title: Clinical evolution after a non-reactive hypothermic EEG following cardiac arrest.
abstract: BACKGROUND
  Lack of electroencephalography (EEG) background reactivity during therapeutic hypothermia (TH) has been associated with poor outcome in post-anoxic comatose patients. However, decision on intensive care withdrawal is based on normothermic (NT) evaluations. This study aims at exploring whether patients showing recovery of EEG reactivity in NT after a non-reactive EEG in TH differ from those remaining non-reactive.
  
  
  METHODS
  Patients with non-reactive EEG during TH were identified from our prospective registry of consecutive comatose adults admitted after successful resuscitation from CA between April 2009 and June 2014. Variables including neurological examination, serum neuron-specific enolase (NSE), procalcitonin, and EEG features were compared regarding impact on functional outcome at 3 months.
  
  
  RESULTS
  Seventy-two of 197 patients (37 %) had a non-reactive EEG background during TH with thirteen (18 %) evolving towards reactivity in NT. Compared to those remaining non-reactive (n = 59), they showed significantly better recovery of brainstem reflexes (p < 0.001), better motor responses (p < 0.001), transitory consciousness improvement (p = 0.008), and a tendency toward lower NSE (p = 0.067). One patient recovering EEG reactivity survived with good functional outcome at 3 months.
  
  
  CONCLUSIONS
  Recovery of EEG reactivity from TH to NT seems to distinguish two patients' subgroups regarding early neurological assessment and transitory consciousness improvement, corroborating the role of EEG in providing information about cerebral functions. Understanding these dynamic changes encourages maintenance of intensive support in selected patients even after a non-reactive EEG background in TH, as a small subgroup may indeed recover with good functional outcome.
authors.affiliation: Neurology Service, Department of Clinical Neurosciences, Lausanne University Hospital (CHUV), Rue du Bugnon, 46, BH 07 300, CH-1011, Lausanne, Switzerland, elsa.juan@chuv.ch.
authors.forename: Elsa
authors.initials: E
authors.lastname: Juan
authors.forename: Jan
authors.initials: J
authors.lastname: Novy
authors.forename: Tamarah
authors.initials: T
authors.lastname: Suys
authors.forename: Mauro
authors.initials: M
authors.lastname: Oddo
authors.forename: Andrea O
authors.initials: AO
authors.lastname: Rossetti
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003128:Coma / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy; D004569:Electroencephalography; D005260:Female; D006323:Heart Arrest / Q000150:complications* / Q000503:physiopathology / Q000628:therapy; D006801:Humans; D007036:Hypothermia, Induced; D020925:Hypoxia-Ischemia, Brain / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D055815:Young Adult