Blood blisterlike aneurysms of the internal carotid artery

Treatment of ruptured blood blister aneurysms using primary flow-diverter stenting with considerations for adjunctive coiling: A single-centre experience and literature review

Objective The objective of this article is to conduct a single-centre evaluation and quick literature review of the effectiveness of primary flow-diverter (FD) treatment of ruptured blood blister aneurysms (BBAs), with additional relevance of adjunctive coiling. Methods Patients presenting with subarachnoid haemorrhage (SAH) due to ruptured BBAs and subsequently treated with FDs were retrospectively selected from June 2010 to January 2017. Treatment techniques, angiographic data on occlusion rates and procedural success as well as clinical outcomes using the modified Rankin Scale (mRS) were collated. Cross-reference of results were made with available literature. Results Thirteen patients harbouring 14 BBAs were recruited. Of the 14 aneurysms, five (35.7%) showed immediate complete occlusion after the procedure (four of these five patients had adjunctive coiling). All of the aneurysms showed complete occlusion by the six- to nine-month control diagnostic angiogram. No rebleed or retreatment was experienced. Twelve of 13 (92%) patients had an mRS score of 0-1 at the last clinical follow-up. From the pooled data of the literature review, eventual aneurysm occlusion was achieved in 48/56 patients, with five patients requiring further endovascular treatment. In the clinical follow-up period, an mRS of 0-2 was recorded for 83.3% (45/54) of patients. Conclusion Endovascular reconstruction of BBAs using FD treatment is an effective method with good final clinical outcomes. Adjunctive use of coiling achieves higher incidence of immediate complete occlusion of BBAs.

Endovascular treatment of blister aneurysms

Blister aneurysms are rare cerebrovascular lesions for which the treatment methods are reviewed here, with a focus on endovascular options. The reported pathogenesis of blister aneurysms varies, and hemodynamic stress, arterial dissection, and arteriosclerotic ulceration have all been described. There is consensus on the excessive fragility of blister aneurysms and their parent vessels, which makes clipping technically difficult. Open surgical treatment is associated with high rates of complications, morbidity, and mortality; endovascular treatment is a promising alternative. Among endovascular treatment options, deconstructive treatment has been associated with higher morbidity compared with reconstructive methods such as direct embolization, stent- or balloon-assisted direct embolization, stent monotherapy, and flow diversion. Flow diversion has been associated with higher technical success rates and similar clinical outcomes compared with non–flow diverting treatment methods. However, delayed aneurysm occlusion and the need for antiplatelet therapy are potential drawbacks to flow diversion that must be considered when choosing among treatment methods for blister aneurysms.

Flow diverter devices in ruptured intracranial aneurysms: a single-center experience

OBJECTIVE In this single-center series, the authors retrospectively evaluated the effectiveness, safety, and midterm follow-up results of ruptured aneurysms treated by implantation of a flow diverter device (FDD). METHODS The records of 17 patients (12 females, 5 males, average World Federation of Neurosurgical Societies score = 2.9) who presented with subarachnoid hemorrhage (SAH) due to the rupture of an intracranial aneurysm treated with an FDD were retrospectively reviewed. Of 17 ruptured aneurysms, 8 were blood blister-like aneurysms and the remaining 9 were dissecting aneurysms. The mean delay between SAH and treatment was 4.2 days. Intraprocedural and periprocedural morbidity and mortality were recorded. Clinical and angiographic follow-up evaluations were conducted between 6 and 12 months after the procedure. RESULTS None of the ruptured aneurysms re-bled after endovascular treatment. The overall mortality rate was 12% (2/17), involving 2 patients who died after a few days because of complications of SAH. The overall morbidity rate was 12%: 1 patient experienced intraparenchymal bleeding during the repositioning of external ventricular drainage, and 1 patient with a posterior inferior cerebellar artery aneurysm developed paraplegia due to a spinal cord infarction after 2 weeks. The angiographic follow-up evaluations showed a complete occlusion of the aneurysm in 12 of 15 surviving patients; of the 3 remaining cases, 1 patient showed a remnant of the aneurysm, 1 patient was retreated due to an enlargement of the aneurysm, and 1 patient was lost at the angiographic follow-up. CONCLUSIONS FDDs can be used in patients with ruptured aneurysms, where conventional neurosurgical or endovascular treatments can be challenging.

Nontraumatic, posterior circulation pseudoaneurysm of the basilar artery summit with complete spontaneous resolution: Case report and literature review

Background:

Intracranial pseudoaneurysms are rare vascular defects of arterial walls that are classically the result of traumatic injury, iatrogenic causes, or infection. Idiopathic pseudoaneurysms are seen even less frequently and are often related to atherosclerosis. Pseudoaneurysms are most commonly found along the distal wall of the internal carotid artery, however, can occur at any location in the cerebrovascular circulation. Treatment of these arterial defects is often challenging due to their frail nature.

Case Description:

A 61-year-old male with a history of hypertension presented with a severe, atypical headache without history of trauma. Computed tomography (CT) and computed tomography angiography (CTA) demonstrated diffuse subarachnoid hemorrhage. Imaging demonstrated a 3.5 mm pseudoaneurysm projecting distally from the basilar artery at the apex. Repeated imaging (CTA, digital subtraction angiography) demonstrated decreased size and flow associated within the aneurysm over the following 2 weeks; as such, the patient was managed conservatively. The patient was discharged in neurologically intact condition when imaging at 14 days confirmed complete and spontaneous resolution of the pseudoaneurysm.

Conclusion:

Idiopathic pseudoaneurysms that are commonly associated with atherosclerosis are most commonly managed surgically or endovascularly. Conservative approach may be considered in a select group of patients that exhibit decreased size and/or flow within the aneurysm in repeated imaging; spontaneous resolution was seen in the present case.

Microsurgical versus endovascular interventions for blood-blister aneurysms of the internal carotid artery: systematic review of literature and meta-analysis on safety and efficacy

OBJECTIVE Blood-blister aneurysms (BBAs) of the internal carotid artery (ICA) have a poor natural history associated with high morbidity and mortality. Currently, both surgical and endovascular techniques are employed to treat BBAs; thus, the authors sought to perform a meta-analysis to compare the efficacy and safety of these approaches. METHODS A literature search of PubMed, MEDLINE, and Google Scholar online databases was performed to include pertinent English-language studies from 2005 to 2015 that discussed the efficacy and safety of either surgical or endovascular therapies to treat BBAs. RESULTS Thirty-six papers describing 256 patients with BBAs treated endovascularly (122 procedures) or surgically (139 procedures) were examined for data related to therapeutic efficacy and safety. Pooled analysis of 9 papers demonstrated immediate and late (mean 20.9 months) aneurysm occlusion rates of 88.9% (95% CI 77.6%-94.8%) and 88.4% (95% CI 76.7%-94.6%), respectively, in surgically treated patients. Pooled analysis of 12 papers revealed immediate and late aneurysm obliteration rates of 63.9% (95% CI 52.3%-74.1%) and 75.9% (95% CI 65.9%-83.7%), respectively, in endovascularly treated aneurysms. Procedure-related complications and overall poor neurological outcomes were slightly greater in the surgically treated cases than in the endovascularly treated cases (27.8% [95% CI 19.6%-37.8%] vs 26.2% [95% CI 18.4%-35.8%]), indicating that endovascular therapy may provide better outcomes. CONCLUSIONS Blood-blister aneurysms are rare, challenging lesions with a poor prognosis. Although surgical management potentially offers superior aneurysm obliteration rates immediately after treatment and at the long-term follow-up, endovascular therapy may have a better safety profile and provide better functional outcomes than surgery. A registry of patients treated for BBAs may be warranted to better document the natural course of the disease as well as treatment outcomes.

Blister Aneurysms of the Internal Carotid Artery: Microsurgical Results and Management Strategy

BACKGROUND: Blister aneurysms of the supraclinoid internal carotid artery (ICA) are challenging lesions with high intraoperative rupture rates and significant morbidity. An optimal treatment strategy for these aneurysms has not been established.

OBJECTIVE: To analyze treatment strategy, operative techniques, and outcomes in a consecutive 17-year series of ICA blister aneurysms treated microsurgically.

METHODS: Seventeen patients underwent blister aneurysm treatment with direct clipping, bypass and trapping, or clip-reinforced wrapping.

RESULTS: Twelve aneurysms (71%) were treated with direct surgical clipping. Three patients required bypass: 1 superficial temporal artery to middle cerebral artery bypass, 1 external carotid artery to middle cerebral artery bypass, and 1 ICA to middle cerebral artery bypass. One patient was treated with clip-reinforced wrapping. Initial treatment strategy was enacted 71% of the time. Intraoperative rupture occurred in 7 patients (41%), doubling the rate of a poor outcome (57% vs 30% for patients with and without intraoperative rupture, respectively). Severe vasospasm developed in 9 of 16 patients (56%). Twelve patients (65%) were improved or unchanged after treatment, and 10 patients (59%) had good outcomes (modified Rankin Scale scores of 1 or 2).

CONCLUSION: ICA blister aneurysms can be cautiously explored and treated with direct clipping as the first-line technique in the majority of cases. Complete trapping of the parent artery with temporary clips and placing permanent clip blades along normal arterial walls enables clipping that avoids intraoperative aneurysm rupture. Trapping/bypass is used as the second-line treatment, maintaining a low threshold for bypass with extensive or friable pathology of the carotid wall and in patients with incomplete circles of Willis.

Stent-Assisted Coiling May Prevent the Recurrence of Very Small Ruptured Intracranial Aneurysms: A Multicenter Study

OBJECTIVE

To evaluate the safety and efficacy of endovascular treatments, including stent-assisted coiling, of very small (≤3 mm), ruptured intracranial aneurysms.

METHODS

Ninety-three endovascularly treated patients with very small ruptured aneurysms were recruited from 4 high-volume centers between September 2010 and February 2014. Factors influencing procedural complications and outcomes were analyzed.

RESULTS

Fifty-one (54.8%) aneurysms were treated by stent-assisted coiling, 41 (44.1%) by coiling alone, and 1 (1.1%) by balloon-assisted coiling. Intraprocedural or postprocedural complications occurred in 13 patients (14.0%): coil migration in 1, intraprocedural rupture in 1, hydrocephalus in 6, and ischemic event in 1. No tested factor was able to predict procedural complications. Angiographic follow-up of 67 aneurysms (72%) revealed recurrence in 5 patients (7.5%). One recurrent case was treated initially by stent-assisted coiling and the remaining four by coiling alone (P = 0.044). Multivariate regression analysis showed that coiling alone was significantly associated with aneurysm recurrence (odds ratio, 13.8; 95% confidence interval, 1.1-175.3; P = 0.043).

CONCLUSIONS

Endovascular treatment of very small ruptured aneurysms was safe and effective and was not associated with a high rate of intraprocedural rupture. Treatment with the use of stents significantly lowered the recurrence rate without additional risks.

Current status of the treatment of blood blister-like aneurysms of the supraclinoid internal carotid artery: A review

Currently, the treatment of blood blister-like aneurysms (BBAs) of the supraclinoid internal carotid artery (ICA) is challenging and utilizes many therapeutic methods, including direct clipping and suturing, clipping after wrapping, clipping after suturing, coil embolization, stent-assisted coil embolization, multiple overlapping stents, flow-diverting stents, covered stents, and trapping with or without bypass. In these therapeutic approaches, the optimal treatment method for BBAs has not yet been defined based on the current understanding of BBAs of the supraclinoid ICA. Therefore, in this study, we aimed to review the literature from PubMed to discuss and analyze the pros and cons of the above approaches while adding our own viewpoints to the discussion. Among the surgical methods, direct clipping was the easiest method if the compensation of the collateral circulation of the intracranial distal ICA was sufficient or direct clipping did not induce stenosis in the parent artery. In addition, the clipping after wrapping technique should be chosen as the optimal surgical modality to prevent rebleeding from these lesions. Among the endovascular methods, multiple overlapping stents (≥3) with coils may be a feasible alternative for the treatment of ruptured BBAs. In addition, flow-diverting stents appear to have a higher rate of complete occlusion and a lower rate of retreatment and are a promising treatment method. Finally, when all treatments failed or the compensation of the collateral circulation of the intracranial distal ICA was insufficient, the extracranial-intracranial (EC-IC) arterial bypass associated with surgical or endovascular trapping, a complex and highly dangerous method, was used as the treatment of last resort.

Surgical Management of Intracranial Artery Dissection

Intracranial artery dissection (IAD) is a relatively rare cause of stroke, but it has been recognized increasingly with recent advances of the neuroimaging technique. Since rebleeding occurs frequently in the acute stage in the ruptured IAD, urgent surgical treatment should be performed to prevent rebleeding. On the other hand, surgical treatment for unruptured IAD is controversial because it has little risk for bleeding. However, surgical treatment for unruptured IAD may be considered if the formation or enlargement of the aneurysmal dilatation has been confirmed. Since there are several proposed surgical strategies for IAD, it is important to select an appropriate strategy on a case-by-case basis. If the risk of infarction due to vessel occlusion is high, combined bypass surgery should be considered.

Oblique Clip Technique via Anterior Temporal Approach for Blood Blister Aneurysm of Distal Portion of Internal Carotid Artery

BACKGROUND

Blood blister aneurysms (BBAs) of the internal carotid artery (ICA) are challenging vascular lesions for neurosurgeons because they are fragile and difficult to clip. They are commonly found at the dorsal wall of the ICA. Trapping is an alternative for these lesions, accompanied by vascular reconstruction. However, they are sometimes close to the posterior communicating artery and anterior choroidal artery.

CASE DESCRIPTION

A 30-year-old man presented with subarachnoid hemorrhage caused by rupture of a BBA in the right distal ICA. After construction of a high-flow bypass, the BBA was accessed via the standard pterional approach to end only in proximal clipping. Two weeks later, the remnant of the BBA showed a tendency to grow. Therefore, the anterior temporal approach was successfully used to obliterate the BBA using an oblique clip technique under direct inspection of patency of the perforators.

CONCLUSIONS

The anterior temporal approach to a BBA in the distal ICA is amenable to application of the oblique clip technique, which can provide direct inspection of the perforators emanating from the posteromedial wall of the ICA as well as obliteration of the pathologic wall. Furthermore, less retraction of the frontal lobe is also reasonable for avoidance of premature rupture of a fragile BBA.

Endovascular Treatment of Ruptured Blister-Like Aneurysms: A Systematic Review and Meta-Analysis with Focus on Deconstructive versus Reconstructive and Flow-Diverter Treatments

BACKGROUND AND PURPOSE

Various endovascular techniques have been applied to treat blister-like aneurysms. We performed a systematic review to evaluate endovascular treatment for ruptured blister-like aneurysms.

MATERIALS AND METHODS

We performed a comprehensive literature search and subgroup analyses to compare deconstructive versus reconstructive techniques and flow diversion versus other reconstructive options.

RESULTS

Thirty-one studies with 265 procedures for ruptured blister-like aneurysms were included. Endovascular treatment was associated with a 72.8% (95% CI, 64.2%-81.5%) mid- to long-term occlusion rate and a 19.3% (95% CI, 13.6%-25.1%) retreatment rate. Mid- to long-term neurologic outcome was good in 76.2% (95% CI, 68.9%-8.4%) of patients. Two hundred forty procedures (90.6%) were reconstructive techniques (coiling, stent-assisted coiling, overlapped stent placement, flow diversion) and 25 treatments (9.4%) were deconstructive. Deconstructive techniques had higher rates of initial complete occlusion than reconstructive techniques (77.3% versus 33.0%, P = .0003) but a higher risk for perioperative stroke (29.1% versus 5.0%, P = .04). There was no difference in good mid- to long-term neurologic outcome between groups, with 76.2% for the reconstructive group versus 79.9% for the deconstructive group (P = .30). Of 240 reconstructive procedures, 62 (25.8%) involved flow-diverter stents, with higher rates of mid- to long-term complete occlusion than other reconstructive techniques (90.8% versus 67.9%, P = .03) and a lower rate of retreatment (6.6% versus 30.7%, P < .0001).

CONCLUSIONS

Endovascular treatment of ruptured blister-like aneurysms is associated with high rates of complete occlusion and good mid- to long-term neurologic outcomes in most patients. Deconstructive techniques are associated with higher occlusion rates but a higher risk of perioperative ischemic stroke. In the reconstructive group, flow diversion carries a higher level of complete occlusion and similar clinical outcomes.

Specific and helpful intraoperative indocyanine green videoangiography finding of blood blister-like aneurysm of internal carotid artery

BACKGROUND

Blood blister-like aneurysms (BBAs) account for 0.5-2.0 % of ruptured intracranial aneurysms. Because of their rarity, the natural history and pathophysiology of such aneurysms are not fully understood. We present two patients with BBAs treated with Bemsheets-covered clipping and discuss their pathophysiological characteristics, through the intraoperative and specific indocyanine green (ICG) video angiography (VA) findings.

CASE REPORT

A 34-year-old male and a 53-year-old female were admitted to our emergency room with suddenly reduced levels of consciousness. Brain imaging studies demonstrated a blood blister-like aneurysm of the supraclinoid segment of the right ICA. Craniotomy and an attempt of surgical clipping were performed. ICG-VA showed the filling defect of dye in aneurysm in the operative field. The BBAs were clipped after being covered by Bemsheets (Kawamoto Corporation, Osaka, Japan) and then confirmed by the ICG-VA. Postoperatively, both patients showed transient neurological deficit due to vasospasms and recovered to their normal statuses within a few months after their respective operations.

CONCLUSIONS

ICG-VA showed the filling defect of dye in BBAs, which supported that BBAs have been a pseudoaneurysm. In addition, although not routinely recommended in the treatment of BBAs, we believe that Bemsheet-covered clipping is a safe and effective treatment option for BBAs.

The unusual angiographic course of intracranial pseudoaneurysms

Although rare, traumatic intracranial pseudoaneurysms remain one of the most difficult vascular lesions to diagnose and treat. A 55-year-old male patient underwent endoscopic endonasal transphenoidal resection for a pituitary macroadenoma. The operation was complicated by an arterial bleed. The initial angiogram revealed pseudoaneurysm of the anterior choroidal artery. Although the pseudoaneurysm completely disappeared on the second angiogram, it was surprisingly found to have enlarged on the third angiogram. The lesion was successfully treated with flow-diversion using a pipeline embolization device. The present case demonstrates that the natural history of iatrogenic pseudoaneurysms may be unpredictable and misleading. Traumatic pseudoaneurysms should, therefore, be carefully followed when conservative treatment is elected or when the lesion seems to have spontaneously regressed. Flow-diversion seems to be a reasonable treatment option.

Long-term Patient Outcomes After Microsurgical Treatment of Blister-Like Aneurysms of the Basilar Artery

BACKGROUND

Blister-like aneurysms (BLAs) are challenging lesions that require unique microsurgical strategies. BLAs are predominantly found along the internal carotid artery; however, BLAs of the basilar artery are a rare subset that requires a modified treatment strategy.

OBJECTIVE

To discuss the microsurgical management and review the long-term outcomes of patients with BLAs of the basilar artery.

METHODS

We retrospectively reviewed the surgical technique, postoperative results, and long-term outcomes of all patients with basilar artery BLAs treated at our institution from 2005 to 2011.

RESULTS

Four patients with basilar artery BLAs were identified over this 6-year interval. All 4 patients were treated by direct microsurgical clipping. A thin layer of cotton reinforcement was used beneath the clip tines to minimize the risk of clip slippage in 2 of 4 patients; 1 patient required adjunctive endovascular stent placement for residual aneurysm after clipping. Complete obliteration of all aneurysms was achieved, and there has been no recurrence at mean clinical follow-up of 72 months (median, 74.5; range, 37-103) and imaging follow-up of 48 months (median, 54; range 12-72).

CONCLUSION

Direct clipping with or without cotton reinforcement can obliterate basilar BLAs with excellent long-term outcomes. Clip wrapping is not an option for these lesions given the proximity to perforating branches. Endovascular techniques provide a useful adjunctive strategy; however, risks with antiplatelet therapy in the acute subarachnoid hemorrhage period must be considered.

High-flow bypass and wrap-clipping for ruptured blood blister-like aneurysm of the internal carotid artery using intraoperative monitoring of cerebral hemodynamics

Aneurysms at non-branching sites in the supraclinoid internal carotid artery (ICA) can be classified as “blood blister-like aneurysms” (BBAs), which have blood blister-like configurations and fragile walls. While surgical treatment for the BBA in the acute stage is recommended, the optimal surgical procedure remains controversial. In the study reported here, we describe the case of a 37-year-old woman with a ruptured BBA in the ophthalmic segment of the right ICA who underwent wrap-clipping with external carotid artery–internal carotid artery bypass by intraoperative estimation of the measurement of cortical cerebral blood flow (CoBF) using a thermal diffusion flow probe. Trapping of the ICA in the acute stage of subarachnoid hemorrhage may result in ischemic complications secondary to hemodynamic hypoperfusion or occlusion of the perforating artery, and/or delayed vasospasm, even with concomitant bypass surgery. We believe that it is important to perform scheduled external carotid artery–internal carotid artery bypass before trapping of the ICA in patients with a ruptured BBA in the acute stage of subarachnoid hemorrhage and to perform wrap-clipping rather than trapping. This would provide much more CoBF if a reduction of CoBF occurs after trapping occlusion of the ICA including a ruptured BBA according to intraoperative CoBF monitoring. As far as we are aware, the case reported here is the first report on high-flow bypass and wrap-clipping for a ruptured BBA of the ICA using intraoperative monitoring of cerebral hemodynamics.

Morphological aspects of blister aneurysms and nuances for surgical treatment

OBJECT

Blister aneurysms of the supraclinoid part of the internal carotid artery (ICA) are known for their high morbidity and mortality rates related to treatment, regardless of whether the treatment is surgical or endovascular. However, this grim prognosis is based on results that indiscriminately group all blister aneurysms together without taking into account the heterogeneous appearance of these lesions. The goal of this study was 2-fold: to determine whether different blister aneurysm morphologies present different pitfalls, which would then require different surgical strategies, as well as to determine whether there are identifiable subgroups of these types of aneurysms based on morphology.

METHODS

The authors reviewed the charts, cerebral catheter angiograms, surgical reports, and intraoperative videos of all ICA blister aneurysms treated surgically at the Centre Hospitalier de l'Université de Montréal from 2005 to 2012 to investigate whether there was a relationship between morphology and pitfalls, and whether different surgical strategies had been used according to these pitfalls. During this review process the authors noted 4 distinct morphological aspects. These 4 aspects led to a review of the English and French literature on blister aneurysms in which imaging was available, to determine whether other cases could also be classified into the same 4 subgroups based on these morphological aspects.

RESULTS

The retrospective review of the authors' series of 10 patients allowed a division into 4 distinct subtypes: Type I (classic), Type II (berry-like), Type III (longitudinal), and Type IV (circumferential). These subtypes may at times be progressive stages in the arterial anomaly, and could represent a continuum. Each subtype described in this paper presented its own pitfalls and required specific surgical adaptations. Upon reviewing the literature the authors retained 35 studies involving a total of 61 cases of blister aneurysms, and all cases were able to be classified into 1 of these 4 distinct subtypes.

CONCLUSIONS

Although they share some common characteristics, blister aneurysms may be divided into distinct subtypes, suggestive of a continuum. Such a classification with a detailed description of each type of blister aneurysm would allow for better recognition to anticipate complications during intervention and better assess the different treatment strategies according to the subtypes.

Pipeline embolization for definitive endoluminal reconstruction of blister-type carotid aneurysms after clip wrapping

Background

Ruptured blister aneurysms of the carotid artery are difficult to safely treat. We present a novel strategy of microsurgical clip wrapping of internal carotid artery blister aneurysms in the setting of acute rupture, followed by delayed placement of a pipeline embolization device for definitive treatment.

Clinical presentation

We present two cases of ruptured blister aneurysms of the internal carotid artery treated by wrapping of the diseased segment of the vessel, followed by delayed deployment of a flow diverting stent once the patient was out of the vasospasm window but during the same hospitalization.

Results

Clip wrapping followed by flow diversion in a delayed fashion results in anatomic remodeling of the diseased artery without a high morbidity.

Conclusions

A combined approach of acute surgical stabilization followed by definitive endovascular reconstruction may reduce hemorrhagic complications while improving long term treatment durability.

Towards a new treatment paradigm for ruptured blood blister-like aneurysms of the internal carotid artery? A rapid systematic review

BACKGROUND AND PURPOSE

Owing to their peculiar features and rare occurrence, ruptured blood blister-like aneurysms (BBAs) of the internal carotid artery are challenging by both surgical and endovascular approaches and their proper management is uncertain. We therefore aimed to define the currently optimal treatment of ruptured BBAs in terms of mortality, outcome, rebleeding, and recurrence.

METHOD

An in-depth search of electronic databases, gray literature and internet resources for ruptured BBAs was performed and complemented by data retrieval during neurosurgical congresses. Clinical and radiological characteristics, intervention details, outcomes, and the impact factor of the source journal were pooled.

RESULTS

The pooled cohort comprised 311 patients. Neither surgical nor endovascular methods had an impact on clinical outcome, aneurysm regrowth, remote bleeding, or complication rate. By contrast, aneurysm clipping was a predictor of intraoperative bleeding (OR 6.5; 95% CI 1.2 to 34.3), and stent-assisted coiling increased the likelihood of a second treatment (OR 4.1; 95% CI 1.3 to 13.1), its conversion to another modality (OR 4.7; 95% CI 1.4 to 16.0), and incomplete aneurysm obliteration (OR 2.6; 95% CI 1.0 to 6.6). Higher impact journals were more likely to publish papers on endovascular techniques, particularly flow-diverter stents.

CONCLUSIONS

None of the methods is unequivocally superior. Considering its inefficiency, stent-assisted coiling should be undertaken with caution. A time-delimited systematic review is needed to establish the most accurate treatment for ruptured BBAs.

Endovascular treatment of supraclinoid internal carotid artery aneurysms

Endovascular management of intracranial aneurysms has advanced significantly over the last couple decades and continues to evolve, including aneurysms within the subgroup of supraclinoid internal carotid artery (ophthalmic, superior hypophyseal, posterior communicating, anterior choroidal, dorsal wall/blister, and carotid terminus).

Use of the sundt clip graft in a previously coiled internal carotid artery blister-like aneurysm

Owing to the focal wall defect covered with thin fibrous tissues, an aneurysm arising from the dorsal wall of the internal carotid artery (ICA) is difficult to manage either surgically or endovascularly and is often associated with high morbidity and mortality. Unfortunately, the definitive treatment modality of such highly risky aneurysm has not yet been demonstrated. Upon encountering the complex intracranial pathophysiology of such a highly precarious aneurysm, a neurosurgeon would be faced with a challenge to decide on an optimal approach. This is a case of multiple paraclinoid aneurysms including the ICA dorsal wall aneurysm, presented with spontaneous subarachnoid hemorrhage. With respect to treatment, direct clipping with a Sundt graft clip was performed after multiple endovascular interventions had failed. This surgical approach can be a treatment modality for a blood blister-like aneurysm after failed endovascular intervention(s).

Blood blister-like aneurysm with rupture point close to origin of anterior choroidal artery

If a ruptured blood blister-like aneurysm (BBA) arises from the lateral or superolateral wall of the internal carotid artery (ICA) at the level of the anterior choroidal artery (AChA), its proximity to the origin of the AChA presents a serious surgical challenge to preserve the patency of the AChA. Two such rare cases are presented, along with successful surgical techniques, including the application of a C-shaped aneurysm clip parallel to the ICA and a microsuture technique to repair the arterial defect. The patency of the AChA and ICA was successfully preserved without recurrence or rebleeding of the BBA during a 1-year follow-up after the operation.

Are blood blister-like aneurysms a specific type of dissection? A comparative study of blood blister-like aneurysms and ruptured mizutani type 4 vertebral artery dissections

Objective

Blood blister-like aneurysms (BBAs) resemble arterial dissections. The purpose of this study was to investigate the relationship between these two disease entities and highlight commonalities and distinct features.

Methods

Among 871 consecutive patients with aneurysmal subarachnoid hemorrhage, 11 BBAs of internal carotid artery and seven vertebral artery dissections (VADs) with a short segmental eccentric dilatation (Mizutani type 4), which is morphologically similar to a BBA, were selected. The following clinical factors were studied in each group : age, gender, risk factors, Hunt and Hess grade (HHG), Fisher grade (FG), vasospasms, hydrocephalus, perioperative rebleeding rate, and treatment outcome.

Results

The mean age was 47.9 years in the BBAs group and 46.4 years in the type 4 VADs group. All the BBA patients were female, whereas there was a slight male predominance in the type 4 VAD group (male : female ratio of 4 : 3). In the BBA and type 4 VAD groups that underwent less aggressive treatment to save the parent artery, 29% (n=2/7) and 66.6% (n=2/3), respectively, eventually required retreatment. Perioperative rebleeding occurred in 72.7% (n=8) and 28.6% (n=2) of patients in the BBA and type 4 VAD groups, respectively. There was no statistical difference in the other clinical factors in both groups, except for the male dominancy in the type 4 VAD group (p=0.011).

Conclusion

BBAs and ruptured type 4 VADs have a similar morphological appearance but there is a distinct clinical feature in gender and perioperative rebleeding rates. Complete isolation of an aneurysm from the parent artery might be the most important discipline for the treatment of these diseases.

Endovascular management of intracranial blister aneurysms: spectrum and limitations of contemporary techniques

Background

Intracranial blister aneurysms are rare lesions that are notoriously more difficult to treat than typical saccular aneurysms. High complication rates associated with surgery have sparked considerable interest in endovascular techniques, though not well-studied, to treat blister aneurysms.

Objective

To evaluate our experience using various endovascular approaches to treat blister aneurysms.

Methods

All consecutive blister aneurysms treated using an endovascular approach by the study authors over a 3-year period were retrospectively analyzed. A literature review was also performed.

Results

Nine patients with blister aneurysms underwent 11 endovascular interventions. In various combinations, stents were used in 8/11, coils in 5/11, and Onyx in 3/11 procedures. At mean angiographic follow-up of 200 days, 8/9 aneurysms were completely occluded by endovascular means alone requiring no further treatment and 1/9 aneurysms required surgical bypass/trapping after one failed surgical and two failed endovascular treatments. At mean clinical follow-up of 416 days, modified Rankin Scale scores were improved in six patients, stable in two, and worsened in one patient. One complication occurred in 11 procedures (9%), resulting in a permanent neurologic deficit. No unintended endovascular parent vessel sacrifice, intraprocedural aneurysmal ruptures, antiplatelet-related complications, post-treatment aneurysmal re-ruptures, or deaths occurred.

Conclusion

This series highlights both the spectrum and limitations of endovascular techniques currently used to treat blister aneurysms, including a novel application of stent-assisted Onyx embolization. Long-term follow-up and experience in larger studies are required to better define the role of endovascular therapy in the management of these difficult lesions.

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

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.

Combination treatment for rapid growth of a saccular aneurysm on the internal carotid artery dorsal wall: case report

Aneurysms arising from non-branching sites of the supraclinoid internal carotid artery (ICA) are considered rare, accounting for only 0.9-6.5% of all ICA aneurysms. They are thin-walled, broad-based, can easily rupture during surgery, and are referred to as dorsal, superior, anterior, or ventral wall ICA aneurysms, as well as blister-like aneurysms. Various treatment modalities are available for blister-like aneurysms, but with varying success. Here, we report on two cases of saccular shaped dorsal wall aneurysms. Both patients were transferred to the emergency department with subarachnoid hemorrhage because of an aneurysmal rupture. Computed tomography angiography and transfemoral cerebral angiography (TFCA) showed a dorsal wall aneurysm in the distal ICA. We performed clipping on the wrapping material (Lyodura®, temporal fascia). Follow-up TFCA showed rapid configuration changes of the right distal ICA. Coil embolization was also performed as a booster treatment to prevent aneurysm regrowth. Both patients were discharged without neurologic deficit. No evidence of aneurysm regrowth was observed on follow-up TFCA at two years. Dorsal wall ICA aneurysms can change in size over a short period; therefore, follow-up angiography should be performed within the short-term. In cases of regrowth, coil embolization should be considered as a booster treatment.

The sundt encircling clip as a vascular rescue: a case report and a review of repair methods for arterial tearing

The Sundt encircling clip was developed to repair defects of the vessel wall. With the advent of microvascular techniques, most parts of the damaged vessel wall during aneurysm surgery can be repaired by primary closure or by the bypass technique. However, these methods are not always successful. Here, we illustrate two cases of surgical clipping with the Sundt encircling clip in the ruptured internal carotid artery trunk aneurysm. The Sundt clip provides prompt control of unexpected tearing of the vessel wall or aneurysm and plays an important role in vascular rescue during aneurysm surgery.

Stenting as monotherapy for uncoilable intracranial aneurysms

BACKGROUND

Small, blister-like aneurysms (BLAs), by virtue of their unique morphology, are difficult to treat with conventional modalities. The use of oversized self-expanding stents as monotherapy for BLAs is a relatively new and promising concept that warrants further investigation.

OBJECTIVE

To clarify the role of oversized self-expanding stents as monotherapy for BLAs.

METHODS

Five consecutive patients were treated for BLAs with oversized self-expanding stents alone by the senior author (K.R.B.). We report on their clinical and radiographic outcomes.

RESULTS

All 5 patients in our series were discharged in good clinical condition. Complete aneurysm occlusion was observed in all patients at the time of most recent radiographic follow-up. Mean follow-up time was 13.6 months (range, 1 month to 4.5 years).

CONCLUSION

The use of oversized self-expanding stents to redirect flow away from aneurysms is an effective option for patients with BLAs. This approach represents an alternative to the use of flow diverters.

Long-term clinical and angiographic outcomes of wrap-clipping strategies for unclippable cerebral aneurysms

PURPOSE

To evaluate the efficacy and stability of the wrap-clipping methods as a reconstructive strategy in the treatment of unclippable cerebral aneurysms.

MATERIALS AND METHODS

Twenty four patients who had undergone wrap-clipping microsurgery were retrospectively reviewed. Type and morphology of the treated aneurysm, utilized technique for wrap-clip procedure, and clinical outcome with angiographic results at their last follow-up were evaluated.

RESULTS

Of 24 patients, eleven patients had internal carotid artery (ICA) blister-like aneurysms, three had dissecting type aneurysms, and ten had fusiform aneurysms. The follow-up period for the late clinical and angiographic results ranged from 10 to 75 months (mean 35 months). Wrap-clipping was performed in eleven, wrap-holding clipping was in ten, and combination of wrap-clip and wrap-holding clip was in three cases. At the last angiographic follow-up study, twelve aneurysms (50%) were found to have completely healed, and nine aneurysms (38%) were at least stable. However, wrap-holding clip for the elongated blister type of ICA aneurysm was found failed, leading to fatal rebleeding in one case, and two cases of combination of wrap-clip-wrap-holding clip revealed delayed branch occlusion and marked regrowing, respectively.

CONCLUSION

Wrap-clipping strategy could be an easy and safe alternative for unclippable aneurysms. The wrapped aneurysm mostly disappeared, or at least remained stationary, after a long-term period. However, surgeons should be aware of that the wrapped aneurysm might become worse. Therefore, follow-up surveillance for an extended period should be mandatory.

Pipeline Embolization Device as primary treatment for blister aneurysms and iatrogenic pseudoaneurysms of the internal carotid artery

BACKGROUND

Blood blister type aneurysms (BBAs) and pseudoaneurysms create a unique treatment challenge. Despite many advances in open surgical and endovascular techniques, this subset of patients retains relatively high rates of morbidity and mortality. Recently, BBAs have been treated with flow-diverting stents such as the Pipeline Embolization Device (PED) with overall positive results.

METHODS

Four patients presented with dissecting internal carotid artery (ICA) aneurysms treated with the PED (two BBAs presenting with subarachnoid hemorrhage (SAH), two pseudoaneurysms after injury during endoscopic trans-sphenoidal tumor surgery).

RESULTS

Three patients had a successful angiographic and neurological outcome. One patient with a BBA re-ruptured during initial PED placement, again in the postoperative period, and later died. Primary PED treatment involved telescoping stents in two patients and coil embolization supplementation in one patient.

CONCLUSIONS

The PED should be used selectively in the setting of acute SAH. Dual antiplatelet therapy can complicate hydrocephalus management, and the lack of immediate aneurysm occlusion creates the risk of short-term re-rupture. PED treatment for iatrogenic ICA pseudoaneurysms can provide a good angiographic and neurological outcome.

Treatment of Blister-Like Aneurysms With the Pipeline Embolization Device

BACKGROUND:

Endovascular vessel reconstruction with the pipeline embolization device (PED) has become common practice. Data on the safety and efficacy of the PED in blister-like aneurysms (BLAs) are limited.

OBJECTIVE:

To retrospectively present our experience with use of the PED in BLAs.

METHODS:

A total of 8 patients harboring 8 BLAs were treated with the PED at our institution between November 2011 and April 2013.

RESULTS:

Aneurysm size was 2.5 mm on average. Five patients had sustained a subarachnoid hemorrhage (SAH), 1 patient presented with sentinel headaches, and in 2 patients the aneurysm was incidentally discovered. Seven aneurysms arose from the ICA and 1 from the basilar artery. Placement of the PED was successful in all 8 patients. There were no procedural or perioperative complications in any of the patients. At the latest follow-up, all 8 patients achieved a favorable outcome (mRS 0-2). Angiographic follow-up was available for 6 patients at a mean time point of 3.9 months. Follow-up angiography showed 100% aneurysm occlusion in 5 patients and marked decrease in aneurysm size in 1 patient.

CONCLUSION:

The findings of this study suggest that the PED may be a safe and effective treatment for BLAs. Given the limitations of other treatment modalities and the challenging nature of BLAs, flow diversion may be a valuable option for these lesions.

Endovascular internal carotid artery trapping for ruptured blood blister-like aneurysms: long-term results from a single centre

INTRODUCTION

Endovascular internal carotid artery (ICA) trapping was performed to treat ruptured blood blister-like aneurysms (BBAs). The aim of this study was to evaluate the procedural risks and long-term follow-up results.

METHODS

The records of 11 consecutive patients with BBAs who underwent endovascular ICA trapping between 2005 and 2010 were reviewed. Clinical outcomes were assessed with modified Rankin Scale (mRS) scores.

RESULTS

Endovascular ICA trapping was performed in 11 patients as either the primary treatment (7 patients) or the secondary treatment (4 patients) after the patient underwent other treatments. Three patients underwent superficial temporal artery (STA)-middle cerebral artery (MCA) bypass when balloon test occlusion (BTO) revealed inadequate collateral circulation. In the primary ICA trapping group (seven patients), six patients had good outcomes (mRS 0 in five, mRS 1 in one), and one patient had a poor outcome (mRS 6: dead). In the secondary ICA trapping group (four patients), two patients had good outcomes (mRS 0), and two patients had poor outcomes (mRS 4, 5). All ten of the surviving patients were clinically stable during the follow-up period (mean 39 months). A radiological follow-up of nine patients (mean 22 months) demonstrated stable occlusion, with the exception of one reopening of the ICA because of coil migration. Perfusion studies of nine patients (mean: 23 months) demonstrated no perfusion decrease.

CONCLUSION

Endovascular ICA trapping is an effective and durable treatment for BBAs.

High incidence of ICA anterior wall aneurysms in patients with an anomalous origin of the ophthalmic artery: possible relevance to the pathogenesis of aneurysm formation

OBJECT

Surgery for aneurysms at the anterior wall of the internal carotid artery (ICA), which are also referred to as ICA anterior wall aneurysms, is often challenging. A treatment strategy needs to be determined according to the pathology of the aneurysm-namely, whether the aneurysm is a saccular aneurysm with firm neck walls that would tolerate clipping or coiling, a dissecting aneurysm, or a blood blister-like aneurysm. However, it is not always possible to properly evaluate the condition of the aneurysm before surgery solely based on angiographic findings.

METHODS

The authors focused on the location of the ophthalmic artery (OA) in determining the pathology of ICA anterior wall aneurysms. Between January 2006 and December 2012, diagnostic cerebral angiography, for any reason, was performed on 1643 ICAs in 855 patients at Saitama Medical Center. The authors also investigated the relationship between the origin of the OA and the incidence of ICA anterior wall aneurysms. The pathogenesis was also evaluated for each aneurysm based on findings from both angiography and open surgery to identify any correlation between the location where the OA originated and the conditions of the aneurysm walls.

RESULTS

Among 1643 ICAs, 31 arteries (1.89%) were accompanied by an anomalous origin of the OA, including 26 OAs originating from the C3 portion, 3 originating from the C4 portion, and 2 originating from the anterior cerebral artery. The incidence of an anomalous origin of the OA had no relationship to age, sex, or side. Internal carotid artery anterior wall aneurysms were observed in 16 (0.97%) of 1643 ICAs. Female patients had a significantly higher risk of having ICA anterior wall aneurysms (p = 0.026). The risk of ICA anterior wall aneurysm formation was approximately 50 times higher in patients with an anomalous origin of the OA (25.8% [8 of 31]) than in those with a normal OA (0.5% [8 of 1612], p < 0.0001). Based on angiographic classifications, saccular aneurysms were significantly more common in patients with an anomalous origin of the OA than in those with a normal OA (p = 0.041). Ten of 16 patients with ICA anterior wall aneurysms underwent craniotomies. Based on the intraoperative findings, all 6 aneurysms with normal OAs were dissecting or blood blister-like aneurysms, not saccular aneurysms.

CONCLUSIONS

There was a close relationship between the location of the OA origin and the predisposition to ICA anterior wall aneurysms. Developmental failure of the OA and subsequent weakness of the vessel wall might account for this phenomenon, as previously reported regarding other aneurysms related to the anomalous development of parent arteries. The data also appear to indicate that ICA anterior wall aneurysms in patients with an anomalous origin of the OA tend to be saccular aneurysms with normal neck walls. These findings provide critical information in determining therapeutic strategies for ICA anterior wall aneurysms.

Long-term Follow-up of Blister Aneurysms of the Internal Carotid Artery

BACKGROUND:

Blister aneurysms of the internal carotid artery (ICA) are uncommon. There is a paucity of data on the long-term outcomes of patients.

OBJECTIVE:

To review our experience with the treatment of these lesions.

METHODS:

We retrospectively reviewed all aneurysms treated at our institution between 1994 and 2005. Relevant operative notes, radiology reports, and inpatient/outpatient records were reviewed.

RESULTS:

Seventeen patients (3 male, 14 female) with 18 blister aneurysms of the ICA were identified. The mean age was 44.6 years (range, 17–72; median, 42 years). Twelve patients (70.6%) presented with aneurysmal subarachnoid hemorrhage. The mean admission Glasgow Outcome Scale score was 4.3 (range, 2–5; median, 5). All patients were initially treated using microsurgical technique with direct clipping (n = 15; 83.3%) or clip-wrapping with Gore-Tex (n = 3, 16.7%). There were 4 cases of intraoperative rupture, all associated with attempted direct clipping; all 4 cases were successfully clipped. Two cases rebled post-treatment. Both rebleeding episodes were managed with endovascular stenting. Follow-up angiography was available for 14 patients and revealed a new aneurysm adjacent to the site of clipping in 1 patient and in-stent stenosis in 2. At the mean follow-up of 74.5 months (median, 73; range, 7–165), the mean Glasgow Outcome Scale score was 4.6 (range, 2–5; median, 5).

CONCLUSION:

Microsurgical treatment of blister aneurysms of the ICA results in excellent outcome. In the evolution of treating these friable aneurysms, we have modified our clip-wrapping technique and use this technique when direct clipping is not feasible.

Reconstructive Treatment of Ruptured Blood Blister–like Aneurysms With Stent and Coil

BACKGROUND:

Controversy remains about the optimal treatment for blood blister--like aneurysms (BBAs).

OBJECTIVE:

To evaluate clinical and angiographic outcomes after reconstructive treatment for BBA with stent and coil.

METHODS:

Thirty-four patients (6 men, 28 women; mean age, 47.3 years) with ruptured BBAs underwent reconstructive treatment with stent and coil. Posttreatment courses and outcomes were retrospectively evaluated.

RESULTS:

Initial treatments were ≥ 2 overlapping stents with or without coiling (n = 28) and single stent with coiling (n = 6). Three BBAs rebled on days 9, 11, and 15 after treatment, resulting in 1 death. Except for 3 patients who died early, 31 patients were followed up for 7 to 80 months (median, 32 months). One patient recovered completely but died of complications of systemic lupus erythematosus at 25 months. Of the remaining 30 patients, 25 had favorable outcomes (modified Rankin scale, 0-2) and 5 had unfavorable outcomes. Angiographic follow-up was available in the 32 BBAs. Eight (25.0%) recurred, all within 5 weeks. In the multiple stents group (n = 26), 22 BBAs showed improvement or complete healing, but 4 (15.4%, 2 rebleedings) had recurrence. In the single stent with coiling group (n = 6), 2 BBAs were stable but 4 (66.7%, 1 rebleeding) had recurrence. Single stent with coiling and Hunt and Hess grade ≥ 4 were 2 independent risk factors for recurrence (P &lt; .05).

CONCLUSION:

Reconstructive treatment with stent and coil appears a viable option for BBAs. Single stent with coiling and Hunt and Hess grade ≥ 4 were 2 independent risk factors for recurrence. Follow-up angiography should be considered mandatory soon after treatment.

Angiographic characteristics of ruptured paraclinoid aneurysms: risk factors for rupture

BACKGROUND

The diagnosis and treatment of unruptured paraclinoid aneurysms has been increasing with the recent advent of diagnostic tools and less invasive endovascular therapeutic options. Considering the low incidence of rupture, investigation of the characteristics of ruptured paraclinoid aneurysm is important to predict rupture risk of the paraclinoid aneurysms. The objective of this study is to evaluate probable factors for rupture by analyzing the characteristics of ruptured paraclinoid aneurysms.

METHODS

A total of 2,276 aneurysms (1,419 ruptured and 857 unruptured) were diagnosed and treated endovascularly or microsurgically between 2001 and 2011. Among them, 265 were paraclinoid aneurysms, of which 37 were ruptured. Removing 12 blister-like aneurysms, 25 ruptured and 228 unruptured saccular aneurysms were included and the medical records and radiological images were retrospectively analyzed.

RESULTS

Of 25 aneurysms, 16 (64.0%) were located in the superior direction. Five were inferior located lesions (20%) and four were medially located lesions (16.0%). Laterally located lesions were not found. The mean size of aneurysms was 9.4 ± 5.6 mm. Ten aneurysms (40.0%) were ≥ 10 mm in size. Thirteen aneurysms (52.0%) were lobulated. The superiorly located aneurysms were larger than the other aneurysms (10.3 ± 5.8 mm vs. 7.7 ± 4.9 mm) and more frequently lobulated (ten of 16 vs. three of nine). In a comparative analysis, the ruptured aneurysms were located more in the superior direction compared with unruptured aneurysms (64 vs. 23.2%, p < 0.0001). Large aneurysms (36.0 vs. 7.9%, p < 0.0001), longer fundus diameter (mean 9.4 ± 5.6 vs. 4.8 ± 3.3 mm, p = 0.001), dome-to-neck ratio (mean 1.8 ± 0.9 vs. 1.2 ± 0.5, p < 0.0001), and lobulated shape aneurysms were more likely to be ruptured aneurysms (13 of 25 ruptured aneurysms, 52.0%, p = 0.001).

CONCLUSIONS

Rupture risk of the paraclinoid aneurysm is very low. However, superiorly located paraclinoid aneurysms appear more likely to rupture than other locations. Angiographically, more conservative indication for the treatment of paraclinoid aneurysm should be recommended except for superior located lesions.