title: NMO-IgG predicts the outcome of recurrent optic neuritis.
abstract: OBJECTIVE
  To determine the prognostic value of neuromyelitis optica (NMO)-immunoglobulin G (IgG) in patients with recurrent optic neuritis (ON). The aquaporin-4-specific serum autoantibody, NMO-IgG, is a biomarker for NMO and relapsing transverse myelitis. Recurrent ON may herald multiple sclerosis (MS) or NMO, or it may occur as an isolated syndrome. The prognosis and response to therapy differs in each of these contexts.
  
  
  METHODS
  We evaluated 34 patients who were tested for NMO-IgG between 2000 and 2007 and who had two or more episodes of ON without satisfying a diagnosis of MS or NMO prior to serologic testing. Clinical data were available for 25 Mayo Clinic patients (5 NMO-IgG positive and 20 NMO-IgG negative) and for an additional 9 seropositive patients whose serum was referred to the Mayo Clinic Neuroimmunology laboratory for testing.
  
  
  RESULTS
  Twenty percent of the patients with recurrent ON seen at Mayo Clinic were seropositive. All NMO-IgG-positive patients (vs 65% NMO-IgG-negative patients) had at least one attack with visual acuity in the affected eye worse than 20/200 (p = 0.05). In seropositive patients for whom long-term follow-up was possible (median 8.9 years after the initial ON), 6 of 12 (50%) experienced an episode of myelitis and fulfilled criteria for NMO. In contrast, 1 of 15 seronegative patients (6.7%) fulfilled McDonald criteria for MS (p = 0.03). Seropositive patients had a final visual score which was worse than that of seronegative patients (p = 0.02).
  
  
  CONCLUSIONS
  Neuromyelitis optica (NMO)-immunoglobulin G seropositivity predicts poor visual outcome and development of NMO. Seropositive recurrent optic neuritis is a limited form of NMO.
authors.affiliation: Department of Neurology, Mayo Clinic College of Medicine, 200 First St SW, Rochester, MN 55905, USA.
authors.forename: M
authors.initials: M
authors.lastname: Matiello
authors.forename: V A
authors.initials: VA
authors.lastname: Lennon
authors.forename: A
authors.initials: A
authors.lastname: Jacob
authors.forename: S J
authors.initials: SJ
authors.lastname: Pittock
authors.forename: C F
authors.initials: CF
authors.lastname: Lucchinetti
authors.forename: D M
authors.initials: DM
authors.lastname: Wingerchuk
authors.forename: B G
authors.initials: BG
authors.lastname: Weinshenker
mesh_terms: D000293:Adolescent; D000328:Adult; D001323:Autoantibodies / Q000097:blood*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D008279:Magnetic Resonance Imaging; D008297:Male; D009471:Neuromyelitis Optica / Q000175:diagnosis* / Q000276:immunology* / Q000517:prevention & control; D009902:Optic Neuritis / Q000175:diagnosis / Q000276:immunology / Q000517:prevention & control; D011237:Predictive Value of Tests; D055502:Secondary Prevention; D016896:Treatment Outcome
chemical_list: D001323:Autoantibodies; D007074:Immunoglobulin G