title: Transorbital sonography in acute optic neuritis: a case-control study.
abstract: OBJECTIVE
  Acute unilateral optic neuritis is associated with a thickening of the retrobulbar portion of the optic nerve as revealed by transorbital sonography, but no comparison has been made between nerve sheath diameter and optic nerve diameter in patients with acute optic neuritis versus healthy controls. We evaluated optic nerve sheath diameter and optic nerve diameter in patients with acute optic neuritis and healthy controls and compared optic nerve sheath diameter and optic nerve diameter with visual-evoked potentials in patients.
  
  
  METHODS
  A case-control study was performed in 2 centers. Twenty-one consecutive patients with onset of visual loss during the prior 10 days and established acute noncompressive unilateral optic neuritis were compared with 21 healthy controls, matched for sex and age (±5 years). Two experienced vascular sonographers performed the study by using B-mode transorbital sonography. Visual-evoked potentials were performed on the same day as the transorbital sonography and were evaluated by an expert neurophysiologist. Sonographers and the neurophysiologist were blinded to the status of the patient or control and to clinical information, including the side of the affected eye.
  
  
  RESULTS
  The median optic nerve sheath diameter was thicker on the affected side (6.3 mm; interquartile range, 5.9-7.2 mm) compared with the nonaffected side (5.5 mm; interquartile range, 5.1-6.2 mm; P < .0001) and controls (5.2 mm; interquartile range, 4.8-5.5 mm; P < .0001). The median optic nerve diameter was 3.0 mm (range, 2.8-3.1 mm) on the affected side and 2.9 mm (range, 2.8-3.1 mm) on the nonaffected side (P = not significant.). Both sides were thicker than those in controls (2.7 mm; interquartile range, 2.5-2.8 mm; P = .001 and .009). No correlation was found between optic nerve sheath diameter and optic nerve diameter and amplitude and latency of visual-evoked potentials in patients with optic neuritis.
  
  
  CONCLUSIONS
  Transorbital sonography is a promising tool to support the clinical diagnosis of acute optic neuritis. Further studies are needed to define its specific role in the diagnosis and follow-up of optic neuritis.
authors.affiliation: From the Department of Neurology (P.L., F.B., F.T.), General Hospital, Merano, Italy Section of Neurology (P.L., R.C., L.C., G.S., C.C.), Department of Translational Medicine, University of Piemonte Orientale "A. Avogadro," Novara, Italy piergiorgio.lochner@gmail.com.
authors.forename: P
authors.initials: P
authors.lastname: Lochner
authors.affiliation: Section of Neurology (P.L., R.C., L.C., G.S., C.C.), Department of Translational Medicine, University of Piemonte Orientale "A. Avogadro," Novara, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Cantello
authors.affiliation: From the Department of Neurology (P.L., F.B., F.T.), General Hospital, Merano, Italy Department of Neurological and Movement Sciences (F.B.), Section of Clinical Neurology, University of Verona, Verona, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Brigo
authors.affiliation: Section of Neurology (P.L., R.C., L.C., G.S., C.C.), Department of Translational Medicine, University of Piemonte Orientale "A. Avogadro," Novara, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Coppo
authors.affiliation: Department of Neurology (R.N.), Christian Doppler Clinic, Paracelsus Medical University, Salzburg, Austria.
authors.forename: R
authors.initials: R
authors.lastname: Nardone
authors.affiliation: From the Department of Neurology (P.L., F.B., F.T.), General Hospital, Merano, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Tezzon
authors.affiliation: Head and Neck Department (O.R.), SCDU Neurology, MS Centre, AOU "Maggiore della Carità," Novara, Italy.
authors.forename: O
authors.initials: O
authors.lastname: Raymkulova
authors.affiliation: Section of Neurology (P.L., R.C., L.C., G.S., C.C.), Department of Translational Medicine, University of Piemonte Orientale "A. Avogadro," Novara, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Strigaro
authors.affiliation: Section of Neurology (P.L., R.C., L.C., G.S., C.C.), Department of Translational Medicine, University of Piemonte Orientale "A. Avogadro," Novara, Italy Interdisciplinary Research Center of Autoimmune Diseases (C.C., M.A.L.), Novara, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Comi
authors.affiliation: Interdisciplinary Research Center of Autoimmune Diseases (C.C., M.A.L.), Novara, Italy.
authors.forename: M A
authors.initials: MA
authors.lastname: Leone
mesh_terms: D000208:Acute Disease; D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D009900:Optic Nerve / Q000000981:diagnostic imaging; D009902:Optic Neuritis / Q000000981:diagnostic imaging*; D009915:Orbit / Q000000981:diagnostic imaging*; D012680:Sensitivity and Specificity; D014463:Ultrasonography