Purpose Intraprocedural rupture is a dangerous complication of endovascular treatment. Small ruptured, 3–4 mm aneurysms of the anterior communicating artery (AcoA) are at increased risk for re-rupture during endovascular occlusion. Given this risk, microsurgical management may confer improved outcomes.

Methods We performed a retrospective review of 409 AcoA aneurysms treated in 409 consecutive patients at Emory University over a 10-year period. Patient demographics, aneurysmal rupture, size, therapeutic approach (microsurgical or endovascular), patient outcomes, intraprocedural rupture and rerupture were reviewed. Aneurysm retreatments were noted, but excluded.

Results Rupture rates were examined by size for all patients and subgroups as well as dichotomized to evaluate for size ranges associated with increased rupture rates. The highest risk of rupture was noted in aneurysms <4 mm. Of 409 aneurysms, 110 (26.8%) were ≤4 mm. The intraprocedural rupture rate was 7.1% (29/409) for AcoA aneurysms of any size. There was an intraprocedural rupture rate of 6.7% (20/299) among AcoA aneurysms >4 mm compared to 8.2% (9/110) in <4 mm aneurysms. In aneurysms ≤4 mm, the endovascular procedural rupture rate was 12.5% (7/56), while the microsurgical rate was 3.7% (2/54), p=0.16. In the >4 mm aneurysms, the endovascular rupture rate was 2.7% (5/182) while the microsurgical rate was 12.8% (15/117), p=0.0013. There was no statistically significant difference in Modified Rankin Scores between ruptured or non-ruptured aneurysms of any size once Age, Hunt and Hess and modified Fisher Grades were included in the model. Rupture rates tended to be higher in the microsurgical cases (10% vs 5%; p=0.078) but not statistically significant. In small aneurysms, endovascular rupture rate was higher (12.5% vs 4%, p=0.16). In larger aneurysms, microsurgery tended to have higher ruptures (13% vs 3%, p=0.0013). However, despite the intra-procedural rupture, the dichotomized mRS did not demonstrate statistically significant differences between endovascular and microsurgical therapy overall (p=0.23), in aneurysms <4 mm (p=0.82), or >4 mm (p=0.37).

Conclusions Microsurgical treatment of small ACOM aneurysms ≤4 mm appears to confer a lower intraprocedural re-rupture rate than endovascular management, but may have a higher procedural rupture rate in larger aneurysms. In this retrospective data set, there was no statistically significant difference in outcomes irrespective of the treatment modality and aneurysm size. Aneurysms ≤4 mm trend toward having a higher rate of rupture with endovascular techniques, while aneurysms >4 mm tend to have a higher rate of intraprocedural rupture during microsurgery. However, despite the ruptures, there is no statistically significant difference in outcomes.