Lumbar extradural arteriovenous malformation: case report and literature review

Background contextMost 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.PurposeTo fully document the rare occurrence of a symptomatic E-AVM producing spinal claudication.Study designCase report.Patient sampleOne patient.Outcome measuresRadiological and functional.MethodsThis 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.ResultsFollow-up at 8 weeks after this procedure confirmed significantly increased walking distance, improved distal sensation, and normal power in both legs, with insignificant claudication.ConclusionsWhen associated with canal stenosis, E-AVMs may exacerbate claudication by both compressive and venous-hypertensive mechanisms. Treatment should be by embolization, with laminectomy deferred.