Unruptured middle cerebral artery bifurcation aneurysms: long-term outcomes of endovascular techniques from an 'endovascular-first' policy center

This study examines the long-term outcomes of different endovascular techniques for unruptured middle cerebral artery (MCA) bifurcation aneurysms at a center with an endovascular-first policy over a 13-year period.

We performed a retrospective analysis of endovascular treatment (EVT) for unruptured MCA bifurcation aneurysms at a tertiary neurocenter between 2008 and 2020, evaluating outcomes of different techniques and factors associated with aneurysm recurrence.

A total of 169 aneurysms in 139 patients were analyzed. Adequate occlusion was achieved in 90.5% (152/168) of cases, with 6% (10/168) requiring retreatment during a median follow-up of 29 months (IQR: 18-55). Procedure-related complications occurred in 11.5% (16/139) of patients, with permanent neurological deficits in 2.9% (4/139) and good long-term clinical outcomes in 91.4% (127/139). Stent-assisted coiling (SAC) resulted in a 97.6% (41/42) adequate occlusion rate, no retreatments and good clinical outcomes in 94.4% (34/36). Balloon-assisted coiling (BAC) and flow diversion (FD) were in small subsets (n = 13 & 5 respectively) achieving a 100% adequate occlusion rate and good clinical outcomes in 92.3% (12/13) and 100% (4/4) respectively. For Woven EndoBridge (WEB) and simple coiling, adequate occlusion rates were 86.4% (38/44) and 85.9% (55/64) respectively, with good clinical outcomes in 95% (38/40) and 84.8% (39/46).

EVT for unruptured MCA bifurcation aneurysms demonstrated high rates of occlusion and favorable clinical outcome with low rates of retreatment. SAC in particular was associated with excellent angiographic outcomes without increased complications. Further studies are needed to compare endovascular techniques and to evaluate modern EVT practice against surgical clipping.