Brain Bypass Surgery for Complex Middle Cerebral Artery Aneurysms: Evolving Techniques, Results, and Lessons Learned

In situ interposition bypass for complex intracranial aneurysms: A single-center experience and efficacy analysis

The purpose of this study was to investigate the application and efficacy analysis of in situ interposition bypass in complex intracranial aneurysms. This study retrospectively analyzed the clinical data of 21 patients with complex intracranial aneurysms treated with in situ interposition bypass grafting in the Department of Neurosurgery at Tianjin Huanhu Hospital from June 2015 to December 2022. The aneurysms were located in the middle cerebral artery in 16 cases, the anterior cerebral artery in 3 cases, the posterior cerebral artery in 1 case, and the posterior inferior cerebellar artery in 1 case. The interposition graft vessels were taken from the radial artery in 15 cases, the superficial temporal artery in 5 cases, and the occipital artery in 1 case. All patients underwent end-to-end anastomosis with in situ interposition bypass after aneurysm resection, including 13 cases of "I-shaped" type, 5 cases of "V-shaped" type, and 3 cases of "Y-shaped" type. Postoperative digital subtraction angiography (DSA) or computed tomography angiography (CTA) reviews were performed for all the patients, and modified Rankin Scale (mRS) score was used to assess patient prognosis. Three patients developed postoperative basal ganglia infarction and two of them recovered well. One case developed transient incomplete aphasia and one case developed mild hemiparesis, which recovered well after 3 months. The remaining 16 patients did not develop new neurological deficits. Postoperative DSA or CTA showed that the anastomosis of the bypass graft and the graft vessels were patent, and all aneurysms were completely eliminated. Regular postoperative follow-up ranged from 3 to 89 months, and no aneurysm recurred. The percentage of patients with mRS ≤ 2 at the final follow-up was 90.5%. Based on the experience of surgical treatment in our center, in situ interposition bypass technique is a safe and effective option for the treatment of some complex intracranial aneurysms.

Dome Resection and End-to-End Reanastomosis for a Middle Cerebral Artery Fusiform Aneurysm of the M1 Segment: 2-Dimensional Operative Video

Fusiform aneurysms of the middle cerebral artery (MCA) are both relatively uncommon and challenging to treat given their pathophysiology, morphology, and anatomy (e.g., perforating arteries involvement).1,2 Endovascular treatment of fusiform MCA aneurysms can achieve good outcomes in well-selected cases.3,4 Open microsurgical strategies are effective in a case of fusiform MCA aneurysms with complex anatomy or perforator involvement.2,5,6 We demonstrate the bypass strategy for resection of a fusiform M1 MCA aneurysm (Video 1). A 48-year-old female was referred for the treatment of a growing incidental right M1 MCA fusiform aneurysm. Imaging showed a tortuous M1 segment with no apparent perforator involvement, which we considered a candidate for resection and reanastomosis. A modified minipterional transsylvian approach was performed as described earlier.7,8 A double superficial temporal artery to middle cerebral artery bypass was performed to maintain flow to MCA territory and distal perforators in anticipation of a long temporary flow arrest due to complex aneurysmal dissection and reanastomosis and also to serve as long-term protective insurance. Resection and end-to-end reanastomosis will preserve the antegrade flow and prevent the risk stump thrombosis carried by a simple trapping.9,10 We cover the nuances of this technique including key steps to an efficient aneurysmal resection and complication avoidance. The patient tolerated the procedure well, and postoperative imaging showed no aneurysmal remnant and flow restoration with no evidence of stroke. We discharged the patient home with a modified Rankin scale of 0. The patient consented to the procedure and publication of his or her image.

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.

Extracranial-intracranial bypass surgery for intracranial aneurysm of the anterior cerebral circulation: A systematic review and meta-analysis

Background

The safety of extracranial–intracranial (EC–IC) bypass in the management of anterior circulation intracranial aneurysms (IAs) remains to be determined. This systematic review aims to summarize the existing evidence and provide guidance for the precise management of IAs.

Data source

We constructed search strategies and comprehensively searched Pubmed, Medline, Embase, Web of science, and Cochrane library.

Methods

This systematic review was actualized according to the PRISMA statement. We evaluated study quality using the methodological index for non-randomized study (MINORS). Effect sizes were pooled using a random-effects model. Heterogeneity between studies was assessed using the I2 test. Publication bias was assessed using the Egger's test. The registration number for this systematic review is CRD42023396730.

Result

This systematic review included a total of 21 articles, involving 915 patients. Postoperative bypass patency rate was 99% (95% CI 0.98–1.00); short-term follow-up was 98% (95% CI 0.94–1.00); long-term follow-up was 95% (95% CI 0.93–0.97). The long-term follow-up occlusion rate of saphenous vein was higher than that of radial artery (OR 6.10 95% CI 1.04–35.59). Short-term surgery-related mortality was 0.3% (95% CI 0.000–0.012); long-term follow-up was 0.4% (95% CI 0.000–0.013); The proportion of patients with a score of 0–2 on the modified Rankin Scale (mRS) during long-term follow-up was 92% (95% CI 0.86–0.98). The incidence rates of long-term follow-up complications were: ischemic 3% (95% CI 0.01–0.06); hemorrhagic 1% (95% CI 0.00–0.03); neurological deficit 1% (95% CI 0.00–0.03); other 3% (95% CI 0.01–0.06).

Limitation

Most of the included studies were retrospective studies. Studies reporting preoperative status were not sufficient to demonstrate postoperative improvement. Lack of sufficient subgroup information such as aneurysm rupture status.

Conclusion

EC–IC therapy for anterior circulation IAs has a high safety profile. Higher level of evidence is still needed to support clinical decision.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023396730, identifier: CRD42023396730.

Cerebral revascularization for complex middle cerebral artery aneurysms: surgical strategies and outcomes in a single center

Cerebral revascularization is the ultimate treatment for a subset of complex middle cerebral artery (MCA) aneurysms. The decision for the revascularization strategy should be made during the treatment process. This study aimed to summarize the revascularization strategies for different types of complex MCA aneurysms and their outcomes. The clinical data of patients with complex MCA aneurysms who underwent cerebral revascularization since 2015 were analyzed retrospectively. The aneurysms were classified according to the location and other main characteristics that affect the selection of surgical modalities. The corresponding surgical modalities and treatment outcomes were summarized. A total of 29 patients with 29 complex MCA aneurysms were treated with cerebral revascularization from 2015 to 2022. Treated aneurysms were located at the prebifurcation segment in 7 patients, bifurcation segment in 12 patients, and postbifurcation segment in 10 patients. Surgical modalities in the prebifurcation segment included four high-flow extracranial-to-intracranial (EC-IC) bypasses with aneurysm trapping or proximal occlusion, two IC-IC bypasses with aneurysm excision, and one combination bypass with aneurysm excision. In the bifurcation segment, surgical modalities included two low-flow EC-IC bypasses with aneurysm excision or trapping, six IC-IC bypasses with aneurysm excision, three combination bypasses with aneurysm excision, and one constructive clipping with IC-IC bypass. In the postbifurcation segment, surgical modalities included nine IC-IC bypasses with aneurysm excision and low-flow EC-IC bypass with aneurysm trapping. The revascularization strategy for prebifurcation aneurysms was determined based on the involvement of lenticulostriate arteries, whereas the strategy for bifurcation aneurysms was determined based on the number of distal bifurcations and the shape of the aneurysm. The location of the aneurysm determined the revascularization strategy for aneurysms in the postbifurcation segments. Angiography demonstrated that aneurysms were completely obliterated in 26 cases and shrank in 3 cases, and all bypasses except one were patent. The mean follow-up period was 47.5 months. Three patients developed hemiplegic paralysis, and one developed transient aphasia postoperatively due to cerebral ischemia. No new neurological dysfunction occurred in the other 25 patients with no recurrence or enlargement of aneurysms during the follow-up. Prebifurcation aneurysms involving the lenticulostriate arteries require proximal occlusion with high-flow bypass. Most of the other aneurysms can be safely excised or trapped by appropriate revascularization strategies according to their location and orientation.

Interposition Intracranial-Intracranial Bypass Based on Anterior Cerebral Artery A1 Donor Anastomosis: Technical Advances, Outcomes, and Literature Review

BACKGROUND

The bypass technique is important for treating complex intracranial aneurysms and is infrequently performed. Intracranial-intracranial (IC-IC) bypass has shown many advantages in recent years.

OBJECTIVE

To review the techniques and outcomes of bypass based on anterior cerebral artery (ACA) A1 donor anastomosis in patients with intracranial aneurysm.

METHODS

We retrospectively reviewed the clinical and imaging data, surgical strategy, and follow-up outcomes of 7 patients treated from 2019 to 2022. Neurological function was assessed by the modified Rankin Scale (mRS). A literature review was performed using PubMed.

RESULTS

All 7 patients (3 male patients and 4 female patients; mean age, 50.4 ± 15.5 years) underwent aneurysm trapping or clipping using interposition IC-IC bypass based on ACA-A1 donor anastomosis. There were 6 middle cerebral artery (MCA) aneurysms and 1 posterior cerebral aneurysm in the series. One IC-IC bypass failed and was changed to extracranial-intracranial bypass. Three patients with MCA M1 aneurysm showed perforator-related infarction after the operation. The modified Rankin Scale score was 0 in 4 patients, 2 in 2 patients, and 1 in 1 patient. The long-term graft patency rate was 100%.

CONCLUSION

Interposition IC-IC bypass based on ACA-A1 donor anastomosis provides an effective way to achieve blood flow reconstruction in the treatment of complex aneurysms. This technique provides better caliber and volume compatibility and diminishes neck incision. Perforator-related infarction was the main complication because of involvement of the MCA M1 aneurysm location. Proximal clipping is preferred to avoid perforator-related infarction.

Surgical Anatomy of the Middle Communicating Artery and Guidelines for Predicting the Feasibility of M2-M2 End-to-End Reimplantation

BACKGROUND

M2-M2 end-to-end reimplantation that creates a middle communicating artery has recently been proposed as a reconstruction technique to treat complex aneurysms of the middle cerebral artery that are not amenable to clipping.

OBJECTIVE

To examine the surgical anatomy, define anatomic variables, and explore the feasibility of this bypass.

METHODS

Sixteen cadaver heads were prepared for bypass simulation. After the middle cerebral artery bifurcation was approached, the proximal insular (M2) segments and perforators were explored. To define the maximal distance between the M2 segments that allows the bypass to be performed, the M2 segments were mobilized and reimplanted in an end-to-end fashion.

RESULTS

Successful reimplantation was performed in all specimens. The mean maximal distance between the M2 segments to create the proposed reimplantation was 9.1 ± 3.2 mm. The mean vessel displacement was significantly greater for the superior (6.0 ± 2.3 mm) M2 segment than for the inferior (3.2 ± 1.4 mm) M2 segment (P < .001).

CONCLUSION

In this cadaveric study, the stumps of the M2 segments located at a distance of ≤9.1 mm could be approximated to create a feasible M2-M2 end-to-end anastomosis. Intraoperative inspection of the M2 segments and their perforators could allow further assessment of the feasibility of the procedure before final revascularization decisions are made.

Giant Aneurysm Management

The treatment of giant aneurysms has always been a challenge in the field of neurovascular disease. Giant aneurysms are larger in size and are associated with thrombosis development and the calcification of the aneurysmal wall and neck, which often interfere with direct clipping. Most giant aneurysms have a wide neck with an incomplete thrombus, making complete embolization almost impossible. Giant aneurysms of different sites have entirely different hemodynamic characteristics. Moreover, aneurysms at the same site may exhibit very different hemodynamics among different individuals. Therefore, careful assessment of each case is required before and during treatment to develop and carry out an individualized treatment plan.

Giant Middle Cerebral Artery Aneurysms: A 55-Patient Series

BACKGROUND

The treatment of middle cerebral artery (MCA) giant aneurysms (GAs) represents a challenging task.

METHODS

The data for 55 patients treated for MCA GA (≥25 mm) at the N.N. Burdenko NMRCN between 2010 and 2019 were analyZed.

RESULTS

The GAs were located in the M1 segment in 11 (20%) patients, MCA bifurcation in 33 (60%), M2 in 7 (12.7%), and M3 in 4 (7.3%). There were 32 (58.2%) saccular and 23 (41.8%) fusiform GAs. MCA GAs were treated with neck clipping (50.9%), clipping with the artery lumen formation (3.6%), bypass surgeries (34.5%), wrapping (3.6%), and endovascular surgery (7.3%). A worsening of the neurologic state in the perioperative period was observed in 50.9% of patients. The complete closure of GA was achieved in 78.2%. Surgery-related mortality was 1.8%. The long-term outcome was favorable in 76.9% of patients. Surgery-related and disease-related plus treatment failures-related mortality was 9.6%.

CONCLUSIONS

Microsurgical clipping and bypass surgery are the main operative interventions for MCA GA treatment. These operations are technically complex and are followed by a relatively high percentage of complications. The main tasks that require further investigations are the introduction of new precise diagnostic methods for the collateral circulation assessment in the cortical MCA branches, the perfection of the algorithm for the bypass selection, and investigation of the long-term results of the endovascular and combined treatments. It is of major importance to thoroughly observe the patients long-term after the surgery and ensure the possibility for further angiographic studies.

Microsurgical Clipping and Bypass for Fusiform Middle Cerebral Artery Aneurysm: 2-Dimensional Operative Video

Fusiform middle cerebral artery (MCA) aneurysms that require treatment can often necessitate complex endovascular or microsurgical treatment. We present a case of a 25-yr-old female with an incidentally discovered left 14-mm fusiform MCA aneurysm incorporating the frontal MCA trunk origin in its dome. The location and anatomy were not favorable for endovascular treatment with flow diversion.  The patient was offered continued observation or microsurgical treatment. Direct clipping of this aneurysm was not possible. After a thorough discussion of the risks, benefits, indications, and natural history of the lesion, the patient desired to have the aneurysm treated given her young age, location, size of the aneurysm, and the significant clinical experience of the treating team in bypass surgery.  The patient underwent superficial temporal artery to frontal M2 (STA-FM2) direct bypass for flow replacement followed by microsurgical trapping and clip ligation. The patient was maintained on antiplatelet therapy preoperatively and postoperatively. The patient had a transient aphasia and mild right upper extremity weakness (4/5) in the immediate postoperative period, which fully recovered by the time of patient discharge. The case presentation, surgical anatomy, technique, and postoperative course and outcome are reviewed. The different strategies for bypass and clip ligation are reviewed with particular focus on the anatomic constraints for each bypass configuration. The outcomes of bypass surgery for MCA aneurysms are reviewed.1-7 The patient gave verbal consent for participating in the procedure, surgical video, and publication of their image.

Coding cerebral bypasses: a proposed nomenclature to better describe bypass constructs and revascularization techniques

OBJECTIVE

Bypass surgery has evolved into a complex surgical art with a variety of donor arteries, recipient arteries, interpositional grafts, anastomoses, and suturing techniques. Although innovation in contemporary bypasses has increased, the literal descriptions of these new bypasses have not kept pace. The existing nomenclature that joins donor and recipient arteries with a hyphen is simplistic, underinformative, and in need of improvement. This article proposes a nomenclature that systematically incorporates anatomical and technical details with alphanumeric abbreviations and is a clear, concise, and practical "code" for bypass surgery.

METHODS

Detailed descriptions and illustrations of the proposed nomenclature, which consists of abbreviations for donor and recipient arteries, arterial segments, arteriotomies, and sides (left or right), with hyphens and parentheses to denote the arteriotomies joined in the anastomosis and brackets and other symbols for combination bypasses, are presented. The literature was searched for articles describing bypasses, and descriptive nomenclature was categorized as donor and recipient arteries (donor-recipient), donor-recipient with additional details, less detail than donor-recipient, and complete, ambiguous, or descriptive text.

RESULTS

In 483 publications, most bypass descriptions were categorized as donor-recipient (335, 69%), with superficial temporal artery-middle cerebral artery bypass described most frequently (299, 62%). Ninety-seven articles (20%) used donor-recipient descriptions with additional details, 45 (9%) were categorized as ambiguous, and none contained a complete bypass description. The authors found the proposed nomenclature to be easily applicable to the more complex bypasses reported in the literature.

CONCLUSIONS

The authors propose a comprehensive nomenclature based on segmental anatomy and additional anastomotic details that allows bypasses to be coded simply, succinctly, and accurately. This alphanumeric shorthand allows greater precision in describing bypasses and clarifying technical details, which may improve reporting in the literature and thus help to advance the field of bypass surgery.

Controversies and Advances in Adult Intracranial Bypass Surgery in 2020

Cerebral revascularization utilizing a variety of bypass techniques can provide either flow augmentation or flow replacement in the treatment of a range of intracranial pathologies, including moyamoya disease, intracranial atherosclerotic disease, and complex aneurysms that are not amenable to endovascular or simple surgical techniques. Though once routine, the publication of high-quality prospective evidence, along with the development of flow-diverting stents, has limited the indications for extracranial-to-intracranial (EC-IC) bypass. Nevertheless, advances in imaging, assessment of cerebral hemodynamics, and surgical technique have changed the risk-benefit calculus for EC-IC bypass. New variations of revascularization surgery involving multiple anastomoses, flow preserving solutions, IC-IC constructs, and posterior circulation bypasses have been pioneered for otherwise difficult to treat pathology including giant aneurysms, dolichoectasia, and medically refractory intracranial atherosclerosis. This review provides a practical update on recent advances in adult intracranial bypass surgery.

Perioperative Management of Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage is an acute neurologic emergency. Prompt definitive treatment of the aneurysm by craniotomy and clipping or endovascular intervention with coils and/or stents is needed to prevent rebleeding. Extracranial manifestations of aneurysmal subarachnoid hemorrhage include cardiac dysfunction, neurogenic pulmonary edema, fluid and electrolyte imbalances, and hyperglycemia. Data on the impact of anesthesia on long-term neurologic outcomes of aneurysmal subarachnoid hemorrhage do not exist. Perioperative management should therefore focus on optimizing systemic physiology, facilitating timely definitive treatment, and selecting an anesthetic technique based on patient characteristics, severity of aneurysmal subarachnoid hemorrhage, and the planned intervention and monitoring. Anesthesiologists should be familiar with evoked potential monitoring, electroencephalographic burst suppression, temporary clipping, management of external ventricular drains, adenosine-induced cardiac standstill, and rapid ventricular pacing to effectively care for these patients.

Natural Y-shaped radial artery graft bypass for a complex middle cerebral artery aneurysm: A case report

Giant thrombosed middle cerebral artery (MCA) aneurysms are difficult to treat and sometimes require complex revascularization using allografts. We describe a technical method using revascularization with a natural Y-shaped graft that provides a normal variation for a complex MCA aneurysm. A 65-year-old man with a giant thrombosed MCA aneurysm presented with right hemiparesis and aphasia. The patient had a history of clipping surgery for the ipsilateral side of the MCA aneurysm 25 years before, and a de novo aneurysm developed over the previous 18 years. For the giant thrombosed aneurysm, trapping and revascularization were performed. A natural radial artery Y-graft was used as the graft and anastomosed to both M2 trunks. The symptoms improved after surgery, and the patient was discharged 3 weeks later. This is the first report of a double-barrel bypass using a natural Y-graft. This method attained a normal variation, and the flow of the Y-graft was physiological. For the radical cure of giant thrombosed MCA aneurysms, multiple revascularizations might be required. With this natural Y-graft, complex transpositions could be avoided.

Three-Vessel Anastomosis for Direct Bihemispheric Cerebral Revascularization

BACKGROUND

In rare, complex cerebrovascular pathologies, patients may benefit from simultaneous revascularization of multiple arterial territories. Traditional strategies for these situations include the use of more than 1 interposition graft, multiple microvascular anastomoses, vessel reimplantations, and staged procedures.

OBJECTIVE

To improve upon traditional revascularization strategies by describing a novel 3-vessel microvascular anastomosis. This technique combines a side-to-side and an end-to-side anastomoses to facilitate simultaneous direct revascularization of 2 arterial territories in a single procedure, with a single donor vessel.

METHODS

We present an illustrative case of moyamoya angiopathy in which a 3-vessel anastomosis was performed in the interhemispheric fissure to simultaneously directly revascularize bilateral anterior cerebral artery (ACA) territories. A detailed step-by-step depiction of the anastomosis technique is provided. In the presented case, 3-vessel anastomosis was combined with a radial artery fascial flow-through free flap, allowing for an additional indirect revascularization.

RESULTS

Technical execution of the 3-vessel anastomosis was uncomplicated. The patency of the anastomosis providing direct bilateral ACA territory revascularization was demonstrated intra- and postoperatively.

CONCLUSION

With this report, we demonstrate technical feasibility of a novel 3-vessel anastomosis for direct 2 arterial territory revascularization This single-stage approach combines side-to-side and end-to-side techniques and has benefits over traditional revascularization techniques, as it is not deconstructive, requires only a single craniotomy and a single interposition graft, and does not require lengthy recipient artery dissection.