Anterior Cerebral Artery Bypass for Complex Aneurysms: Advances in Intracranial-Intracranial Bypass Techniques

A novel intraoperative "Faucet" technique for assessing patency of superficial temporal artery to middle cerebral artery bypass and for prevention of microemboli

PURPOSE

This technical note introduces the novel faucet technique, which enables neurosurgeons to evaluate the patency of a bypass during superficial temporal artery-middle cerebral artery bypass surgery. The technique is particularly useful when there is a lack of equipment such as micro-Doppler or indocyanine green in the operating rooms. This is often the case in Central Asian countries.

METHODS

The faucet technique involves carefully examining the graft by gently opening a valve, comparable to a faucet, to observe the blood flow through the bypassed vessel. Overall, 36 procedures underwent the faucet technique for assessing the superficial temporal artery-middle cerebral artery bypass patency.

RESULTS

The results indicate that the bypass remained patent in all cases, as confirmed through the intraoperative faucet technique, postoperative magnetic resonance angiography, or cerebral angiography.

CONCLUSION

By visually inspecting the blood flow through the faucet technique, surgeons can confirm the effectiveness of the graft and ensure that the bypass remains unobstructed during the surgery.

A Unique and Effective Bypass Technique to Treat Partially Thrombosed Giant Distal Anterior Cerebral Artery Aneurysms in Extremely Narrow Surgical Corridors

BACKGROUND

Surgical treatment of large or giant thrombosed anterior cerebral artery (ACA) aneurysms often involves revascularization. Herein, we describe a unique and effective bypass technique to treat partially thrombosed giant distal ACA aneurysms in extremely narrow surgical corridors.

METHODS

A 68-year-old man underwent aneurysm trapping and ACA revascularization for a partially thrombosed giant ACA aneurysm in a surgical corridor that was narrow due to anatomic factors. By combining a side-to-side anastomosis and an end-to-side anastomosis at a single anastomotic site, we successfully redirected blood flow from the left pericallosal artery to the right pericallosal and callosomarginal arteries.

RESULTS

Postoperatively, cerebral angiography showed that the blood flow in the aneurysm had disappeared, and the bypass remained open. The patient's functional disability gradually improved, and he reported consistently positive outcomes at the 6-month postoperative follow-up examination.

CONCLUSIONS

This revascularization technique may represent an effective novel treatment option, particularly when multiple revascularization procedures are required within a narrow surgical field.

Total removal of anaplastic meningioma infiltrating an artery by performing an A3-A3 side-to-side anastomosis

Background

Meningiomas are histologically benign tumors and generally have a good prognosis. However, some are classified as high-grade meningiomas due to their strong invasion of surrounding tissues and high postoperative recurrence rates, resulting in a poor prognosis. Postoperative radiotherapy is often administered for the most malignant anaplastic meningiomas; however, its contribution to improving prognosis and reducing recurrence rates in patients with residual tumors is limited.

Case Description

We present here a 48-year-old man with an anaplastic meningioma that recurred repeatedly and had invaded the right anterior cerebral artery (ACA) despite two postoperative radiotherapy sessions. Dissecting the tumor from the blood vessels was extremely difficult and would only have achieved a partial resection. However, we achieved complete resection by performing a pericallosal artery-pericallosal artery (A3-A3) side-to-side anastomosis and excising the infiltrated blood vessels along with the tumor en bloc. No neurological deficits or complications, such as cerebral infarction, were detected postoperatively.

Conclusion

Although reports of performing an A3-A3 side-to-side anastomosis to enable complete resection of tumors invading the ACA are extremely rare worldwide, this procedure should be recognized as a safe and effective treatment option when complete tumor resection is strongly desired, as in the present patient.

Angiographic and Clinical Outcomes of Various Techniques of Intracranial-to-Intracranial Bypass for Complex Cases with a Review of Pertinent Literature and Illustrated Cases

BACKGROUND

We sought to determine the utility of intracranial-to-intracranial bypass (IIB) surgery and the available bypass options for complex cases.

METHODS

A total of 18 IIB cases were included. Each case was classified as IIB with or without an interposition graft. The clinical and angiographic status were evaluated pre- and postoperatively and at the last follow-up. Angiographic images were analyzed and reconstructed schematically. Postoperative angiography was used to measure the bypass patency and the presence of postoperative cerebral infarction. The recipient artery occlusion time for each bypass was measured.

RESULTS

Of the 18 patients, 14 had presented with a complex intracranial aneurysm (IA), 1 with vertebrobasilar dolichoectasia, and 3 with intracranial arterial steno-occlusive disease. Ten patients had an incidentally discovered IA. Seven patients had presented with neurological deficits due to ischemia or aneurysmal mass effects. Of the 18 cases, 10 were IIBs with an interposition graft, including 4 cases of superficial temporal artery and 6 of radial artery graft bypass, and 8 were IIBs with a noninterposition graft, including 3 cases of in situ bypass, 1 case of reanastomosis, and 4 cases of reimplantation. The pre- and postoperative modified Rankin scale score did not change or improve, and all the bypasses were patent. No patient had died during the mean follow-up period of 50.0 months. The mean occlusion time of the recipient artery was 59.5 minutes. A total of 8 patients experienced postoperative cerebral infarction but all had almost recovered at discharge.

CONCLUSIONS

With proper selection of the IIB type, IIB can be a suitable treatment option for some patients with complex IAs and intracranial arterial steno-occlusive disease when extracranial-to-intracranial bypass is not feasible.

Clinical and Technical Outcomes of Intracranial-Intracranial Bypass for Treating Complex Intracranial Aneurysms: An Analysis of 255 Patients

BACKGROUND

Despite the recent increase in publications centered on intracranial-intracranial (IC-IC) bypasses for complex aneurysms, there is no systematic evidence regarding their outcomes. The purpose was to assess the outcomes of patients subjected to IC-IC bypass for aneurysms.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis, a systematic review was conducted. Criteria for inclusion entailed studies with a cohort of at least 4 patients having undergone IC-IC bypass for aneurysms, detailing at least one outcome, such as patency, clinical outcomes, complications, and procedure-related mortality. When the study included patients who had undergone extracranial-intracranial (EC-IC) bypass, the authors extracted the patency and clinical data to juxtapose them with the results of IC-IC.

RESULTS

Of the 2509 shortlisted studies, 22 met our inclusion criteria, encompassing 255 patients and 263 IC-IC bypass procedures. The IC-IC bypass procedure exhibited a patency rate of 93% (95% confidence interval [CI]: 89%-95%). The patency rate of IC-IC and EC-IC bypasses did not significantly differ (odds ratio=0.60 [95% CI: 0.18-1.96]). Concerning clinical outcomes, 91% of the IC-IC patients had positive results (95% CI: 85%-97%), with no significant disparity between the IC-IC and EC-IC groups (odds ratio=1.29 [95% CI: 0.43-3.88]). After analysis, the complication rate was 11% (95% CI: 5%-18%). Procedure-related mortality was 1% (95% CI: 0%-4%).

CONCLUSIONS

IC-IC bypass is valuable for the treatment of complex intracranial aneurysms, boasting high patency and positive clinical outcomes. Complications are unusual, and procedure-related mortality is minimal. Comparing IC-IC and EC-IC led to no significant differences.

Intracranial-intracranial bypass strategies for the treatment of complex intracranial aneurysms: anatomical characteristics and surgical intervention

OBJECTIVE

The effectiveness of revascularization for complex aneurysms is well-established. This study aimed to describe the technical characteristics and clinical efficacy of intracranial-to-intracranial (IC-IC) bypass for the treatment of complex intracranial aneurysms.

METHODS

We retrospectively reviewed all patients with aneurysms who underwent a preplanned combination of surgical or endovascular treatment and IC-IC bypass at our institution between January 2006 and September 2023. IC-IC bypass techniques included four strategies: type A (end-to-end reanastomosis), type B (end-to-side reimplantation), type C (in situ side-to-side anastomosis), and type D (IC-IC bypass with a graft vessel).

RESULTS

During the study period, ten patients with aneurysms each underwent IC-IC bypass surgery. Aneurysms were located in the middle cerebral artery (60.0%), anterior temporal artery (10.0%), anterior cerebral artery (20.0%), and vertebral artery (10.0%). There were three saccular aneurysms (30.0%), two fusiform aneurysms (20.0%), one dissecting aneurysm (10.0%), and four pseudoaneurysms (40.0%). We performed the type A strategy on five patients (50.0%), type B on one (10.0%), type C on one (10.0%), and type D on three (30.0%). During a mean period of 68.3 months, good clinical outcomes (modified Rankin Scale score, 0-2) were observed in all patients. Follow-up angiography demonstrated complete aneurysmal obliteration in all patients and good bypass patency in nine of ten patients (90.0%).

CONCLUSION

The treatment of complex aneurysms remains a challenge with conventional surgical or endovascular treatments. IC-IC bypass surgery is a useful technique, associated with favorable clinical outcomes, for treating complex aneurysms.

Aneurysmoraphy or bypass? Surgical strategy for large M1 bifurcation aneurysm involving two branches based on vessel wall high-resolution MRI and intraoperative angiography

BACKGROUND

Middle cerebral artery (MCA) M1 bifurcation aneurysms are common because of hemodynamic. For regular-shaped and small aneurysms, direct clipping is optimal. Aneurysmoraphy or bypass blood flow reconstruction are most commonly used in large aneurysm clipping. Based on preoperative vessel wall high-resolution magnetic resonance imaging (VW-HRMRI) and intraoperative angiography, an appropriate surgery strategy could be decided.

METHOD

We report a case of large MCA M1 bifurcation aneurysm aneurysmoraphy according to preoperative VW-HRMRI. Intraoperative digital subtraction angiography (DSA) showed an aneurysm neck remnant, and we adjusted clips according to intraoperative DSA. This patient recovered well with a modified Rankin scale of 0 at discharge.

CONCLUSION

This case demonstrates that preoperative VWHRMRI could supply more aneurysm characteristics for direct aneurysmoraphy. Intraoperative DSA effectively reduces the possibility of aneurysm remnant.

The application of high-resolution vessel wall imaging in the in situ bypass surgeries for complex anterior cerebral artery aneurysms

OBJECTIVE

Complex anterior cerebral artery (ACA) aneurysms are still technically challenging to treat. Bypass surgery is needed to achieve aneurysm obliteration and ACA territory revascularization. Severe atherosclerosis of aneurysm walls can cause clip slippage, intraoperative rupture, postoperative ischemic events. How to assess the atherosclerotic changes in vascular walls by high-resolution vessel wall magnitude resonance imaging (VWI) is the key question in complex ACA aneurysm surgical management.

METHODS

This retrospective single-center study included eight patients diagnosed with complex anterior cerebral arteries admitted to our hospital for bypass surgery from January 2019 to April 2022. We discussed the application of VWI in aneurysms treated with in situ bypass and reviewed previous experience of revascularization strategies for complex ACA aneurysms.

RESULTS

In this study, we treated 8 cases of complex ACA aneurysms (3 communicating aneurysms/5 postcommunicating aneurysms) over the prior one year. In situ side-to-side anastomosis (1 A2-to-A2/6 A3-to-A3) was performed in seven cases, and trapping combined with excision was performed in another case. Following bypass, complete trapping was performed in 4 cases, and proximal clipping was performed in 3 cases. No surgery-related neurological dysfunctions were observed. The final modified Rankin scale was 0 in seven of the eight cases and 2 in one case.

CONCLUSION

High-resolution VWI, as a favorable preoperative assessment tool, provides insight into patient-specific anatomy and microsurgical options before operations, which can help neurosurgeons develop individualized and valuable surgical plans.

Reconstruction of both M2 blood flow with a "Y" fashion anastomosis after excision of a large M1 bifurcation aneurysm: advantages and challenges

BACKGROUND

Middle cerebral artery (MCA) M1 aneurysms with M2 branches originating from the aneurysm neck are difficult to treat because of blood flow reconstruction method selection, graft blood volume matching and various anastomoses.

METHOD

We report a case of MCA M1 bifurcation aneurysm resection and reconstruction of the bifurcation using "Y" fashion anastomosis. Intraoperative DSA showed anastomotic stoma patency. This patient suffered transient left temporal ischemia and recovered well with a modified Rankin scale of 0 at discharge.

CONCLUSION

This case demonstrates the application of "Y" fashion anastomosis after the excision of a large M1 bifurcation aneurysm. This bifurcation reconstruction method showed advantages and challenges in specific situations.

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 Treatment of Large and Giant Anterior Cerebral Artery Aneurysms in the Endovascular Era: Analysis of Large Clinical Series

OBJECTIVE

Analysis of results of surgical treatment of 112 patients with large and giant anterior cerebral artery (ACA) aneurysms.

METHODS

This is the largest clinical series of large and giant ACA aneurysms ever reported. Retrospective analysis of medical charts, radiographic studies, and intraoperative videos was performed. Univariate and multivariate analysis of relations among 3 types of outcomes (complete aneurysm occlusion, ischemic complications, and clinical outcomes) and predicting factors was performed.

RESULTS

Most aneurysms were communicant (84.8%). Aneurysms of the A1 segment and distal segments (A2-A5) were encountered rarely. Complete aneurysm occlusion (class I) was shown in 95 cases (90.5%). In 4 patients, only exploration and wrapping were performed because of severe atherosclerosis and chronic intraluminal thrombi. Partial occlusion (class III) was shown in 2 patients, and neck residual (class II) in 4 patients. Cerebral ischemia developed in 29 patients postoperatively. Occlusion or injury of the A1 segment and anterior communicating artery perforators and recurrent branch of Heubner were the most common reason for ischemic complications. At follow-up, 97 patients (86.6%) had favorable outcomes. Ten patients (8.9%) had unfavorable outcomes because of postoperative complications.

CONCLUSIONS

Microsurgery provides effective and relatively safe occlusion of complex ACA aneurysms. Direct clipping can be applied in most cases independent of their precise location. In certain cases, alternative methods can be safely used. According to multivariate analysis, giant aneurysm size, aneurysm-related mass effect, involvement of large arterial branches in the aneurysm wall, and intraoperative complications were significant predicting factors for ischemic complications.

Evolution of Intracranial-Intracranial Bypass Surgery: A Bibliometric Analysis

OBJECTIVE

Modern cerebrovascular bypass surgery uses either extracranial-intracranial (EC-IC) or intracranial-intracranial (IC-IC) approaches. Compared with EC-IC bypasses, IC-IC bypasses allow neurosurgeons to safely address tumors, aneurysms, and other lesions using shorter grafts that are well matched to the size of recipient vessels. Fewer than 100 articles have been published on IC-IC bypasses compared with more than 1000 on EC-IC bypasses. This study examined the increase of interest and innovation in IC-IC bypass.

METHODS

PubMed and Web of Science were searched using keywords specific to IC-IC bypass, yielding 717 articles supplemented with 36 reports from other databases and gray literature. The articles were reviewed, and 98 articles were selected for further evaluation. Final articles were categorized as innovations or retrospective studies. Publication metrics were passed through an analytic program to assess statistical measures of growth.

RESULTS

The number of publications describing innovations (n = 52) and retrospective studies (n = 46) in IC-IC surgical techniques increased exponentially (R2 = 0.983 and R2 = 0.993, respectively), with both interest and research in the field increasing. The rate of publications in each group also increased. In recent years, increasing numbers of global institutions have researched and published on IC-IC bypasses.

CONCLUSIONS

As more work is undertaken on IC-IC bypasses, it is critical for knowledge to be shared through research, collaboration, publication, and early teaching within residency training programs. This field has increased exponentially in the past 2 decades and has yet to reach an inflection point, indicating possible additional interest and growth over time.

Management of Complex Cerebral Aneurysms

BACKGROUND

Complex intracranial aneurysms (CIAs) are challenging pathologies to treat. Characteristics making an aneurysm complex include dimension, history of previous treatment, location, absence of collateral circulation, intraluminal thrombosis, and calcification of the wall. The goal of the therapeutic process is to exclude the malformation from the cerebral circulation and both endovascular and surgical treatments are valid procedures.

METHODS

Between 1990 and 2020, 170 CIAs were treated at our institution (33 ruptured, 137 unruptured). They were 3 prepetrous segment of the internal carotid artery (ICA), 14 purely intracavernous sinus, 27 intracavernous with subarachnoid extension, 60 paraclinoid, 4 ICA bifurcation, 15 anterior communicating artery, 24 middle cerebral artery, and 23 in the posterior circulation. All the patients underwent neuroradiologic examinations and images were evaluated by the neurosurgical and interventional radiologist team. Endovascular treatment was considered as the treatment of choice. Alternative treatment was surgical clipping; revascularization procedures were performed when neither endovascular treatment nor direct clipping were possible.

RESULTS

Of 170 patients, 45 underwent endovascular treatment, 77 surgical clipping, and 55 revascularization procedures. In the unruptured group, 12 patients died, 22 reported major complications, 3 had minor complications, and 101 had an uneventful postoperative course. In the ruptured group, 9 patients died, 10 had minor complications, 1 minor complication, and 13 had a complete recovery.

CONCLUSIONS

Endovascular treatment should represent the treatment of choice for CIAs. Alternative treatments include direct surgical clipping and revascularization. Overall, the correct identification of the therapeutic process guarantees a good clinical outcome.

Complex Intracranial Aneurysms

Complex intracranial aneurysms remain challenging to treat using standard microsurgical or endovascular techniques. These aneurysms often require a combination of deconstructive and reconstructive procedures, such as parent artery occlusion, flow alteration, and blind-alley formation with or without bypass surgery, for effective and enduring therapeutic effects. It is important to determine the type of bypass based on the site of occlusion of the patent artery, anatomical features of the distal vessels, and expected adequate blood flow. In this chapter, we describe the "Standards," "Advances," and "Controversies" in the context of a microsurgical treatment strategy for complex intracranial aneurysms. "Standards" include a combination of frequent and commonly used procedures that have been gathering a certain consensus on their effectiveness. "Advances" include infrequent, demanding, and/or uncertain surgical procedures that are currently under debate. Finally, "Controversies" discuss a number of unsolved issues.

Recovery of Visual Loss Following Internal Trapping of Anterior Cerebral Artery (A1 Segment) for Partially Thrombosed Large Anterior Communicating Artery Aneurysm: A Case Report

A 60-year-old woman, who experienced progressive right visual loss, was diagnosed with an unruptured large cerebral aneurysm. Magnetic resonance imaging (MRI) and angiography revealed a large partially thrombosed anterior communicating artery (Acom) aneurysm. The aneurysmal neck was located at the junction of the left A1–A2 segments, and the aneurysmal dome communicated with the right A1–A2 junction by the Acom. Endovascular treatment using the flow alteration technique was selected. Following an oral antiplatelet therapy for 9 days, balloon test occlusion (BTO) of the medial portion of the left A1 segment was performed under local anesthesia. After confirming the tolerance of the BTO, internal trapping of the medial portion of the left A1 segment by detachable coils was performed following intra-aneurysmal coil embolization. Oral antiplatelet treatment was continued for 19 days postoperatively. Within 3 months following the operation, her right visual acuity dramatically improved to the original level. Owing to aneurysmal recanalization and the disappearance of the thrombus, the second and third embolization was performed through the Acom route, 4 months and 3 years following the first embolization, respectively, and followed up for an additional 7 years by MRI; no deterioration of her visual acuity and no aneurysmal recanalization was observed. Thus, endosaccular embolization combined with flow alteration is considered a useful alternative treatment for large and partially thrombosed Acom aneurysms.

Revisiting the Morphology and Classification of the Paracingulate Gyrus with Commentaries on Ambiguous Cases

The anterior cingulate cortex is considered to play a crucial role in cognitive and affective regulation. However, this area shows a high degree of morphological interindividual variability and asymmetry. It is especially true regarding the paracingulate sulcus and paracingulate gyrus (PCG). Since the reports described in the literature are mainly based on imaging techniques, the goal of this study was to verify the classification of the PCG based on anatomical material. Special attention was given to ambiguous cases. The PCG was absent in 26.4% of specimens. The gyrus was classified as present in 28.3% of cases. The prominent type of the PCG was observed in 37.7% of the total. Occasionally, the gyrus was well-developed and roughly only a few millimeters were missing for classifying the gyrus as prominent, as it ended slightly anterior the level of the VAC. The remaining four cases involved two inconclusive types. We observed that the callosomarginal artery ran within the cingulate sulcus and provided branches that crossed the PCG. Based on Klingler’s dissection technique, we observed a close relationship of the PCG with the superior longitudinal fascicle. The awareness of the anatomical variability observed within the brain cortex is an essential starting point for in-depth research.