Clinical characteristics, misdiagnosis and outcomes of patients with low-flow spinal arteriovenous fistulas

Objective: To describe the clinical characteristics, delay to diagnosis and post-intervention outcomes of patients with low-flow spinal arteriovenous fistulas (SAVFs). Methods: In this retrospective observational study, we reviewed all patients with low-flow SAVFs angiographically diagnosed at our institution between 2008 and 2018. Pre- and post-intervention disability levels were recorded using the modified Aminoff and Logue scale (mALS). Results: One-hundred and five patients were included. Median age was 62 years and 79% were male. Most patients (56%) presented to neurologists and 41% were misdiagnosed with myelitis. Patients underwent unnecessary treatment with corticosteroids (44%), other immunosuppressive therapies (8%) and spinal surgery (10%). Inappropriate corticosteroid treatment led to a precipitous clinical decline in 30% of patients exposed. Only 21% percent of patients were correctly diagnosed after initial evaluation; the median delay to diagnosis in the rest of the cohort was of 12 months (IQR 7 to 24 months). Longer delays to diagnosis were associated with higher levels of disability (p = .002). Treatment of SAVF was endovascular in 64% and surgical in 26%; 13% of patients required further intervention due to incomplete initial treatment or fistula recurrence. Greater than 6 months after intervention, disability scores were improved in 52% and stable in 43% of patients. In individual patients, pre- and post-intervention disability scores were strongly correlated (p < .001). Conclusions: Low-flow SAVFs are associated with substantial disability and are frequently misdiagnosed. Timely diagnosis of SAVF needs to improve, as endovascular or surgical treatment results in stabilization or improvement of disability in the vast majority of patients.