Document Detail

Correlation of optic nerve sheath diameter with direct measurement of intracranial pressure.
MedLine Citation:
PMID:  18275454     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Measurements of the optic nerve sheath diameter (ONSD) using bedside ultrasound (US) have been shown to correlate with clinical and radiologic signs and symptoms of increased intracranial pressure (ICP). OBJECTIVES: Previous literature has identified 5 mm as the ONSD measurement above which patients exhibit either clinical or radiologic signs of elevated ICP. The goals of this study were to evaluate the association between ONSD and ICP and to validate the commonly used ONSD threshold of 5 mm using direct measurements of ICP as measured by ventriculostomy. METHODS: A prospective blinded observational study was performed using a convenience sample of adult patients in both the emergency department (ED) and the neurologic intensive care unit (ICU) who had invasive intracranial monitors placed as part of their clinical care. Ocular USs were performed with a 10(-5) MHz linear probe. Emergency physicians (EPs) with previous ocular US experience performed ONSD measurements while blinded to the contemporaneous ICP reading obtained directly from invasive monitoring. The association between ONSD and ICP was assessed with the Spearman rank correlation coefficient, and a receiver operator characteristic (ROC) curve was created to determine the optimal ONSD cutoff to detect ICP > 20 cm H2O. RESULTS: Thirty-eight ocular USs were performed on 15 individual patients. Spearman rank correlation coefficient of ONSD and ICP was 0.59 (p < 0.0005) demonstrating a significant positive correlation. An ROC curve was created to assess the ability of ONSD to distinguish an abnormal ICP greater than 20 cm H2O. The area under the ROC curve was 0.93 (95% confidence interval [CI] = 0.84 to 0.99). Based on inspection of the ROC curve, ONSD > 5 mm performed well to detect ICP > 20 cm H(2)O with a sensitivity of 88% (95% CI = 47% to 99%) and specificity of 93% (95% CI = 78% to 99%). CONCLUSIONS: Using an ROC curve the authors systematically confirmed the commonly used threshold of ONSD > 5 mm to detect ICP > 20 cm H2O. This study directly correlates ventriculostomy measurements of ICP with US ONSD measurements and provides further support for the use of ONSD measurements as a noninvasive test for elevated ICP.
Heidi Harbison Kimberly; Sachita Shah; Keith Marill; Vicki Noble
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Publication Detail:
Type:  Journal Article; Validation Studies    
Journal Detail:
Title:  Academic emergency medicine : official journal of the Society for Academic Emergency Medicine     Volume:  15     ISSN:  1553-2712     ISO Abbreviation:  Acad Emerg Med     Publication Date:  2008 Feb 
Date Detail:
Created Date:  2008-02-15     Completed Date:  2008-02-28     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9418450     Medline TA:  Acad Emerg Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  201-4     Citation Subset:  IM    
Department of Emergency Medicine, Massachusetts General Hospital, Boston, MA, USA.
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MeSH Terms
Academic Medical Centers
Aged, 80 and over
Emergency Service, Hospital
Intracranial Hemorrhages / complications
Intracranial Hypertension / diagnosis*,  etiology
Middle Aged
Optic Nerve / ultrasonography*
Prospective Studies
Single-Blind Method
Urban Population
Wounds and Injuries / complications

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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