Early angiographic occlusion of ruptured blister aneurysms of the internal carotid artery using the Pipeline Embolization Device as a primary treatment option

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.

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.

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.

Flow diverting devices in acute ruptured blood blister aneurysms: a three centric retrospective study

BACKGROUND

Blood blister aneurysms (BBAs) are a rare tiny subset of intracranial aneurysms, located at the nonbranching site of an artery, representing a therapeutic challenge from both surgical and endovascular approach. Flow-diverting efficacy, by preserving flow through the parent artery, was approved for its use in unruptured cerebral aneurysms, but no consensus was reached on its use for BBAs ruptured in the acute setting. We report a multicenter experience of use of flow diversion in acute setting of ruptured BBA, to analyze the safety and efficacy of these devices.

METHODS

We performed a retrospective study of 6 consecutive intracranial BBAs treated with flow diverter devices (FDD) between 2018 and 2020 at 3 italian institutions. Materials, therapy used, complications, clinical and radiographic outcomes were reviewed.

RESULTS

We used different FDD, in all cases immediate change in contrast opacification at the end of the procedure was reported. Intraprocedural IIb/IIIa inhibitor agent was the major antiplatelet protocol administered. Any complications occurred. All patients showed complete BBA obliteration at 3 months follow-up. 5/6 patients achieved good clinical outcome (0-2 mRS) at 3 months, all of which were presented with low grade SAH (Hunt Hess I-III) and a lower Fisher grade.

CONCLUSION

Our data support this endovascular technique as a safe and effective therapeutic modality for this pathology in the acute setting.

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.

Microsurgical clipping and endovascular flow diversion of ruptured anterior circulation blood blister-like aneurysms

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.

Treatment of blood blister aneurysms of the internal carotid artery with flow diversion

Background

Blood blister aneurysms (BBA) are a rare subset of intracranial aneurysms that represent a therapeutic challenge from both a surgical and endovascular perspective.

Objective

To report multicenter experience with flow diversion exclusively for BBA, located at non-branching segments along the anteromedial wall of the supraclinoidal internal carotid artery (ICA).

Methods

Consecutive cases of BBA located at non-branching segments along the anteromedial wall of the supraclinoidal ICA treated with flow diversion were included in the final analysis.

Results

49 patients with 51 BBA of the ICA treated with devices to achieve the flow diversion effect were identified. 43 patients with 45 BBA of the ICA were treated with the pipeline embolization device and were included in the final analysis. Angiographic follow-up data were available for 30 patients (32 aneurysms in total); 87.5% of aneurysms (28/32) showed complete obliteration, 9.4% (3/32) showed reduced filling, and 3.1% (1/32) persistent filling. There was no difference between the size of aneurysm (≤2 mm vs >2 mm) or the use of adjunct coiling and complete occlusion of the aneurysm on follow-up (P=0.354 and P=0.865, respectively). Clinical follow-up data were available for 38 of 43 patients. 68% of patients (26/38) had a good clinical outcome (modified Rankin scale score of 0–2) at 3 months. There were 7 (16%) immediate procedural and 2 (5%) delayed complications, with 1 case of fatal delayed re-rupture after the initial treatment.

Conclusions

Our data support the use of a flow diversion technique as a safe and effective therapeutic modality for BBA of the supraclinoid ICA.

Rerupture of a Blister Aneurysm After Treatment With a Single Flow-Diverting Stent

BACKGROUND AND IMPORTANCE

As the use of flow-diverting stents (FDSs) for intracranial aneurysms expands, a small number of case reports have described the successful treatment of blister aneurysms of the internal carotid artery with flow diversion. Blister aneurysms are uncommon and fragile lesions that historically have high rates of morbidity and mortality despite multiple treatment strategies. We report a case of rebleeding after treatment of a ruptured blister aneurysm with deployment of a single FDS.

CLINICAL PRESENTATION

A 29-year-old man presented with subarachnoid hemorrhage and a ruptured dorsal variant internal carotid artery aneurysm. Despite a technically successful treatment with a single FDS, a second catastrophic hemorrhage occurred during the course of his hospitalization.

CONCLUSION

This case highlights the risk of hemorrhage during the period after deployment of a single FDS. Ruptured aneurysms, especially of the blister type, are at risk for rehemorrhage while the occlusion remains incomplete after flow diversion.

ABBREVIATIONS

FDS, flow-diverting stentICA, internal carotid arterySAH, subarachnoid hemorrhage.

Pipeline embolization device retraction and foreshortening after internal carotid artery blister aneurysm treatment

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.

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

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

Pipeline flow diversion of ruptured blister aneurysms of the supraclinoid carotid artery using a single-device strategy

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.

Endovascular treatment of blister aneurysms

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

Pipeline embolization device as primary treatment for cervical internal carotid artery pseudoaneurysms

Background:

Limited data exists on the durability and occlusion rate of treating extracranial cervical internal carotid artery pseudoaneurysms using the pipeline embolization device (PED) flow-diverting stent.

Methods:

Three patients presenting with dissecting cervical internal carotid artery pseudoaneurysms were treated with the PED as the sole treatment modality.

Results:

In all three patients, successful aneurysmal occlusion and parent vessel reconstruction occurred on immediate angiography and continued on 6-month follow-up. No immediate or delayed complications were seen, and all patients remained neurologically intact.

Conclusion:

Complete aneurysmal occlusion and long-term angiographic occlusion can occur after PED treatment of cervical carotid pseudoaneurysms. In select patients, the PED can be a suitable primary treatment modality with good neurological outcome for cervical carotid pseudoaneurysms.

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.

Flow diversion with Pipeline Embolic Device as treatment of subarachnoid hemorrhage secondary to blister aneurysms: dual-center experience and review of the literature

Background

Aneurysmal subarachnoid hemorrhage (aSAH) secondary to blister-type aneurysms (BAs) is associated with high morbidity and mortality. Microsurgical clipping or wrapping and/or use of traditional endovascular techniques to repair the lesion result in frequent regrowth and rebleeds and ultimately high fatality rates. Because of the purely endoluminal nature of arterial reconstruction, flow diversion may represent an ideal option to repair ruptured BAs.

Methods

We performed a retrospective analysis of our database including all consecutive patients with aSAH secondary to BAs treated with the Pipeline Embolic Device (PED) between November 2013 and November 2015 in two institutions. We collected basic patient demographics, aneurysm size, location, number and sizes of PEDs used, use of coiling, 30-day modified Rankin Scale (mRS) score, and follow-up imaging data.

Results

Ten cases of aSAH were found as a result of a ruptured BA. Patients had a mean age of 47.2 years (range 27–68). Mean Hunt and Hess score was 1.6 (range 1–4). Lesions were predominantly left-sided, mostly along the dorsal aspect of the internal carotid artery, either paraclinoid or paraophthalmic (8/10). In two patients the BA was located in the left middle cerebral artery. All lesions were very small (mean 1.4×1.5 mm; range 0.75–2.1 mm). Placement of a single PED resulted in immediate occlusion or near-occlusion of the BA in 9 out of 10 patients. Nine patients did very well; eight had a 90-day mRS score of 0 and one had a 90-day mRS score of 1. Follow-up digital subtraction angiography was performed in all patients (mean 15 months; range 7–24). In the surviving nine patients there was complete occlusion of the BA on long-term follow-up angiography.

Conclusions

Repair of ruptured BA with PED may be a safe and durable option.

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

BACKGROUND AND PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

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

Background

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

Objective

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

Methods

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

Results

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

Conclusion

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