title: Reliability of optic nerve ultrasound for the evaluation of patients with spontaneous intracranial hemorrhage.
abstract: BACKGROUND
  The aim of our study is to confirm the reliability of optic nerve ultrasound as a method to detect intracranial hypertension in patients with spontaneous intracranial hemorrhage, to assess the reproducibility of the measurement of the optic nerve sheath diameter (ONSD), and to verify that ONSD changes concurrently with intracranial pressure (ICP) variations.
  
  
  METHODS
  Sixty-three adult patients with subarachnoid hemorrhage (n = 34) or primary intracerebral hemorrhage (n = 29) requiring sedation and invasive ICP monitoring were enrolled in a 10-bed multivalent ICU. ONSD was measured 3 mm behind the globe through a 7.5-MHz ultrasound probe. Mean binocular ONSD was used for statistical analysis. ICP values were registered simultaneously to ultrasonography. Twenty-eight ONSDs were measured consecutively by two different observers, and interobserver differences were calculated. Twelve coupled measurements were taken before and within 1 min after cerebrospinal fluid (CSF) drainage to control elevated ICP.
  
  
  RESULTS
  Ninety-four ONSD measurements were analyzed. 5.2 mm proved to be the optimal ONSD cut-off point to predict raised ICP (>20 mmHg) with 93.1% sensitivity (95% CI: 77.2-99%) and 73.85% specificity (95% CI: 61.5-84%). ONSD-ICP correlation coefficient was 0.7042 (95% CI for r = 0.5850-0.7936). The median interobserver ONSD difference was 0.25 mm. CSF drainage to control elevated ICP caused a rapid and significant reduction of ONSD (from 5.89 ± 0.61 to 5 ± 0.33 mm, P < 0.01).
  
  
  CONCLUSIONS
  Our investigation confirms the reliability of optic nerve ultrasound as a non-invasive method to detect elevated ICP in intracranial hemorrhage patients. ONSD measurements proved to have a good reproducibility. ONSD changes almost concurrently with CSF pressure variations.
authors.affiliation: Department of Anesthesia and Critical Care, Ospedale SS Antonio e Biagio e Cesare Arrigo, via Venezia 16, 15100 Alessandria, Italy. rmoretti@ospedale.al.it
authors.forename: Riccardo
authors.initials: R
authors.lastname: Moretti
authors.forename: Barbara
authors.initials: B
authors.lastname: Pizzi
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Cassini
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Vivaldi
mesh_terms: D000328:Adult; D003627:Data Interpretation, Statistical; D006801:Humans; D019586:Intracranial Hypertension / Q000000981:diagnostic imaging*; D009900:Optic Nerve / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results; D013345:Subarachnoid Hemorrhage / Q000000981:diagnostic imaging*; D014463:Ultrasonography / Q000592:standards*