title: ERPs obtained with the auditory oddball paradigm in coma and altered states of consciousness: clinical relationships, prognostic value, and origin of components.
abstract: OBJECTIVE
  To study the event related potentials (ERPs) in coma and altered states of consciousness, their relationship with the clinical status and coma outcome.
  
  
  METHODS
  ERPs were recorded with a passive auditory oddball paradigm in 103 patients. Their probability of occurrence and the peak latencies and amplitudes were studied as a function of the Glasgow Coma Score (GCS). Their relationship with outcome was studied in a subset of 83 patients examined within the first 4 days, and expressed in terms of sensitivity, specificity, and negative or positive prognostic values.
  
  
  RESULTS
  When present, the ERPs to rare stimuli consisted of a fronto-central negativity (N(endog), mean latency: 330 ms) and a fronto-central positivity (P(endog), mean latency: 431 ms) following the exogenous N100-P200 complex. Both their probability of occurrence and their latencies and amplitudes were related with the GCS in anoxic and traumatic comas. The N(endog) and P(endog) had high sensitivity with a negative predictive value of 70% and 100%, respectively, but a low specificity, with a positive predictive value of 44% and 41%, respectively.
  
  
  CONCLUSIONS
  ERPs can be recorded in some comatose patients and are likely to reflect implicit orienting processes rather than preserved consciousness. Their presence implies a good prognosis but no conclusion can be drawn from their absence.
authors.affiliation: Clinical Neurophysiology Unit, Cliniques Universitaires Saint-Luc, University of Louvain Medical School, Brussels, Belgium.
authors.forename: J M
authors.initials: JM
authors.lastname: Guérit
authors.forename: D
authors.initials: D
authors.lastname: Verougstraete
authors.forename: M
authors.initials: M
authors.lastname: de Tourtchaninoff
authors.forename: D
authors.initials: D
authors.lastname: Debatisse
authors.forename: C
authors.initials: C
authors.lastname: Witdoeckt
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000368:Aged; D001921:Brain / Q000503:physiopathology*; D003128:Coma / Q000503:physiopathology*; D003243:Consciousness / Q000502:physiology*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D011930:Reaction Time / Q000502:physiology; D012680:Sensitivity and Specificity