title: Delayed Deterioration of EEG Background Rhythm Post-cardiac Arrest.
abstract: BACKGROUND
  Electroencephalogram (EEG) background continuity is associated with a favorable prognosis in cardiac arrest patients post-therapeutic hypothermia. However, the continuous EEG in a subset of patients will undergo 'delayed EEG deterioration'; they will invariably have poor outcome. The aim of this study was to characterize this phenomenon.
  
  
  METHODS
  We studied a prospectively collected cohort of consecutive cardiac arrest patients who underwent therapeutic hypothermia between July 2012 and May 2015. We identified patients with an initially favorable EEG rhythm post-cooling and characterized a subset of patients with delayed EEG deterioration.
  
  
  RESULTS
  A total of 133 patients were included in the analysis. Of these, 69/133 (51.9%) had an initially favorable EEG. Of those patients with initially favorable EEG, 7/69 (10.1%) had a subsequent deterioration. Delayed EEG deterioration was associated with poor outcome. The median time to deterioration was 55 h.
  
  
  CONCLUSIONS
  Delayed EEG deterioration is associated with poor clinical outcomes. We hypothesize that this is the result of delayed neuronal degeneration, the exact mechanism requiring further exploration. Identifying patients with delayed EEG deterioration post-therapeutic hypothermia is paramount as further interventions may yet salvage their outcomes, though further study is needed.
authors.affiliation: Department of Neurology, Brigham and Women's Hospital, 75 Francis St, Boston, MA, 02115, USA.
authors.forename: Tadeu A
authors.initials: TA
authors.lastname: Fantaneanu
authors.affiliation: Department of Neurology, Brigham and Women's Hospital, 75 Francis St, Boston, MA, 02115, USA.
authors.forename: Rani
authors.initials: R
authors.lastname: Sarkis
authors.affiliation: CICU Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Avery
authors.affiliation: Cardiovascular Division, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Scirica
authors.affiliation: Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA.|Brigham and Women's Center for Clinical Investigation, Boston, MA, USA.
authors.forename: Shelley
authors.initials: S
authors.lastname: Hurwitz
authors.affiliation: Department of Neurology, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Galen V
authors.initials: GV
authors.lastname: Henderson
authors.affiliation: Department of Neurology, Brigham and Women's Hospital, 75 Francis St, Boston, MA, 02115, USA. Jlee38@partners.org.
authors.forename: Jong Woo
authors.initials: JW
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D058256:Brain Waves / Q000502:physiology*; D005260:Female; D006323:Heart Arrest / Q000503:physiopathology* / Q000628:therapy*; D006801:Humans; D007036:Hypothermia, Induced / Q000379:methods*; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D013997:Time Factors
keywords: Anoxia; Cardiac arrest; Coma; Continuous EEG monitoring; EEG; EEG deterioration