Infratentorial brain arteriovenous malformations: natural history and long-term outcome-a propensity score matched analysis using nationwide multicenter prospective registry data.

[OBJECTIVES] This study evaluated the natural history of infratentorial brain arteriovenous malformations (AVMs) and compared long-term outcomes of intervention versus conservative management.

[MATERIALS AND METHODS] Infratentorial AVMs from the nationwide MATCH registry were analyzed. Propensity score matching was used to balance the baseline characteristics. The primary outcome was long-term hemorrhagic stroke or death, while secondary outcomes included obliteration rates and neurological status. Subgroup and sensitivity analyses were used to assess the robustness of the results.

[RESULT] Of 4286 AVMs, 523 (12.2%) were infratentorial. The pretreatment annual rupture rate was 7.05% per patient-year. Independent hemorrhage risk factors included flow-related aneurysms, single draining vein, and vein stenosis. After matching, 144 cases (72 per group) were analyzed with a median follow-up of 6.12 years. Post-intervention the annual rupture risk was 2.17% and obliteration rate was 72.22%. Intervention was linked to higher rates of hemorrhagic stroke or death and higher obliteration rates compared with conservative management, with no significant neurological status difference. Only embolization increased the risk of hemorrhage, while microsurgery and radiosurgery did not. Trends were consistent in subgroup analyses.

[CONCLUSION] Intervention for infratentorial AVMs may increase the risk of hemorrhagic stroke or death. Embolization therapy may pose long-term risks, and there is no evidence to suggest that surgical resection and stereotactic radiosurgery carry higher risks compared with conservative treatment.