title: A clinical and EEG scoring system that predicts early cortical response (N20) to somatosensory evoked potentials and outcome after cardiac arrest.
abstract: BACKGROUND
  Anoxic coma following cardiac arrest is a common problem with ethical, social, and legal consequences. Except for unfavorable somatosensory-evoked potentials (SSEP) results, predictors of unfavorable outcome with a 100% specificity and a high sensitivity are lacking. The aim of the current research was to construct a clinical and EEG scoring system that predicts early cortical response (N20) to somatosensory evoked potentials and 6-months outcome in comatose patients after cardiac arrest.
  
  
  METHODS
  We retrospectively reviewed the records of all consecutive patients who suffered cardiac arrest outside our hospital and were subsequently admitted to our facility from November 2002 to July 2006. We scored each case based on early clinical and EEG factors associated with unfavorable SSEPs, and we assessed the ability of this score to predict SSEP results and outcome.
  
  
  RESULTS
  Sixty-six patients qualified for inclusion in the cohort. Among them, 34 (52%) had unfavorable SSEP results. At day three, factors independently associated with unfavorable SSEPs were: absence of corneal (14 points) and pupillary (21 points) reflexes, myoclonus (25 points), extensor or absent motor response to painful stimulation (28 points), and malignant EEG (11 points). A score >40 points had a sensitivity of 85%, a specificity of 84%, and a positive predictive value (PPV) of 85% to predict unfavorable SSEP results. A score >88 points had a PPV of 100%, but a sensitivity of 18%. Overall, this score had an area under ROC curves of 0.919. In addition, at day three, a score > 69 points had a PPV of 100% with a sensitivity of 32% to predict death or vegetative state.
  
  
  CONCLUSIONS
  A scoring system based on a combination of clinical and EEG findings can predict the absence of early cortical response to SSEPs. In settings without access to SSEPs, this score may help decision-making in a subset of comatose survivors after a cardiac arrest.
authors.affiliation: Department of Medical Intensive Care, Caen University Hospital, Caen, France. daubin-c@chu-caen.fr
authors.forename: Cédric
authors.initials: C
authors.lastname: Daubin
authors.forename: Damien
authors.initials: D
authors.lastname: Guillotin
authors.forename: Olivier
authors.initials: O
authors.lastname: Etard
authors.forename: Cathy
authors.initials: C
authors.lastname: Gaillard
authors.forename: Damien
authors.initials: D
authors.lastname: du Cheyron
authors.forename: Michel
authors.initials: M
authors.lastname: Ramakers
authors.forename: Bruno
authors.initials: B
authors.lastname: Bouchet
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Parienti
authors.forename: Pierre
authors.initials: P
authors.lastname: Charbonneau
mesh_terms: D000368:Aged; D001767:Blinking; D002540:Cerebral Cortex / Q000473:pathology / Q000503:physiopathology; D003128:Coma / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D004569:Electroencephalography / Q000379:methods*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005260:Female; D006323:Heart Arrest / Q000150:complications / Q000503:physiopathology; D006801:Humans; D002534:Hypoxia, Brain / Q000209:etiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D018458:Persistent Vegetative State / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D011237:Predictive Value of Tests; D011379:Prognosis; D012025:Reflex, Pupillary; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index