Background: Although initially considered safe when covering bifurcation sites, flow-diverting stents may provoke thrombosis of side branches that are covered during aneurysm treatment.
Objective: To understand the occurrence and clinical expression of side-branch remodeling in distal intracranial arterial sites after flow diverter (FD) deployment by means of correlation of imaging and clinical data.
Methods: We analyzed our prospectively collected data on a series of patients treated with FDs for intracranial aneurysms at bifurcation sites. From February 2011 to May 2013, 32 patients with 37 aneurysms [Acom: 9 (24.3%), ACA: 5 (13.5%), MCA: 19 (51.4%), Terminal ICA: 4 (10.8%)] were treated. We divided aneurysms into two groups, based on the side branches covered by the stent during treatment. Group A consisted of cases with side branches that supplied brain territories also receiving a direct collateral supply. Group B consisted of cases in which side branches supplied territories without direct collateral supply. The two groups were statistically compared.
Results: Total exclusion occurred in 97.3% of aneurysms at follow-up. Initial mRS was 0-1 for 29 patients (90.6%) and mRS 2 in 3 patients (9.4%). New permanent neurologic deficit was reported in 3 (9.4%) patients. At 6-month follow-up, mRS was 0-1 for 31 patients (96.8%) and mRS 3 for 1 patient (3.2%). Although 78.5% of side branches in group A underwent narrowing or occlusion after 6 months, no new stroke was found on MRI.
Conclusion: Symptomatic modifications of side branches after FD treatment depend on the extent and type of collateral supply.
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