Clinical, radiological, and CSF features distinguishing spinal dural arteriovenous fistula from idiopathic transverse myelitis and seropositive NMOSD-/MOGAD-associated myelopathy: a retrospective observational study.

Misdiagnosis is common in cases of spinal dural arteriovenous fistula (SDAVF), and immune-related myelopathies constitute one of the most frequent diagnostic pitfalls. This study aims to identify the clinical, radiological, and cerebrospinal fluid features that distinguish idiopathic transverse myelitis, seropositive neuromyelitis optica spectrum disorder (NMOSD), and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD)-the immune-mediated myelopathies most often confused with SDAVF. The study included 15 patients with SDAVF, 18 with idiopathic transverse myelitis, 12 seropositive NMOSD patients, and 4 patients with MOGAD, all with spinal cord involvement. Demographic, clinical, cerebrospinal fluid, and radiological imaging data were retrospectively reviewed from medical records. A secondary analysis was performed for patients whose initial clinical presentation was myelitis/myelopathy. In SDAVF, the male-to-female ratio was 3:1, and the mean age at first symptom onset was 56.8 ± 12.11 years. The initial presentation typically involved a progressive (40%) or fluctuating (40%) course, most commonly manifesting as paraparesis (73.3%). Compared with the other three myelopathies, SDAVF was characterized by a higher frequency of male sex (p = 0.032), a longer symptom-to-admission time (p < 0.001), a greater burden of comorbidities (p = 0.038), the presence of provocative factors (p < 0.001), fluctuating symptom onset (p < 0.001), more frequent urinary dysfunction (p < 0.001), absence of lower cervical-upper thoracic involvement (p = 0.012), and involvement of the lower thoracic spinal cord (p < 0.001). No distinguishing differences were observed in CSF characteristics or in other clinical or radiological features. The secondary analysis, limited to patients with the first clinical event being myelitis/myelopathy (excluding MOGAD), showed that these important differences were maintained. SDAVF is a rare but treatable cause of progressive myelopathy that can closely mimic immune-related myelitis/myelopathies. Fluctuating symptom onset, provoking factors, urinary dysfunction, and characteristic lower thoracic involvement may help distinguish SDAVF from seropositive NMOSD, MOGAD, and idiopathic transverse myelitis, supporting earlier diagnosis and improved clinical outcomes.