The surgical strategy and technical nuances of in situ side-to-side bypass for the management of complex intracranial aneurysms

Background

Despite continuous advances in microsurgical and endovascular techniques, the treatment of complex aneurysms remains challenging. Aneurysms that are dilemmatic for conventional clipping or endovascular coiling often require bypass as part of a strategy to reduce the risk of ischemic complications. In anatomically favorable sites, the intracranial-intracranial in situ bypass may be an appealing choice. This article details the surgical strategies, operative nuances, and clinical outcomes of this technique with a consecutive series in our department.

Methods

A retrospective review of a prospectively maintained neurosurgical patient database was performed to identify all patients treated with side-to-side in situ bypass from January 2016 to June 2022. In total, 12 consecutive patients, including 12 aneurysms, were identified and included in the series. The medical records, surgical videos, neuroimaging studies, and follow-up clinic notes were reviewed for every patient.

Results

Of the 12 aneurysms, there were 5 middle cerebral artery aneurysms, 4 anterior cerebral artery aneurysms, and 3 posterior inferior cerebellar artery aneurysms. The morphology of the aneurysms was fusiform in 8 patients and saccular in the remaining 4 patients. There were 3 patients presented with subarachnoid hemorrhage. The treatment modality was simple in situ bypass in 8 cases and in situ bypass combined with other modalities in 4 cases. Bypass patency was confirmed in all cases by intraoperative micro-doppler probe and (or) infrared indocyanine green (ICG) video angiography intraoperatively and with digital subtraction angiography (DSA) or computed tomography angiography (CTA) postoperatively. None of the patients developed a clinically manifested stroke due to the procedure though a callosomarginal artery was intentionally removed in one patient. The median follow-up period was 16.2 months (6-36). All patients had achieved improved or unchanged modified Rankin scale scores at the final follow-ups.

Conclusion

Cerebral revascularization technique remains an essential skill for the treatment of complex aneurysms. The in situ bypass is one of the most effective techniques to revascularize efferent territory when vital artery sacrifice or occlusion is unavoidable. The configuration of in situ bypass should be carefully tailored to each case, with consideration of variations in anatomy and pathology of the complex aneurysms.

In-situ Bypass Is Associated with Superior Infection-free Survival Compared to Extra-Anatomic Bypass for the Management of Secondary Aortic Graft Infections Without Enteric Involvement

OBJECTIVE

The optimal revascularization modality following complete resection of aortic graft infection (AGI) without enteric involvement remains unclear. The purpose of this investigation is to determine the revascularization approach associated with the lowest morbidity and mortality using real-world data in patients undergoing complete excision of AGI.

METHODS

A retrospective, multi-institutional study of AGI from 2002-2014 was performed using a standardized database. Baseline demographics, comorbidities, and perioperative variables were recorded. The primary outcome was infection-free survival. Descriptive statistics, Kaplan-Meier survival analysis, and univariate and multivariable analyses were performed.

RESULTS

241 patients at 34 institutions from 7 countries presented with AGI during the study period (median age 68 years; 75% male). The initial aortic procedures that resulted in AGI were 172 surgical grafts (71%) and 66 endografts (27%) and 3 unknown (2%). 172 (71%) of the patients underwent complete excision of infected aortic graft material followed by in situ (in-line) bypass (ISB), including antibiotic-treated prosthetic graft (35%), autogenous femoral vein (NAIS) (24%), and cryopreserved allograft (41%). 69 patients (29%) underwent extra-anatomic bypass (EAB). Overall median Kaplan-Meier (KM) estimated survival was 5.8 years. Perioperative mortality was 16%. When stratified by ISB versus EAB, there was a significant difference in KM estimated infection-free survival (2910 days, IQR 391, 3771 versus 180 days, IQR 27, 3750 days; p<0.001). There were otherwise no significant differences in presentation, comorbidities, nor perioperative variables. Multivariable Cox regression showed lower infection-free survival among patients with EAB (HR 2.4, 95% CI 1.6-3.6; p<0.001), polymicrobial infection (HR 2.2, 95% CI 1.4-3.5; p=0.001), MRSA infection (HR 1.7, 95% CI 1.1-2.7; p=0.02), as well as the protective effect of omental/muscle flap coverage (HR 0.59, 95% CI 0.37-0.92; p=0.02).

CONCLUSIONS

After complete resection of AGI, perioperative mortality is 16% and median overall survival is 5.8 years. EAB is associated with nearly a two-and-half fold higher re-infection/mortality compared to ISB. Omental and/or muscle flap coverage of the repair appear protective.