title: Type I spinal arteriovenous fistulae exception: a case for reclassification.
abstract: OBJECTIVE
  Type I spinal arteriovenous lesions represent dorsal dural arteriovenous fistulae with no spinal artery involvement. We report an exception to this and propose dividing Type I lesions into dorsal and ventral categories.
  
  
  METHODS
  A 51-year-old patient presented with a partial Brown-Sequard syndrome. An angiogram revealed a spinal arteriovenous fistula, most prominently being fed a radicular artery arising from the right vertebral artery with only ventral venous drainage.
  
  
  RESULTS
  This feeder was selected and embolized with onyx, however residual fistula persisted and the patient subsequently underwent microsurgical disconnection. At six-month follow-up, patient motor deficits have resolved and difficulty with proprioception is improving.
  
  
  CONCLUSIONS
  Type I dural arteriovenous fistulae are associated with dorsal venous drainage. Our case demonstrates an exception to this. Recognizing this exception was crucial, because it allowed for simple microsurgical disconnection. We propose that type I dural arteriovenous fistulae be subdivided into ventral and dorsal based on their drainage pattern. This differentiation is critical because lesions with ventral drainage have traditionally been classified as type IV. These lesions have a different treatment method given involvement of spinal arteries.
authors: Yale Department of Neurosurgery, Neurovascular and Spine Sections, 333, Cedar Street, TMP 4, New Haven, 06520 CT, USA. Ketan.bulsara@yale.edu
authors: K R
authors: KR
authors: Bulsara
authors: R
authors: R
authors: Hebert
authors: D
authors: D
authors: Gimbel
authors: K
authors: K
authors: Abbed
mesh_terms: D001164:Arteriovenous Fistula / Q000175:diagnosis / Q000601:surgery*; D018437:Brown-Sequard Syndrome / Q000473:pathology / Q000601:surgery*; D020785:Central Nervous System Vascular Malformations / Q000601:surgery*; D002533:Cerebral Angiography / Q000379:methods; D004388:Dura Mater / Q000473:pathology / Q000601:surgery; D004621:Embolization, Therapeutic / Q000379:methods; D006801:Humans; D008875:Middle Aged; D013116:Spinal Cord / Q000098:blood supply; D016896:Treatment Outcome