Blister aneurysms of the internal carotid artery: Surgical treatment and management outcome from a single center experience

Blood Blister-Like Aneurysms of the Internal Carotid Artery

Internal carotid artery blood blister-like aneurysms are challenging lesions that arise from the artery trunk at non-branching sites. They have been recognized since 1969 and are distinct from typical saccular aneurysms. Usually, these aneurysms are broad-based, with no clearly identifiable neck and have extremely friable and fragile walls, thus with a great propensity to cause subarachnoid hemorrhage and to rupture during treatment. Apparently, blister-like aneurysms are formed through an acquired defect of the inner layers (tunica intima and media) of the internal carotid artery wall, probably due to hemodynamic stress in the carotid siphon.Several surgical and endovascular techniques have been described for the treatment of these aneurysms, however, there is still no consensus on the best technique or method, exposing how challenging the treatment of internal carotid artery blister-like aneurysms is, for both neurosurgeons and neurointerventionists. In this chapter, we review the main aspects of the pathogenesis, diagnosis, and therapeutics and report our experience in the microsurgical treatment of these formidable lesions.

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

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

Contemporary Treatment of Intracranial Blood Blister Aneurysms - A Systematic Review

INTRODUCTION

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

MATERIALS AND METHODS

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

RESULTS AND DISCUSSION

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

CONCLUSION

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

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.

Clinical Research of Combined Arteriovenous Approach Embolization on Complex Carotid-Cavernous Fistulas

The objective of this study was to observe the curative effect of combined arteriovenous approach embolization on complex carotid-cavernous fistulas. The clinical data of 13 patients with complex carotid-cavernous fistulas treated with combined arteriovenous approach embolization in our department between January 2017 and January 2020 were analyzed retrospectively. All 13 patients received the combined arteriovenous approach embolization with coil combined with Onyx glue. The intraoperative angiography immediately showed that the fistula could be completely blocked, and the carotid artery was/got unobstructed. The patients had no clinical symptoms recurring during a follow-up period of 3-18 months, on average 9.1 ± 6.3 months. A combined arteriovenous approach embolization on complex carotid-cavernous fistulas is safe and effective since it can improve the occlusion rate and reduce the relapse rate.

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

BACKGROUND

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

METHODS AND MATERIALS

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

RESULTS

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

CONCLUSIONS

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

Surgical treatment of intracranial blister aneurysms: A systematic review

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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