title: Sonographic optic nerve sheath diameter as an estimate of intracranial pressure in adult trauma.
abstract: BACKGROUND
  Intracranial pressure (ICP) is currently measured with invasive monitoring. Sonographic optic nerve sheath diameter (ONSD) may provide a noninvasive estimate of ICP. Our hypothesis was that bedside ONSD accurately estimates ICP in acutely injured patients. The specific aims were (1) to determine the accuracy of ONSD in estimating elevated ICP, (2) to correlate ONSD and ICP in unilateral and bilateral head injuries, and (3) to determine the effect of ICP monitor placement on ONSD measurements.
  
  
  METHODS
  A blinded prospective study of adult trauma patients requiring ICP monitoring was performed at a University-based urban trauma center. The ONSD was measured by ultrasound pre- and post-placement of an ICP monitor (Camino Bolt or Ventriculostomy).
  
  
  RESULTS
  One-hundred fourteen measurements were obtained in 10 trauma patients requiring ICP monitoring. Pre- and post-ONSD were compared with side of injury in the presence of an ICP monitor. ROC analysis demonstrated ONSD poorly estimates elevated ICP (AUC = 0.36). Overall sensitivity, specificity, PPV, NPV, and accuracy for estimating ICP with ONSD were 36%, 38%, 40%, 16%, and 37%. Poor correlation of ONSD to ICP was observed with unilateral (R(2) = 0.45, P < 0.01) and bilateral (R(2) = 0.21, P = 0.01) injuries. ICP monitor placement did not affect ONSD measurements on the right (P = 0.5), left (P = 0.4), or right and left sides combined (P = 0.3).
  
  
  CONCLUSIONS
  Sonographic ONSD as a surrogate for elevated ICP in lieu of invasive monitoring is not reliable due to poor accuracy and correlation.
authors.affiliation: Department of Surgery, University of California, San Francisco-East Bay, Oakland, California, USA.
authors.forename: Aaron
authors.initials: A
authors.lastname: Strumwasser
authors.forename: Rita O
authors.initials: RO
authors.lastname: Kwan
authors.forename: Louise
authors.initials: L
authors.lastname: Yeung
authors.forename: Emily
authors.initials: E
authors.lastname: Miraflor
authors.forename: Alex
authors.initials: A
authors.lastname: Ereso
authors.forename: Frederico
authors.initials: F
authors.lastname: Castro-Moure
authors.forename: Atul
authors.initials: A
authors.lastname: Patel
authors.forename: Javid
authors.initials: J
authors.lastname: Sadjadi
authors.forename: Gregory P
authors.initials: GP
authors.lastname: Victorino
mesh_terms: D000328:Adult; D001930:Brain Injuries / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D019586:Intracranial Hypertension / Q000000981:diagnostic imaging*; D007427:Intracranial Pressure; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D009900:Optic Nerve / Q000000981:diagnostic imaging*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014463:Ultrasonography / Q000379:methods / Q000592:standards*