Flow diverter treatment for MCA M1 aneurysms: clinical outcomes and predictors of occlusion

Background The role of flow diverters (FDs) in middle cerebral artery (MCA) M1 aneurysms is not well established. We assessed their safety, efficacy, and predictors of incomplete occlusion. Methods Consecutive MCA M1 aneurysms treated with FDs (January 2022–May 2024) were retrospectively reviewed. Clinical, imaging, and procedural variables were analyzed for associations with ischemic complications and angiographic outcomes. Results Fifty-eight patients (mean age 57.5 years; 46.6% female) underwent treatment with Pipeline (56.9%), Tubridge (20.7%), Surpass Evolve (12.1%), or Lattice (10.3%) devices. Postprocedural cerebral ischemia occurred in 25.9% (15/58), significantly more often in ruptured versus unruptured aneurysms (26.7% vs. 2.3%, p = 0.013). Rupture independently predicted ischemia (OR 15.273, 95% CI 1.547–150.765; p = 0.020). At a median follow-up of 13 months, complete occlusion was achieved in 77.4% (41/53). Aneurysm wall enhancement on MRI independently predicted incomplete occlusion (OR 6.566, 95% CI 1.395–30.903; p = 0.017). Conclusion FDs may be an option for carefully selected MCA M1 aneurysms. Ruptured aneurysms are associated with a markedly higher risk of postoperative ischemic complications, and aneurysm wall enhancement on preoperative MRI independently predicts incomplete aneurysm occlusion after FDs treatment.