Outcomes of Microsurgical, Endovascular, Multimodal, and Radiosurgical Management of Spinal Intramedullary Arteriovenous Malformations: A Systematic Review and Exploratory Meta-Analysis.

INTRODUCTION: Spinal intramedullary arteriovenous malformations (Si-AVMs) are rare lesions determined by angioarchitecture, location, clinical presentation, and procedural intent, making comparisons between modalities vulnerable to confounding by indication. RESEARCH QUESTION: To characterize radiographic, functional, and safety outcomes after microsurgical, endovascular, combined, and radiosurgical management of Takai Type II/III Si-AVMs while distinguishing complete treatment, planned partial embolization, residual disease, recanalization, and multimodality care. MATERIALS AND METHODS: A PRISMA-guided systematic review and exploratory meta-analysis of studies published from 2000 to 2024 included seven retrospective studies comprising up to 672 Type II/III or nidus-type lesions. Treatment pathways and embolization intent were analyzed separately. Combined-treatment patients were retained as a distinct group unless outcomes were disaggregated. Because outcome definitions were heterogeneous, pooled estimates were considered descriptive and hypothesis-generating. RESULTS: Microsurgical series generally reported higher complete angiographic obliteration than embolization-only series; however, lesion selection and planned multimodality treatment precluded causal comparison. In the largest cohort, 68/258 (26.4%) embolization-only patients achieved complete obliteration. Recanalization occurred in 15/30 (50.0%) lesions initially considered completely obliterated and in 73/219 (33.3%) embolized lesions. After partial embolization, lesion proliferation and de novo aneurysm formation each occurred in 22/191 (11.5%) patients. Permanent neurological deterioration occurred more often after microsurgery than embolization (16.1% vs. 5.6%). DISCUSSION AND CONCLUSION: The available evidence supports lesion-specific, complementary use of microsurgery, embolization, combined treatment, and radiosurgery rather than modality-wide superiority. Microsurgery may provide durable obliteration in selected lesions, whereas embolization may be curative, staged, neoadjuvant, or palliative. Radiosurgery remains a niche option for selected, inaccessible lesions. All conclusions are hypothesis-generating.