Object: Our understanding of spinal extradural arteriovenous fistulas (eAVFs) is relatively limited. In this study the authors aimed to provide the demographics, natural history, and treatment results of these rare lesions.
Methods: The authors performed a pooled analysis of data in the PubMed database through December 2012. Individualized patient data were extracted to elucidate demographic, clinical, and angioarchitectural features of spinal eAVFs as well as outcomes following different treatment strategies.
Results: Information on 101 patients was extracted from 63 eligible studies. The mean patient age was 45.9 years, and there was no significant overall sex predilection. Only 3% of the lesions were incidental, whereas 10% occurred in patients who had presented with hemorrhage. None of the 64 patients with at least 1 month of untreated follow-up sustained a hemorrhage over a total of 83.8 patient-years. Patients with lumbosacral eAVFs were significantly older (mean age 58.7 years, p < 0.0001), were significantly more often male (70% male, p = 0.02), had significantly worse presenting Aminoff-Logue motor and bladder scores (p = 0.0008 and < 0.0001, respectively), and had the greatest prevalence of lesions with intradural venous drainage (62% of cases, p < 0.0001). Neurofibromatosis Type 1 (30% of cases, p < 0.0001) and subarachnoid hemorrhage (9% of cases, p = 0.06) were associated with and exclusively found in patients with cervical eAVFs. The overall complete obliteration rate was 91%. After a mean follow-up of 1.7 years, the clinical condition was improved in 89% of patients, the same in 9%, and worse in 2%. Obliteration rates and outcome at follow-up did not significantly differ between surgical and endovascular treatment modalities.
Conclusions: Spinal eAVFs are rare lesions with a low risk of hemorrhage; they cause neurological morbidity as a result of mass effect and/or venous hypertension. Their treatment is associated with a high rate of complete obliteration and improvement in preoperative symptoms.