Middle Cerebral Artery Bifurcation Aneurysms Treated by Extrasaccular Flow Diverters: Midterm Angiographic Evolution and Clinical Outcome

BACKGROUND AND PURPOSE:Flow diverters have been increasingly used lately in off-label, distal intracranial aneurysm treatments. Our aim was to evaluate the effectiveness of flow diverters in the treatment of middle cerebral artery bifurcation aneurysms and to analyze midterm angiographic patterns of regional flow modifications for safety and clinical outcomes.MATERIALS AND METHODS:Consecutive patients treated from January 2010 to December 2014 by the authors by using endovascular flow-diverting stents for MCA bifurcation aneurysms were evaluated retrospectively with prospectively maintained data. All patients had been followed for at least 12 months after treatment, with at least 2 control angiograms; regional flow-related angiographic modifications were registered by using a new angiographic outcome scale for flow diverters. Data were analyzed with emphasis on procedure-related events, angiographic results, and clinical outcome.RESULTS:Fifty-eight patients were included in the study, with 63 MCA bifurcation aneurysms; 13 of these were large and giant. Pretreatment mRS was 0 for 12 patients (20.7%), 1 for 41 (70.7%), and 2 for 5 patients (8.6%). Six-month control revealed mRS 0–2 for 57 (98.3%) patients and 3 for 1 (1.7%) patient. Procedure-related morbidity and mortality were 8.6% (5/58) and 0%, respectively. From 95% of still circulating immediate postprocedure angiographic outcomes, 68% progressed to aneurysm occlusion at 6 months and 95%, to occlusion at 12 months, with a 0% aneurysm rupture rate.CONCLUSIONS:Flow diverters seem to be an effective treatment alternative for complex MCA bifurcation aneurysms, with reasonable complication rates. Longer angiographic follow-ups are needed to assess the morphologic outcome; immediate subtotal occlusions do not seem to be related to rupture.

Flow-diverter (FD) stents have provided a paradigm shift in endovascular cerebral aneurysm treatment. Initially approved for carotid aneurysms, their use has been extended to include distal intracranial localizations such as MCA aneurysms.¹ Covering intracranial arteries with FDs has recently been the subject of debate. While for localizations such as the posterior communicating artery,² side branch coverage does not seem to have clinical consequences for patients, controversy exists regarding MCA branches.The objectives of our study were to evaluate the clinical and midterm angiographic outcomes of FD stent placement for MCA bifurcation aneurysms with emphasis on the regional flow-induced modifications and their impact; the analysis was performed by using an angiographic classification³ that takes into account the hemodynamic evolution of the aneurysm and the regional anatomy with time.