title: Compensatory mechanisms for chronic cerebral hypoperfusion in patients with carotid occlusion.
abstract: OBJECTIVE
  The purpose of this experiment was to assess long-term cerebral hemodynamic and metabolic changes in patients with increased oxygen extraction fraction (OEF) in the hemisphere distal to an occluded carotid artery who remain free of stroke. Methods--Ten patients with increased OEF and no interval stroke underwent repeated positron emission tomography examinations 12 to 59 months after the initial examination. Quantitative regional measurements of cerebral blood flow, cerebral blood volume, cerebral rate of oxygen metabolism (CMRO2), and OEF were obtained. Regional measurements of the cerebral rate of glucose metabolism (CMRGlc) were made on follow-up in 5 patients. Statistical significance (P<0.05) was measured with t tests and linear regression analysis.
  
  
  RESULTS
  The ipsilateral/contralateral OEF ratio declined from a mean of 1.16 to 1.08 (P=0.022). Greater reductions were seen with longer duration of follow-up (P=0.023, r=0.707). The cerebral blood flow ratio improved from 0.81 to 0.85 (P=0.021). No change in cerebral blood volume or CMRO2 was observed. CMRGlc was reduced in the ipsilateral hemisphere (P=0.001 compared with normal), but the CMRO2/CMRGlc ratio was normal.
  
  
  CONCLUSIONS
  Increased OEF improves in patients with carotid occlusion and no interval stroke. This improvement in OEF is due to an improvement in collateral blood flow.
authors.affiliation: Mallinckrodt Institute of Radiology, Department of Neurology, 510 S. Kingshighway Blvd., St. Louis, MO 63110, USA. derdeyn@mirlink.wustl.edu
authors.forename: C P
authors.initials: CP
authors.lastname: Derdeyn
authors.forename: T O
authors.initials: TO
authors.lastname: Videen
authors.forename: S M
authors.initials: SM
authors.lastname: Fritsch
authors.forename: D A
authors.initials: DA
authors.lastname: Carpenter
authors.forename: R L
authors.initials: RL
authors.lastname: Grubb
authors.forename: W J
authors.initials: WJ
authors.lastname: Powers
mesh_terms: D000368:Aged; D001157:Arterial Occlusive Diseases / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology*; D002545:Brain Ischemia / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology*; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology*; D002540:Cerebral Cortex / Q000098:blood supply / Q000000981:diagnostic imaging / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002908:Chronic Disease; D005260:Female; D005500:Follow-Up Studies; D005947:Glucose / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D014055:Tomography, Emission-Computed
chemical_list: D005947:Glucose