Clinical and neuroimaging findings of spinal dural arteriovenous fistulas: How to avoid misdiagnosis of this disease

Objective: Spinal dural arteriovenous fistulas (DAVFs) are rare but can cause serious gait and micturition disturbances. Delays in diagnosis and treatment result in poor clinical outcomes; however, the process of misdiagnosis is unknown. Methods: Forty consecutive patients were retrospectively analyzed. Results: Thirty-one patients (78%) were initially misdiagnosed with lumbar spinal stenosis or other diseases, mostly by orthopedic surgeons, even though most patients (85%) had specific symptoms or characteristic neuroimaging findings of spinal DAVFs: they often presented with spastic gait (thoracic myelopathy), progressive ascending numbness that begins in the distal lower extremities (epicous syndrome), and urinary tract symptoms (conus medullaris syndrome); initial lumbar MRI showed T2 signal change in the conus medullaris and vascular flow voids around the cord. The median time from onset to treatment was longer in patients with a misdiagnosis than in those with the correct diagnosis (11 vs 4 months). In all patients, the fistula was completely obliterated by the direct microsurgical procedure; however, patients with a misdiagnosis had developed additional disabilities by the time a correct diagnosis was made (Aminoff-Logue gait grade of 3.6 +/- 1.4 vs 2.1 +/- 1.5 p = 0.013), and achieved markedly smaller improvements after the treatment (Aminoff-Logue gait grade of 3.0 +/- 1.6 vs 1.1 +/- 1.5, p = 0.006) than those with the correct diagnosis of spinal DAVFs. Conclusions: When common spinal stenosis fail to explain the symptoms such as thoracic myelopathy, epiconus syndrome, and conus medullaris syndrome, the possibility of spinal DAVFs should be considered. If lumbar MRI shows conus medullaris lesions, thoracic MRI should be performed to confirm the diagnosis. (c) 2019 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.