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.