title: Patterns of cortical oxygen saturation changes during CO2 reactivity testing in the vicinity of cerebral arteriovenous malformations.
abstract: OBJECTIVE
  The aim of this study was to test the hypothesis that patterns of cerebrovascular reactivity (CVR) in the vicinity of cerebral arteriovenous malformations (AVMs) before and after resection are not specific for this disease.
  
  
  METHODS
  With a microspectrophotometer, cortical oxygen saturation (So2) was measured under steady-state conditions (Paco2, 33 mm Hg) before and after removal of 22 AVMs and in 30 control subjects before and after transsylvian amygdalohippocampectomy. Intraoperative vasoreactivity tests were performed by induced changes of end-tidal CO2 (25, 45, and 25 mm Hg) with simultaneous recording of local So2 in all patients. CVR patterns were established by linear regression analysis (P<0.05) to define parallel (positive) versus inverse (negative) behavior, and reactivity indexes were calculated to define their degree.
  
  
  RESULTS
  Cortical oxygenation under steady-state conditions increased significantly (P<0.05) from preoperative to postoperative levels equally in both groups (preoperative AVM, 54.8+/-10.4%So2; postoperative AVM, 73.1+/-10.1%So2; preoperative control, 52.7+/-9.1%So2; postoperative control, 73.6+/-8.9%So2). The rate of inverse CVR patterns increased significantly (P<0.05) from before to after resection without showing statistically significant differences between groups.
  
  
  CONCLUSIONS
  Local CVR patterns on presumably normal human cortex of control subjects are heterogeneous, including inverse behavior, and are similar to those of AVM patients before surgery. After surgery, cortical hyperemia is present in both groups, and a significant increase in inverse reactivity patterns interpreted as microvascular steal is noted. An AVM-specific CVR pattern could not convincingly be proved.
authors.affiliation: Department of Neurosurgery, University of Bonn, Germany.
authors.forename: Carlo
authors.initials: C
authors.lastname: Schaller
authors.forename: Johannes
authors.initials: J
authors.lastname: Schramm
authors.forename: Dorothee
authors.initials: D
authors.lastname: Haun
authors.forename: Bernhard
authors.initials: B
authors.lastname: Meyer
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000465:Algorithms; D002245:Carbon Dioxide / Q000737:chemistry; D002540:Cerebral Cortex / Q000098:blood supply / Q000737:chemistry* / Q000378:metabolism; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000378:metabolism* / Q000503:physiopathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000032:analysis*; D010101:Oxygen Consumption; D013053:Spectrophotometry
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen