(Kiosk 3) Spinal Dural AV Fistula as the Cause of Progressive Bilateral Lower Extremity Weakness Immediately Following Spinal Cord Stimulator Placement: A Case Report

Case Diagnosis: 72-year-old male with spinal dural arteriovenous fistula (AVF).

Case Description or Program Description: The patient presented for percutaneous trial electrode placement to evaluate for a spinal cord stimulator. Afterwards he complained of lower back cramping and progressive bilateral lower extremity weakness. There was associated gait dysfunction and urinary/bowel pattern changes. Trial electrodes were removed 10 days later but his symptoms persisted. Analgesics and steroids provided some improvement in long-standing RIGHT foot neuropathic pain only.

Setting: Inpatient Rehabilitation Facility.

Assessment/Results: Outpatient thoracic & lumbar spine MRIs demonstrated intramedullary T2 signal elevation involving greater than 2/3rds of the thoracic cord cross-section from T7 to conus; MRI brain and cervical spine were unremarkable. Inflammatory markers and nutritional labs were noncontributory. An LP was considered but the patient was emergently admitted for further management. He underwent 5 days of high-dose steroids with PLEX with minimal clinical improvement. Repeat imaging demonstrated evolving T2/STIR hyperintense signal within the thoracic cord with improvement in some areas. Spinal angiogram demonstrated RIGHT T12 dural AVF. He underwent Onyx embolization. He completed 2 and a half weeks of comprehensive inpatient rehabilitation. His course was complicated by acute constipation and urinary retention but his motor symptoms improved. He was discharged modified independent with ambulation at walker level, required intermittent catheterization to void, and had full resolution of bowel symptoms.

Discussion (relevance): This is an unfortunate case of vascular spinal cord injury resembling inflammatory myelopathy. Both present with abnormal T2-weighted signals on MRI as well as motor weakness and sensory changes, back and/or lower extremity pain, and bowel/bladder changes. Ischemic cord injuries are often neglected due to their rarity and variable presentation. Despite the temporal association with recent surgery, the correct diagnosis was not considered until the patient failed management for suspected thoracic transverse myelitis. The cause of his neurologic changes was subsequently identified weeks into hospitalization but responded favorably to embolization. His functional outcomes were similar to those reported in the literature.

Conclusions: Spinal arteriovenous malformation is an easily overlooked cause of progressive lower extremity weakness and sphincter dysfunction. Sagacious clinical suspicion during initial evaluation is warranted to initiate appropriate treatment, avoid diagnostic delay, & prevent disability.