title: Embolization of arteriovenous malformations with Onyx: clinicopathological experience in 23 patients.
abstract: OBJECTIVE
  To report our experience in treatment of arteriovenous malformations (AVMs) using a new liquid embolic agent, Onyx (Micro Therapeutics, Inc., Irvine, CA).
  
  
  METHODS
  Between January 1998 and May 1999, 23 patients (8 men and 15 women) were treated. The patients' average age was 40 years, with seizure being the most common presenting symptom (39%). The average Spetzler-Martin grade on presentation was 3. The average AVM volume before embolization was 14.5 cm3.
  
  
  RESULTS
  We observed an average 63% reduction in AVM volume after 129 arterial feeders were embolized. There were four adverse events. Two patients experienced ischemia because of inadvertent occlusion of an arterial feeder. One of these patients made a full recovery, but the other patient had a permanent deficit. Two other patients experienced transient neurological deficits that resolved within 1 week of embolization. Permanent morbidity was thus 4% (1 of 23 patients). There were no deaths. Twelve patients underwent subsequent radiosurgery, and 11 patients had surgery that resulted in complete resection of their AVMs. Histopathological examinations showed mild acute inflammation in specimens resected 1 day after embolization. Chronic inflammatory changes were observed in specimens resected more than 4 days after embolization. In two patients, angionecrosis of the embolized vessels was noted. No evidence of parenchymal hemorrhage was observed in these patients, and vessel wall integrity was maintained as well.
  
  
  CONCLUSIONS
  Onyx is a new nonadhesive liquid embolic agent that has been used to treat 23 patients at our institution with good results. Its nonadhesive nature and ease of use make it a promising agent in the future treatment of AVMs.
authors.affiliation: Division of Interventional Neuroradiology, Center for the Health Sciences, University of California at Los Angeles School of Medicine, 90095-1721, USA. rjahan@mednet.ucla.edu
authors.forename: R
authors.initials: R
authors.lastname: Jahan
authors.forename: Y
authors.initials: Y
authors.lastname: Murayama
authors.forename: Y P
authors.initials: YP
authors.lastname: Gobin
authors.forename: G R
authors.initials: GR
authors.lastname: Duckwiler
authors.forename: H V
authors.initials: HV
authors.lastname: Vinters
authors.forename: F
authors.initials: F
authors.lastname: Viñuela
mesh_terms: D000328:Adult; D000368:Aged; D002545:Brain Ischemia / Q000209:etiology; D002533:Cerebral Angiography; D004121:Dimethyl Sulfoxide; D004172:Diplopia / Q000209:etiology; D004621:Embolization, Therapeutic / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006429:Hemiplegia / Q000209:etiology; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000175:diagnosis / Q000473:pathology / Q000601:surgery / Q000628:therapy*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009422:Nervous System Diseases / Q000209:etiology; D011145:Polyvinyls / Q000009:adverse effects / Q000627:therapeutic use*; D013635:Tantalum; D016896:Treatment Outcome
chemical_list: D011145:Polyvinyls; C020320:ethylene-vinyl alcohol copolymer; D013635:Tantalum; D004121:Dimethyl Sulfoxide