister without a sac in the angiography, whereas in BBLA type II a sac (neck not longer than diameter) can be identified. In BBLA type III a long portion is involved, which is longer than the diameter of the vessel. In BBLA type IV the artery is affected circumferential.

Results: Between 1999 and 2014 a total of 27 patients had subarachnoid hemorrhage (SAH) from BBLA. Mean age (±SD) was 56±15 years. 12 patients (44%) had poor admission status (WFNS 4+5) and 24 (89%) a Fisher 3 or 4 SAH. 13 patients (48%) had a BBLA of the internal carotid artery, 6 of the anterior cerebral artery (22%), 5 of the middle cerebral artery (19%) and 3 of the basilar artery (11%). The majority of the patients (n=12) had a type IV BBLA (44%). 13 patients (48%) were treated by clip-reinforced wrapping only, 8 patients by clipping alone (30%) and 3 received no treatment (11%). The other patients were treated endovascularly (n=1), combined (n=1) or by fenestration tube technique (n=1). 13 patients (48%) had vasospasm-associated cerebral infarction and 6 patients (22%) developed a shunt-dependent hydrocephalus. Rerupture after treatment occurred in five patients (19%), any of them type IV BBLA. Outcome was unfavorable (modified Rankin scale score 3-6) in 52% (n=14) and 33% (n=9) of the patients died. The highest rate of elderly patients (≥60y; 67%), rerupture (33%), delayed infarctions (67%), unfavorable outcome (75%) and deaths (50%) was identified in type IV BBLA, whereas type I-III had a better course: delayed infarctions (33%), unfavorable outcome (27%), deaths (13%). Due to two intraoperative ruptures we would not recommend a direct clipping of BBLA type IV.

Conclusion: Treatment of BBLA is still challenging. However, especially patients with type IV BBLA were prone to rerupture, to have delayed infarctions, unfavorable outcome and death. Interestingly, patients with BBLA type IV were older than the other subgroups, so this could indicate a chronic process underlying BBLA. In multivariate analysis independent risk factors for unfavorable outcome of BBLA were advanced age (≥60 years) and BBLA type IV.