Neuromyelitis Optica Spectrum Disorder (NMOSD)

Inflammatory, antibody mediated, immunologic disease of the central nervous system that causes demyelination of the optic nerve and spinal cord

Aetiology

  • Greater incidence in females (5:1)
  • Average age of onset - mid 30s

Pathophysiology

  • Involves demyelination and inflammation of multiple spinal cord segments and the optic nerves

Clinical presentation

  • Patients can initially present with an acute flu-like illness (fever, myalgia, and headache)
  • Later, more suggestive and specific signs and symptoms of NMO may start to develop including optic neuritis or myelitis
  • As opposed to MS related optic neuritis, patients with NMOSD may have a worse visual prognosis after optic neuritis and many patients are left with residual visual disability

Investigations

Diagnostic criteria

  • Core clinical criteria:
    • Optic neuritis
    • Longitudinal transverse myelitis
    • Area prostrema syndrome
  • Bloods - anti-aquaporin 4 antibodies (99% specific but only 75% sensitive)
  • Diagnosis - 2 core clinical with aquaporin 4

Management

  • Steroids - IV methyprednisolone, prolonged oral course
  • Immunosuppression - cyclophosphamide, azathioprine
  • Plasma exchange
  • Monoclonal antibodies - rituximab