title: Intra- and interobserver reliability of transorbital sonographic assessment of the optic nerve sheath diameter and optic nerve diameter in healthy adults.
abstract: OBJECTIVE
  Transorbital optic nerve sonography (TOS) can measure the optic nerve inclusive the sheath diameter (ONSD) and the optic nerve diameter (OND), which are useful parameters in the diagnosis of several neurological disorders. Data on the reproducibility of TOS are, however, required to use B-mode sonography for clinical purposes. The aim of this study was to assess intra- and interobserver reliability of ultrasound-based evaluations of both OND and ONSD in healthy subjects.
  
  
  METHODS
  Using a 4-11-MHz linear array transducer, the OND and ONSD of 20 healthy subjects were independently measured by two expert investigators.
  
  
  RESULTS
  Depicting the optic nerve and its sheath was possible in all subjects. The intra- and interobserver reliability was high for both ONSD and OND measurements. Intraobserver agreement, analyzed with Cronbach´s Alpha, was higher for ONSD (range: 0.69-0.72) than for OND measurements (range: 0.55-0.65). No differences in interobserver reliability between ONSD and OND measurements were found (p = 0.83 for right and 0.47 for left eye).
  
  
  CONCLUSIONS
  Transorbital B-mode sonography is a feasible method to assess both ONSD and OND with a high intra- and interobserver reliability. Technical difficulties in differentiating the optic nerve from its sheaths may explain the lower intraobserver agreement for OND than that for ONSD measurements.
authors.affiliation: Department of Neurology, General Hospital, Merano, Italy ; Section of Neurology, Department of Translational Medicine, University of Piedmont East ''A. Avogadro'', Novara, Italy.
authors.forename: Piergiorgio
authors.initials: P
authors.lastname: Lochner
authors.affiliation: Section of Neurology, Department of Translational Medicine, University of Piedmont East ''A. Avogadro'', Novara, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Coppo
authors.affiliation: Section of Neurology, Department of Translational Medicine, University of Piedmont East ''A. Avogadro'', Novara, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Cantello
authors.affiliation: Department of Neurology, General Hospital, Merano, Italy.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Nardone
authors.affiliation: Section of Neurology, Department of Translational Medicine, University of Piedmont East ''A. Avogadro'', Novara, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Naldi
authors.affiliation: Neurology Unit, Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy.
authors.forename: Maurizio A
authors.initials: MA
authors.lastname: Leone
authors.affiliation: Section of Clinical Neurology, Department of Neurological and Movement Sciences, University of Verona, Piazzale L.A. Scuro, 10-37134 Verona, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Brigo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008875:Middle Aged; D009900:Optic Nerve / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D014159:Transducers; D014463:Ultrasonography
keywords: Interobserver reliability; Intraobserver reliability; Optic nerve diameter; Optic nerve sheath diameter; Transorbital sonography