title: The relationship between transorbital ultrasound measurement of the optic nerve sheath diameter (ONSD) and invasively measured ICP in children. : Part II: age-related ONSD cut-off values and patency of the anterior fontanelle.
abstract: OBJECTIVE
  To analyse the diagnostic accuracy of age-related optic nerve sheath diameter (ONSD) cut-off values in children for detecting raised intracranial pressure (ICP) and to assess the benefit of using patency of the anterior fontanelle in describing a different set of cut-off values.
  
  
  METHODS
  The ONSD measurement was performed prior to invasive ICP measurement in children under general anesthesia. The diagnostic accuracy of the ONSD measurement was compared to ICP at thresholds of 20, 15, 10, and 5 mmHg. This was further analysed in children above and below the age of 1 year, with a subgroup analysis of age at 4 years, and assessment of the anterior fontanelle (AF) as a reliable physiological marker in part II of this study.
  
  
  RESULTS
  Data from 174 children were analysed. In children ≤1 year old, the ONSD measurement with the best diagnostic accuracy for detecting ICP ≥ 20 mmHg was 5.16 mm, compared to 5.75 mm in children >1 year old (p < 0.001). In addition, patency of the anterior fontanelle (AF) was found to be a useful clinical marker for defining different ONSD cut-off values at ICP thresholds of 20, 15, 10 and 5 mmHg.
  
  
  CONCLUSIONS
  Transorbital ultrasound measurement of the ONSD is a reliable non-invasive marker of ICP particularly at higher thresholds of 20 and 15 mmHg. Patency of the AF is a useful clinical marker for defining different ONSD cut-off values in children.
authors.affiliation: Paediatric Neurosurgery Unit, Division of Neurosurgery, Faculty of Health Sciences, Red Cross War Memorial Children's Hospital, University of Cape Town, Cape Town, South Africa. llewesp@yahoo.com.
authors.forename: Llewellyn C
authors.initials: LC
authors.lastname: Padayachy
authors.affiliation: Trauma Unit, Red Cross War Memorial Children's Hospital, University of Cape Town, Cape Town, South Africa.
authors.forename: Vaishali
authors.initials: V
authors.lastname: Padayachy
authors.affiliation: Department of Statistical Sciences, University of Cape Town, Cape Town, South Africa.
authors.forename: Ushma
authors.initials: U
authors.lastname: Galal
authors.affiliation: Paediatric Opthalmology Unit, Red Cross War Memorial Children's Hospital, University of Cape Town, Cape Town, South Africa.
authors.forename: Travis
authors.initials: T
authors.lastname: Pollock
authors.affiliation: Paediatric Neurosurgery Unit, Division of Neurosurgery, Faculty of Health Sciences, Red Cross War Memorial Children's Hospital, University of Cape Town, Cape Town, South Africa.
authors.forename: A Graham
authors.initials: AG
authors.lastname: Fieggen
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000375:Aging; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D055762:Cranial Fontanelles / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007223:Infant; D019586:Intracranial Hypertension / Q000000981:diagnostic imaging / Q000473:pathology*; D007427:Intracranial Pressure / Q000502:physiology*; D008297:Male; D009186:Myelin Sheath / Q000473:pathology*; D009900:Optic Nerve / Q000000981:diagnostic imaging*; D009915:Orbit / Q000000981:diagnostic imaging; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D014463:Ultrasonography
keywords: ICP monitoring; Non-invasive; Optic nerve sheath diameter; Ultrasound