Bedside Sonographic Measurement of Optic Nerve Sheath Diameter as a Predictor of Increased Intracranial Pressure in Children
Received 29 July 2008; received in revised form 21 October 2008; accepted 25 November 2008. published online 27 January 2009.
Study objective
We investigate the test performance of emergency physician–performed sonographic measurement of optic nerve sheath diameter for diagnosis of increased intracranial pressure.
Methods
Children between the ages of 0 and 18 years with suspected increased intracranial pressure were prospectively recruited from the emergency department and ICU of an urban, tertiary-level, freestanding pediatric facility. Pediatric emergency physicians with goal-directed training in ophthalmic sonography measured optic nerve sheath diameter. Images were recorded and subsequently reviewed by a pediatric ophthalmologist and an ophthalmic sonographer, both of whom were blind to the patient's clinical condition. Measurements obtained by the ophthalmic sonographer were considered the criterion standard. An optic nerve sheath diameter greater than 4.0 mm in subjects younger than 1 year and greater than 4.5 mm in older children was considered abnormal. The diagnosis of increased intracranial pressure was based on results of cranial imaging or direct measurement of intracranial pressure.
Results
Sixty-four patients were recruited, of whom 24 (37%) had a confirmed diagnosis of increased intracranial pressure. The sensitivity of optic nerve sheath diameter as a screening test for increased intracranial pressure was 83% (95% confidence interval [CI] 0.60 to 0.94); specificity was 38% (95% CI 0.23 to 0.54); positive likelihood ratio was 1.32 (95% CI 0.97 to 1.79) and negative likelihood ratio was 0.46 (95% CI 0.18 to 1.23). There was fair to good interobserver agreement between the pediatric emergency physician and ophthalmic sonographer (κ 0.52) and pediatric ophthalmologist (κ 0.64).
Conclusion
The sensitivity and specificity of bedside sonographic measurement of optic nerve sheath diameter is inadequate to aid medical decisionmaking in children with suspected increased intracranial pressure. Pediatric emergency physicians with focused training by a pediatric ophthalmologist familiar with ophthalmic sonography can measure optic nerve sheath diameter accurately.
aDepartment of Pediatrics, University of Tennessee Health Sciences Center, Le Bonheur Children's Medical Center, Memphis, TN
bDepartment of Ophthalmology, University of Tennessee Health Sciences Center, Le Bonheur Children's Medical Center, Memphis, TN
Address for correspondence: Audrey Le, MD, Le Bonheur Children's Medical Center, Emergency Department, 50 North Dunlap Street, Memphis, TN 38104
Author contributions: AL and JP conceived the study and designed the trial. AL was responsible for patient recruitment and data management. MEH and MES provided training in ophthalmic sonography and served as independent reviewers of all images. TS assisted with recruiting. DS provided statistical advice and analyzed the data. AL and JP drafted the article, and all authors contributed substantially to its revision. AL takes responsibility for the paper as a whole.
Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article that might create any potential conflict of interest. The authors have stated that no such relationships exist. See the Manuscript Submission Agreement in this issue for examples of specific conflicts covered by this statement.
Publication date: Available online January 23, 2009.
ABSTRACT