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

Endovascular treatment of intracranial blood blister-like aneurysms with the Willis covered stent: a case series

BACKGROUND AND PURPOSE

To evaluate the safety, feasibility, and effectiveness of the Willis covered stent (WCS) in treating blood blister-like aneurysms (BBAs).

MATERIALS AND METHODS

Twenty-one consecutive patients with BBAs treated with the WCS were identified between July 2017 and July 2022. The demographic, clinical, and angiographic data and procedural-related complications were collected from the medical records and the operative reports.

RESULTS

The present study included six men and fifteen women, with a mean age of 51.6 years (31-70 years). The immediate postoperative angiography demonstrated that the complete occlusion rate was 100%, with no endoleak. Ophthalmic artery (OA) occlusion occurred in five patients (23.8%). One patient developed delayed stent thrombosis on the third postoperative day. The mean angiographic follow-up time was 9.2 months (range 3-21 months). All twenty-one BBAs were occluded entirely, and the patency of the parent arteries was preserved. No aneurysm rupture or recurrence was found, and no retreatment was needed. Two patients developed mild to moderate asymptomatic in-stent stenosis. The clinical follow-up time was 20.0 months (range 15-33 months). Twenty patients had an mRS score of zero, and one had an mRS score of one.

CONCLUSIONS

Our series indicates that treating BBAs with WCSs was relatively safe and efficacious. However, the incidence of stent delivery failure and complications should not be neglected.

High False-Negative Rate of Intraoperative Neurophysiologic Monitoring in Blood Blister-Like Aneurysm Surgery: Insights from a Retrospective Case Series

OBJECTIVE

Surgical management of blood blister-like aneurysm (BBA) is challenging and contentious because of high morbidity and mortality. Intraoperative neurophysiologic monitoring (IONM) is a well-established tool in intracranial aneurysm surgery, although its application in BBA surgery lacks reports. This study retrospectively analyzes the usefulness of IONM in BBA surgery between 2018 and 2023.

METHODS

We used somatosensory evoked potentials (SSEPs) and transcranial motor evoked potentials to monitor ischemia during operations. Neurologic outcomes were mainly assessed through daily assessment with the Glasgow Coma Scale, computed tomography within 24 hours, and modified Rankin Scale at discharge.

RESULTS

Thirteen patients with ruptured BBAs (9 Tibetan, 4 Han; 10 women, 3 men; mean age, 55 years) underwent surgical procedures involving 10 clippings (6 direct, 2 wrapping-assisted, and 2 balloon-assisted) and 3 trappings. There were 8 clipping procedures applied for temporary arterial occlusion ranging from 5 to 125 minutes. Irreversible change of SSEPs/transcranial motor evoked potential (tcMEPs) occurred in 3 clippings; all these patients developed postoperative neurologic deficits. Reversible signal change of SSEPs occurred in 3 clippings, with 1 neurologic deficit. As for 3 trapping surgeries, all showed significant deficits regardless of reversible signal change or unchanged signals in IONM.

CONCLUSIONS

Our results show that IONM has low sensitivity (37.5%) and high specificity (100%) in detecting ischemic events during BBA surgery. The high rate of false-negative results in BBA-IONM suggests that its predictive value is limited particularly in complex maneuvers such as trapping and advanced vasoreconstruction, warranting cautious interpretation and further investigation of IONM modalities for BBA management.

Silk vista baby flow diversion beyond the circle of Willis: A single-center experience with long-term outcomes

INTRODUCTION

There is a lack of evidence of flow diversion (FD) safety for aneurysms treatment beyond the circle of Willis. Therefore, we provide a single-center real-world experience with the Silk Vista Baby (SVB).

METHODS

A single-center database was retrospectively reviewed for aneurysms treated with SVB flow diverters. Demographic information, clinical presentation, radiographic characteristics, procedural complications, and outcomes were assessed.

RESULTS

About 57 patients (66.7% female, mean age 54.3 ± 13.2) encompassing 57 aneurysms were included. Overall, 40.4% were ruptured: 68.4% saccular, 17.5% blister, 8.7% fusiform, and 5.3% dissecting. The majority were in the anterior circulation (68.4%), and in 48.2% of cases, the distal vessel diameter was inferior to 2 mm. The symptomatic ischemic rate was 5.2%, with one case due to in-stent thrombosis (1.8%). There were no hemorrhagic complications. Complication rates did not differ between ruptured and unruptured lesions (p = 0.356). There were no cases of delayed aneurysm rupture, and overall mortality was 1.8%. The median follow-up time was 18 ± 12 months. In-stent stenosis rate was 10.5% (6/57), all of which were asymptomatic. At the last follow-up, 70.2% of cases had an adequate occlusion (OKM C and D), and 96.5% had an mRS of 0-2.

CONCLUSION

In our series, SVB was shown to be a safe device in the treatment of not only distal anterior circulation aneurysms but also in the management of complex posterior fossa and ruptured blister aneurysms. Multicenter studies are needed to confirm and generalize these results.

Endovascular Coiling for a Ruptured Middle Cerebral Artery-lenticulostriate Artery Bifurcation Aneurysm Suspected to Be a Pseudoaneurysm: A Case Report

Intracranial pseudoaneurysm is a rare entity. Pseudoaneurysm can change its shape dynamically, and the optimal treatment must be selected on the basis of the individual situation. Due to the fragility of the pseudoaneurysm wall, surgical intervention can be difficult. Moreover, a middle cerebral artery-lenticulostriate artery bifurcation aneurysm is uncommon. Surgical intervention carries a risk of ischemic complications in perforating branches. We treated a 43-year-old woman with cardiopulmonary arrest due to a subarachnoid hemorrhage. A right middle cerebral artery-lenticulostriate artery bifurcation aneurysm was detected, which was suspected to be a pseudoaneurysm. The aneurysmal shape changed dynamically, probably because of thrombus formation and resolution. Delayed cerebral vasospasm was also observed. A simple coil embolization was performed initially on day 13 after onset, but early recanalization was observed on day 26, and a second coil embolization was carried out with good obliteration on day 34. The patient subsequently had mild left hemiparesis and mild cognitive dysfunction. After 4 months of rehabilitation, the hemiparesis resolved. Angiography 6 months after onset showed that good obliteration was maintained. For this rare complex condition of a pseudoaneurysm and middle cerebral artery-lenticulostriate artery bifurcation aneurysm, tailored endovascular treatment may be a feasible option.

Considerations and Literature Review for Treating Subarachnoid Hemorrhage due to Blood Blister-Like Aneurysms

Objective

Subarachnoid hemorrhage (SAH) due to blood blister-like aneurysm (BBA) is rare but very risky during treatment. Moreover, there is no established treatment method. In this study, we performed endovascular treatment (EVT) as the first-line treatment on patients with SAH during the subacute phase, and cases were analyzed in this series.

Methods

Patients with SAH due to BBA who visited our hospital between April 2021 and March 2023 were enrolled in this study. We waited as long as possible during the acute phase and performed EVT during the subacute phase. We performed stent-assisted coiling (SAC) as the first-line treatment and performed DSA approximately 6 months after treatment.

Results

Ninety-six patients with SAH visited our hospital during the study period and six had SAH due to BBAs. There were two males and four females aged 56.2 ± 14.6 years. We performed SAC in five patients, and one died owing to rebleeding before treatment. Two patients received treatments because of rebleeding. One patient died on the day after rebleeding, whereas the other experienced rebleeding and treatments twice and achieved a good outcome. Four patients had good outcomes (modified Rankin scale [mRS]: 0). The surviving patients achieved complete occlusion at follow-up DSA. However, two patients had poor outcomes (mRS: 6).

Conclusion

Patients with SAH due to BBA treated in the subacute phase may achieve good outcomes; however, there is a risk of rebleeding during the waiting period, which often causes poor outcomes.

Periprocedural management of ruptured blister aneurysms treated with pipeline flow diversion

Background

Blister aneurysms are high-risk intracranial vascular lesions. Definitive treatment of these lesions has been challenging. Severe disability or mortality rates are as high as 55% when these lesions are treated with open surgery. Recent data show that flow diversion is a safe and effective alternative treatment for blister aneurysms. Rerupture of the functionally unsecured lesion remains a concern as flow diversion does not immediately exclude the aneurysm from the circulation.

Methods

A retrospective review was performed of any patients with ruptured blister aneurysms treated with a pipeline embolization device between 2010 and 2020 at the University of Colorado.

Results

In this paper, we present the results of the intensive care management of ruptured intracranial blister aneurysms after flow-diverting stent placement.

Conclusion

Despite the need for dual antiplatelet therapy and the delayed occlusion of blister aneurysms treated with flow diversion, we did not find an increase in periprocedural complications.

Treatment with a flow diverter-assisted coil embolization for ruptured blood blister-like aneurysms of the internal carotid artery: a technical note and analysis of single-center experience with pooled data

Treatment of blood blister-like aneurysms (BBAs) of the supraclinoid internal carotid artery (ICA) with flow diverters (FDs) has become widespread in recent years. However, ruptured blood blister-like aneurysm (BBA) of ICA treatment with flow diverter-assisted coil embolization (FDAC) remains controversial. Moreover, limited direct comparative studies have been conducted between the two treatment modalities, FDs and FDAC, for BBAs. The purpose of this study was to document our experience and evaluate the effectiveness and safety of FDAC. We conducted a retrospective analysis of clinical and radiological information from ten patients who experienced ruptured BBAs of the supraclinoid ICA at our center from January 2021 to February 2023. The technical details of FDAC for ruptured BBAs were described, and the technical steps were named "pipeline embolization device (PED)-Individualized shaping(microcatheter)-Semi deploying-Rivet(coils)-Massage(microwire)" as the PEISSERM technique. Clinical outcomes were assessed using the modified Rankin Scale (mRS), whereas radiological results were determined through angiography. A pooled analysis was implemented, incorporating data from literature sources that reported perioperative and long-term clinical and angiographic outcomes of ruptured BBAs treated with FD and FDAC strategies, along with our data. Data in our analysis pool were categorized into FD and FDAC strategy groups to explore the preferred treatment modalities for BBAs. The PEISSERM technique was utilized to treat ten patients, seven males, and three females, with an average age of 41.7 years. A single PED was deployed in conjunction with coils in all ten patients. All PEDs were documented to have good wall apposition. The immediate postoperative angiograms demonstrated Raymond grade I in ten aneurysms. Angiographic follow-up of nine patients at 4-25 months showed total occlusion of the aneurysms. At the most recent follow-up, the mRS scores of nine patients hinted at a good prognosis. Pooled analysis of 233 ICA-BBA cases of FD revealed a technical success rate of 91% [95% confidence interval (CI), 0.88 to 0.95], a rate of complete occlusion of 79% (95% CI, 0.73 to 0.84), a recurrence rate of 2% (95% CI, 0.00 to 0.04), a rebleed rate of 2% (95% CI, 0.00 to 0.04), and the perioperative stroke rate was 8% (95% CI, 0.04 to 0.11). The perioperative mortality was 4% (95% CI, 0.01 to 0.07). The long-term good clinical outcome rate was 85% (95% CI, 0.80 to 0.90). The mortality rate was 6% (95% CI, 0.03 to 0.09). Results from the subgroup analysis illustrated that the FDAC strategy for BBAs had a significantly higher immediate postoperative complete occlusion rate (P < 0.001), total occlusion rate (P = 0.016), and a good outcome rate (P = 0.041) compared with the FD strategy. The FDAC strategy can yield a higher rate of good outcomes than the FD strategy. The PEISSERM technique employed by the FDAC is a reliable and effective treatment approach as it can minimize the hemodynamic burden of BBA's fragile dome, thereby achieving an excellent occlusion rate. The PEISSERM technique in the FDAC strategy contributes to understanding the BBA's treatment and offers a potentially optimal treatment for BBA.

Interventions to treat patients with blood blister-like aneurysms of the internal carotid artery: a protocol for a network meta-analysis

INTRODUCTION

Blood blister-like aneurysm (BBA) is a special type of intracranial aneurysm with relatively low morbidity and high mortality. Various microsurgical techniques and endovascular approaches have been reported, but the optimal management remains controversial. For a better understanding of the treatment of BBA patients, a network meta-analysis that comprehensively compares the effects of different therapies is necessary.

METHODS AND ANALYSIS

This protocol has been reported following the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols. Related studies in the following databases will be searched until November 2022: PubMed, Embase, Scopus, Web of Science, Cochrane Library, China National Knowledge Infrastructure (CNKI), VIP and Wanfang. Randomised controlled trials (RCTs) and non-randomised studies comparing at least two different interventions in BBA patients will be included. Quality assessment will be conducted using Cochrane Collaboration's tool or Newcastle-Ottawa Scale based on their study designs. The primary outcome is the composite of the incidences of intraoperative bleeding, postoperative bleeding and postoperative recurrence. The secondary outcome is an unfavourable functional outcome. Pairwise and network meta-analyses will be conducted using STATA V.14 (StataCorp, College Station, Texas, USA). Mean ranks and the surface under the cumulative ranking curve will be used to evaluate every intervention. Statistical inconsistency assessment, subgroup analysis, sensitivity analysis and publication bias assessment will be performed.

ETHICS AND DISSEMINATION

Ethics approval is not necessary because this study will be based on publications. The results of this study will be published in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42022383699.

Flow Diverter Device-Assisted Coiling Treatment for Cerebral Blister Aneurysm: A Single-Center Study

Although endovascular treatment is a promising approach, blood blister-like aneurysms (BBAs) still present treatment challenges. This study aimed to assess the effectiveness and safety of flow diverter device-assisted coiling (FDDAC) for the treatment of BBAs, which are broad based and friable with a high rebleeding risk. Eight patients (five females and three males) who presented with subarachnoid hemorrhages (SAH) due to BBA ruptures between May 2020 and May 2022 were retrospectively enrolled. All patients were treated by flow diverter device (Tubridge) adjunctive coil embolization using a semi-deploying technique. The demographic information, angiographic data, interval between admission and treatment, materials, therapy, clinical outcomes (including periprocedural and intraprocedural mortality and morbidity), and follow-up results of all patients were reviewed. The mean age of the patients with BBAs was 48.5 years (range 31–62 years); aneurysm sizes ranged from 2.2 × 1.7 mm to 4.6 × 3.2 mm, and the median Hunt–Hess score was 3. All aneurysms were completely closed at follow-up, and all 8 patients had excellent clinical outcomes (modified Rankin scores = 0–2) at discharge. Angiograms showed complete aneurysm occlusion after 6 months to 1 year. In addition, there were no cases of re-rupture, re-treatment, or recurrence of the aneurysms. FDDAC is safe to use in patients with BBAs and provides an alternative treatment option for this disease.

Endovascular Treatment of Ruptured Blood Blister-like Aneurysms Using the LVIS EVO Stents

Blood blister-like aneurysms (BBAs) are rare cerebrovascular lesions that face serious challenges in surgical as well as endovascular treatment. In this paper, we present our experience in treating BBAs using the LVIS EVO stents. A total of 10 patients (mean age of 56.1 years) with 13 BBAs, who were admitted to our university hospital between April 2020 and November 2021 with a subarachnoid hemorrhage (SAH) due to aneurysm rupture, were treated using the LVIS EVO stents. Treatment of the BBAs consisted of stent-assisted coiling in four patients and stenting in six patients. The aneurysms were located within ICA (84.6%), VA (7.7%), and MCA (7.7%). Placement of the LVIS EVO stents was successful in all patients. No technical complications were observed. One in-stent thrombotic event occurred during the procedure. MRA for one-year follow-up was performed in nine patients. One patient died (Hunt and Hess Grade IV). LVIS EVO stents may be a beneficial treatment option for BBAs, as they provide high occlusion rates. However, the long-term efficacy remains uncertain.

Endovascular intervention vs. microsurgery on the prognosis of anterior circulation blood blister-like aneurysm: A cohort study

Background

There are no universally acknowledged standardized treatment strategies for blood blister-like aneurysms (BBAs). This study compared the prognosis of patients with BBA who underwent craniotomy microsurgery vs. endovascular intervention.

Methods

This retrospective cohort study included patients with BBA treated between September 2009 and August 2020 at Sichuan Provincial People's Hospital affiliated to the Sichuan Academy of Medical Science. Patients were divided into the microsurgery and endovascular groups. The preoperative Hunt-Hess grade and modified Fisher grade were collected. The intraoperative and postoperative complications (including intraoperative aneurysm rupture and hemorrhage, postoperative cerebral hemorrhage, and BBA recurrence) were recorded.

Results

Seventy-two patients were included: 28 and 44 in the microsurgery and endovascular groups, respectively. Only the preoperative Fisher grade was different between the two groups (P = 0.041). The proportion of patients with good outcomes was lower in the microsurgery group (28.6%) than in the endovascular group (72.7%), and the mortality rate was higher in the microsurgery group (32.1%) than in the endovascular group (11.4%) (P < 0.05). After adjustment for the modified Fisher grade, the multivariable analysis showed that compared with craniotomy microsurgery, an endovascular intervention was associated with the prognosis of patients with BBA (OR = 0.128, 95%CI: 0.040-0.415, P < 0.001). The rate of complications (intraoperative hemorrhage, cerebral infarction, and recurrence) was higher in the microsurgery group than in the endovascular group.

Conclusion

In patients with BBA, an endovascular intervention appears to be associated with a better prognosis compared with craniotomy microsurgery.

Endovascular treatment of a ruptured blister-like aneurysm at an azygos anterior cerebral artery: A case report and review of the literature

Background

Endovascular treatment for a ruptured blister-like aneurysm (BLA) has recently become a hopeful approach. BLAs are usually located on the dorsal wall of the internal carotid artery, whereas one located on the azygos anterior cerebral artery (ACA) is so rare, it has never been reported. We report a case of a ruptured BLA arising at the distal bifurcation of an azygos ACA treated by stent-assisted coil embolization.

Case Description

A 73-year-old woman presented with a disturbance of consciousness. Computed tomography showed diffuse subarachnoid hemorrhage, which was observed to be particularly dense in the interhemispheric fissure. Three-dimensional rotation angiography showed a tiny and conical bulge on the distal bifurcation of the azygos trunk. Follow-up digital subtraction angiography performed on day 4 showed enlargement of the aneurysm, and a BLA arising at the azygos bifurcation was diagnosed. Stent-assisted coiling (SAC) was performed using a low-profile visualized intraluminal support (LVIS) Jr. stent, which was implanted from the left pericallosal artery to the azygos trunk. Follow-up angiography showed that the aneurysm thrombosed gradually and reached complete occlusion 90 days after onset.

Conclusion

SAC for a BLA at the distal bifurcation of an azygos ACA might be an effective treatment option leading to early complete occlusion, but thrombus formation as an intraoperative complication should be noted in the BLA at the bifurcation or the peripheral artery, as in the present case.

Stent-assisted Coiling vs. Flow Diverter for Treating Blood Blister-like Aneurysms : A Proportion Meta-analysis

PURPOSE

Blood blister-like aneurysms (BBAs) are rare vascular lesions and a therapeutic challenge. Although endovascular treatment of BBA is a promising approach, the optimal treatment remains controversial. The purpose of this study was to compare the safety and efficacy of stent-assisted coiling (SAC) and flow diverter (FD) in the management of BBAs.

METHODS

A proportion meta-analysis including a published series of BBAs treated with endovascular approaches from 2009 to 2020 including SAC and FD was performed by searching English language studies via MEDLINE and EMBASE.

RESULTS

The 32 studies included 16 based on SAC and 16 involving FD. The long-term complete occlusion rate was higher in FD (89.26%, 95% confidence interval, CI 82.93-94.26%, I² = 14.42%) than in SAC (70.26%, 95% CI 56.79-82.13%, I² = 70.60%). The rate of aneurysm recanalization was lower in FD (4.54%, 95% CI 1.72-8.16%, I² = 0%) than in SAC (25.38%, 95% CI 14.44-38.19%, I² = 67.31%). Rates of mortality, favorable functional outcome, procedural complications, and rebleeding showed no differences between the two procedures.

CONCLUSION

In a proportion meta-analysis comparing FD with SAC, the FD was associated with more favorable angiographic outcomes but similar complications and clinical outcomes.

Early surgical versus endovascular repair of ruptured blood-blister aneurysm of the internal carotid artery: a single-center 20-year experience

OBJECTIVE

Early repair of ruptured blood-blister aneurysms (BBAs) of the internal carotid artery (ICA) remains challenging. Although both surgical and endovascular therapies have been established, their relative superiority remains debated. The authors assessed their single-center experience and compared early deconstructive versus reconstructive repair and early reconstructive surgical versus endovascular repair of ruptured BBAs of the ICA.

METHODS

The study included patients who underwent repair of ruptured BBAs of the ICA within 1 week after the ictus during a 20-year period. Multiple variables were recorded, including clinical state, severity of subarachnoid hemorrhage (SAH), characteristics of the BBA, treatment details, complication profile, need for secondary treatment, and clinical outcome.

RESULTS

In total, 27 patients underwent early surgical (n = 16) or endovascular (n = 11) repair of BBAs at a median of 24 hours (range 9-120 hours) after the ictus during the period from September 2000 to June 2021 (20.4 years). Primary deconstructive repair (n = 6) without bypass was accompanied by middle cerebral artery (MCA) territory infarction in 5 of 6 (83%) patients and a high mortality rate (4/6 [67%]). Among the 21 patients who underwent early reconstructive repair, surgery was performed in 11 patients (clipping in 6 and clip-wrapping in 5 patients) and endovascular repair in 10 patients (flow diversion in 7 and stent/stent-assisted coiling in 3 patients). No differences were found in complication profiles or clinical outcomes between the surgical and endovascular groups. The mortality rate was low (2/21 [9.5%]), with 1 fatality in each group.

CONCLUSIONS

From the authors' experience, both surgical and endovascular approaches permitted reconstructive repair of ruptured BBAs of the ICA, with no modality proving superior. Reconstructive treatment is preferable to ICA sacrifice, and if sacrifice is chosen, it should be accompanied with bypass surgery or delayed to the phase when cerebral vasospasm has resumed. The rare occurrence of this disease calls for prospective multicenter studies to improve treatment and delineate which modality is preferable in individual cases.

Blister-like aneurysm of the anterior communicating artery treated with only Low-profile Visualized Intraluminal Support Junior stent

Background:

Endovascular treatment is becoming a mainstream treatment for blister-like aneurysms in recent years. Blister-like aneurysms are usually located in the internal carotid artery, whereas that of the anterior communicating artery (AcomA) are very rare. We report the first case of blister-like aneurysm of AcomA that was treated solely with a neck bridging stent that resulted in complete occlusion without complication.

Case Description:

A 50- year- old woman was admitted to our hospital due to a subarachnoid hemorrhage. Digital subtraction angiography showed a very small aneurysm in the dorsal side of the AcomA. We considered it a blister-like aneurysm based on its size and shape. She underwent endovascular treatment under general anesthesia on day 15 after vasospasm period. Dual antiplatelet therapy was administrated 1 week prior. A Low-profile Visualized Intraluminal Support Junior stent was implanted from the left A2 to the right A1, covering the AcomA. The postoperative course was uneventful, and she was discharged with no neurological deficit. The aneurysm remained unchanged on postoperative day 14; however, complete occlusion was achieved 3 months after the treatment.

Conclusion:

Monotherapy with a neck bridging stent is an effective treatment option for blister-like aneurysms. Treatment with a single stent could achieve complete occlusion especially if the aneurysms occur elsewhere than the internal carotid artery. We should consider immediate additional treatment if the aneurysm grows within 1 month after initial treatment.

Endovascular treatment of ruptured blister-like aneurysms: A case report and review of the literature

A ruptured blister-like aneurysm of the internal carotid artery is a rare event with a high risk of recurrence and mortality. Selecting an appropriate treatment modality remains challenging due to a lack of consensus or specific recommendations in the literature. In this article, we present the case of a 68-year-old man who presented with ruptured blister-like aneurysms in the supraclinoid portion of the internal carotid artery. The patient was diagnosed and successfully managed using an endovascular coil embolization technique at our hospital. We aim to illustrate and share our experiences with this rare occurrence, which may assist in the treatment of similar cases in the future.

Wrap-Clipping for Patients with Ruptured Blood Blister-Like Aneurysms of the Internal Carotid Artery: Case Series and Literature Review

OBJECTIVE

 Blood blister-like aneurysms (BBAs) of the internal carotid artery (ICA) are challenging to treat. We assessed the clinical and radiologic outcomes in patients with ruptured BBAs of the ICA treated with wrap-clipping.

METHODS

 From November 2016 to January 2020, the clinical and radiologic data of patients with subarachnoid hemorrhage (SAH) caused by ICA BBAs who underwent wrap-clipping were retrospectively analyzed. The clinical outcomes were evaluated according to the modified Rankin Scale (mRS). Radiologic follow-up examinations included digital subtraction angiography (DSA), computed tomography angiography (CTA), and magnetic resonance angiography (MRA).

RESULTS

 Seven patients were enrolled in this study. All BBAs were wrap-clipped successfully, including two BBAs that exhibited intraoperative bleeding and required balloon-assistance during surgery. All patients had favorable clinical outcomes during follow-up. Among the six patients who completed the radiologic follow-up visit, one patient presented ICA occlusion at the 6-month DSA follow-up, but no neurologic dysfunction was noted. We did not observe the progression of ICA stenosis in other patients.

CONCLUSION

 All BBAs in this study were wrap-clipped successfully and completely occluded. Wrap-clipping is effective for BBAs of the ICA and has favorable clinical outcomes. A multicenter study with a large sample size and a longer radiologic follow-up is necessary.

Contemporary Management of Distal Anterior Cerebral Artery Aneurysms: A Dual-Trained Neurosurgeon's Perspective

Objectives  Distal anterior cerebral artery (DACA) aneurysms are a subset of aneurysms located in the anterior circulation but away from the circle of Willis. We analyze the clinical presentation and outcomes of two treatment groups-surgical and endovascular-for DACA aneurysms managed by a dual-trained neurosurgeon. Material and Methods  A retrospective evaluation of radiological and operative/interventional data of 34 patients with 35 DACA aneurysms over a 12-year period was analyzed. Twenty-seven patients underwent surgery, whereas seven underwent endovascular coiling of the aneurysms. Modified Fisher grade and World Federation of Neurosurgical Societies scale (WFNS) were used to note the subarachnoid hemorrhage (SAH) severity. Statistical Analysis  Categorical data were presented as frequency and percentage, while noncategorical data were represented as mean ± SD. Statistical significance for difference in outcome between the two groups was analyzed using Chi-square test, and p  < 0.05 was considered statistically significant. Results  Of 34 patients, 33 presented with a bleed and 23.5% patients were noted to have another aneurysm in addition to the DACA aneurysm. Patients who underwent clipping for another aneurysm along with the DACA aneurysm in a single surgical exercise had a poor outcome compared with those who underwent surgery for the lone DACA aneurysm (7 vs. 20, p  = 0.015). Most patients in both surgical (70.37%) and endovascular (85.71%) groups had good outcome (mRS ≤ 2). Conclusions  A good outcome can be achieved with either surgery or endovascular coiling in the management of DACA aneurysms. In patients with multiple aneurysms, SAH with aneurysmal rupture of DACA should be managed first; the other unruptured aneurysm may be operated after an interval to avoid morbidity.

Early Treatment of Ruptured Blood Blister-Like Aneurysms of the Internal Carotid Artery With Flow Diverters Using Single Antiplatelet Therapy: A Single-Center Experience With Long-Term Follow-Up

Background and Purpose: Blood Blister-like aneurysms (BBAs) of the internal carotid artery (ICA) are rare entities of cerebral aneurysms. FD use in acutely ruptured aneurysms, timing of treatment and antiplatelet regimen are main debate topics in clinical practice when the treatment decision is flow diversion. The aim of this study is to report the safety and efficacy of a single-center FD treatment for ruptured BBAs in the early phase of SAH using the SAPT regimen.

Material and Method: This study involved a retrospective analysis of a prospectively collected database. Records of patients admitted to our clinic and treated by endovascular route on ruptured BBA between January 2013 and December 2020 were reviewed. Ruptured supraclinoid ICA BBAs treated with FD devices with SAPT within 48 h from ictus of SAH are included. BBA of atypical anatomic locations, other endovascular techniques performed, and delayed admissions (>48 h) were excluded from the study. Demographic, clinical and angiographic features of patients and aneurysms, FD types and numbers, periprocedural complications, immediate and follow-up angiographic and clinical outcomes were recorded.

Results: A total of six patients with ruptured BBAs treated via FDs within 48 h and used SAPT were included in the study. The mean age was 41.6 years (range from 34 to 45 years), and four of six patients were female. All patients were treated within 48 h after ictus, and the mean treatment day was 1.33 days. One patient received ticagrelor, and five patients received prasugrel as SAPT for one year after treatment. No procedure-related death and rebleeding were recorded. One (16.7 %) treatment responsive procedure-related complication occurred (transient ischemia). Overall good outcome rate was 83.3%. One patient died due to pneumonia. The immediate control angiograms showed complete occlusions of BBAs in one patient (16.6%). The complete occlusion rate was 100 % for five survivors at the control angiogram. The median follow-up was 49.5 months.

Conclusion: This single-center experience suggests that early treatment (<2 days) within SAH of ruptured BBAs with FDs using SAPT is safe and effective in terms of clinical and radiological long-term outcomes.

Comparison of Blister Aneurysm Treatment Techniques: A Systematic Review and Meta-Analysis

OBJECTIVE

Blood blister aneurysms are small, thin-walled, rapidly growing side-wall aneurysms that have proved particularly difficult to treat, and evidence-based guidance for treatment strategies is lacking. A systematic review and meta-analysis was performed to aggregate the available data and compare the 3 primary treatment modalities.

METHODS

We performed a comprehensive literature search according to PRISMA guidelines followed by an indirect meta-analysis that compares the safety and efficacy of surgical, flow-diverting stents (FDS), and other endovascular approaches for the treatment of ruptured blood blister aneurysms.

RESULTS

A total of 102 studies were included for quantitative synthesis, with sample sizes of 687 treated surgically, 704 treated endovascularly without FDS, and 125 treated via flow diversion. Comparatively, FDS achieved significantly reduced rates of perioperative retreatment compared with both surgical (P = 0.025) and non-FDS endovascular (P < 0.001). The FDS subgroup also achieved a significantly lower incidence of perioperative rebleed (P < 0.001), perioperative hydrocephalus (P = 0.012), postoperative infarction (P = 0.002), postoperative hydrocephalus (P < 0.001), and postoperative vasospasm (P = 0.002) compared with those patients in the open surgical subgroup. Although no significant differences were found among groups on the basis of functional outcomes, angiographic outcomes detailed by rates of radiographic complete occlusion were highest for surgical (90.7%, 262/289) and FDS (89.1%, 98/110) subgroups versus the non-FDS endovascular subgroup (82.7%, 268/324).

CONCLUSIONS

Flow diversion seems to be an effective treatment strategy for ruptured blood blister aneurysms, with lower rates of perioperative complications compared with surgical and other endovascular techniques, but studies investigating long-term outcomes after flow diversion warrant further study.

Cerebral vasospasm resulted in "stent shortening" after pipeline assisted coil embolization for blood blister aneurysms

Blood blister aneurysms (BBAs) are intracranial arterial lesions appearing in nonbranching sites of the supraclinoid internal carotid artery as well as the basilar artery. Endovascular treatment of BBAs is still not well established because of the rarity of these lesions. We report incidences of BBAs with associated vasospasms. Treatment of the BBAs and associate vasospasms with single Pipeline Flex embolization device (PLED) assisted coiling resulted in seemly shorting of the PLEDs in 3 patients.A retrospective analysis of patients with BBAs who were treated with single PLED assisted coiling from July 2018 to October 2019 was conducted. Patients' ethnic and medical records, aneurysmal characteristics, intraoperative-rupture, cerebral vasospasm (CVS), postprocedure contrast filling, follow-up imaging, and results were analyzed. Neurological examination at baseline and outcome based on modified Rankin scale (mRS) at discharge as well as follow-ups were also documented.Six patients consisting of 5 females and 1 male, with a mean age of 48.3 years (range from 34-67) were identified during our analysis. All the BBAs were located in nonbranching site of supra-clinoidal segment of internal carotid artery with a mean neck width of 4.5 mm and mean aneurysm size of 4.23 mm. PLED assisted coiling's were performed in all of them. CVS was observed in 3 patients while 1 patient had an intraoperative-rupture of the BBA. Postprocedure contrast filling was still present in 1 patient. All the patients had good outcomes with discharge and follow-up mRS scores ≤ 2 except 1 patient with mRS score = 3 with aphasia.PLED assisted endovascular coiling is very safe and efficient in treating patients with BBAs. Resolution of CVSs after treatment made the PLEDs seemly shorter. Furthermore, a combination of arterial lengthening after gaining their tensile strength back and radical expansion of the PLED could account for the shortening.

Microsurgical Clip Trapping of Dorsal Internal Carotid Artery Blister Ruptured Aneurysm: 2-Dimensional Operative Video

Dorsal internal carotid artery (ICA) blister aneurysms are an uncommon aneurysm variant constituting 0.3% to 1% of intracranial aneurysms and can be due to ulceration, atherosclerosis, or dissection.1-3 Despite its rarity, it carries a high risk of rupture with an estimation of 0.9% to 6.5% among intracranial aneurysms.1,2 Blister aneurysms are small in size, have no distinguishable neck, and have a friable wall that can easily rupture if manipulated, hence the difficulty in its treatment utilizing both microsurgical and endovascular techniques.1,2,4-6 Endovascular coiling of these lesions may not be adequate due to the broad-based size; stenting requires the use of antiplatelet medications, which could lead to rebleeding; flow diversion takes longer to exert its treatment effect.1,4 Conversely, microsurgical management carries a higher intraoperative rupture rate.2 Microsurgical options include clipping, clip reconstruction, trapping with bypass, and wrapping.4,7 We present a case of a 38-yr-old man who presented with a ruptured right dorsal ICA blister aneurysm treated with microsurgical trapping with intraoperative flow measurements. We demonstrate how the use of quantitative intraoperative flow measurements allows confident sacrifice of the supraclinoid ICA. We also demonstrate in contrast another case example of utilizing a clip-graft repair. The patient remained unchanged with an intact neurological exam, and postoperative imaging showed no aneurysm remnant and patent anterior choroidal artery. We review the literature and management of dorsal ICA aneurysms.8-15 We also review the technical nuances and different endovascular and microsurgical treatments that can be used for this condition.  The patient gave informed consent for the procedure and verbal consent to the publication.

Endovascular treatment of blood blister-like aneurysms of internal carotid artery: Stent-assisted coiling and pipeline flow diversion

OBJECTIVE

To report the stent-assisted coil embolization and flow diversion treatments of blood-blister-like aneurysms based on the theory of acute dissection of the internal carotid artery.

PATIENTS AND METHODS

From July 2016 through July 2020, 27 patients presenting with subarachnoid hemorrhage (SAH) due to rupture of internal carotid artery blood blister-like aneurysms were subjected to endovascular treatment with stent-assisted coiling or Pipeline flow diversion. Clinical outcomes were evaluated using modified Rankin Scale score (mRS).

RESULTS

A proximal stenosis caused by angiopathology adjacent to aneurysms were found on internal carotid artery angiograms in all 27 cases. The angiopathology combining with the aneurysms implement that acute dissection of the supraclinoid segment of the internal carotid artery indicated the pathogenesis of blood blister-like aneurysm formation. All aneurysms were treated successfully with alleviation of the adjacent angiopathology after stenting on angiograms. During 1-12 months, mean 3.5 months, complete aneurysm obliteration without adjacent stenosis were found in 25(92.6%) patients. Two (7.4%) cases of recanalization were retreated with complete obliteration at 1 week and 3 months after initial treatment. Clinical mRS 0 and 1 outcomes were observed in 23(85.2%) patients, mRS 2 in 3(11.1%) patients and mRS 6 in 1(3.7%) not related to aneurysm treatment during follow-up.

CONCLUSIONS

Acute focal dissection of supraclinoid segment of internal carotid artery underlies the development of blood blister-like aneurysm. Stent-assisted coiling and flow diversion treatments constitute appropriate treatment based on the arterial dissection pathology.

Contemporary Treatment of Intracranial Blood Blister Aneurysms - A Systematic Review

INTRODUCTION

Blood blister aneurysms (BBAs) are rare aneurysms affecting non-branched points of intracerebral arteries. Due to their small size and fragility, BBAs are prone to rupture, and can be challenging to diagnose and treat. Several treatment options have been suggested yet there is no consensus regarding the best modality to reduce morbidity and mortality.

MATERIALS AND METHODS

A systematic review of the literature was conducted searching for articles discussing the treatment of BBAs. Inclusion criteria included: articles published between January 2010 and August 2020, English language, with each paper including at least 15 patients. Studies included required detailed reporting of patient demographics, treatment, and patient outcomes (including complications, recurrence, neurologic functional status, and mortality).

RESULTS AND DISCUSSION

A total of 25 studies with 883 patients were included. Most were female (n = 594, 67.3%) and aneurysms were overwhelmingly located in the supraclinoid internal carotid artery (99%). Aneurysms were variable in size and mostly presented with subarachnoid haemorrhage. Endovascular treatment (n = 518, 58.7%) was more common than microsurgery (n = 365, 41.1%) while only 2 patients were managed conservatively. Complications were more common in patients treated microsurgically. Microsurgical procedures had an unfavorable outcome (mRS 4-6, GOS 1-3) rate of 27.8% (n = 100/360) while that of endovascular procedures was 14.7% (n = 70/477). Endovascular procedures had a lower mortality rate than microsurgical interventions (8.4% vs 11%).

CONCLUSION

This review demonstrates that endovascular treatment of blood blister aneurysm has reduced morbidity and mortality when compared with microsurgical treatment. Small sample sizes and substantial study heterogeneity makes strong conclusions difficult.

Stent-in-stent technique for the management of blood blister-like basilar apex aneurysms

Blood blister-like basilar apex aneurysms are rare thin-walled vascular lesions with a poorly defined aneurysmal neck. We present two patients with ruptured blister aneurysms of the basilar apex who were treated using the stent-in-stent technique. Long-term follow-up showed persistent and complete occlusion of the aneurysms without radiographically or neurological complications. There is no optimal treatment of choice for the basilar apex blood blister-like aneurysms. Double- or triple-stent placement using the stent-in-stent technique can be a safe and feasible option for these uncommon and challenging intracranial aneurysms.

Lesion Trapping with High-Flow Bypass for Ruptured Internal Carotid Artery Blood Blister-Like Aneurysm Has Little Impact on the Anterior Choroidal Artery Flow: Case Series and Literature Review

OBJECTIVE

To examine the relationship between trap location and cerebral infarction in the anterior choroidal artery (AChA) region and associated risks in ruptured internal carotid artery blood blister-like aneurysm (BLA) treatment with high-flow bypass and lesion trapping.

METHODS

We included 26 patients diagnosed with BLAs and treated with high-flow bypass and trapping. We examined clinical characteristics including age, aneurysm trap location, final prognosis, cerebral infarction on postoperative magnetic resonance imaging, and modified Rankin Scale score at discharge. We also searched the literature for similar studies.

RESULTS

The modified Rankin Scale score at discharge was 0-2 in 20 patients, 3-5 in 2 patients, and 6 in 2 patients. In 19/26 patients (73.1%), the trapped segment was between the posterior communicating (PcomA) and the ophthalmic arteries. In 2 patients (7.7%), the trapped segment included the PcomA and the AChA; in 4 patients (15.4%), the trapped segment was within the PcomA. In these patients, the PcomA was occluded, and blood from the high-flow bypass flowed out to the AChA alone. No patient showed cerebral infarction. Our systematic review identified 70 patients. Of all 96 patients, 12 had AChA cerebral infarction; however, the infarction affected the prognosis of only 2 patients.

CONCLUSIONS

When treating BLAs with high-flow bypass and lesion trapping, the frequency of AChA cerebral infarction is low even when the PcomA is occluded, leaving the AChA as the only outflow vessel during high-flow bypass. However, PcomA occlusion may be associated with risks when treating patients with advanced arteriosclerosis near C1-2.

The formation mechanism of acute dissection of blood blister-like aneurysm and its implication of endovascular treatment

BACKGROUND

Acute mural dissection of the anterior wall of the internal carotid artery which may contribute to the development of blood blister-like aneurysms (BBLAs) was postulated, and stenting or flow diversion treatment across the soi-disant aneurysm was reported in this study.

METHODS

From December 2016 to December 2018, 8 patients presenting with subarachnoid hemorrhage (SAH) due to BBLA were subjected to endovascular treatment with stent-assisted coiling. Clinical outcomes were evaluated using a clinical outcome score scale.

RESULTS

Based on angiograms, pathologic change involving the supraclinoid segments of the internal carotid artery (ICA) adjacent to BBLA was found in all patients. This pathologic change meant a focal dissection of the supraclinoid segment of the ICA which constituted the pathogenesis of BBLAs. Closed-cell, open-cell, and braided stents were used in 1, 1, and 6 patients, respectively. Complete obliteration was achieved following endovascular treatment among all 8 patients harboring BBLA. One re-bleeding successive to a closed-cell stent across the aneurysmal neck was observed. Follow-up angiograms revealed stable complete exclusion of all BBLAs from the parent vessel at 3 to 8 months. All patients had a favorable clinical outcome score of 0-1.

CONCLUSIONS

Acute dissection of a focal point of the intracranial vessels underlies the development of BBLAs. Open-cell and braided-cell stent-assisted coiling may constitute appropriate treatment due to good apposition against the vascular walls. Adjunctive coils may facilitate immediate complete occlusion of BBLAs.

Internal Carotid Artery Blister Aneurysm: Review of Endovascular Techniques

Cerebral blister aneurysms are very difficult vascular lesions in terms of accurate diagnosis as well as proper management strategy for vascular neurosurgeons and neurointerventionists. Histopathological analysis has revealed their nature to be more akin to pseudoaneurysms in comparison to the typical berry aneurysms. This explains their fragile nature, with high probability of rerupture and regrowth during the follow-up if not addressed properly. Even though surgical approaches have evolved over the years to minimize intraprocedural rupture and recurrence, they still have relatively high morbidity as well as mortality in comparison to endovascular treatment. Over the last few years, endovascular treatment has evolved significantly, with introduction of new devices and techniques. Focus of the endovascular management has shifted from the deconstructive techniques to reconstructive ones with parent artery preservation. Recent introduction of flow diverter technology has enabled neurointerventionists to manage these difficult lesions with more confidence in terms of avoiding rerupture and recurrence. Flow diverter (FD) use in blister aneurysm resulted in high-technical success, complete aneurysm occlusion, and less complications in comparison to other reconstructive techniques like simple coiling, stent assisted coiling, and overlapping/monotherapy stent placement. Few debatable issues like use of dual antiplatelets in the setting of acute subarachnoid hemorrhage (SAH), timing of drugs in relation to procedures, single/overlapping devices, and concerns during cerebral vasospasm phase need further detailed analysis and standardized protocols. In this article, we have done a review of different endovascular treatment options in the management of internal carotid artery blister aneurysms with special focus on FD and issues related to it.

Real-world treatment results for ruptured blood-blister aneurysm of the internal carotid artery: analysis of a Japanese nationwide multicenter study

Ruptured blood-blister aneurysm (BBA) of the internal carotid artery (ICA) remains a challenging lesion, even in the age of modern neurosurgery and endovascular treatment. This retrospective multicenter study aimed to investigate the real-world treatment choice and treatment results. We included 182 ruptured BBAs of the ICA treated at 51 neurosurgical centers in Japan between 2013 and 2017. The baseline patient characteristics, radiological features of the aneurysm, treatment modality, details of treatment, complications of treatment, and treatment results were retrospectively collected. The treatment strategy was divided into deconstructive and reconstructive procedures. Primary clinical outcomes were evaluated using the modified Rankin scale (mRS) at final follow-up. Direct surgery was performed in 144 (79%) cases, and the remaining 38 (21%) cases received endovascular treatment. The majority of treatment selections were deconstructive and reconstructive procedures in the direct surgery group and endovascular treatment group, respectively. Overall, favorable clinical outcomes (mRS 0 to 2) were achieved in 66% of cases, and the mortality rate was 15% at the final follow-up (mean 23 months). There was no significant difference in clinical outcome between direct and endovascular treatment groups. Our large nationwide study compared the real-world treatment options for ruptured BBAs and their results. Our findings may offer beneficial information for treatment decision and for future studies investigating ruptured BBAs.

Comparison of clinical and histopathological characteristics of short-term progressive and non-progressive blood blister-like aneurysms

BACKGROUND

Many blood blister aneurysms (BBAs) have been documented with a rapid progression history in repeated angiography. The underlying mechanism and clinical significance remained elusive. This current study aims to clarify the clinical and histopathological differences between short-term progressive BBA and non-progressive BBAs.

METHODS AND MATERIALS

Eighty-one patients with BBAs were consecutively included for this single-center retrospective analysis. Clinical and radiological data on these patients were retrieved from 2017 to 2019. BBAs were defined as either progressive or non-progressive based on observed growth based on repeated imaging. Histopathological examinations of a saccular aneurysm, a progressive BBA, and a non-progressive BBA were conducted using representative aneurysm samples.

RESULTS

Among all enrolled patients, 26 of the them were identified with progressive BBAs, while the other 55 with non-progressive BBAs. Progressive BBAs were diagnosed significantly earlier in angiography (3.36 ± 0.61 vs. 6.53 ± 1.31 days, p < 0.05) and showed a higher presence rate of daughter sacs (61.5 vs. 38.2%, p < 0.05). Three different progression patterns were identified. BBAs that developed daughter sac enlargement are diagnosed significantly later than BBAs exhibiting other progression patterns. Patients with progressive and non-progressive BBAs exhibited similar overall clinical outcomes and incidence for complications. For patients with non-progressive BBAs, microsurgery appears to be inferior to endovascular treatment, while for patients with progressive BBAs, the short-term outcomes between microsurgery and endovascular treatment were identical. Histopathological analysis revealed that both subtypes shared a similar pseudoaneurysms structure, but non-progressive BBAs had more histologically destructed aneurysm wall with less remnant fibrillar collagen in adventitia.

CONCLUSIONS

Progressive and non-progressive BBAs may not be distinct pathological lesions but represent different stages during the BBA development. Early intervention, regardless of treatment methods, is recommended for salvageable patients with progressive BBAs, but microsurgery should be performed with caution for non-progressive BBAs due to increased surgical risk.

Is Stent-Assisted Coil Embolization for the Treatment of Ruptured Blood Blister-Like Aneurysms of the Supraclinoid Internal Carotid Artery Effective? : An Analysis of Single Institutional Experience with Pooled Data

Objective

Given the high risk of rebleeding and recurrence of blood blister-like aneurysms (BBAs), we treated ruptured BBAs of the internal carotid artery (ICA) with stent-assisted coil embolization (SAC). This study aimed to evaluate the efficacy and safety of SACs.

Methods

We retrospectively reviewed clinical and radiological data from eight patients with ruptured BBAs of the supraclinoid ICA. The modified Rankin Scale (mRS) was used to assess clinical outcomes, while radiological outcomes were evaluated on angiographs. For a pooled analysis, data from literature reporting the outcomes of ruptured BBAs treated with SAC were collected and analyzed in conjunction with our data.

Results

In our cohort, the mean Raymond classification score was 1.57±0.53 immediately after initial endovascular treatment. There were no perioperative complications or rebleeding events during the follow-up period. The mean mRS score at patient discharge was 1.00±0.81 and improved to 0.28±0.48 by the last follow-up day. The recurrence rate was 25% with an asymptomatic presentation and successful treatment with multiple stent insertion. Pooled analysis of 76 cases of SAC revealed a complete occlusion rate immediately after treatment of 54.8%, rebleeding rate 7.94%, and recurrence rate 24.2%. Good clinical outcomes with mRS score 0–2 were observed in 89.9% by the last clinical follow-up. Total mortality rate was 7.7%.

Conclusion

This treatment appears to not only minimize the hemodynamic burden on the fragile dome specific to this type of aneurysm, but also provides an opportunity for safe and effective treatment in recurrent cases.

Surgical treatment of intracranial blister aneurysms: A systematic review

BACKGROUND

Intracranial blister aneurysms (BAs) are challenging vascular lesions related to high morbidity and mortality rates. Different surgical and endovascular techniques have been proposed to treat BAs; however, there is no consensus on a preferred treatment.

OBJECTIVE

To systematically review the pertinent literature on clinical and radiological outcomes of different surgical treatments for BAs management, to meta-analyze their clinical and radiological outcomes, and compare these results with those from recent meta-analyses on endovascular treatments for BAs.

METHODS

The present study was consistently conducted according to the PRISMA guidelines. Five different online medical databases (PubMed, Medline, EMBASE, Scopus, and Web-of-Science) were screened from 2010 through 2020. Papers reporting clinical and radiological outcomes of different surgical treatments for BAs were considered. Event rates were pooled across studies using random-effects meta-analysis.

RESULTS

A total of 35 studies reporting on 514 patients (534 aneurysms) were included. Aneurysm clipping in 223 patients (45.4%; 95% CI 21.9-53.8), bypass and trapping in 87 (17.7%; 95% CI 1.89-21.6), clipping and wrapping in 82 (16.7%; 95% CI 3.71-19.0), and wrapping in 33 (6.7%; 95% CI 0.0-4.87) were the mostly common performed treatments. Complete occlusion rate was reported in 90.7% of patients. The complication rate was as high as 61.1%, the mortality rate was 7.4%, and the mean mRS at follow-up was 2.5.

CONCLUSIONS

Our meta-analysis suggests that surgical treatments for BAs are related to higher occlusion, complications and mortality rate than endovascular strategies. However, there is a high-heterogeneity among the included studies and data are poorly reported; so comparing the two type of treatments is unreliable in order to establish which one is better.

Endovascular treatment for aneurysms at the A1 segment of the anterior cerebral artery: current difficulties and solutions

Aneurysms located at the A1 segment of the anterior cerebral artery are considered rare and unique entities. Endovascular treatment (EVT) is effective in preventing aneurysmal bleeding. However, EVT for A1 aneurysms is difficult due to their distinctive configurations. A current review of EVT for A1 aneurysms is lacking. Therefore, we focused on the available literature on this specific issue. To more clearly expound this entity, we also provided some illustrative cases. The A1 segment can be equally divided into the proximal, middle, and distal segments. Proximal aneurysms are most common and difficult to treat via EVT. The A1 segment has a complex anatomy and many important branches. Due to the small size, predominant posterior direction, and sharp upturn of the microcatheter from the parent artery, microcatheter positioning and support is difficult for A1 aneurysms. EVT for A1 aneurysms mainly includes reconstructive and deconstructive strategies. The complications of EVT for A1 aneurysms include aneurysmal perforation, thromboembolic events, and coil protrusion related to stent-assisted embolization. A1 aneurysms represent rare and difficult vascular lesions. EVT is quite challenging for A1 aneurysms due to their distinctive configurations. The outcomes are acceptable.

Supraclinoid internal carotid artery blister-like aneurysms: hypothesized pathogenesis and microsurgical clipping outcomes

BACKGROUND

Blister-like aneurysms (BLAs) on the supraclinoid segment of the internal carotid artery (ICA) are an enigma of cerebrovascular disease. Neither has a definite pathogenesis been so far identified, nor have uniform treatment guidelines been established for them. Our aim was to develop a hypothesis regarding the evolution of BLAs according to their macroscopic morphologies and to evaluate the efficacy of microsurgical clipping.

METHODS

The clinical data and morphological features of 15 consecutive patients with 16 BLAs on the supraclinoid ICA were retrospectively reviewed. The treatment strategies were analyzed, and functional outcomes were evaluated using the modified Rankin scale (mRS). Favorable outcomes were defined as a mRS score of 0-2.

RESULTS

Morphologically, aneurysm growth with expansion of the aneurysm neck before the surgical procedure occurred in two ruptured and one unruptured aneurysm. Daughter bleb formation was observed in two ruptured and five unruptured aneurysms. A varied degree of parent artery sclerosis was observed in nine patients. Thirteen patients were treated with direct surgical clipping, one patient was treated with clipping and wrapping, and the remaining patient was treated with an encircling clipping graft. Favorable and unfavorable outcomes were observed in 13 and two cases, respectively. Follow-up angiograms revealed 4 cases of stenosis with respective degree of mild, 30%, 50%, and 80% without any neurological dysfunction.

CONCLUSIONS

We suggest a hypothesis that BLAs on the supraclinoid ICA may share different evolving mechanisms between ruptured and unruptured lesions. A majority of them can be reliably and safely obliterated by direct clipping technique, except for the aneurysms accompanied with severely atherosclerotic parent walls.

Flow diverter stents in the treatment of recanalized intracranial aneurysms

BACKGROUND

We assessed the safety and efficacy of flow diverter stents (FDSs) in the treatment of recanalized or residual intracranial aneurysms treated endovascularly.

MATERIALS & METHODS

Patients whose recanalized or residual aneurysms were treated with FDSs in five tertiary hospitals were reviewed retrospectively. The patients' demographic data, aneurysm characteristics, types of previous treatment, and clinical complications, or serious adverse events associated with FDSs, as well as the results of neurological and angiographic follow-up assessments, were recorded.

RESULTS

Eighty-six patients (37 males) with 87 aneurysms were included in this study. Eighty (91.9%) aneurysms were in the anterior and seven (8.1%) in the posterior circulation. The initial treatment methods were the primary coiling or balloon remodeling technique in 69 (79.3%) and stent-assisted coiling in 18 (20.7%) aneurysms. The endovascular procedure was successful in all patients. Complications occurred in four patients, for a total complication rate of 4.6%. A technical complication developed in one patient (1.2%). An in-stent thrombosis treated with tirofiban was seen in two cases. Late in-stent stenosis exceeding 50% was treated with balloon angioplasty in one patient. The mean length of follow-up was 21.0 months. The first angiographic follow-up (3-6 months) revealed the complete occlusion of 74 aneurysms (85.1%). While 76 aneurysms (87.4%) were occluded at the last angiographic follow-up (mean: 26.0 months), 11 aneurysms (12.6%) were still filling. Morbimortality was zero.

CONCLUSION

The drawback of endovascular treatment is aneurysmal remnants or recurrences, which is safely and durably amenable to flow diversion.

Ruptured blood blister like aneurysm: does the best therapeutic option really exist?

Our study aimed to evaluate the outcome of patients with ruptured blood-blister like aneurysm (BBLA) in our institution by comparing microsurgical selective treatment to endovascular treatment using flow-diverter stent (FD). Our study included 18 consecutive patients treated for BBLA between 2004 and 2020. Until 2014, microsurgery was preferred in all patients with BBLA (n = 10). Significant postoperative morbi-mortality was recorded at this time and led us to change therapeutic strategy and to favor FD as first-line treatment in all patients (n = 8). Postprocedural complications and BBLA occlusion were recorded. High WFNS score (> 2) was noted in 6 patients of microsurgical group and in 2 of endovascular group. In microsurgical group, ischemic lesions were noted in 6 patients and led to death in 3 patients. Immediate BBLA occlusion was obtained in all patients. Favorable outcome after 3 months (mRS < 3) was recorded in 4 of the 7 survivors. In endovascular group, ischemic lesions were noted in 4 patients. One patient died from early postprocedural BBLA rebleeding. Scarpa hematoma was noted in 3 patients with surgical evacuation in 1. Persistent BBLA at 3 months was recorded in 4 patients without rebleeding, but further FD was required in 1 with growing BBLA. Favorable outcome was noted in 6 of the 7 survivors. Although, rate of morbi-mortality appear lower in patients treated with FD, neurological presentation was better and BBLA diagnosis remains questionable in this group. Moreover, persistent BBLA imaging with potential risk of rebleeding after FD deserves to be discussed.

Current Knowledge of and Perspectives about the Pathogenesis of Blood Blister-like Aneurysms of the Internal Carotid Artery: A Review of the Literature

Blood blister-like aneurysms (BBAs) are rare and usually appear at nonbranching sites in the supraclinoid portion of the internal carotid artery (ICA). Because it is difficult to obtain histological specimens of the aneurysm wall and because experimental models are challenging to establish, the pathogenesis of BBAs remains uncertain. In this paper, we reviewed the diagnostic, radiological, and pathophysiological characteristics of patients with BBAs. We also summarized the existing evidence and potential mechanisms related to the causes of BBAs. Current evidence indicates that atherosclerosis and dissection are the main prerequisites for the formation of BBAs. Hemodynamics may play a role in the process of BBA formation due to the unique vascular anatomy of the supraclinoid ICA. Further research on histopathology and hemodynamics is warranted in this field.

Endovascular Treatment of Ruptured Intracranial Blister Aneurysms: A Systematic Review and Meta-analysis

BACKGROUND

Endovascular treatment of blister aneurysms is a promising approach, even though they are vascular lesions challenging to treat due to their angioarchitectural characteristics.

PURPOSE

Our aim was to investigate clinical and radiologic outcomes after endovascular treatment of ruptured blister aneurysms.

DATA SOURCES

PubMed, Ovid MEDLINE, Ovid EMBASE, Scopus, and the Web of Science were screened.

STUDY SELECTION

We performed a comprehensive review of the literature from 2010 to 2019 reporting series of patients with blister aneurysms treated with an endovascular approach.

DATA ANALYSIS

Event rates were pooled across studies using a random effects meta-analysis.

DATA SYNTHESIS

A total of 32 studies reporting on 684 patients (707 aneurysms) were included. Stent placement, stent-assisted coiling, and flow diversion were the most commonly described treatments (282, 256, and 155 patients, respectively). The long-term complete occlusion rate was 76.9% (95% CI, 69.2%-83.9%). The perioperative complication rate was 8.9%, and clinical outcome at final follow-up was mRS <2 in 76.6% (95% CI, 68.2%-84.2%) of patients. The mortality rate was 4.7% (95% CI, 2.30%-7.80%). Among the different techniques, stent-assisted coiling is the one that had the higher rate of immediate occlusion (63.4%); however, the occlusion rate at the final follow-up was comparable among the different techniques.

LIMITATIONS

Different techniques were described and data were reported in a nonhomogeneous way, possibly representing a bias in the present study.

CONCLUSIONS

This study suggests that endovascular treatment of blister aneurysms is associated with good long-term occlusion rates and reasonable complication and mortality rates. There is no consensus on the best endovascular techniques in blister aneurysm management.

Ruptured Blister-like Aneurysm Arising From the Proximal Posterior Cerebral Artery

BACKGROUND

Blister-like aneurysms (BLAs) arise mostly at the supraclinoid internal carotid artery. We report a rare case of ruptured BLA arising at the P1 segment of the posterior cerebral artery (PCA).

CASE DESCRIPTION

A 34-year-old woman presented with disturbance of consciousness. Computed tomography (CT) of the head showed diffuse subarachnoid hemorrhage (SAH). A tiny bulge on the right PCA P1 segment was observed on initial CT angiography. The lesion enlarged little-by-little, with re-rupture occurring 10 days after initial hemorrhage. We diagnosed BLA arising at the P1 segment, and performed emergent endovascular parent artery occlusion (PAO) of the P1 segment. No infarction was observed in the territory of the PCA postoperatively.

CONCLUSIONS

Proximal PCA is a rare but possible location for BLA. When the cause of bleeding SAH cannot be identified, repeated radiologic assessments including posterior circulation should be performed. If perforators of the unaffected site supply the thalamus and midbrain bilaterally and an ipsilateral posterior communicating artery exists, PAO of P1 seems feasible as a treatment. Elective intervention is not recommended because of the characteristics of ruptured BLAs.

Treatment of Ruptured Blister-Like Aneurysms with the FRED Flow Diverter: A Multicenter Experience

BACKGROUND AND PURPOSE

Treatment of ruptured blister-like aneurysms is technically challenging. This study aimed at analyzing the safety and efficacy of the Flow-Redirection Endoluminal Device (FRED) in the treatment of ruptured blister-like aneurysms.

MATERIALS AND METHODS

In a retrospective multicenter study, all patients treated with the FRED due to a ruptured intracranial blister-like aneurysm between January 2013 and May 2019 were analyzed. The primary end points for clinical safety were mRS 0-2 at 6 months after treatment and the absence of major ipsilateral stroke or death. The primary end points for efficacy were the absence of rebleeding after treatment and complete angiographic occlusion according to the O'Kelly-Marotta classification at 6 months after treatment.

RESULTS

In total, 30 patients with 30 ruptured blister-like aneurysms were treated. Immediate complete aneurysm obliteration (O'Kelly-Marotta classification D) with the FRED was achieved in 10 patients (33%). Of the 26 patients with follow-up, complete obliteration was achieved in 21 patients (80%) after 6 months and in 24 patients (92%) in the final follow-up (median, 22 months). Twenty-three patients (77%) achieved mRS 0-2 at 6 months. Major stroke or death occurred in 17%. Two patients died due to pneumonia, and 2 patients died due to infarction following cerebral vasospasm. There was no case of rebleeding after FRED implantation. There was 1 case of delayed asymptomatic stent occlusion.

CONCLUSIONS

Treatment of ruptured blister-like aneurysms with the FRED is safe and effective.

Comparison of Bypass and Non-Bypass Surgical Treatments for Internal Carotid Artery Blood Blister-Like Aneurysms: A Meta-Analysis of Efficacy, Safety, and Outcomes

BACKGROUND

The optimal surgical strategy for treating internal carotid artery (ICA) blood blister-like aneurysms (BBAs) has remained unclear. Although some have preferred bypass surgery, others have favored less-demanding surgical methods. The aim of the present meta-analysis was to assess the efficacy, safety, and outcomes of bypass and non-bypass surgical methods when intended as primary treatment of ICA BBAs.

METHODS

Studies reporting data on the outcomes of interest for surgically treated patients with ICA BBAs were searched for in the PubMed/MEDLINE, Evidence-Based Medicine Reviews, Cochrane Central, ProQuest, and Scopus databases. The data were analyzed using random effects modeling.

RESULTS

Seven observational studies involving 140 patients met the inclusion criteria. The patients treated with bypass surgery, compared with those treated with non-bypass techniques, had lower odds of poor outcomes (odds ratio [OR], 0.75; 95% confidence interval [CI], 0.28-2.02; P = 0.57; I² = 0%), postoperative vasospasm (OR, 1.73; 95% CI, 0.38-7.92; P = 0.48; I² = 19%), intraoperative bleeding (OR, 3.37; 95% CI, 0.82-13.90; P = 0.09; I² = 0%), postoperative bleeding (OR, 1.91; 95% CI, 0.47-7.76; P = 0.36; I² = 0%), and postoperative recurrence of BBAs (OR, 2.16; 95% CI, 0.54-8.66; P < 0.28; I² = 0%). No comparison, however, achieved statistical significance.

CONCLUSIONS

For surgeons who use both bypass and non-bypass surgical strategies, the 2 methods seemed comparable in terms of the outcomes of interest, although the bypass technique appeared superior. However, comparisons with studies reporting bypass as the uniquely preferred technique have indicated that specialization in, and preference for, the bypass procedure has been associated with more favorable outcomes.

Using overlapping low-profile visualized intraluminal support stent-assisted coil embolization for treating blood blister-like aneurysms of the internal carotid artery

Blood blister-like aneurysm (BBA) of the internal carotid artery (ICA) is highly challenging to treat owing to its variable morphology and tendency for rupture and regrowth. In this study, we attempted to discuss the key techniques for overlapping low-profile visualized intraluminal support (LVIS) stent-assisted coil embolization, which is used for treating BBAs in our center. Clinical characteristics, endovascular treatment details, outcomes, and follow-up results of 13 patients with BBA treated at our center were retrospectively evaluated in this study. Overlapping LVIS stent-assisted coil embolization was successfully performed in all 13 patients of ruptured BBAs located in the ICAs. Recurrence of aneurysm was observed in 4 cases (30.8%) during the angiographic follow-up; in 2 of these cases, spontaneous healing was observed after discontinuation of antiplatelet therapy. Further, 2 patients with recurrence underwent endovascular treatment with complete obliteration of the aneurysm in one and occlusion of the parent artery after Onyx embolization and stent placement in the other. The overall obliteration rate of the BBAs was 92.3% (12/13). One patient (7.7%) developed intraoperative rupture of the aneurysm with coils protruding outside; however, no severe hemorrhage or neurological dysfunction occurred owing to timely embolization. Overlapping LVIS stent-assisted coil embolization is effective for management of BBA of the ICA. Appropriate adjustment in antiplatelet therapy may improve healing in recurrent cases.

A Patient with a Ruptured Blood Blister-like Aneurysm of the Internal Carotid Artery in Whom Two LVIS Stents Were Inserted

Objective

We report a case in which multiple overlapping low-profile visualized intraluminal support (LVIS) stents were used as monotherapy for ruptured blood blister-like aneurysm (BBA) of the internal carotid artery (ICA).

Case Presentation

A 48-year-old female presented to the emergency room with acute-onset headache. She was alert without neurological deficit with subarachnoid hemorrhage (SAH) Hunt and Kosnik grade I. Emergency angiography revealed a BBA from the supraclinoid ICA. This aneurysm had a small diameter, which makes coil embolization difficult. Therefore, we planned to use multiple overlapping LVIS stents as monotherapy for the ruptured aneurysm. The postoperative course was uneventful without rebleeding. The patient exhibited no neurological deficits on the clinical follow-up at 1 year.

Conclusion

Multiple overlapping LVIS stents as monotherapy is useful for ruptured BBAs of the ICA.

A Ruptured Blood Blister-Like Aneurysm Associated with Intraperitoneal Hemorrhage due to Segmental Arterial Mediolysis: A Case Report and Literature Review

BACKGROUND

Segmental arterial mediolysis (SAM) is a rare non-atherosclerotic, noninflammatory vascular disease, characterized by mediolysis. We report an extremely rare case of subarachnoid hemorrhage (SAH) due to a ruptured blood blister-like aneurysm (BBA) of the internal carotid artery associated with SAM-related arteriopathy.

CASE DESCRIPTION

We experienced a case of SAH followed by intraperitoneal hemorrhage that occurred 12 days after the SAH onset. SAH was caused by a ruptured BBA of the internal carotid artery, which was treated by trapping with high-flow bypass. Intraperitoneal hemorrhage was caused by a rupture of a posterior inferior pancreaticoduodenal artery (PIPDA) aneurysm, which induced hypovolemic shock resulting in death in spite of endovascular internal trapping. Postmortem pathologic examination revealed that the PIPDA pseudoaneurysm was due to SAM.

CONCLUSIONS

We should pay attention to the association of SAM, which is a potentially life-threatening pathology when treating cerebral BBAs.

De Novo Blister Aneurysm Formation in 16 Days Associated with Mucorales Fungi

Although blister aneurysms represent a small percentage of all intracranial aneurysms, they are generally considered to be a more morbid and challenging entity than the more common saccular intracranial aneurysms. Despite this, the etiology of blister aneurysms is still unknown, though there are several theories. We present the case of a 54-year-old man who initially presented with vision loss and normal intracranial computed tomography angiography imaging. Only 16 days thereafter, he underwent rapidly progressive clinical decline, which was found to be due to the development and rupture of a de novo supraclinoidal blister aneurysm. Autopsy results showed fungal infection of the arterial wall by Mucorales fungi at the site of the aneurysm. Our case report supports the theory that blister aneurysms can be caused by fungal infection of the wall of the internal carotid artery.

Endovascular treatment of intracranial 'blister' and dissecting aneurysms

INTRODUCTION

Blister and dissecting aneurysms may have a different pathological background but they are commonly defined by instability of the vessel wall and bear a high risk of fatal rupture and rerupture. Lack of aneurysm sack makes treatment challenging.

PURPOSE

The purpose of this study was to assess the safety and feasibility of endovascular treatment of intracranial blister and dissecting aneurysms.

METHODS

We retrospectively analysed all patients with ruptured and unruptured blister and dissecting aneurysms treated endovascularly between 2004-2018. Procedural details, complications, morbidity/mortality, clinical favourable outcome (modified Rankin Scale ≤2) and aneurysm occlusion rates were assessed.

RESULTS

Thirty-four patients with endovascular treatment of 35 aneurysms (26 dissecting aneurysms and 9 blister aneurysms) were included. Five aneurysms were treated by parent vessel occlusion, and 30 aneurysms were treated by vessel reconstruction using stent monotherapy (n = 9), stent-assisted coiling (n = 7), flow diverting stents (n = 13) and coiling + Onyx embolization (n = 1). No aneurysm rebleeding and no procedure-related major complications or deaths occurred. There were five deaths in consequence of initial subarachnoid haemorrhage. Complete occlusion (79.2%) was detected in 19/24 aneurysms available for angiographic follow-up, and aneurysm recurrence in 2/24 (8.3%). The modified Rankin Scale ≤2 rate at mean follow-up of 15.1 months was 64.7%.

CONCLUSION

Treatment of blister and dissecting aneurysms developed from coil embolization to flow diversion with multiple stents to the usage of flow diverting stents. Results using modern flow diverting stents encourage us to effectively treat this aneurysm entity endovascularly by vessel reconstruction. Therefore, we recommend preference of vessel reconstructive techniques to parent vessel occlusion.

Endovascular treatment of blood blister-like aneurysms in the internal carotid artery using a Willis covered stent

Background Despite the current availability of flow diverter devices (FDD), problems remains regarding optimal endovascular treatment (EVT) for blood blister-like aneurysms (BBAs) of the internal carotid artery (ICA). Objective To evaluate the safety and efficacy of EVT of BBAs in the ICA with a Willis covered stent. Methods 20 consecutive patients (5 men and 15 women) with ruptured BBAs underwent EVT using a Willis covered stent in two institutions from March 2013 to March 2018. Clinical observations, angiographic characteristics, and procedural and follow-up outcomes were retrospectively evaluated. Results 20 consecutive patients (5 men and 15 women) with ruptured BBAs underwent EVT using a Willis covered stent in two institutions from March 2013 to March 2018. Clinical observations, angiographic characteristics, and procedural and follow-up outcomes were retrospectively evaluated. Conclusion Our initial results demonstrate that reconstructive EVT using a Willis covered stent provides a viable approach to treat ICA BBAs. However, an expanded clinical evaluation and larger cohort are needed to confirm the results.