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Spinal dural arteriovenous fistula (sdAVF) is the most common spinal vascular malformation. Its presenting symptoms are often non-specific, and it does not always demonstrate typical radiographic findings, leading to diagnostic delay, inappropriate treatments, and likely permanent neurological deficits when left untreated.

Case series.

Case 1: A 55-year-old male presented with two years of progressive numbness and weakness in his bilateral lower extremities. MRI of the cervical and thoracic spine demonstrated a confluent signal abnormality from C7 to T4 with areas of enhancement. Flow voids were not visualized. Cerebrospinal fluid analysis was only notable for elevated protein. He was initially diagnosed with longitudinally extensive transverse myelitis (LETM) and treated with intravenous corticosteroids and plasmapheresis. Despite these therapies, he continued to clinically worsen. He was admitted for further evaluation including diagnostic spinal angiogram, which revealed a T5 sdAVF. He underwent neurosurgical ligation of the sdAVF and experienced significant improvement in his lower extremity sensation.

Case 2: A 67-year-old male presented with two years of back pain and fluctuating bilateral lower extremity weakness. He had previously been evaluated elsewhere and diagnosed with LETM based on MRI showing a long segment of hyperintense signal from T6 to conus. There was only slight prominence of perimedullary vessels at the level of T6 and T7. He had undergone plasmapheresis, intravenous immunoglobulin, corticosteroids, rituximab, and methotrexate. Diagnostic spinal angiogram revealed a T7 sdAVF, and he subsequently underwent embolization of the fistula. Afterward, he experienced modest improvement in strength with rehabilitation.

We present two cases initially diagnosed as LETM but eventually found to be sdAVF. In patients who are not responding to appropriate therapies, sdAVF should be considered even in the absence of specific MRI findings such as prominent flow voids.