title: Bedside sonographic measurement of optic nerve sheath diameter as a predictor of increased intracranial pressure in children.
abstract: 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 (kappa 0.52) and pediatric ophthalmologist (kappa 0.64).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Pediatrics, University of Tennessee Health Sciences Center, Le Bonheur Children's Medical Center, Memphis, 38104, USA. ahlegory@gmail.com
authors.forename: Audrey
authors.initials: A
authors.lastname: Le
authors.forename: Mary Ellen
authors.initials: ME
authors.lastname: Hoehn
authors.forename: Mary E
authors.initials: ME
authors.lastname: Smith
authors.forename: Thomas
authors.initials: T
authors.lastname: Spentzas
authors.forename: David
authors.initials: D
authors.lastname: Schlappy
authors.forename: Jay
authors.initials: J
authors.lastname: Pershad
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002983:Clinical Competence; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D015278:Intensive Care Units, Pediatric; D019586:Intracranial Hypertension / Q000000981:diagnostic imaging*; D016013:Likelihood Functions; D008297:Male; D009900:Optic Nerve / Q000000981:diagnostic imaging* / Q000473:pathology*; D019095:Point-of-Care Systems; D012372:ROC Curve; D014463:Ultrasonography