title: Edema formation in the hyperacute phase of ischemic stroke. Laboratory investigation.
abstract: OBJECTIVE
  Brain edema formation is a serious complication of ischemic stroke and can lead to mechanical compression of adjacent brain structures, cerebral herniation, and death. Furthermore, the space-occupying effect of edema impairs regional cerebral blood flow (rCBF), which is particularly important in the penumbra phase of stroke. In the present study, the authors evaluated the natural course of edema formation in the hyperacute phase of focal cerebral ischemia.
  
  
  METHODS
  Middle cerebral artery occlusion (MCAO) or a sham procedure was performed in rats within an MR imaging unit (in-bore occlusion). Both pre- and postischemic images could be compared on a pixel-by-pixel basis. The T2 relaxation time (T2RT), a marker for brain water content, was measured in regions of interest.
  
  
  RESULTS
  A significant increase in the T2RT was detectable as early as 20-45 minutes after MCAO. At this early time point the midline shift (MLS) amounted to 0.214 +/- 0.092 cm in the MCAO group and 0.061 +/- 0.063 cm in the sham group (p < 0.007). The T2RT and MLS increased linearly thereafter. Evans blue dye was intravenously injected in additional animals 20 and 155 minutes after MCAO. Extravasation of the dye was visible in all animals, indicating increased permeability of the blood-brain barrier.
  
  
  CONCLUSIONS
  Vasogenic brain edema occurs much earlier than expected following permanent MCAO and leads to MLS and mechanical compression of adjacent brain structures. Since compression effects can impair rCBF, early edema formation can significantly contribute to infarct formation and thus represents a promising target for neuroprotection.
authors.affiliation: Department of Neurology, Justus Liebig-University Giessen, Giessen, Germany. tibo.gerriets@neuro.med.uni-giessen.de
authors.forename: Tibo
authors.initials: T
authors.lastname: Gerriets
authors.forename: Maureen
authors.initials: M
authors.lastname: Walberer
authors.forename: Nouha
authors.initials: N
authors.lastname: Ritschel
authors.forename: Marlene
authors.initials: M
authors.lastname: Tschernatsch
authors.forename: Clemens
authors.initials: C
authors.lastname: Mueller
authors.forename: Georg
authors.initials: G
authors.lastname: Bachmann
authors.forename: Markus
authors.initials: M
authors.lastname: Schoenburg
authors.forename: Manfred
authors.initials: M
authors.lastname: Kaps
authors.forename: Max
authors.initials: M
authors.lastname: Nedelmann
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000502:physiology; D001929:Brain Edema / Q000209:etiology*; D002545:Brain Ischemia / Q000150:complications*; D005070:Evans Blue; D006439:Hemodynamics / Q000502:physiology; D020244:Infarction, Middle Cerebral Artery / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D020521:Stroke / Q000150:complications* / Q000209:etiology; D013997:Time Factors
chemical_list: D005070:Evans Blue