Exclusive Spinal Epidural Arteriovenous Malformation: Taming the Serpent in the Canal

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. We report this case and review the relevant literature to document the rare occurrence of a symptomatic E-AVM producing compressive spinal myelopathy like symptoms. Adult patient presented with 7-month progressive spastic quadriparesis, hypertonia in lower limbs and graded sensory loss below c6 level. Magnetic resonance imaging revealed a T2 hypointese extradural lesion at C4-5 level and CT angiography revealed an epidural vascular malformation.DSA revealed a Type A epidural AVM. Preoperative embolisation of the AVM with Onyx and coils was done and later a C4-5 laminectomy with excision of the entire Epidural AVM nidus with prolapsed coils was done. Surgical excision was done in view of compressive symptoms Post operatively patient had considerable improvement in power as well decrease in hypertonia. Postoperative MRI imaging after 3 months of surgery revealed complete excision of the malformation and resolution of cord edema. Based on the literature review done, ours is a first of its kind case of Exculsive Epidural AVM (EEAVMs) presenting with symptoms suggestive of Compressive spinal myelopathy. To conclude, E-AVMs may present with compressive myelopathy like symptoms. Treatment should be by tailored to benefit the patient like in our case.