Blood-Blister Aneurysms of the Internal Carotid Artery in Tibetan and Han Populations : A Retrospective Observational Study

OBJECTIVE

Blood-blister aneurysms (BBAs) of the internal carotid artery (ICA) are challenging lesions with high morbidity and mortality rates. Although research on BBAs is well documented in different populations, the study of BBAs in the Tibetan population is extremely rare. This study aimed to evaluate the characteristics of BBAs and analyze the treatment modalities and long-term outcomes in the Tibetan population in comparison with the Han population.

METHODS

The characteristics of patients with BBAs of the ICA from January 2009 to January 2021 at our institution were reviewed. The features of aneurysms, treatment modalities, complications, and follow-up outcomes were retrospectively analyzed.

RESULTS

A total of 130 patients (41 Tibetan and 89 Han patients) with BBAs of the ICA who underwent treatment were enrolled. Compared with the Han group, the Tibetan group significantly demonstrated a high ratio of BBAs among ICAs (8.6%, 41/477 vs. 1.6%, 89/5563; p<0.05), a high ratio of vasospasm (34.1%, 14/41 vs. 6.7%, 6/89; p=0.001), a high risk of ischemic events (43.9%, 18/41 vs. 22.5%, 20/89; p<0.05), and a low ratio of good outcomes (modified Rankin scale, 0-2) at the 1-year follow-up (51.2%, 21/41 vs. 74.2%, 66/89; p<0.05). The multivariate regression model showed that ischemic events significantly contributed to the prediction of outcomes at 1 year. Further analysis revealed that microsurgery and vasospasm were associated with ischemic events.

CONCLUSION

In comparison with Han patients, the Tibetan population had a high ratio of BBA occurrence, a high incidence of ischemic events, and a high ratio of poor outcomes. The endovascular approach showed more benefits in BBA patients.

A Case of Ruptured Carotid Traumatic Blood Blister-like Aneurysm

Ruptured cerebral aneurysms that occur in the anterior wall of the internal carotid artery (ICA) are known as blood blister-like aneurysms (BBAs); they have been reported to account for 0.3% to 1% of all ruptured ICA aneurysms. In this report, we describe the treatment of an unusual traumatic BBA (tBBA) with high-flow bypass using a radial artery graft, which resulted in a favorable outcome. A 59-year-old female suffered from an acute epidural hematoma, traumatic subarachnoid hemorrhage, and traumatic carotid-cavernous sinus fistula (tCCF) after being involved in a motor vehicle accident. Her angiography results showed tCCF and a tBBA on the anterior wall of the right ICA. On the fourth day after injury, we found rebleeding from the tBBA and performed an emergency high-flow bypass using a radial artery graft with lesion trapping as a curative procedure for the tCCF and tBBA. Postoperatively, right abducens nerve palsy appeared, but no other neurological symptoms were noted; the patient was thereafter transferred to a rehabilitation hospital 49 days after injury. Traumatic ICA aneurysms commonly occur close to the anterior clinoid process, form within 1 to 2 weeks of injury, and often rupture around 2 weeks after trauma. This case was considered rare as the ICA was likely injured and bleeding at the time of injury, resulting in a form of tBBA; this allowed early detection and appropriate treatment that resulted in a good outcome.

Clip-reinforced wrapping using the Y-shaped temporalis fascia technique for intracranial aneurysms

Objectives

This study aims to identify the effectiveness of the clip-reinforced wrapping using the Y-shaped temporalis fascia (CRYST) technique for treating intracranial aneurysms (IAs).

Methods

We retrospectively reviewed five patients with ruptured IAs treated using the CRYST technique from July 2016 to May 2021. Three patients had blood blister-like aneurysms (BBAs) (one with intraoperative rupture), and two had anterior communicating artery (AcoA) aneurysms (one with intraoperative rupture). All patients had intraoperative indocyanine green angiography, and digital subtraction angiography (DSA) was reviewed 10–14 days after surgery. At 1 year postoperatively, three patients (two BBAs and one AcoA aneurysm) underwent DSA and two patients (one BBA and one AcoA aneurysm) underwent computed tomographic angiography (CTA).

Results

Two aneurysms ruptured intraoperatively during the clipping, and no severe complications occurred. No patients had neurological deficits after surgery, and they had good outcomes. Four DSAs showed no aneurysms and no significant stenosis of the parent artery 10–14 days after surgery. One patient had mild stenosis of the parent artery on DSA 10 days after surgery; the stenosis improved on DSA 1 year after surgery. No other aneurysms recurred, and parent arteries were clear on CTA or DSA 1 year after surgery.

Conclusions

Combining our accumulated experience in the work and literature, we described the CRYST technique to treat intractable IAs with specific morphologies and irregular wall structures in our patients. All outcomes and follow-up results were favorable.

Application of the Willis covered stent in the treatment of internal carotid artery blood blister-like aneurysms

The optimal treatment for blood blister-like aneurysm (BBA) has not yet been determined, and BBA has a high recurrence rate after stent-assisted embolization. The purpose of the present study was to evaluate the safety and feasibility of patients with BBA rupture in the acute phase or patients with BBA who have recurrence after stent-assisted coil embolization. Eight patients (8 women, mean age 50.3 ± 3.7 years) who presented with ruptured BBA or recurrence BBA that had been treated by stent-assisted embolization (5 patients after primary treatment of stent-assisted embolization) were retrospectively reviewed. Clinical follow-up was performed at 1 year after endovascular treatment. All patients were successfully treated with the WCS, and immediate postoperative angiography showed that the aneurysms were completely isolated. The ophthalmic artery was covered by WCS in one patient; however, this patient did not show any clinical visual field or vision symptoms. Procedure-related complications such as aneurysm rupture, vasospasm, acute thrombosis, or thromboembolism did not occur in any case. All patients were followed up for 1 year after endovascular treatment, and they were in good condition without recurrence. One patient developed delayed bleeding at the right temporal lobe. All patients had good clinical prognosis (modified Rankin Scale score ≤ 2). WCS implantation may be a safe and feasible strategy for patients with BBA rupture in the acute phase and patients with BBA who have recurrence after stent-assisted coil embolization and is a promising option worth exploring.

Microsurgical Treatment Strategy of Vertebral Artery Fusiform Aneurysm-From the Standpoint of Hemodynamic Integrity and Perforator Preservation

During treatment of vertebral artery (VA) fusiform aneurysms, it is critical to preserve peripheral perforators and anterograde blood flow of the VA and to reduce hemodynamic load to the contralateral VA. Even in the era of endovascular treatment, there are still many benefits to using microsurgical treatments with appropriate clip application and preservation of the perforators around the aneurysm, in conjunction with various bypass techniques. The ideal microsurgical technique involves reconstructive clipping that obliterates the aneurysm but preserves anterograde blood flow of the VA, followed by isolation of the aneurysm and VA reconstruction. If these two methods are unavailable, proximal clipping of the aneurysm combined with flow-augmentation bypass to the distal branch can be considered as an alternative surgical management. We discuss the microsurgical treatment of unruptured VA fusiform aneurysms in our surgical cases on the basis of a review of the current literature.

Microsurgical Clip Reconstruction of a Ruptured Internal Carotid Artery Terminus Blister Aneurysm Using a Reverse Picket Fence Technique

BACKGROUND

Blister aneurysms are rare, technically challenging lesions that are typically ill defined and arise at nonbranch points of arteries.

OBJECTIVE

To describe the microsurgical treatment of a ruptured blister aneurysm at the internal carotid artery (ICA) terminus using the reverse picket fence clipping technique.

METHODS

The patient was a 60-yr-old male. He presented with a Hunt and Hess Grade 2, Fisher Grade 3 subarachnoid hemorrhage located in the bilateral sylvian fissures (right > left) and suprasellar cisterns. Computed tomography angiography demonstrated 2 aneurysms: a 2-mm right middle cerebral artery (MCA) aneurysm and a 2.5-mm right internal carotid artery (ICA) terminus blister aneurysm. Transradial cerebral angiography was undertaken which showed these similar sized aneurysms. Microsurgical treatment was chosen, and the patient underwent a right pterional craniotomy for clipping of his aneurysms. The patient consented to the procedure.

RESULTS

The combination of stacked fenestrated clips repaired the vessel, with intraoperative fluorescein and indocyanine green angiography demonstrated normal filling of the MCA and ICA circulation with no delay. Intraoperative angiography confirmed induced moderate stenosis of the ICA terminus at about 50%, which is essential to close the blister aneurysm site by utilizing a portion of the normal vessel wall.

CONCLUSION

Ruptured blister aneurysms at the ICA terminus can be safely repaired using the reverse picket fence technique for clipping.

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.

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.

A scoring system to discriminate blood blister-like aneurysms: a multidimensional study using patient-specific model

Presurgical discrimination of blood blister-like aneurysms (BBAs) can assist neurosurgeons in clinical decision-making. The aim of this study was to investigate the characteristics of BBAs and construct a useful tool to distinguish BBAs. This study reviewed patients with small/median, hemispherical, and wide-necked aneurysms of the internal carotid artery in our institution. BBAs were identified via their intraoperative findings. A hemodynamic analysis was performed using a patient-specific model. The independent risk factors of BBAs were investigated using a logistic analysis. A scoring system was then established to discriminate BBAs, in which its predicting value was analyzed using receiver operating characteristic (ROC) analysis. A total of 67 aneurysms comprising 21 BBAs were enrolled. Comparing features between BBAs and non-BBAs, statistical significances were found in the aspect ratio (AR), height-to-width ratio, aneurysm angle (AA), wall shear stress gradient (WSSG), and normalized wall shear stress average. A multivariate logistic analysis identified AR (OR = 0.29, p = 0.021), WSSG (OR = 1.54, p = 0.017) and AA (OR = 2.49, p = 0.039) as independent risk factors for BBAs. A scoring system was constructed using these parameters, effectively distinguishing BBAs (AUC = 0.931, p < 0.01). Our multidimensional scoring system may effectively assist in the discrimination of BBAs from wide-necked non-BBAs.

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 Complex Vascular Diseases of the Internal Carotid Artery Using the Willis Covered Stent: Preliminary Experience and Technical Considerations

Purpose: The Willis covered stent (WCS) is used to treat complex vascular diseases of the internal carotid artery; however, its performance requires further investigation. This study aimed to present our single-center clinical results and experience of endovascular repair of complex vascular diseases of the internal carotid artery using the WCS.

Methods: Patients who presented with complex vascular diseases of the internal carotid artery and who were treated with the WCS from December 2013 to September 2018 were retrospectively reviewed. Procedural results, perioperative complications, incidence of endoleak, and follow-up outcomes were analyzed.

Results: Sixty-five patients were enrolled. A total of 25 large aneurysms, 10 pseudoaneurysms, 14 blood blister-like aneurysms, 11 carotid–cavernous fistulas, and 5 surgical injuries were assessed. WCS placement was successful in all patients. Immediate angiography showed that complete repair of the target artery was achieved in 56 patients (86.2%). Endoleak was observed in nine patients, including seven type I endoleaks and two type II endoleaks. Occlusion of a side-branch vessel occurred in four patients. Acute in-stent thrombosis occurred in one patient. No ischemic or hemorrhagic events or other complications developed during the perioperative and follow-up periods. Angiographic follow-up (mean duration, 12 ± 3.29 months) was performed in 60 patients and showed complete target artery repair in 58 patients, and asymptomatic mild to moderate in-stent stenosis was observed in four patients. Slight endoleak persisted in two patients without enlargement or rupture of the residual lumen.

Conclusion: WCS implantation is safe, feasible, and efficacious for endovascular repair in patients with complex vascular diseases of the internal carotid artery, showing excellent short-term target artery patency and clinical outcomes.

Ruptured Fisher grade 3 blister aneurysms have a higher incidence of delayed cerebral ischemia than ruptured Fisher grade 3 saccular aneurysms

BACKGROUND

Blister aneurysms are a rare subclass of aneurysms, which remain challenging to treat both with open cerebrovascular and endovascular techniques, and clinicians continue to see poor outcomes in some cases despite improvements in technology. Based on our clinical observations, we hypothesized that patients with a Fisher grade 3 subarachnoid hemorrhage (SAH) from a ruptured anterior circulation blister aneurysm are significantly more likely to develop poor outcome due to delayed cerebral ischemia than patients with a Fisher grade 3 SAH from a ruptured anterior circulation saccular aneurysm.

METHODS

In this consecutive case series, we reviewed management, outcomes, and rates of delayed cerebral ischemia for all ruptured anterior circulation blister aneurysms from 2012 to 2018 at our institution and compared them to a concurrent cohort of ruptured saccular anterior circulation aneurysms. A blister aneurysm was defined as an aneurysm that arises from a nonbranching point and demonstrates hemispherical anatomy on diagnostic angiography.

RESULTS

We identified 14 consecutive ruptured anterior circulation blister aneurysms. Thirteen aneurysms were treated operatively- 5 with clip remodeling and 8 with flow diversion embolization. While clip remodeling had a high intraoperative rupture rate (80%), there was only one (12.5%) intraoperative rupture with flow diversion embolization. Outcomes were worsened by delayed cerebral ischemia from vasospasm in patients with Fisher 3 hemorrhages from blister aneurysms (86%). The rate of delayed cerebral ischemia from vasospasm was significantly higher for ruptured blister aneurysms than for a concurrent cohort of ruptured saccular aneurysms (8.6%, P = 0.0001).

CONCLUSION

Ruptured Fisher grade 3 anterior circulation blister aneurysms have a significantly higher incidence of delayed cerebral ischemia from vasospasm compared to saccular aneurysms, regardless of the treatment modality.

The role of EC-IC bypass in ICA blood blister aneurysms-a systematic review

To perform a systematic review of extracranial-to-intracranial (EC-IC) bypass surgery with parent vessel trapping for blood blister–like aneurysms (BBAs) of the internal carotid artery (ICA) according to PRISMA guidelines. Search of PubMed using “bypass” [all fields] and “ICA” [all fields] or “internal carotid artery” [all fields] and (“blood blister–like aneurysm” [MeSH terms]. Thirty-four original articles were identified, of which 21 were excluded (treatment not including bypass or insufficient details on complications or clinical outcomes). Thirteen articles published between 2008 and 2019 were included, totaling 98 patients, with a median of 7.5 patients per article (range 1–17). Mean age was 53.3 years (range 23–80). The main techniques were external carotid artery to middle cerebral artery (ECA-MCA) in 81% and superficial temporal artery to MCA (STA-MCA) in 19%. The most common grafts were radial artery (74%) and STA (19%). The risk of intraoperative rupture varied from 0 to 75%, with a mean of 12%. With respect to clinical outcomes, the modified Rankin Scale (mRS) was not stated in 30% of the cases. When stated, mRS was ≤ 2 in 79%, mRS was 3–5 in 10%, and 4% had mRS 6 (death). We identified only 13 articles, with no prospective studies. Outcomes were better than generally reported for ruptured aneurysms, both with respect to poor outcome (mRS > 2) and in-hospital mortality, perhaps reflecting a selection bias. In general, the data reporting quality was low, precluding any firm conclusions, but EC-IC bypass with ICA trapping may be a valid treatment option for ruptured ICA BBAs.

Clipping on Crossed Wrapping Method for Ruptured Blood Blister-Like Aneurysm of the Internal Carotid Artery: Technical Note and Long-Term Results

Background

We have been performing the clipping on crossed wrapping (COCW) method using 2 strips of cotton on patients with an internal carotid artery blood blister-like aneurysm (IC-BLA). This method is reliable in preventing the clips from slipping off and the aneurysm walls from being damaged during clipping, and it enables more appropriate and safer clipping. Here we report the technical details of this method and the long-term outcomes of patients receiving this procedure.

Methods

Fifteen of 1275 (1.5%) patients with a ruptured cerebral aneurysm who received treatment at the Saiseikai Kumamoto Hospital during the period from January 1, 1999, to December 31, 2016, had an IC-BLA. All 15 patients were treated with COCW, except for the first patient, who was treated using a single strip of cotton. The long-term outcome of the treatment was analyzed.

Results

The mean follow-up period was 74 months. The first patient experienced rerupture of an aneurysm 10 days after the operation. No complications or regrowth of an aneurysm were observed in the remaining 14 patients during the follow-up period, except for 1 patient who received a reoperation for the regrowth of an aneurysm. As the final outcome, the numbers of patients with a Modified Rankin Score of 0, 3, and 6 were 13, 1, and 1, respectively.

Conclusions

It is suggested that COCW is a treatment that enables safe and long-term management of lesions in IC-BLAs.

Acutely Ruptured Intracranial Aneurysms Treated with Flow-Diverter Stents: A Systematic Review and Meta-Analysis

BACKGROUND

The implantation of flow-diverter stents for the treatment of ruptured intracranial aneurysms required further investigation.

PURPOSE

Our aim was to analyze the outcomes after flow diversion of ruptured intracranial aneurysms.

DATA SOURCES

A systematic search of 3 databases was performed for studies published from 2006 to 2018.

STUDY SELECTION

According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we included studies (from 2010 to 2018) reporting acutely ruptured intracranial aneurysms treated with flow diversion.

DATA ANALYSIS

Random-effects meta-analysis was used to pool the following: aneurysm occlusion rate, complications, rebleeding, and factors influencing the studied outcomes.

DATA SYNTHESIS

We included 20 studies evaluating 223 patients with acutely ruptured intracranial aneurysms treated with flow-diverter stents. Immediate angiographic occlusion was obtained in 32% (29/86; 95% CI, 15.4%-48%; I² = 79.6%) of aneurysms, whereas long-term complete/near-complete aneurysm occlusion was 88.9% (162/189; 95% CI, 84%-93.5%; I² = 20.9%) (mean radiologic follow-up of 9.6 months). The treatment-related complication rate was 17.8% (42/223; 95% CI, 11%-24%; I² = 52.6%). Complications were higher in the posterior circulation (16/72 = 27%; 95% CI, 14%-40%; I² = 66% versus 18/149 = 11.7%; 95% CI, 7%-16%; I² = 0%) (P = .004) and after treatment with multiple stents (14/52 = 26%; 95% CI, 14%-45%; I² = 59%) compared with a single stent (20/141 = 10%; 95% CI, 5%-15%; I² = 0%) (P = .004). Aneurysm rebleeding after treatment was 4% (5/223; 95% CI, 1.8%-7%; I² = 0%) and was higher in the first 72 hours.

LIMITATIONS

Small and retrospective series.

CONCLUSIONS

Flow-diversion treatment of ruptured intracranial aneurysms yields a high rate of long-term angiographic occlusion with a relatively low rate of aneurysm rebleeding. However, treatment is associated with a complication rate of 18%. When coiling or microsurgical clipping are not feasible strategies, anterior circulation ruptured aneurysms can be effectively treated with a flow-diversion technique, minimizing the number of stents deployed. Given the 27% rate of complications, flow diversion for ruptured posterior circulation aneurysms should be considered only in selected cases not amenable to other treatments.

Current Treatment Strategies for Intracranial Aneurysms: An Overview

Intracranial aneurysm is a leading cause of stroke. Its treatment has evolved over the past 2 decades. This review summarizes the treatment strategies for intracranial aneurysms from 3 different perspectives: open surgery approach, transluminal treatment approach, and new technologies being used or trialed. We introduce most of the available treatment techniques in detail, including contralateral clipping, wrapping and clipping, double catheters assisting coiling and waffle-cone technique, and so on. Data from major trials such as Analysis of Treatment by Endovascular approach of Non-ruptured Aneurysms (ATENA), Internal Subarachnoid Trial (ISAT), Clinical and Anatomical Results in the Treatment of Ruptured Intracranial Aneurysms (CLARITY), and Barrow Ruptured Aneurysm Trial (BRAT) as well as information from other clinical reports and local experience are reviewed to suggest a clinical pathway for treating different types of intracranial aneurysms. It will be a valuable supplement to the current existing guidelines. We hope it could help assisting real-time decision-making in clinical practices and also encourage advancements in managing the disease.

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.

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.

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.

How I do it: treatment of blood blister-like aneurysms of the supraclinoid internal carotid artery by extracranial-to-intracranial bypass and trapping

BACKGROUND

Blood blister-like aneurysms (BBAs) pose a significant challenge to neurosurgeons and neuro-interventionalists. These fragile broad-based aneurysms have a propensity to rupture with minimal manipulation during surgical or endovascular explorations because, unlike saccular aneurysms, they lack all layers of the arterial wall. Aneurysm trapping with extracranial-intracranial (EC-IC) bypass is a safe and durable treatment for BBAs.

METHODS

We describe our technique and the guiding principles for surgical bypass and trapping of BBAs of the supraclinoid internal carotid artery (ICA).

CONCLUSIONS

Treatment of BBAs of the supraclinoid ICA remains difficult. Aneurysm trapping with EC-IC bypass treats BBAs definitively by eliminating the diseased segment of the ICA. We have found the technique and principles described here to be safe and durable in our hands.