Giant intracranial aneurysms: natural history and 1-year case fatality after endovascular or surgical treatment

Giant unruptured middle cerebral artery aneurysm revealed by intracranial hypertension: is a systematic decompressive hemicraniotomy mandatory?

Our study aimed to evaluate the postoperative outcome of patients with unruptured giant middle cerebral artery (MCA) aneurysm revealed by intracranial hypertension associated to midline brain shift. From 2012 to 2022, among the 954 patients treated by a microsurgical procedure for an intracranial aneurysm, our study included 9 consecutive patients with giant MCA aneurysm associated to intracranial hypertension with a midline brain shift. Deep hypothermic circulatory flow reduction (DHCFR) with vascular reconstruction was performed in 4 patients and cerebral revascularization with aneurysm trapping was the therapeutic strategy in 5 patients. Early (< 7 days) and long term clinical and radiological monitoring was done. Good functional outcome was considered as mRS score ≤ 2 at 3 months. The mean age at treatment was 44 yo (ranged from 17 to 70 yo). The mean maximal diameter of the aneurysm was 49 mm (ranged from 33 to 70 mm). The mean midline brain shift was 8.6 mm (ranged from 5 to 13 mm). Distal MCA territory hypoperfusion was noted in 6 patients. Diffuse postoperative cerebral edema occurred in the 9 patients with a mean delay of 59 h and conducted to a postoperative neurological deterioration in 7 of them. Postoperative death was noted in 3 patients. Among the 6 survivors, early postoperative decompressive hemicraniotomy was required in 4 patients. Good functional outcome was noted in 4 patients. Complete aneurysm occlusion was noted in each patient at last follow-up. We suggest to discuss a systematic decompressive hemicraniotomy at the end of the surgical procedure and/or a partial temporal lobe resection at its beginning to reduce the consequences of the edema reaction and to improve the postoperative outcome of this specific subgroup of patients. A better intraoperative assessment of the blood flow might also reduce the occurrence of the reperfusion syndrome.

Application of 3D printing to create an in vitro aneurysm rupture model

Currently available benchtop (in vitro) aneurysm models are inadequate for testing the efficacy of endovascular device treatments. Specifically, current models do not represent the mechanical instability of giant aneurysms (defined as aneurysms with 25 mm in height or width) and do not predictably rupture under simulated physiological conditions. Hence, in vitro aneurysm models with biomechanically relevant material properties and a predictable rupture timeframe are needed to accurately assess the efficacy of new medical device treatment options. Understanding the material properties of an aneurysm (e.g., shear and compression modulus) as it approaches rupture is a crucial step toward creating a pathologically relevant and sophisticated in vitro aneurysm rupture model. We investigated the change in material properties of a blood vessel, via enzymatic treatment, to simulate the degradation of an aneurysm wall and used this information to create a sophisticated aneurysm rupture model using the latest in additive manufacturing technologies (3D printing) with tissue-like materials. Mechanical properties (shear and compression modulus) of swine carotid vessels were evaluated before and after incubation with collagenase D enzyme (30 min at 37°C) to simulate the effect of biochemical activity on aneurysm wall approaching rupture compared to control vessels (untreated). Mechanical strength of a soft and flexible 3D-printed material (VCA-A30: 30 shore A hardness) was tested for comparison to these arterial vessels. This material was then used to create spherical shaped, giant-sized (25-mm diameter) aneurysm phantoms and were run under neurovascular pressures (120/80 ± 5 mmHg), beats per minute (BPM = 70) and flows representing the middle cerebral artery [MCA: 142.67 (±20.13) mL/min] using a blood analog [3.6 (±0.4) cP viscosity] with non-Newtonian shear-thinning properties. The shear modulus of swine carotid vessel before treatment was 12.2 (±2.7) KPa and compression modulus was 663.5 (±111.6) KPa. After enzymatic treatment by collagenase D, shear modulus of animal tissues reduced by 33% (p-value = .039) while compression modulus remained statistically unchanged (p-value = .615). Control group (untreated vessels) showed minimal reduction (13%, p-value = .226) in shear modulus and 78% increase (p-value = .034) in compression modulus. The shear modulus of the 3D-printed material was 228.59 (±24.82) KPa while its compression modulus was 668.90 (±13.16) KPa. This material was used to prototype a sophisticated in vitro giant aneurysm rupture model. When subjected to physiological pressures and flow rates, the untreated models consistently ruptured at ~12 min. These results indicate that aneurysm rupture can be recreated consistently in a benchtop in vitro model, utilizing the latest 3D-printed materials, connected to a physiologically relevant programmable pump. Further studies will investigate the optimization of various aneurysm dome thickness regions within the aneurysm, with tunable rupture times for comparison of aneurysm device deployment and benchtop controls based on the measurable effects of pressure and flow changes within the aneurysm models. These optimized in vitro rupture models could ultimately be used to test the efficacy of device treatment options and rupture risk by quantifying specific device rupture times and aneurysm rupture position.

Microsurgical and endovascular treatment of large and giant aneurysms of the anterior circulation: A systematic review

Introduction

Large and Giant intracranial aneurysms (LGIAs) have become the paradigm for which endovascular techniques do not provide satisfactory results. Yet, microsurgery is followed by non-negligible rates of morbimortality. This scenario may have changed since the introduction of flow-diversion devices.

Research question

Contemporary and standardised revision on microsurgical and endovascular results, with emphasis on anterior circulation LGIAs.

Materials and methods

A systematic literature search was conducted in two databases (PubMed and Embase) on treatment outcomes of LGIAs of the anterior circulation, after the introduction of flow-diverters 2008/01/01, till 2023/05/20. Small case series (<5 cases), series including >15% of posterior circulation aneurysms, and studies not reporting clinical and/or angiographic outcomes were excluded.

Results

44 relevant studies (observational cohorts) were identified, including 2923 LGIAs predominantly from anterior circulation. Mean follow-up 22 (±20) months. 1494 (51%) LGIAs were treated endovascularly and 1427 (49%) microsurgically. According to the random effects model, pooled rates of favourable clinical outcomes were 85.8% (CI 95% 82.6-88.4), complete occlusion 69.4% (CI 95% 63.7-7.46), complications 19.6% (CI 95%16-23.9) and mortality 5.6% (CI 95% 4.4-7.1). Focusing on type of treatment, occlusion rates are higher with microsurgical (842/993, 85% vs 874/1,299, 67%), although good outcomes are slightly more frequent with endovascular (1045/1,135, 92% vs 1120/1,294, 87%).

Discussion and conclusions

According to contemporary data about occlusion rates, functional outcomes, and complications, primary or secondary treatment of LGIAs of the anterior circulation seems justified. Microsurgical occlusion rates are higher in LGIAs. An expert consensus on reporting complications and management strategies is warranted.

High-Flow Bypass and Clip Trapping of a Giant Fusiform Middle Cerebral Artery (M1) Aneurysm: Technical Case Instruction

BACKGROUND AND IMPORTANCE

Giant intracranial aneurysms have a poor natural history with mortality rates of 68% and 80% over 2-year and 5-year, respectively. Cerebral revascularization can provide flow preservation while treating complex aneurysms requiring parent artery sacrifice. In this report, we describe the microsurgical clip trapping and high-flow bypass revascularization for a giant middle cerebral artery (MCA) aneurysm.

CLINICAL PRESENTATION

A 19-year-old man was diagnosed with a giant left MCA aneurysm after he suffered a left hemispheric capsular stroke 6 months ago. Since then, the patient recovered from the right hemiparesis and dysarthria with residual symptoms. Neuroimaging demonstrated a giant fusiform aneurysm encompassing the entire M1 segment. The bilobed aneurysm measured 37 × 16 × 15 mm. Endovascular treatment options included partial coiling of the aneurysm followed by deployment of flow-diverting stent spanning from the M2 branch-through the aneurysm neck-into the internal carotid artery. Because of the high risk of lenticulostriate artery stroke with endovascular treatment, the patient opted for microsurgical clip trapping and bypass. The patient consented to the procedure. High-flow bypass from internal carotid artery to M2 MCA was performed using radial artery graft, followed by aneurysm clip trapping using 3 clips.

CONCLUSION

We demonstrate the successful microsurgical treatment for a complex case of giant M1 MCA aneurysm with fusiform morphology. High-flow revascularization using radial artery graft helped in achieving good clinical outcome with complete aneurysm occlusion with flow preservation despite the challenging morphology and location. Cerebral bypass continues to be a useful tool to tackle complex intracranial aneurysms.

Dolenc approach for clipping of giant C6 and C7 segment aneurysms of the internal carotid artery

Objective

Surgical treatment for giant aneurysms of the ICA-ophthalmic segment (C6) and communicating artery segment (C7) is a challenge for neurosurgeons because of their high risks and poor outcomes. We aim to explore the advantages and disadvantages of the Dolenc approach in the treatment of giant C6-C7 segment aneurysms.

Methods

We retrospectively reviewed the clinical data of 13 cases with giant C6 aneurysms and 4 cases with giant C7 aneurysms treated with the Dolenc approach.

Results

All 17 cases of aneurysms were clipped successfully using the Dolenc approach, of which, 1 case with ipsilateral MCA occlusion underwent extracranial-intracranial artery bypass after the aneurysm clipping. Regarding clinical outcomes, six out of nine cases with preoperative visual impairment improved after surgery, two cases saw no change, and one case deteriorated. Of all the cases, one had new-onset vision loss, four had new-onset oculomotor paralysis, three had surgical side cerebral infarction, and two had diabetes insipidus. DSA or CTA examination within 2 weeks after surgery showed that all aneurysms were completely clipped without residual. After a follow-up of 9-12 months, 17 patients were evaluated based on GOS and CTA examination. A total of 14 cases had GOS 5 scores, 2 cases had GOS 4 scores, 1 case had GOS 2 scores, and no cases had death. None of the patients had recurrence based on CTA examinations.

Conclusion

Through the Dolenc approach, we could achieve more operation space and expose clinoid segments for temporary occlusion. Therefore, the Dolenc approach was shown to be a safe, effective, and feasible treatment for giant C6-C7 aneurysms.

The Influence of Aneurysm Size on the Outcomes of Endovascular Management for Aneurysmal Subarachnoid Hemorrhages: A Comparison of the Treatment Results of Patients with Large and Small Aneurysms

The influence of aneurysm size on the outcomes of endovascular management (EM) for aneurysmal subarachnoid hemorrhages (aSAH) is poorly understood. To evaluate the outcomes of EM for ruptured large cerebral aneurysms, we retrospectively analyzed the medical records of patients with aSAH that were treated with coiling between 2013 and 2020 and compared the differences in outcomes depending on aneurysm size. A total of 469 patients with aSAH were included; 73 patients had aneurysms measuring ≥10 mm in diameter (group L), and 396 had aneurysms measuring <10 mm in diameter (group S). The median age; the percentage of patients that were classified as World Federation of Neurological Surgeons grade 1, 2, or 3; and the frequency of intracerebral hemorrhages differed significantly between group L and group S (p = 0.0105, p = 0.0075, and p = 0.0458, respectively). There were no significant differences in the frequencies of periprocedural hemorrhagic or ischemic events. Conversely, rebleeding after the initial treatment was significantly more common in group L than in group S (6.8% vs. 2.0%; p = 0.0372). The frequency of a modified Rankin Scale score of 0-2 at discharge was significantly lower (p = 0.0012) and the mortality rate was significantly higher (p = 0.0023) in group L than in group S. After propensity-score matching, there were no significant differences in complications and outcomes between the two groups. Rebleeding was more common in large aneurysm cases. However, propensity-score matching indicated that the outcomes of EM for aSAH may not be affected markedly by aneurysm size.

The changing landscape of cerebral revascularization surgery: A United Kingdom experience

Objective

We describe the chronological trends in cerebral revascularization surgery through a single-surgeon experience; and we review whether in the context of giant and fusiform cerebral aneurysms, flow-diverting stents have impacted on the use of cerebral revascularization surgery.

Methods

We review our single institution prospectively collected database of cerebral revascularization procedures between 2006 and 2018. Comparing this to our database of flow-diverting endovascular stent procedures, we compare the treatment of fusiform and giant aneurysms. We describe patient demographics, procedural incidence, complications, and outcomes.

Results

Between 2006 and 2018, 50 cerebral revascularization procedures were performed. The incidence of cerebral revascularization surgery is declining. In the context of giant/fusiform aneurysm treatment, the decline in cerebral revascularization is accompanied by a rise in the use of flow-diverting endovascular stents. Thirty cerebral revascularizations were performed for moyamoya disease and 11 for giant/fusiform aneurysm. Four (14%) direct bypass grafts occluded without neurological sequela. Other morbidity included hydrocephalus (2%), transient ischemic attacks (2%), and ischemic stroke (2%). There was one procedure-related mortality (2%). Flow-diverting stents were inserted for seven fusiform and seven giant aneurysms. Comparing the treatment of giant/fusiform aneurysms, there was no significant difference in morbidity and mortality between cerebral revascularization and flow-diverting endovascular stents.

Conclusion

We conclude that with the decline in the incidence of cerebral revascularization surgery, there is a need for centralization of services to allow high standards and outcomes to be maintained.

Flow diversion for internal carotid artery aneurysms with compressive neuro-ophthalmologic symptoms: clinical and anatomical results in an international multicenter study

BACKGROUND

Scientific data on the safety and efficacy of flow diverter stents (FDS) for the treatment of unruptured internal carotid artery (ICA) aneurysms with compressive neuro-ophthalmological symptoms are scarce. We studied this subject in a retrospective international multicenter series, pooling data of 9 tertiary care neurointerventional departments.

OBJECTIVE

To investigate, in a retrospective, multicentric cohort of patients presenting with visual or oculomotor symptoms attributed to a compressive carotid artery in an unruptured intracranial aneurysm, the safety and efficacy profiles of FDS, by analyzing neuro-opthalmologic symptom evolution following FDS placement, complications, and aneurysm obliteration rates.

METHODS

All patients treated since 2015 with a FDS for an unruptured aneurysm of the ICA with signs of compressive cranial nerve symptoms (CN II, III, IV, VI) were included.

RESULTS

We treated 55 patients with 55 aneurysms; 21 (38.2%) patients had oculomotor and 15 (27.3%) visual symptoms only; 19 (34.5%) presented with a combination of both. Treatment-related morbidity/mortality occurred in 7.2% and 3.6%, respectively. At last imaging follow-up (13.1±10.5 months) rates of complete aneurysm occlusion, neck remnant, and aneurysm remnant were 72%, 14%, and 14%, respectively. At last clinical follow-up after 13±10.5 months, 19/51 (37.3%) patients had recovered completely and 18/51 (35.3%) had recovered at least partially from their neuro-ophthalmological symptoms. In multivariable models, a longer delay between symptom onset and treatment was associated with higher odds for incomplete recovery and lower odds for any improvement (aOR 1.03 (95% CI 1.01 to 1.07), p=0.047 and 0.04 (0-0.81), p=0.020). Incomplete recovery was independently associated with older age and fusiform aneurysms.

CONCLUSION

FDS are effective to treat patients with compressive aneurysms of the ICA causing neuro-ophthalmological symptoms, especially when treatment is initiated early after symptom onset, and aneurysm occlusion is adequate. However, serious complications are not rare.

[Unfavorable outcome of giant vertebral artery aneurysm. Clinical case and literature review]

OBJECTIVE

To demonstrate the unfavorable natural course and prognosis of giant vertebral artery aneurysm, to analyze the literature, and to conduct a postmortem histopathological study of the features of this disease.

Remarkable shrinkage of a thrombosed giant aneurysm by stent-assisted jam-packed coil embolization

Background:

Large and giant aneurysms are known to involve intra-aneurysmal thrombosis and present a poor prognosis because of compression of the surrounding brain tissue with enlargement of the aneurysm. These aneurysms are difficult to cure by endovascular treatment due to involvement of the vasa vasorum in their pathology. We report this technical note to describe stent-assisted jam-packed coil embolization for the treatment of a giant thrombosed aneurysm.

Case Description:

A 62-year-old man presented with right homonymous hemianopsia, and magnetic resonance imaging (MRI) showed a giant thrombosed aneurysm with poor wall contrast enhancement, which indicates little involvement of the vasa vasorum, at the terminal part of the left internal carotid artery. To block blood flow into the aneurysmal dome, stent-assisted “jam-packed” coil embolization was performed. For this, a braided stent was shortened to enhance metal coverage ratio and tight aneurysmal coil packing was performed using a hydrogel coil. Our technique resulted in complete obliteration of the aneurysm, and MRI performed 1 year later showed remarkable shrinkage of the aneurysm dome.

Conclusion:

Stent-assisted jam-packed coil embolization technique might be effective in shrinking the dome of giant thrombosed aneurysms with poor wall contrast enhancement.

A Hybrid Strategy for Patients With Complex Cerebral Aneurysm: STA-MCA Bypass in Combination With Endovascular Embolization

Objective: This work aims to present our experience of patients with complex cerebral aneurysm treated with a hybrid approach: superficial temporal artery–middle cerebral artery (STA–MCA) bypass in combination with endovascular exclusion of the aneurysm.

Method: Patients with aneurysms deemed unclippable and uncoilable were included. All patients were treated with a hybrid approach. After STA–MCA bypass, the parent artery was temporarily occluded. If the intraoperative motor evoked potential (MEP) and somatosensory evoked potential (SEP) waveforms remain normal and last for 30 min, the aneurysm and te parent artery will be embolized permanently with detachable balloons or coils.

Results: A total of 20 patients with 22 aneurysms were included in this study. There were 13 women and 7 men, with an average age of 42.5 years. Intraoperative angiography showed the good patency of all the STA grafts, and neither SEP nor MEP abnormalities were detected. After the parent artery and the aneurysm were occluded, the intraoperative angiography showed an immediately successful exclusion of the aneurysm in 20 aneurysms and immediate contrast stasis in two. All patients recovered uneventfully without ischemic or hemorrhagic complication. Angiography at 6-month follow-up showed the total obliteration in 20 aneurysms. Two aneurysms showed residuals and were recoiled. All STA grafts showed a good patency, and the mean graft flow was 124.2 ml/min.

Conclusion: STA–MCA bypass in combination with endovascular exclusion is an appropriate option for patients with complex cerebral aneurysms that are not amenable to direct surgical clipping or endovascular embolization.

Unruptured Giant Intracranial Aneurysms: Risk Factors for Mortality and Long-Term Outcome

This study aims to investigate the long-term outcomes of unruptured giant intracranial aneurysms (GIAs) with different treatment modalities and to analyze the factors affecting prognosis. We performed a retrospective medical record review of patients with unruptured GIAs treated at our institution from 2011 to 2018. Prognosis was compared to the best medical treatment without intervention (conservative treatment, CT) and surgical (ST) or endovascular (ET) treatment. Risk factors for mortality were investigated. A total of 276 patients were included in this study. Patients received CT in 16.3%, ST in 30.1%, and ET in 53.6% of cases. After an average 7-year follow-up, the rupture rate after CT was 22.2%, accounting for an annual rupture rate of 7.3%. The postoperative complication rate was 30.1% and 8.1% after ST and ET, respectively. The recurrence rate after ET was 10.1%, compared with ST which was 1.2%. The follow-up mortality in unruptured GIAs was 26.7% after CT, 7.2% after ST, and 5.4% after ET. Older age (50~59, HR 5.877; 60~69, HR 8.565), size ≥ 40 mm (HR 3.916), and posterior circulation location (HR 6.411) were associated with increased mortality. ET significantly decreased mortality (HR 0.191). Unruptured GIAs warrant treatment if feasible due to the high rupture rate and mortality of the natural history. Older age, posterior circulation location, and larger size are risk factors for poor prognosis. Both ST and ET showed a lower mortality rate than CT. ST showed less likely recurrence compared to ET, while ET had a lower complication rate than ST.

Diagnostic reliability of the Berlin classification for complex MCA aneurysms-usability in a series of only giant aneurysms

Background and objective

The main challenge of bypass surgery of complex MCA aneurysms is not the selection of the bypass type but the initial decision-making of how to exclude the affected vessel segment from circulation. To this end, we have previously proposed a classification for complex MCA aneurysms based on the preoperative angiography. The current study aimed to validate this new classification and assess its diagnostic reliability using the giant aneurysm registry as an independent data set.

Methods

We reviewed the pretreatment neuroimaging of 51 patients with giant (> 2.5 cm) MCA aneurysms from 18 centers, prospectively entered into the international giant aneurysm registry. We classified the aneurysms according to our previously proposed Berlin classification for complex MCA aneurysms. To test for interrater diagnostic reliability, the data set was reviewed by four independent observers.

Results

We were able to classify all 51 aneurysms according to the Berlin classification for complex MCA aneurysms. Eight percent of the aneurysm were classified as type 1a, 14% as type 1b, 14% as type 2a, 24% as type 2b, 33% as type 2c, and 8% as type 3. The interrater reliability was moderate with Fleiss’s Kappa of 0.419.

Conclusion

The recently published Berlin classification for complex MCA aneurysms showed diagnostic reliability, independent of the observer when applied to the MCA aneurysms of the international giant aneurysm registry.

Surgical Management of Giant Intracranial Aneurysms: Overall Results of a Large Series

OBJECTIVE

To review and discuss surgical treatment options for giant intracranial aneurysms (GIAs), focusing on indications, technical aspects, and results, along with some illustrative cases.

METHODS

We reviewed the data of 82 consecutive patients surgically managed between January 2000 and December 2019 for treatment of a GIA.

RESULTS

Male sex and hemorrhage at presentation were prevalent. The average follow-up was 81.2 ± 45 months. The anterior circulation was involved in 76.8% of GIAs. If the GIA showed a clear neck, minimal atherosclerosis, or intrasaccular thrombosis, and ≤2 branches arising from the neck, it was reconstructed. This procedure was possible in 78% of cases. The technique also involved temporary clipping, remodeling, and thrombectomy, as well as fragmentation techniques. Angioarchitectural features other than these techniques underwent bypass and aneurysm trapping. Most bypasses were extracranial to intracranial and high flow. Flow capacity, collateral circulation, and availability of the donor vessel mainly affected the choice of the type of bypass. Overall, successful exclusion of the GIA was 91.4%. The need for retreatment and complication rate were 3.6% and 19.5%, respectively. A good overall outcome (modified Rankin Scale score 0-3) was achieved in 84.2% of patients, and mortality was 10%.

CONCLUSIONS

Microneurosurgical techniques still maintain a significant role for most GIAs, with a high durability and acceptable rate of morbidity and mortality. Clip reconstruction is the first-line surgical treatment option, whereas bypass is indicated in cases of planned or unplanned sacrifice of the parent artery to prevent long-term ischemic complications.