title: Short-duration hypothermia after ischemic stroke prevents delayed intracranial pressure rise.
abstract: BACKGROUND
  Intracranial pressure elevation, peaking three to seven post-stroke is well recognized following large strokes. Data following small-moderate stroke are limited. Therapeutic hypothermia improves outcome after cardiac arrest, is strongly neuroprotective in experimental stroke, and is under clinical trial in stroke. Hypothermia lowers elevated intracranial pressure; however, rebound intracranial pressure elevation and neurological deterioration may occur during rewarming.
  
  
  OBJECTIVE
  (1) Intracranial pressure increases 24 h after moderate and small strokes. (2) Short-duration hypothermia-rewarming, instituted before intracranial pressure elevation, prevents this 24 h intracranial pressure elevation.
  
  
  METHODS
  Long-Evans rats with two hour middle cerebral artery occlusion or outbred Wistar rats with three hour middle cerebral artery occlusion had intracranial pressure measured at baseline and 24 h. Wistars were randomized to 2·5 h hypothermia (32·5°C) or normothermia, commencing 1 h after stroke.
  
  
  RESULTS
  In Long-Evans rats (n = 5), intracranial pressure increased from 10·9 ± 4·6 mmHg at baseline to 32·4 ± 11·4 mmHg at 24 h, infarct volume was 84·3 ± 15·9 mm(3) . In normothermic Wistars (n = 10), intracranial pressure increased from 6·7 ± 2·3 mmHg to 31·6 ± 9·3 mmHg, infarct volume was 31·3 ± 18·4 mm(3) . In hypothermia-treated Wistars (n = 10), 24 h intracranial pressure did not increase (7·0 ± 2·8 mmHg, P < 0·001 vs. normothermia), and infarct volume was smaller (15·4 ± 11·8 mm(3) , P < 0·05).
  
  
  CONCLUSIONS
  We saw major intracranial pressure elevation 24 h after stroke in two rat strains, even after small strokes. Short-duration hypothermia prevented the intracranial pressure rise, an effect sustained for at least 18 h after rewarming. The findings have potentially important implications for design of future clinical trials.
authors.affiliation: University of Newcastle and Hunter Medical Research Institute, School of Biomedical Sciences & Pharmacy, University of Newcastle, Callaghan, NSW, Australia.
authors.forename: L A
authors.initials: LA
authors.lastname: Murtha
authors.forename: D D
authors.initials: DD
authors.lastname: McLeod
authors.forename: S K
authors.initials: SK
authors.lastname: McCann
authors.forename: D
authors.initials: D
authors.lastname: Pepperall
authors.forename: S
authors.initials: S
authors.lastname: Chung
authors.forename: C R
authors.initials: CR
authors.lastname: Levi
authors.forename: M B
authors.initials: MB
authors.lastname: Calford
authors.forename: N J
authors.initials: NJ
authors.lastname: Spratt
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D007036:Hypothermia, Induced / Q000379:methods*; D020244:Infarction, Middle Cerebral Artery / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D019586:Intracranial Hypertension / Q000503:physiopathology / Q000517:prevention & control*; D007427:Intracranial Pressure / Q000502:physiology; D008297:Male; D011897:Random Allocation; D020318:Rats, Long-Evans; D017208:Rats, Wistar; D017694:Rewarming / Q000379:methods*; D012720:Severity of Illness Index; D013045:Species Specificity; D013997:Time Factors
keywords: hypothermia; intracranial pressure; ischemic stroke