title: Blood-brain barrier permeability following traumatic brain injury.
abstract: Brain edema and intracranial hypertension is deleterious after traumatic brain injury (TBI), but the underlying pathophysiology is complex and poorly understood. One major subject of controversy is the time course and extent of blood-brain barrier (BBB) dysfunction following trauma, and previous studies in humans have only provided semi-quantitative data. The objective of the present study was therefore to quantify changes in BBB-permeability in the early course of TBI, when brain edema is still evolving.
  
  
  
  Sixteen non-consecutive brain trauma patients and two controls were included. Following i.v. injection of iohexol and CT perfusion scans, patients were scanned eight times from 4 to 25 minutes. Blood to brain transfer constant (Ki) for iohexol (molecular weight 821 D), reflecting permeability and available area for diffusion, was calculated offline by Patlak plot analysis of the enhancement curves of intracerebral large venous vessels and pericontusional brain parenchyma.
  
  
  
  In non-ischemic tissue surrounding contusions and hematomas Ki was increased 2- to 10-fold compared to normal tissue, reaching maximal values of 0.5 mL/min/100 g. In non-injured areas and in controls Ki was about 0.06 mL/min/100 g. The increase was more pronounced in the most severely injured patients, and was detectable within 24 hours after trauma and up to five days after.
  
  
  
  Our results suggest that traumatic brain injury is associated with early focal increases in small molecular BBB-permeability. The results indicate that in the injured brain, capillary hydrostatic and oncotic pressures may influence edema formation.
authors.affiliation: Department of Anesthesiology and Intensive Care, Lund University and Skåne University Hospital, Lund, Sweden - peter.bentzer@hotmail.com.
authors.forename: Mårten
authors.initials: M
authors.lastname: Jungner
authors.forename: Roger
authors.initials: R
authors.lastname: Siemund
authors.forename: Daniele
authors.initials: D
authors.lastname: Venturoli
authors.forename: Peter
authors.initials: P
authors.lastname: Reinstrup
authors.forename: Wilhelm
authors.initials: W
authors.lastname: SCHALéN
authors.forename: Peter
authors.initials: P
authors.lastname: Bentzer
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D001812:Blood-Brain Barrier / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology; D001929:Brain Edema / Q000503:physiopathology; D000070642:Brain Injuries, Traumatic / Q000503:physiopathology*; D002199:Capillary Permeability / Q000502:physiology; D016022:Case-Control Studies; D003287:Contrast Media / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D007472:Iohexol / Q000493:pharmacokinetics; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D055815:Young Adult
chemical_list: D003287:Contrast Media; D007472:Iohexol