title: [Neuromyelitis optica].
abstract: BACKGROUND
  Neuromyelitis optica (NMO) is a rare autoimmune inflammatory disease of the central nervous system that is characterized mainly by recurrent optic neuritis and longitudinally extensive transverse myelitis. The aim of this article is to present current knowledge on the clinical features, diagnosis, pathogenesis and treatment of the condition.
  
  
  METHODS
  The article is based on a discretionary selection of English-language original articles, meta-analyses and review articles found in PubMed, and on the authors' own experience with the patient group.
  
  
  RESULTS
  Neuromyelitis optica was previously assumed to be a variant of multiple sclerosis (MS), but the discovery of aquaporin-4 antibodies in patients with neuromyelitis optica has led to this view being revised. The cause of the condition is still unknown, but it has been shown that the antibodies bind selectively to a water channel expressed mainly on astrocytes at the blood-brain-barrier, which has an important role in the regulation of brain volume and ion homeostasis. Clinically, the condition presents as optic neuritis and/or transverse myelitis. A diagnosis is made on the basis of case history, clinical examination, MRI of the brain and spinal cord, analysis of cerebrospinal fluid, visual evoked potentials and a blood test with analysis of aquaporin-4 antibodies. Once a diagnosis has been made, rapid treatment is important. In the acute phase, intravenous methylprednisolone is recommended. There are several options for preventative treatment, but the primary recommendations are oral prednisolone and azathioprine or intravenous infusion of rituximab. Treatment is distinct from the treatment of MS and some of the immunomodulatory drugs commonly used in MS can lead to worsening of neuromyelitis optica.
  
  
  CONCLUSIONS
  The condition is an important differential diagnosis of MS, but differs from MS in terms of clinical features, prognosis and treatment. Patients have a high risk of sequelae following relapses, and therefore early diagnosis and treatment is important.
authors.forename: Silje Agnethe Stokke
authors.initials: SA
authors.lastname: Kvistad
authors.forename: Stig
authors.initials: S
authors.lastname: Wergeland
authors.forename: Øivind
authors.initials: Ø
authors.lastname: Torkildsen
authors.forename: Kjell-Morten
authors.initials: KM
authors.lastname: Myhr
authors.forename: Christian A
authors.initials: CA
authors.lastname: Vedeler
mesh_terms: D058846:Antibodies, Monoclonal, Murine-Derived / Q000008:administration & dosage / Q000627:therapeutic use; D051401:Aquaporin 4 / Q000276:immunology; D001253:Astrocytes / Q000276:immunology; D001323:Autoantibodies / Q000097:blood; D001379:Azathioprine / Q000008:administration & dosage / Q000627:therapeutic use; D003937:Diagnosis, Differential; D006801:Humans; D007155:Immunologic Factors / Q000008:administration & dosage / Q000627:therapeutic use; D007166:Immunosuppressive Agents / Q000008:administration & dosage / Q000627:therapeutic use; D008279:Magnetic Resonance Imaging; D008775:Methylprednisolone / Q000008:administration & dosage / Q000627:therapeutic use; D009103:Multiple Sclerosis / Q000175:diagnosis; D009471:Neuromyelitis Optica / Q000175:diagnosis / Q000188:drug therapy / Q000276:immunology / Q000473:pathology; D000069283:Rituximab
chemical_list: D058846:Antibodies, Monoclonal, Murine-Derived; D051401:Aquaporin 4; D001323:Autoantibodies; D007155:Immunologic Factors; D007166:Immunosuppressive Agents; D000069283:Rituximab; D001379:Azathioprine; D008775:Methylprednisolone