title: A novel quantitative EEG injury measure of global cerebral ischemia.
abstract: OBJECTIVE
  To develop a novel quantitative EEG (qEEG) based analysis method, cepstral distance (CD) and compare it to spectral distance (SD) in detecting EEG changes related to global ischemia in rats.
  
  
  METHODS
  Adult Wistar rats were subjected to asphyxic-cardiac arrest for sham, 1, 3, 5 and 7 min (n=5 per group). The EEG signal was processed and fitted into an autoregressive (AR) model. A pre-injury baseline EEG was compared to selected data segments during asphyxia and recovery. The dissimilarities in the EEG segments were measured using CD and SD. A segment measured was considered abnormal when it exceeded 30% of baseline and its duration was used as the index of injury. A comprehensive Neurodeficit Score (NDS) at 24 h was used to assess outcome and was correlated with CD and SD measures.
  
  
  RESULTS
  A higher correlation was found with CD and asphyxia time (r=0.81, P<0.001) compared to SD and asphyxia time (r=0.69, P<0.001). Correlation with cardiac arrest time (MAP<10 mmHg) showed that CD was superior (r=0.71, P<0.001) to SD (r=0.52, P=0.002). CD obtained during global ischemia and 90 min into recovery correlated significantly with NDS at 24 h after injury (Spearman coefficient=-0.83, P<0.005), and was more robust than the traditional SD (Spearman coefficient=-0.63, P<0.005).
  
  
  CONCLUSIONS
  The novel qEEG-based injury index from CD was superior to SD in quantifying early cerebral dysfunction after cardiac arrest and in providing neurological prognosis at 24 h after global ischemia in adult rats. Studying early qEEG changes after asphyxic-cardiac arrest may provide new insights into the injury and recovery process, and present opportunities for therapy.
authors.affiliation: Department of Neurology, The Johns Hopkins University School of Medicine, MD 21205, Baltimore, USA.
authors.forename: R G
authors.initials: RG
authors.lastname: Geocadin
authors.forename: R
authors.initials: R
authors.lastname: Ghodadra
authors.forename: T
authors.initials: T
authors.lastname: Kimura
authors.forename: H
authors.initials: H
authors.lastname: Lei
authors.forename: D L
authors.initials: DL
authors.lastname: Sherman
authors.forename: D F
authors.initials: DF
authors.lastname: Hanley
authors.forename: N V
authors.initials: NV
authors.lastname: Thakor
mesh_terms: D000818:Animals; D001921:Brain / Q000503:physiopathology*; D002545:Brain Ischemia / Q000503:physiopathology*; D004195:Disease Models, Animal; D004569:Electroencephalography; D008297:Male; D008959:Models, Neurological; D011379:Prognosis; D051381:Rats; D017208:Rats, Wistar