title: Electroencephalogram silence ratio for early outcome prognosis in severe head trauma.
abstract: OBJECTIVE
  To introduce the electroencephalogram silence-ratio (ESR) as a variable derived from mathematically processed electroencephalogram for early outcome prognosis in patients with severe head trauma and to comparatively assess sensitivity, specificity and predictive value vs. somatosensory evoked potentials and brainstem auditory evoked potentials.
  
  
  METHODS
  Prospective, interventional study.
  
  
  METHODS
  Intensive care unit of a university hospital.
  
  
  METHODS
  A total of 32 adults with severe acute head trauma (Glasgow Coma Scale score < or = 8).
  
  
  RESULTS
  In all patients, electroencephalographic recording was continuously performed by frontomastoid electrode montage for 24-96 hrs after admission to the ICU. The data were subsequently computed by fast Fourier analysis and the ESR (intervals of suppression as periods >240 msecs during which the electroencephalographic voltage did not exceed 5 microV) was displayed and recorded on a computer for further evaluation. Somatosensory evoked potentials and brainstem auditory evoked potentials were elicited during the first 2 days after admission. Outcome evaluation was performed 6 months after trauma using the Glasgow Outcome Scale and the Rappaport Disability Rating Scale. After careful artifact exclusion, the ESR depicted the highest sensitivity, specificity, and positive predictive value compared with evoked potentials. Even a highly significant correlation between outcome and ESR was found (p < .0001).
  
  
  CONCLUSIONS
  The ESR is a valuable variable showing a high reliability with respect to outcome prediction in severe head trauma with a higher predictive value than short latency somatosensory evoked potentials. Evidence exists that the ESR provides at least partial information regarding adequate cerebral oxygen delivery.
authors.affiliation: University Hospital of the Technical University of Dresden, Department of Anesthesiology, Germany. theilen@rcs.urz.tu-dresden.de
authors.forename: H J
authors.initials: HJ
authors.lastname: Theilen
authors.forename: M
authors.initials: M
authors.lastname: Ragaller
authors.forename: U
authors.initials: U
authors.lastname: Tschö
authors.forename: S A
authors.initials: SA
authors.lastname: May
authors.forename: G
authors.initials: G
authors.lastname: Schackert
authors.forename: M D
authors.initials: MD
authors.lastname: Albrecht
mesh_terms: D000203:Activities of Daily Living; D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D006259:Craniocerebral Trauma / Q000175:diagnosis*; D004569:Electroencephalography / Q000379:methods* / Q000592:standards; D016057:Evoked Potentials, Auditory, Brain Stem; D005073:Evoked Potentials, Somatosensory; D005260:Female; D005583:Fourier Analysis; D015600:Glasgow Coma Scale; D023261:Glasgow Outcome Scale; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods / Q000592:standards; D011379:Prognosis; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013997:Time Factors