Lumbar extradural arteriovenous malformation: case report and literature review.

Abstract

Most spinal arteriovenous malformations (AVMs) are dural arteriovenous fistulas in which a singularly intradural venous drainage emanates from an extradural nidus. A pure extradural spinal arteriovenous malformation (E-AVM), in the absence of a vertebral body (cavernous) hemangioma, is extremely rare, and full clinical, radiological, and operative descriptions are scant. To fully document the rare occurrence of a symptomatic E-AVM producing spinal claudication. Case report. One patient. Radiological and functional. This 62-year-old man presented with 6-month progressive spinal claudication, leg weakness, and diminished sensation. Electromyography revealed bilateral acute and chronic partial degeneration of L3-S1 nerve roots. Magnetic resonance imaging revealed moderate canal stenosis between L2-L4, with prominent epidural veins on the left at L3-L4. Spinal angiography was unsuccessful, and computed tomographic myelography merely confirmed minimal lumbosacral root filling. At decompressive L2-L4 laminectomy, inadvertent hemorrhage from varicose epidural veins released arterialized blood under considerable pressure. Only minor clinical improvement was noted after this procedure. Spinal angiography 6 weeks later subsequently confirmed an E-AVM on the left at L3-L4 which was successfully embolized. Follow-up at 8 weeks after this procedure confirmed significantly increased walking distance, improved distal sensation, and normal power in both legs, with insignificant claudication. When associated with canal stenosis, E-AVMs may exacerbate claudication by both compressive and venous-hypertensive mechanisms. Treatment should be by embolization, with laminectomy deferred.