The Role of Bypass Surgery for the Management of Complex Intracranial Aneurysms in the Anterior Circulation in the Flow-Diverter Era: A Single-Center Series

Abstract

Despite the increasing popularity of flow diverters (FDs) as an endovascular option for intracranial aneurysms, the treatment of complex aneurysms still represents a challenge. Combined strategies using a flow-preservation bypass could be considered in selected cases. In this study, we retrospectively reviewed our series of patients with complex intracranial aneurysms submitted to bypass. From January 2015 to May 2022, 23 patients were selected. We identified 11 cases (47.8%) of MCA, 6 cases (26.1%) of ACA and 6 cases (26.1%) of ICA aneurysms. The mean maximal diameter was 22.73 ± 12.16 mm, 8 were considered as giant, 9 were fusiform, 8 presented intraluminal thrombosis, 10 presented wall calcification, and 18 involved major branches or perforating arteries. Twenty-five bypass procedures were performed in 23 patients (two EC-IC bypasses with radial artery graft, seventeen single- or double-barrel STA-MCA bypasses and six IC-IC bypasses in anterior cerebral arteries). The long-term bypass patency rate was 94.5%, and the total aneurysm exclusion was 95.6%, with a mean follow-up of 28 months. Median KPS values at last follow-up was 90, and a favorable outcome (KPS ≥ 70 and mRS ≤ 2) was obtained in 87% of the cases. The use of bypass techniques represents, in selected cases, a valid therapeutic option in the management of complex anterior circulation aneurysms when a simpler direct approach, including the use of FD, is considered not feasible.

Keywords: CEUS; ICG videoangiography; bypass; combined treatment; complex intracranial aneurysms; fluorescein.

Figure 1

Illustrative case of “Complex” aneurysms with only surgical treatment (bypass and trapping): (a) CT-angio showing M2 trifurcation aneurysm (arrow); (b) 3D reconstruction of aneurysm (arrow); (c) Intraoperative view of STA–MCA bypass (arrow); (d) Intraoperative view of aneurysm trapping; (e) Intraoperative SF-VA showing the patency of the bypass with an adequate parenchymal perfusion as detectable by the visualization of small cortical vessels; (f) FLOW800 analysis showing bypass patency (large arrow) and fronto-temporal branches perfusion (thin arrows); (g) Postoperative DSA showing aneurysm exclusion (arrow); (h,i) Postoperative DSA showing STA–MCA bypass patency in frontal and lateral view (arrow); (j) Follow-up Angio-MRI showing bypass patency; (k) NOVA MRI showing a good arterial flow.

Figure 2

Illustrative case of “Complex” aneurysms with multidisciplinary treatment (bypass for flow preservation due to MCA compression/stenosis and endovascular coiling): (a,b) Preoperative DSA showing in frontal and lateral view MCA stenosis (arrow) and ICA aneurysm (*); (c) Preoperative T2 MRI showing aneurysm partial thrombosis; (d) 3D reconstruction of ICA aneurysm and identification of a second ICA aneurysm; (e) Postoperative DSA showing STA–MCA bypass patency in lateral view; (f) Follow-up DSA showing hypertrophic bypass patency (thin arrow) and aneurysm endovascular occlusion (large arrow).

Figure 3

Illustrative case of “Complex” aneurysms with only surgical treatment (bypass and partial trapping because of subsequent aneurysm thrombotic occlusion): (a) CT-angio showing giant R ICA aneurysm (arrow); (b,c) 3D reconstruction of aneurysm (arrow); (d,e) Preoperative DSA showing R ICA aneurysm (arrow) in sagittal and coronal view; (f) Intraoperative view of STA–MCA bypass; (g,h) Intraoperative pre- and post-surgical clipping view of supraclinoid ICA (large arrow) and ophthalmic artery (thin arrow); (i–k) Intraoperative view of distal clipping (aneurysm = a); (l) Postoperative 3D reconstruction showing aneurysm trapping (circle) and bypass patency (arrow); (m,n) Postoperative DSA showing STA–MCA bypass patency in lateral view and aneurysm partial trapping with slow perfusion flow from PcommA; (o,p) Follow-up CT-angio showing bypass patency and aneurysm occlusion.

Figure 4

Illustrative case of “Complex” aneurysms with multidisciplinary treatment (bypass for flow preservation and endovascular proximal occlusion): (a,b) CT-angio showing large fusiform L ACA aneurysm (arrow); (c,d) Preoperative DSA showing L ACA aneurysm (arrow); (e,f) Intraoperative view of PerA–PerA latero-lateral bypass (arrow); (g,h) Intraoperative ICA–VA and FLOW800 analysis showing bypass patency with good perfusion (arrows); (i) Postoperative DSA showing endovascular aneurysm trapping with coiling; (j) Postoperative DSA showing PerA–PerA bypass patency with flow preservation; (k,l) Follow-up CT-angio showing bypass patency and aneurysm occlusion.