Strategic endovascular approach for a rare type IVa perimedullary spinal arteriovenous fistula.

A 74-year-old man with a history of lumbar decompression for cauda equina syndrome presented with 1 month of progressive weakness and numbness of his legs and urinary incontinence. MRI revealed lower thoracic spinal cord edema and serpiginous perimedullary flow voids, prompting suspicion for an underlying vascular lesion. Spinal angiography identified a rare type IV (perimedullary) spinal arteriovenous fistula (AVF) supplied by the anterior spinal artery corresponding with the artery of Ademkiewickz arising from the left L1 segmental artery. A 3.7 mm venous varix was noted just beyond the fistulous point on conventional angiography. The lesion was successfully treated via a transarterial approach using selective n-butyl cyanoacrylate (n-BCA) embolization, achieving complete angiographic cure. The patient demonstrated substantial neurological recovery and regained assisted ambulation at 2-month follow-up with resolution of cord edema and flow voids on repeat MRI. This case reviews the technical challenges of treating rare type IV spinal AVFs.