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Spinal Dural Arteriovenous Fistulas: How Can I Prevent Irreversible Myelopathy? 2013

Category Interventional Iftikhar Ahmad
Ammar Taha, MD
Supakul Tanya, MD
Juan Tejada, MD
Purpose
  1. To understand the Pathophysiology of Spinal Dural Arterio venous Fistulas.
  2. To learn common and uncommon radiological presentations, mapping teachniques and classifications      
  3. To describe treatment options available for each category with examples to prevent Irreversible Myelopathy. 
  Materials & Methods We present several didactic cases highlighting early detection of this entity among radiologists, leading to prompt management of this treatable cause of irreversible neurological deficits.Spinal vascular malformations are unique lesions needing an individualized treatment options. The asymptomatic AVF are primarily treated with elective endovascular methods. If preoperative imaging mapping is possible surgery may be a feasible option. Dural AVF has its shunt at the dura and can be treated with either surgery or embolization with onyx.  Peri medullary AVF carry shunt on the spinal cord surface and can be divided into 3 types. Types 1 and 2 are treated with surgery, type 3 by balloon or coil embolization.  We discuss with examples the types of AVF that leads to correct treatment.     Results Spinal dural arteriovenous fistula (SDAVF) is the most common vascular malformation of the spinal cord.  This entity commonly affects middle aged or elderly men.  Pathologically there is demonstration of segmental radiculo meningeal arteries in the nerve root sleeves forming an abnormal direct connection with intradural veins, classically affecting the lower half of the spinal cord . The engorged serpentine veins drain superiorly in the spinal coronal venous plexus.  From the clinic standpoint SDAVF result in venous hypertension and progressive congestive myelopathy with loss of sensory and motor function of the  extremities.  Other symptoms are urinary and fecal incontinence and erectile dysfunction. MR with contrast bolus spinal angiography is a great screening tool for early detection of abnormal vasculature and spinal cord abnormality   whereas the gold standard test  is still catheter spinal  angiography  for detailed mapping of the angioarchitecture, classification that leads to  correct endovascular treatment planning . Cervical SDAVF are rare and often present with subarachnoid hemorrhage.  In any middle age male with ascending motor or sensory deficits in the lower extremities the diagnosis of SDAVF should be considered, so that adequate management is timely instituted and irreversible deficits may be prevented. The treatment is surgical or endovascular obliteration of the abnormal Arteriovenous connection relieving spinal venous hypertension. Despite availability of new sophisticated diagnostic tools the entity remains under diagnosed. Picture5a.pdf   Conclusion SDAVF is a treatable cause of myelopathy predominantly in middle age and elderly men. Early detection, adequate mapping and classification resulting in a  timely management are keys to prevent venous infarction of the spinal cord leading to irreversible deficits. Awareness of imaging findings  and treatment options for each category  is helpful for proper patient management.   References (1) Bostroem A, Thron A, Hans FJ, Krings T. Spinal vascular malformations--typical and atypical findings. Zentralbl Neurochir 2007 Nov;68(4):205-213. (2) Eicker S, Turowski B, Steiger HJ, Hanggi D. Diagnostic work-up and therapy of spinal vascular malformations: an update. Nervenarzt 2010 Jun;81(6):719-726. (3) Hessler C, Regelsberger J, Grzyska U, Illies T, Zeumer H, Westphal M. Therapeutic clues in spinal dural arteriovenous fistulas - a 30 year experience of 156 cases. Cent Eur Neurosurg 2010 Feb;71(1):8-12. (4) Ito O, Ido K, Ishido K, Hitotsumatsu T. Usefulness of dynamic MRA and CTA in diagnosis and postoperative evaluation in spinal dural arteriovenous fistula: a case report. No Shinkei Geka 2012 Feb;40(2):173-180. (5) Koch C. Spinal dural arteriovenous fistula. Curr Opin Neurol 2006 Feb;19(1):69-75. (6) Krings T, Mull M, Gilsbach JM, Thron A. Spinal vascular malformations. Eur Radiol 2005 Feb;15(2):267-278. (7) Ropper AE, Gross BA, Du R. Surgical treatment of Type I spinal dural arteriovenous fistulas. Neurosurg Focus 2012 May;32(5):E3.