Object: Owing to their rarity, demographics, natural history, and treatment, results for spinal juvenile (Type III) extradural-intradural arteriovenous malformations (AVMs) are frequently only provided in case report format.
Methods: A pooled analysis was performed utilizing the PubMed database through April 2013. Individualized patient data were extracted to elucidate demographics, hemorrhage risk, and treatment result information.
Results: Twenty-nine studies describing 51 patients were included. The mean age at presentation was 15.0 ± 10.5 years with a slight male predilection (63%, 1.7:1 sex ratio). Presentation modality included progressive deficits in 35%, hemorrhage in 31%, acute deficits not attributed to hemorrhage in 22%, and asymptomatic/incidental in 12% of patients. The annual hemorrhage rate was 2.1%; statistically significant risk factors for hemorrhage included presentation age (HR 0.39 [95% CI 0.18-0.87]) and associated aneurysms (HR 8.74 [95% CI 1.76-43.31]). Seventy-seven percent of patients underwent treatment; after a mean follow-up of 2.6 ± 3.2 years, 73% were improved, 10% were the same, and 17% were worse neurologically. Of 25 cases with described angiographic results, 8 lesions were obliterated (32%). Of these 25 patients, 8 had AVMs with associated aneurysms, and the aneurysm was obliterated in all 8 patients. Over the course of 57.9 patient-years of follow-up, including 55.3 patient-years for partially treated AVMs, no hemorrhages were described, reflecting a trend toward protection from hemorrhage after treatment (p = 0.12, likelihood ratio test).
Conclusions: Spinal juvenile (Type III) extradural-intradural AVMs commonly present symptomatically. Associated arterial aneurysms increase their hemorrhage risk, and protection from hemorrhage may be achieved from partial obliteration of these lesions, particularly if targeted toward associated aneurysms.