The authors report on a 69-year-old man presenting with progressive leg weakness and gait ataxia over two years. A central intramedullary cord lesion ranging from T8-12 on MR imaging was misdiagnosed as a low-grade glioma and a biopsy was attempted followed by temporary clinical deterioration. Selective spinal angiography revealed a spinal dural arteriovenous (AV) fistula on the left L3 nerve root sheath despite the absence of pathological vessels on MR imaging. The fistula was successfully treated by microsurgical interruption of the arterialized intradural vein. The present case should remind us to include selective spinal angiography in our diagnostic work-up in patients predisposed for spinal dural AV fistula by male sex, advanced age and clinical presentation of slowly progressive sensorimotor symptoms with myelopathy on MR imaging, even in the absence of any pathological vascular structures.