title: High-concentration ethylene-vinyl alcohol copolymer and endovascular treatment of experimental aneurysms: feasibility of embolization without protection devices at the neck.
abstract: OBJECTIVE
  Coiling of intracranial aneurysms is both safe and effective but may be followed by recurrences. The purpose of this study was to assess the feasibility of endovascular treatment of aneurysms with high-concentration ethylene-vinyl alcohol copolymer (HCEVOH), without the use of protection devices at the neck.
  
  
  METHODS
  Wide-necked bifurcation aneurysms with a high propensity for recurrences were constructed in 22 dogs. HCEVOH embolization was performed with a dedicated high-pressure microcatheter in 12 animals. Angiographic results at 3 and 12 weeks and pathologic results at 12 weeks were compared with those of a separate group of 10 animals treated with platinum coils. We used a qualitative scoring system to grade angiographic results, neointima formation, and recanalization at the neck.
  
  
  RESULTS
  Intraaneurysmal HCEVOH injections could be performed without carotid emboli and without a protection device in 11 of 12 animals. Fragments detached upon traction of the microcatheters at the end of the procedure on two occasions. Immediate and late angiographic results were not significantly different between the two groups (P =.807), with a tendency for angiographic recurrences at 3 months (angiographic scores were significantly worse in both groups at 12 weeks as compared with T0 [P <.02]). A complete occlusion, including the neck, even at the cost of protrusion of material at the level of the branches, is necessary to decrease risks of recurrences. Neointima formation at the surface of the embolic agent was complete at the neck of aneurysms treated with HCEVOH. The neointimal score was significantly improved with HCEVOH as compared with coil embolization (P =.03).
  
  
  CONCLUSIONS
  HCEVOH embolization of aneurysms without neck protection is feasible. It does not, however, eliminate recurrences in an experimental wide-necked aneurysm model.
authors.affiliation: Department of Radiology, Centre Hospitalier de l'Université de Montréal (CHUM), Notre-Dame Hospital, Montreal, Quebec, Canada.
authors.forename: Jean
authors.initials: J
authors.lastname: Raymond
authors.forename: Igor
authors.initials: I
authors.lastname: Salazkin
authors.forename: Annick
authors.initials: A
authors.lastname: Metcalfe
authors.forename: François
authors.initials: F
authors.lastname: Guilbert
authors.forename: Alain
authors.initials: A
authors.lastname: Weill
authors.forename: Daniel
authors.initials: D
authors.lastname: Roy
mesh_terms: D000818:Animals; D002533:Cerebral Angiography; D004285:Dogs; D004621:Embolization, Therapeutic / Q000295:instrumentation / Q000379:methods; D005240:Feasibility Studies; D007267:Injections; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy*; D011145:Polyvinyls / Q000008:administration & dosage*; D012008:Recurrence
chemical_list: D011145:Polyvinyls; C020320:ethylene-vinyl alcohol copolymer