Introduction: Spinal glomus arteriovenous malformations are rare lesions that are a considerable source of neurologic morbidity as a result of progressive neurologic deficits or hemorrhage.

Methods: We performed a meta-analysis via the PubMed database through March 2012. We included all studies with at least 3 cases allowing us to calculate an overall hemorrhage rate, risk factors for hemorrhage, and/or results of surgical or endovascular treatment. Hazard ratios were calculated using univariate and multivariate Cox proportional hazards regression models.

Results: Across 11 studies with 135 patients and 774.8 patient-years of follow-up prior to treatment, the overall annual hemorrhage rate was 7% (95% CI 1-21%), increasing to 24% (95% CI 4-80%) for AVMs with a prior history of hemorrhage (HR 12.6, p = 0.013). Lumbar location (HR 7.55, p = 0.016) and younger age (HR 1.05, p = 0.0001) were also significant risk factors for hemorrhage. AVMs with associated aneurysms demonstrated a trend toward a greater risk of hemorrhage (HR = 1.77, p = 0.086). We evaluated thirteen surgical series with 195 patients and sixteen endovascular series with 104 patients. The overall rates of complete obliteration were 73% (95% CI 57-94%) and 33% (95% CI 22-45%), respectively. Long term clinical worsening occurred in 9% of patients after surgical treatment (95% CI 0.6-15%) and in 8% of patients after endovascular treatment (95% CI 0.4-17%). No hemorrhages were reported after complete surgical or endovascular obliteration. After partial surgical treatment, the annual rate of hemorrhage was 1% (95% CI 0.4-3%); no hemorrhages were reported over 196 patient-years after partial endovascular treatment.

Conclusions: Spinal AVMs with prior hemorrhage, in a lumbar location, and in younger patients demonstrated a greater risk of hemorrhage. Complete and even partial surgical or endovascular treatment decreased their risk of hemorrhage.

Patient Care: We hope these results illustrate the potentially malevolent natural history for these lesions while identifying specific risk factors for spinal AVM hemorrhage. In addition, the illustration that partial embolization or surgery may prove beneficial may also improve patient care for challenging lesions that cannot be safely completely obliterated.

Learning Objectives: 1) Identify the annual rate of hemorrhage for spinal AVMs. 2) Identify risk factors for spinal AVM hemorrhage. 3) Note rates of obliteration and long term outcomes after surgical and endovascular treatment. 4) Awareness of the potential protective effect against hemorrhage of partial surgical or endovascular treatment.

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