title: Optic nerve sonography in the diagnostic evaluation of adult brain injury.
abstract: BACKGROUND
  The optic nerve sheath diameter (ONSD) may be increased in brain-injured patients, especially children, with intracranial hypertension. We investigated whether measurements of ONSD correlated with simultaneous noninvasive and invasive measurements of the intracranial pressure (ICP) in brain-injured adults.
  
  
  METHODS
  Seventy-six critical care patients (58 males; 47 +/- 18 years old) were included in the study. Fifty patients suffered from brain injury, whereas 26 had no intracranial pathology and served as control individuals. Initially, brain-injured patients were evaluated clinically (Glasgow Coma Scale) and using a semiquantitative (I to VI) neuroimaging scale (Marshall Scale). Thereafter, the patients were divided into those with moderate (Marshall Scale = I and Glasgow Coma Scale > 8 [n = 18]) and severe (Marshall Scale = II to VI and Glasgow Coma Scale < or =8 [n = 32]) brain injury. All patients underwent noninvasive measurement of the ICP (estimated ICP) by transcranial Doppler sonography, and synchronous ONSD measurements by optic nerve sonography. Finally, invasive ICP measurement using an intraparenchymal catheter was performed in patients with severe brain injury.
  
  
  RESULTS
  ONSD and estimated ICP were both significantly increased (6.1 +/- 0.7 mm and 26.2 +/- 8.7 mmHg, respectively; P < 0.0001) in patients with severe brain injury as compared with patients with moderate brain injury (4.2 +/- 1.2 mm and 12.0 +/- 3.6 mmHg) and compared with control individuals (3.6 +/- 0.6 mm and 10.3 +/- 3.1 mmHg). Furthermore, in patients with severe brain injury the ONSD measurements were strongly correlated with estimated ICP values (r = 0.80, P < 0.0001) as well as with the neuroimaging scale results (r = 0.82, P < 0.001). In the patients with severe brain injury, ONSD measurements correlated with invasive ICP values (r = 0.68, P = 0.002). The best cut-off value of ONSD for predicting elevated ICP was 5.7 mm (sensitivity = 74.1% and specificity = 100%).
  
  
  CONCLUSIONS
  ONSD measurements correlate with noninvasive and invasive measurements of the ICP, and with head computed tomography scan findings in brain-injured adults. Hence, optic nerve sonography may serve as an additional diagnostic tool that could alert clinicians to the presence of elevated ICP, whenever invasive ICP evaluation is contraindicated and/or is not available. This trial is International Standard Randomised Controlled Trial Number registered (ISRCTN 91941687).
authors.affiliation: Second Department of Radiology, Attikon University Hospital, 1 Rimin st, 124 62, Athens, Greece.
authors.forename: Theodoros
authors.initials: T
authors.lastname: Soldatos
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Karakitsos
authors.forename: Katerina
authors.initials: K
authors.lastname: Chatzimichail
authors.forename: Matilda
authors.initials: M
authors.lastname: Papathanasiou
authors.forename: Athanasios
authors.initials: A
authors.lastname: Gouliamos
authors.forename: Andreas
authors.initials: A
authors.lastname: Karabinis
mesh_terms: D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging; D001930:Brain Injuries / Q000175:diagnosis*; D016022:Case-Control Studies; D002408:Catheters, Indwelling; D003422:Critical Care / Q000379:methods; D005260:Female; D015600:Glasgow Coma Scale; D006801:Humans; D015601:Injury Severity Score; D007362:Intensive Care Units; D007427:Intracranial Pressure; D008297:Male; D008875:Middle Aged; D009900:Optic Nerve / Q000000981:diagnostic imaging*; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D017585:Ultrasonography, Doppler, Transcranial