title: Measurement of Optic Nerve Sheath Diameter: Differences between Methods? A Pilot Study.
abstract: BACKGROUND
  Quantification of the optic nerve sheath diameter is a promising approach for the detection of elevated intracranial pressure. The comparability of current methods is unclear. The objective of this study was to assess the relationship between optic nerve sheath diameter as measured with computed tomography, magnetic resonance tomography and ultrasound in patients without known optic nerve disease or increased intracranial pressure.
  
  
  METHODS
  15 patients (60.8 [years]±16.73 SD; 7 female) with paranasal sinus pathology in whom computed tomography and magnetic resonance imaging were performed underwent optic nerve sheath diameter measurements by ultrasound, as well as an ophthalmological examination. Ultrasound-, computed tomography- and magnetic resonance imaging-derived maximal optic nerve sheath diameter values 3 mm behind the globe were compared.
  
  
  RESULTS
  Optic nerve sheath diameter measured (n=30) by ultrasound (mean 6.2 [mm]±0.84 SD) was significantly (p<0.01) higher than optic nerve sheath diameter in computed tomography (5.2±1.11) or magnetic resonance imaging (5.3±1.14). There was no significant (p=0.24) difference between optic nerve sheath diameter measured in computed tomography and magnetic resonance tomography.
  
  
  CONCLUSIONS
  The comparability of optic nerve sheath diameter measurements in patients without known optic nerve disease and assumed normal intracranial pressure appears to be given between computed tomography and magnetic resonance tomography, while comparability between ultrasound and computed tomography or magnetic resonance tomography seems to be less reliable.
authors.affiliation: University Hospital Zurich, Department of Ophthalmology, Zurich, Switzerland (Chair: Prof. Klara Landau).
authors.forename: C
authors.initials: C
authors.lastname: Giger-Tobler
authors.affiliation: University Hospital Zurich, Department of Ophthalmology, Zurich, Switzerland (Chair: Prof. Klara Landau).
authors.forename: J
authors.initials: J
authors.lastname: Eisenack
authors.affiliation: University Hospital Zurich, Department of ENL, Zurich, Switzerland (Chair: Prof. Rudolf Probst).
authors.forename: D
authors.initials: D
authors.lastname: Holzmann
authors.affiliation: University Hospital Zurich, Department of Neuroradiology, Zurich, Switzerland (Chair: Prof. Anton Valavanis).
authors.forename: A
authors.initials: A
authors.lastname: Pangalu
authors.affiliation: Cantonal Hospital of St.Gallen, Department of Ophthalmology, St. Gallen, Switzerland (Chair: PD Dr. Christophe Valmaggia).
authors.forename: V
authors.initials: V
authors.lastname: Sturm
authors.affiliation: Cantonal Hospital of Aarau, Department of Ophthalmology, Aarau, Switzerland (Chair: Prof. Hanspeter E. Killer).
authors.forename: H E
authors.initials: HE
authors.lastname: Killer
authors.affiliation: University Hospital Zurich, Department of Ophthalmology, Zurich, Switzerland (Chair: Prof. Klara Landau).
authors.forename: K
authors.initials: K
authors.lastname: Landau
authors.affiliation: University Hospital Zurich, Department of Ophthalmology, Zurich, Switzerland (Chair: Prof. Klara Landau).
authors.forename: G P
authors.initials: GP
authors.lastname: Jaggi
mesh_terms: D001099:Arachnoid / Q000166:cytology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009887:Ophthalmoscopy / Q000379:methods*; D009900:Optic Nerve / Q000166:cytology*; D010865:Pilot Projects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014463:Ultrasonography / Q000379:methods*