Blister-like aneurysms of middle cerebral artery: a multicenter retrospective review of diagnosis and treatment in three patients

Abstract

Blood blister-like aneurysms (BBA) were described for the first time in the 1990s, as small hemispherical bulges arising from a very fragile arterial wall. Until 2008, it was thought that this type of aneurysm almost exclusively affected the internal carotid artery, in particular, its dorsal portion. Subsequently, it was discovered that a BBA may also be present on the anterior communicating artery and on the vessels of the posterior cranial fossa. However, we found no reports in English-language literature of BBA arising from the middle cerebral artery (MCA). In this article, we present three cases of MCA BBA and discuss the unique diagnostic and therapeutic aspects of this vascular lesion. In our retrospective, multicenter review of 1330 patients with non-traumatic subarachnoid hemorrhage admitted to our services from 2000 to 2013, we found three cases (all in men) of MCA BBA. The patients' outcome was assessed using the modified Rankin scale. All three patients underwent angio-computed tomography, which did not reveal any aneurysms. Digital subtraction angiography performed within 24-48 h after admission, in all cases, demonstrated a very small aneurysm (<2 mm), with a triangular shape and abroad base, at non-branching sites of MCA. All the aneurysms were treated: one by wrapping + clipping, one by wrapping + flow-diverter stent, and one with coils. At the time of surgery, the aneurysms appeared on the surface of the parent artery without any involvement of the branches. All presented as blister-like aneurysms that were thin-walled and lacked a surgical neck. At the time of discharge, the outcome was good in one patient and poor in the other two. Our cases demonstrate that BBA can also arise from the MCA, despite the lack of previous reports of this occurrence; a BBA should be suspected, particularly in cases of non-perimesencephalic subarachnoid hemorrhage in which the presence of a MCA aneurysm is suspected but not revealed by digital subtraction angiography or angio-computed tomography.

A Systematic Review and Meta-Analysis of Treatment and Outcome of Blister-Like Aneurysms

“…Specifically, there have been reports of blisterlike aneurysms in the middle cerebral artery, anterior communicating artery, and vertebrobasilar circulation. [4][5][6][7] The above characteristics make them particularly difficult to treat, and patients with these lesions often have a poor outcome. Numerous treatment methods have been proposed: microsurgery, including clipping techniques, titanium vascular miniclip internal carotid artery repair, vessel graft wrapping reinforced by clips, trapping, parent vessel occlusion, and revascularization; and endovascular approaches, which can be performed with coils, coils and stent placement, multiple stents, stent placement alone, or vessel occlusion.…”

Blister-like Aneurysms in Atypical Locations: A Single-Center Experience and Comprehensive Literature Review

“…However, starting from 21 st century atypically located BLAs began to be reported, showing that these vascular lesions do not arise exclusively from the ICA. [1,5,[12][13][14] Regardless of their location, BLAs are characterized by a high risk of intraoperative rupture: However, adding our three cases (table 2) increased this percentage to 8.6%. In this study.…”

“…[13] While the original description of BLAs involved lesions of the dorsal ICA wall, more recent case reports and small clinical series have described aneurysms with similar characteristics in atypical locations such as the middle cerebral artery (MCA), the anterior cerebral artery (ACA) and the basilar artery (BA). [1,5,[12][13][14] Due to the small number of these reported cases, the clinical characteristics, outcome, and therapeutic options for these atypical BLAs are not well defined. Here we have performed a systematic literature review and added a few cases of our own to better define the clinical patterns, treatment options, and outcome of atypical BLAs.…”

Endovascular treatment of blister aneurysms

“…4), and primary coiling without any assistance is rare. 12,15,18,22,36,46,52 The use of a liquid embolic agent for treatment is exceedingly rare and has not been reported without the use of concomitant stenting.…”

“…1,18,24,35,38,40,53 Other authors use the term to describe such aneurysms of both the ICA and basilar artery, 3,7,36,48,52 and some authors include such aneurysms of the middle cerebral artery (MCA), anterior cerebral artery (ACA), vertebral artery (VA), posterior cerebral artery (PCA), and posterior inferior cerebellar artery (PICA). 4,15,31,35,45,46,49 Whether blister aneurysms of the dorsal ICA have the same or different pathogenesis and natural history as similarly shaped aneurysms of nonbranching sites of other cerebral arteries has not been proven.Perhaps due to the rarity of blister aneurysms, the described pathogenesis is not conclusive. Histological examination of blister aneurysms usually reveals a gap in the arterial wall covered by thin, fibrinous tissue, suggesting that the entity is, in fact, a type of pseudoaneurysm ( Figs.…”