title: Dural augmentation: part I-evaluation of collagen matrix allografts for dural defect after craniotomy.
abstract: OBJECTIVE
  Primary closure of the dura remains difficult in many neurosurgical cases. One option for dural grafting is the collagen sponge, which is available in multiple forms, namely, monolayer collagen and bilayer collagen. Our primary goal was to assess differences in the incidence of postoperative cerebrospinal fluid (CSF) leak, including fistula and pseudomeningocele, and postoperative infection between monolayer collagen and bilayer collagen grafts.
  
  
  METHODS
  A single-center retrospective analysis of 475 consecutive neurosurgical procedures was performed. Primary endpoints were CSF leak and infection, adjusting for the impact of additional nonautologous materials. Multivariate regression analysis was used to identify predictors of postoperative CSF leak and infection.
  
  
  RESULTS
  The overall frequency of postoperative CSF leak was 6.7%. There was no significant difference in the incidence of CSF leak based on the type of collagen sponge (monolayer versus bilayer) used (5.5% versus 7.5%, respectively; P = 0.38). The overall frequency of postoperative infection was 4.2%. There was no significant difference in the incidence of infection between groups (4.9% versus 3.8%; P = 0.54). Bilayer sponges were associated with a significantly lower incidence of CSF leak than monolayer sponges (odds ratio, 0.09; 95% confidence interval, 0.01-0.73).
  
  
  CONCLUSIONS
  Bilayer collagen sponges are associated with a reduction in postoperative CSF leak, notably in posterior fossa surgery. The need for additional non-native materials is predictive of postoperative CSF leak, along with location and type of procedure. Intrinsic patient characteristics (e.g., age, diabetes, smoking) do not seem to affect the efficacy of collagen sponge dural grafts.
authors.affiliation: Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon 97239, USA. litvackz@ohsu.edu
authors.forename: Zachary N
authors.initials: ZN
authors.lastname: Litvack
authors.forename: G Alexander
authors.initials: GA
authors.lastname: West
authors.forename: Johnny B
authors.initials: JB
authors.lastname: Delashaw
authors.forename: Kim J
authors.initials: KJ
authors.lastname: Burchiel
authors.forename: Valerie C
authors.initials: VC
authors.lastname: Anderson
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000627:therapeutic use*; D002417:Cattle; D003094:Collagen / Q000627:therapeutic use*; D003399:Craniotomy / Q000009:adverse effects*; D004388:Dura Mater / Q000601:surgery*; D006801:Humans; D011183:Postoperative Complications / Q000517:prevention & control*; D012189:Retrospective Studies; D013353:Subdural Effusion / Q000209:etiology / Q000517:prevention & control*
chemical_list: D001672:Biocompatible Materials; D003094:Collagen