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Background: Blood blister-like aneurysms (BBAs) are a rare but clinically important cause of subarachnoid hemorrhage. Although regrowth or repeat rupture can occur following reconstructive endovascular treatment of BBAs, there is currently a lack of studies reporting the surgical exploration of BBAs after endovascular management. Herein, we present the first case report of a ruptured BBA treated with reconstructive endovascular treatment followed by surgical exploration. Case Presentation: A 42-year-old woman with subarachnoid hemorrhage was found to have the following: a saccular aneurysm of the lateral wall of the right supraclinoid internal carotid artery (ICA); and irregular vessel wall of the anterior wall of the right supraclinoid ICA on angiography. Based on intraoperative findings, the patient was diagnosed with a ruptured BBA of the right ICA. She underwent coating of the dissected ICA followed by overlapping stents; however, angiography showed rapid regrowth of the aneurysm. After high-flow bypass, surgical exploration was performed under proximal control of the cervical ICA. The deployed stent was directly observed through a vessel wall defect of the anterior wall which was consistent with angiographical irregular vessel wall. There was a clear positional discrepancy between angiographical base of the aneurysm and intraoperative laceration site. Conclusions: Surgical exploration indicates there is a potential risk of regrowth and/or repeat rupture of BBAs until the stent is fully endothelialized. Moreover, stent should be deployed to ensure that the irregular vessel wall is included when reconstructive endovascular treatment is employed for ruptured BBAs associated with irregular vessel wall.

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. [ABSTRACT FROM AUTHOR]

Blister aneurysms (BA) are high-risk cerebrovascular lesions accounting for 1% of intracranial aneurysms. The defective vessel wall and broad-based neck make this clinical entity difficult to treat, with high rates of re-rupture and mortality in patients presenting with acute subarachnoid haemorrhage. Blister aneurysms pose substantial challenges for both endovascular and microsurgical management. The objective of this study is to evaluate endovascular and microsurgical outcomes in intracranial blister aneurysm management across two tertiary hospitals. A review of two tertiary hospitals with a systematic imaging database search for term of “blister” in modalities from January 2010 to October 2022 was conducted. Operation reports were screened for the 5-year period since cerebral angiogram reports transitioned to surgical database. Identified reports were screened and reviewed for confirmed diagnosis by consultant neuroradiologist. A total of 21 cases of blister aneurysms managed at respective facilities were included. Sixteen cases (76%) were managed endovascularly. Four cases (19%) were managed surgically—2 with primary clipping, and 2 wrap and clipping. One case was managed conservatively (5%). Clinical outcomes were discharge disposition, aneurysm exclusion and post-operative complications. BAs have challenging considerations with high mortality and morbidity. Endovascular treatment offers a less invasive modality with lower rates of intraoperative rupture and morbidity. Mortality rates and patients discharged home were comparable. Commencement of dual anti-platelet therapy was safe in patients with flow diversion stents despite sub-arachnoid blood volume. Management of blister aneurysms is complex. Endovascular treatment shows promise for acute management but careful collaborative consideration of antithrombotic regime and requirement for further surgery should be considered. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: Cerebral arteries experience aneurysms more commonly than systemic arteries. This case report discusses a blister aneurysm that affected the anterior cerebral artery's A1 segment. The histological and genetic background is related to the aneurysm's unique presentation. Case description: The blister aneurysm ruptured, leading to interventricular and basal subarachnoid hemorrhage. A right sided fronto-temporo-parietal decompressive craniotomy was performed to explore it, along which clipping operation was performed. A communicative hydrocephalus develops after the craniectomy for which a right parietal VP shunt was conducted that underwent malfunction. The patient succumbed due to septic shock after 4 months of VP shunt revision surgery. Discussion: Different forms of cerebral aneurysms were analyzed, with regards to their histo-pathological characteristics and underlying anatomical basis of their formation. Finally, the genetic propensity of all the aneurysm was explained. There was an interventricular and basal subarachnoid hemorrhage because of the blister aneurysm's rupture. To explore it, a fronto-temporo-parietal decompressive craniotomy on the right side was done, along with a clipping operation. After the craniectomy, a right parietal VP shunt was performed, however it malfunctioned, leading to a communicative hydrocephalus. After undergoing VP shunt revision surgery for 4 months, the patient passed away from septic shock. Conclusions: The common types of cerebral aneurysms (saccular, fusiform, mycotic and blister) and the anatomical basis of their occurrence are reviewed in-depth in the histopathological and genetic literature.

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.

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. [ABSTRACT FROM AUTHOR]

It is challenging to safely treat blood blister–like aneurysms (BBAs) of the internal carotid artery. Endovascular surgery has been reported, but the optimal strategy is yet to be established. We report our endovascular treatment strategy using the Low-profile Visualized Intraluminal Support (LVIS) stent. Twelve patients with ruptured BBAs including 1 patient with 2 separate aneurysmal bulges were treated from December 2017 to January 2020. Single LVIS stent-assisted coil embolization was performed as the initial treatment. If the coil could not be placed in the aneurysm, or follow-up angiography showed persistent filling or regrowth of the aneurysm, a second LVIS stent was deployed as an overlapping stent. Clinical characteristics, treatment details, and clinical outcomes were retrospectively examined. Single stent-assisted coiling was performed in 8 patients (69%), 2 overlapping stents with coiling in 1 (8%), a single stent in 2 (15%), and 2 overlapping stents in 2 (15%). Three patients with persistent filling or regrowth of the aneurysm were re-treated with overlapping stents. Follow-up angiography confirmed complete occlusion in 12 aneurysms (92%). No re-rupture occurred. Postoperative symptomatic ischemia was confirmed in 4 patients (33%), and all 4 patients suffered severe subarachnoid hemorrhage. Modified Rankin scale was 0–2 in 8 patients (67%). LVIS stent-assisted coil embolization is effective in preventing re-rupture of BBAs. However, the morphology of the aneurysm may change within a short period, so careful angiographic follow-up is needed. Appropriate preoperative antiplatelet administration and optimal timing of the treatment may reduce the risk of postoperative ischemic complication. [ABSTRACT FROM AUTHOR]

Blister aneurysms are uncommon and difficult-to-treat lesions. They are a substantial cause of morbidity and mortality when encountered. Here, we report a blister aneurysm of the mid A1 segment of the anterior cerebral artery presenting with diffuse basal subarachnoid hemorrhage (SAH). The aneurysm was treated by surgical clipping of the parent vessel. Postoperatively, there was no filling of the parent vessel or aneurysm. A treatment algorithm including direct surgical repair and flow diversion for ruptured blister aneurysms is described. A high level of suspicion should be maintained in the setting of angiographic-negative SAH with an asymmetrically diffuse pattern.

Ruptured blister aneurysms of the internal carotid artery are challenging to treat because of their difficult diagnosis and the fragility of the wall structure. Here, we sought to clarify the efficacy of extracranial-intracranial bypass followed by trapping (bypass/trapping) for ruptured blister aneurysms. A retrospective study identified 45 patients with ruptured blister aneurysms between 1998 and 2017. Our principle was to attempt bypass/trapping as early as possible after diagnosis (early surgery). If early diagnosis was difficult, patients underwent elective surgery in the later stage when aneurysms were detected (elective surgery). Patient characteristics, radiologic findings, clinical course, and outcomes were analyzed. Forty-three patients were treated by bypass/trapping. Twenty-eight patients were classified as early surgery and 15 as elective surgery. Two patients experienced fatal rebleeding and did not undergo surgery. All 15 patients in the elective surgery group showed rebleeding and/or aneurysmal growth while awaiting surgery. In the elective surgery group, 10 aneurysms were missed initially by catheter angiography. In the early surgery group, 9 patients were assessed by vessel wall magnetic resonance imaging, which showed circumferential enhancement along the aneurysm wall, most of which was shown as only a small bulge in the angiography. Postoperative rebleeding did not occur in any of the patients. Bypass/trapping is effective to prevent rebleeding. Early surgery may be beneficial, because most patients in the elective surgery group showed rebleeding or aneurysmal growth. Vessel wall magnetic resonance imaging is a useful adjunct for early diagnosis and may contribute to prompt early surgery. [ABSTRACT FROM AUTHOR]

Blood blister aneurysms are extremely rare, and its treatment continues to be controversial. Although surgery was the only available treatment a decade ago, today newer endovascular devices such as flow diverters (FDs) appears to have very low complication rates with good long-term results. We analyzed our data of seven patients who angiographically had features of a blister aneurysm. All these patients presented with subarachnoid hemorrhage (SAH). Six of these were in anterior circulation, all of which were in internal carotid artery (ICA) and one was in a P1 segment of posterior cerebral artery (PCA). All of the patients except one in PCA were treated with FDs. One of the patients died (14.3%) following the procedure secondary to thrombosis of FD. Rest of the patients did well postprocedure with the good clinical outcome (modified Rankin Scale [mRS] of less than or equal to 2 at 1-month follow-up) in 85.7% patients. Five of the patients showed complete obliteration of an aneurysm (83.3%) on 6-month follow-up angiography. The only patient with an aneurysm in PCA showed persistence of an aneurysm and this particular lesion was instead treated by a single stent. Blister aneurysms pose diagnostic and therapeutic challenges and demand prompt treatment. Considering that all patients who were treated with FD had complete obliteration, it can be inferred that FD can be the treatment of choice in patients with blister aneurysms presenting with SAH. Further, with the introduction of small vessel FD, thrombotic complications may reduce, lowering the morbidity and mortality. Isolated stenting may not be an optimal treatment of a blister aneurysm.

Surgical treatment of ruptured blood blister–like aneurysms (BBAs) arising from the internal carotid artery (ICA) is challenging. We retrospectively reviewed the results of our surgical strategies tailored for each aneurysm site. All ruptured ICA BBAs treated between 2003 and 2015 were reviewed. Aneurysms on the lateral side of the ICA were classified as type A, on the medial side of C2 as type B, and on the medial side of C1 as type C. The principal strategy was high-flow bypass (HFB) by use of a radial artery graft, with clipping, trapping, or proximal occlusion selected on the basis of aneurysm type. The results of each treatment were examined. This study included 20 patients. There were 11 type A aneurysms (55%), 2 type B (10%), and 7 type C (35%). HFB was used in 13 patients (65%) and low-flow bypass in 4 (20%). Except for 1 case, no other cases of rerupture or recurrence occurred. Severe ischemia due to cerebral vasospasm was confirmed in 4 of 20 patients (20%), 3 of whom had not received HFB. Modified Rankin Scale score was 0–2 in 16 of 20 patients (80%). Inadequate cerebral blood flow is a distinct possibility even with HFB, so parent artery flow should be preserved to protect against ischemia whenever possible. However, if preservation of the anterior choroidal artery or posterior communicating artery during clipping or trapping is difficult, HFB combined with occlusion of the proximal portion of the ICA in the neck is a feasible option. [ABSTRACT FROM AUTHOR]

Background Detection and treatment of blister-like intracranial aneurysms as a source of subarachnoid hemorrhage (SAH) can be challenging. In the past the results of both microsurgical and endovascular treatment were difficult. We present our experience with the treatment of blister-like aneurysms in the acute phase of SAH using microsurgical clipping, endovascular parent vessel occlusion or flow diversion. Methods A retrospective analysis of the cases of eight consecutive patients presenting in the acute phase after SAH from an intracranial blister aneurysm was performed. The demographic data of the patients, aneurysm characteristics, the clinical results of the treatment and the follow-up examinations were recorded. Procedural safety margins and aneurysm occlusion on follow-up digital subtraction angiography were the main interest of this evaluation. Results Between January 2012 and November 2017 a total of eight ruptured blister aneurysms were treated in our center, six patients endovascularly. Five patients were treated in the acute phase of SAH, four by flow diversion. All endovascular procedures were feasible and no procedure-related complications were observed, especially no recurrent hemorrhage. In the first angiographic follow-up all blood blister-like aneurysms were completely occluded; two of the six patients treated by flow diverter implantation showed mild, transient intimal hyperplasia without clinical symptoms or the need for treatment. Conclusions Endovascular flow diversion is a viable option in the acute phase after SAH due to the rupture of a blister aneurysm. Implants with reduced thrombogenicity, obviating dual-platelet function inhibition, and flow diverters for vessel bifurcations would extend the indications for this treatment modality. [ABSTRACT FROM AUTHOR]

Highlights • Blood blister-like aneurysms (BBAs) are an important cause of subarachnoid hemorrhage (SAH). • The specimens of BBAs were obtained intraoperatively from live specimens in two patients. • The pathogenesis of BBAs based on histopathologic examination and microscopic configuration, was suggested. Abstract Blood blister-like aneurysms (BBAs) are an important cause of subarachnoid hemorrhage (SAH), but proper treatment is uncertain due to the poor prognosis of these aneurysms. The pathogenesis of BBAs remains unclear and few studies have reported on histological examinations of BBAs because it is difficult to obtain a specimen due to a high risk of intraoperative bleeding. In this report, BBAs were histopathologically examined in two patients who presented with SAH due to rupture of a BBA that was treated with surgical trapping and bypass surgery. BBA specimens including the adjacent internal carotid artery (ICA) walls were obtained intraoperatively. We suggest the pathogenesis of BBAs based on histopathologic examination and microscopic configuration. [ABSTRACT FROM AUTHOR]

Background Subarachnoid hemorrhage (SAH) secondary to rupture of a blister aneurysm (BA) results in high morbidity and mortality. Endovascular treatment with the pipeline embolization device (PED) has been described as a new treatment strategy for these lesions. We present the first reported case of PED retraction and foreshortening after treatment of a ruptured internal carotid artery (ICA) BA. Case description A middle-aged patient presented with SAH secondary to ICA BA rupture. The patient was treated with telescoping PED placement across the BA. After 5 days from treatment, the patient developed a new SAH due to re-rupture of the BA. Digital subtraction angiography revealed an increase in caliber of the supraclinoid ICA with associated retraction and foreshortening of the PED that resulted in aneurysm uncovering and growth. Conclusions PED should be oversized during ruptured BA treatment to prevent device retraction and aneurysm regrowth. Frequent imaging follow up after BA treatment with PED is warranted to ensure aneurysm occlusion. [ABSTRACT FROM AUTHOR]

Blood blister−like aneurysms (BBAs) are infrequent but challenging small aneurysms with fragile domes consisting of a thin adventitia layer. 1 Flow diversion and microsurgical trapping are acceptable treatment options. While endovascular treatment is becoming the first choice in developed countries, it is prohibitive in most developing countries, where microsurgical treatment is the only feasible option. Microsurgical treatment offers superior obliteration rates at similar neurologic outcomes than endovascular treatment. 1-3 Mastering high-flow revascularization and pressure monitoring is necessary to improve outcomes of BBA, especially in the developing world. We present our operative principles, which involve pressure monitoring and a high-flow bypass to ensure sufficient post-trapping cerebral pressure. 4 A 53-year-old lady was found to have a modified Fisher 4 subarachnoid hemorrhage after the worst headache of her life. Endovascular flow diversion and trapping and bypass were discussed with the patient and family. A right internal carotid artery BBA was trapped (Video 1). A right superficial temporal artery to M4 middle cerebral artery (MCA) bypass was used to both maintain perfusion during a high-flow bypass and to measure cerebral blood pressure. An external carotid artery to MCA bypass using a saphenous vein graft provided >80% of baseline MCA arterial pressure, which prevents delayed ischemic strokes. 4 The patient tolerated the procedure well and was discharged home without deficits on postoperative day 15 after vasospasm watch. The patient consented to the procedure and provided consent to the publication of her images. [ABSTRACT FROM AUTHOR]

Blister aneurysms are a separate class of vascular malformations with a unique etiopathogenesis and clinical profile, elusive to radiological imaging and complex to manage. Unless identified and managed appropriately they often lead increased morbidity intra and post operatively. They are commonly reported in internal carotid artery. We are reporting a rare case of intraoperatively diagnosed blister aneurysm of the anterior cerebral artery, the management options and the importance of constant vigilance in cases where the aneurysm appears unruptured intraoperatively.

We describe a series of 14 surgical blister aneurysm (BA) patients and compare outcomes in those with known cerebral BA to those lacking preoperative BA diagnosis/recognition. BA are broad, fragile, pathologic dilatations of the intracranial arteries. They have a low prevalence but are associated with substantially higher surgical morbidity and mortality rates than saccular aneurysms. A confirmed, preoperative BA diagnosis can alter operative management and technique. We performed a retrospective review of prospectively collected data on aneurysm patients undergoing surgery at a major academic institution. All patients from 1990 to 2011 with a postoperative BA diagnosis were included. Chart reviews were performed to identify patients with preoperative BA diagnoses and collect descriptive data. We identified 14 patients, 12 of whom presented with subarachnoid hemorrhage. The age of the cohort (mean ± standard deviation: 41.8 ± 13.9 years) was lower than that generally reported for saccular aneurysm populations. Preoperatively diagnosed BA had an intraoperative rupture (IOR) rate of 28.6% (2/7) compared to a 57.1% (4/7) rate in the undiagnosed patients. The mortality rate in the preoperatively diagnosed cohort was 14.3% (1/7) while that of the undiagnosed group was 42.8% (3/7). BA remain a diagnostic and treatment challenge with morbidity and mortality rates exceeding those of saccular aneurysms. Preoperative BA diagnosis may decrease IOR and mortality rates and improve patient outcomes. [ABSTRACT FROM AUTHOR]

Blister-like internal carotid artery (ICA) aneurysms are known for their fragile and thin-walled morphology associated with a high risk of intraprocedural rupture. Neurosurgical and endovascular options are illustrated on three exemplary cases reviewing the diagnostic and therapeutic implications of these special aneurysms. A 49-year-old woman was admitted with subarachnoid hemorrhage (SAH) in which angiography showed a broad-based, small bulging ectasy of the terminal ICA segment. On the attempt of surgical clipping, the aneurysm ruptured leaving a tear in the ICA. After temporary clipping, the rims of the tear were approximated by sutures. Sufficient closure of the remaining leakage was achieved by circumferential wrapping which was secured by two clips. Postoperative angiography confirmed stenosis of the tightened ICA and patient recovered without neurological deficit. Surgical attempt on a second case with bulging of the C4-segment topped by a small aneurysm was fatal due to extensive laceration of the basal ICA intraoperatively. Endovascular stenting was the choice of treatment in a third SAH patient in which angiography was suspicious of a blister-like ICA aneurysm. Six-month follow-up was uneventful; the patient recovered well and further growth of bulging was not seen. Reviewing the literature, blister-like aneurysms tend to arise at uncommon sites not located at the arterial branches. Small and broad-based bulges with or without true saccular aneurysms have to be assessed as characteristic features of blister-like aneurysms. Rupture of the aneurysm involving the carrying artery has to be considered during therapeutic attempts, in which urgent strategies have to be kept in reserve preventing fatal outcome. Blister-like aneurysms is a hazardous affair for neurosurgeons and neuroradiologists as their fragile structure most likely will lead to intraoperative rupture. If endovascular treatment is not promising, wrapping and revascularization techniques come true to still be an important part of the neurosurgeons toolbox for reconstructing a vessel lumen and preserving a sufficient cerebral blood flow. [ABSTRACT FROM AUTHOR]

Flow diversion is a promising option in selected patients with acutely ruptured microaneurysms. In this article, we reviewed our experience. Patients with acute spontaneous subarachnoid hemorrhage (SAH) after rupture of a blister-like or saccular microaneurysm (≤2 mm maximal diameter) at a nonbranching ICA site treated from January 2016 to June 2019 using flow diversion as standalone therapy were included in this study. An EVD was usually placed preventively. Antiplatelet effects of pre-procedure DAPT were evaluated (target PRU, 80–160). After the intervention, DAPT was continued for ≥6 months, aspirin—indefinitely. Angiographic controls were obtained. Fifteen patients (12 female; mean age, 46.4 years) with 15 ruptured ICA microaneurysms (mean diameter, 1.8 mm) were included. An EVD was placed in 12 patients (75%) before DAPT administration and stenting. PRU values immediately before FDS were 1–134 (mean, 72.1). One patient died 27 days after flow diversion due to a suspected fulminant pulmonary embolism. Aneurysms were completely occluded at the 6–12-month angiographic follow-up in 14/14 surviving patients, with no rebleeding at a mean of 14 months. Late mRS was 0–2 in 13/14 patients and 3 in one due to sequelae of the original hemorrhage. Flow diversion provided robust aneurysm rebleeding control. Angiographic follow-up confirmed complete aneurysm occlusion in all the cases. [ABSTRACT FROM AUTHOR]

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., (© Congress of Neurological Surgeons 2021.)

A male with detected subarachnoid hemorrhage was admitted to our center. During the first angiography, a pulsatile blister aneurysm was revealed and the aneurysm was also noticeably enlarged during the surveillance angiography. The patient accepted balloon-assisted clipping successfully. Blister aneurysms are at a high risk of rupture, high risk of regrowth, and need for multimodal management. [ABSTRACT FROM AUTHOR]

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., Competing Interests: There are no conflicts of interest., (Copyright: © 2020 Brain Circulation.)

Objective: Blood-blister aneurysms (BBAs) of the internal carotid artery (ICA) are rare entities, but clinically important cause of subarachnoid hemorrhage (SAH). Several surgical and endovascular strategies have been attempted for these heterogeneous lesions. In this study, the authors analyzed the treatment strategy and outcomes in a series of cases of ICA blister aneurysms treated microsurgically., Patients and Methods: We retrospectively reviewed 15 consecutive cases of patients harboring ruptured BBAs, microsurgically treated at our institution between 2014 and 2018. We performed an analysis of the clinical and surgical aspects, as well as post-operative angiograms and outcomes., Results: Fifteen patients were identified; 9 (60%) were female. The mean age of presentation was 43,8 years. Most patients presented in good clinical conditions (Hunt-Hess 1-3 = 86%). The most common Fisher grade at presentation was 3 (60% of cases). All patients underwent digital subtraction angiography (DSA), revealing broad-based aneurysms at non-branching sites on the dorsal wall of the ICA. Intraoperatively, BBAs were confirmed in all cases. The lesions were approached through pterional (11-73%) or lateral supraorbital (4-27%) craniotomy. Direct clipping was performed in all but one lesion, in which case the clip-wrapping technique was used. Final angiographic control revealed complete occlusion in 14 cases. One patient required reoperation due to residual aneurysm filling. At discharge, a good outcome (Glasgow Outcome Scale [GOS] 4 or 5) was observed in 12 (80%) patients. Three patients were discharged with a GOS of 3., Conclusion: Blood-blister-type aneurysms are rare and challenging lesions. Preoperative knowledge and careful surgical planning can prevent poor clinical outcomes. Surgical treatment remains an effective and safe option in this context., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Objective Blister aneurysms (BAs) represent a clinical challenge without a consensus treatment strategy. We report our institution's experience with BAs with an emphasis on the use of extracranial-to-intracranial (EC-IC) bypass. Methods Seventeen patients with BAs (88% [15/17] ruptured) were treated with microsurgical techniques (5 clip wrappings, 4 clip ligations, 4 EC-IC bypasses and clip trappings, 2 internal carotid artery ligations [1 combined with clip wrapping], and 2 clip trappings). Results Six of 17 patients experienced intraoperative ruptures. There were no intraoperative ruptures among the bypass cases and 75% (3/4) of patients achieved a good neurologic outcome. Further, a literature review was performed to identify all previously reported cases of BAs undergoing clip ligation, clip wrapping, EC-IC bypass/clip trapping, and endovascular therapies, encompassing 246 BA cases across 33 studies. Intraoperative ruptures occurred in 29% of clip ligations (23/79), 27.2% of clip wrappings (6/35), 16.1% of EC-IC bypasses (5/31), and 0% of endovascular treatments. Aneurysm recurrence occurred in 2.97% (3/101) with endovascular therapies to 0% with EC-IC bypass. Mortality was 8.8% for clip ligation/wrapping (10/114), 6.5% for EC-IC bypass (2/31), and 4.0% for endovascular treatments (4/101). Conclusions Endovascular interventions have a favorable procedural safety profile but high rates of retreatment for persistent filling or posttreatment aneurysmal growth. Clip ligation and clip wrapping techniques have lower retreatment rates but slightly higher intraoperative risk. EC-IC bypass can safely provide definitive aneurysm securement and should be considered as a first-line therapy for BAs at high-volume bypass centers. [ABSTRACT FROM AUTHOR]

Background Supraclinoid blister aneurysms (BAs) of the internal carotid artery are uncommon and deadly, and appropriate treatment is controversial. Endovascular reconstruction may allow treatment through aneurysm isolation. We report a single-institution experience in the use of Enterprise stent-assisted coiling (ESAC) for treating BAs to appraise the safety and efficacy of this technique. Methods Patients treated with ESAC for a BA at our institution between 2013 and 2016 were retrospectively included in this study. Patients' aneurysm characteristics, progression status, aneurysm occlusion on follow-up angiography, and modified Rankin Scale (mRS) score were recorded and analyzed. Occlusion rates and neurologic outcomes were compared between patients treated with a single stent and those treated with multiple telescoping stents. Results Forty-four patients were included (17 males; average age, 47.3 years), and ESAC was successfully performed in all patients. Immediate postprocedure angiography revealed complete occlusion in 23 patients (52.3%), residual neck in 15 (34.1%), and residual aneurysm in 6 (13.6%). Twenty patients (45.5%) suffered perioperative cerebral vasospasm, and 3 (6.8%) died of secondary ischemic stroke. The duration of follow-up ranged from 2.5 to 27 months (mean, 11.59 ± 5.76 months). One patient with recurrence was treated with additional coiling, and another patient was treated with a covered stent. The use of telescoping stents was associated with a better complete aneurysm occlusion rate compared with the use of single stents (84.4% [27 of 34] vs. 44.4% [4 of 9]; P = 0.04). Follow-up mRS score was ≤1 for 32 of 41 patients (78.4%). Conclusions ESAC to treat BAs is safe, effective, and provides good clinical outcomes. ESAC with telescoping stents has a higher follow-up complete occlusion rate compared with ESAC with single stents. [ABSTRACT FROM AUTHOR]

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

OBJECTIVE Ruptured blister aneurysms remain challenging lesions for treatment due to their broad, shallow anatomy and thin, fragile wall. Historical challenges with both open microsurgical approaches and intrasaccular endovascular approaches have led to increased use of flow diversion for management of these aneurysms. However, the optimum paradigm, including timing of treatment, use of dual antiplatelet therapy, and number of flow-diverter devices to use remains unknown. The authors describe their experience with ruptured blister aneurysms treated with flow diversion at their institution, and discuss rates of rebleeding and number of devices used. METHODS All patients presenting with subarachnoid hemorrhage from a ruptured blister aneurysm and treated with Pipeline flow diversion were identified. Patient demographic data, clinical status and course, need for external ventricular drain (EVD), timing of treatment, and angiographic details and follow-up were recorded. RESULTS There were 13 patients identified (11 women and 2 men), and 4 had multiple aneurysms. Two aneurysms were treated on initial angiography, with average time to treatment of 3.1 days for the remainder, after discussion with the family and institution of dual antiplatelet therapy. Device placement was technically successful in all patients, with 2 patients receiving 2 devices and the remainder receiving 1 device. There was 1 intraoperative complication, of a wire perforation causing intracerebral hemorrhage requiring decompressive craniectomy. Three patients had required EVD placement for management of hydrocephalus. There was no rebleeding from the target lesion; however, one patient had worsening intraventricular hemorrhage and another had rupture of an unrecognized additional aneurysm, and both died. Of the other 11 patients, 10 made a good recovery, with 1 remaining in a vegetative state. Nine underwent follow-up angiography, with 5 achieving complete occlusion, 2 with reduced aneurysm size, and 2 requiring retreatment for aneurysm persistence or enlargement. There were no episodes of delayed rupture. CONCLUSIONS Pipeline flow diversion is a technically feasible and effective treatment for ruptured blister aneurysms, particularly in good-grade patients without hydrocephalus. Patients with a worse grade on presentation and requiring EVDs may have higher risk for bleeding complications and poor outcome. There was no rebleeding from the target lesion with use of a single device in this series.

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.