This resource has been developed by Alexion, AstraZeneca Rare Disease.
Neuromyelitis Optica Spectrum Disorder (NMOSD) is a rare, chronic autoimmune neurological disease that is characterised by inflammation and demyelination in the spinal cord, optic nerve and brain. The main clinical features of NMOSD include recurrent attacks or relapses of optic neuritis, transverse myelitis, persistent vomiting and intractable hiccups.1-3

Attacks can be very debilitating and may lead to permanent disability, such as blindness and paralysis,2,3 or even death.4 Within 5 years of the first attack, about half of patients will be blind and require a wheelchair while a third will have died if NMOSD is untreated.3

Seropositive NMOSD, a subset of NMOSD, involves circulating IgG1 autoantibodies targeting the bidirectional water channel protein aquaporin-4 (AQP4), which is expressed at the plasma membrane of astrocytes throughout the central nervous system (CNS).5,6
An acute attack of NMOSD is a new onset of patient-reported or objectively observed neurological signs and symptoms or worsening of existing neurological symptoms attributable to NMOSD in the absence of other recognised causes.7

Suspected Acute Attack
In the case of a suspected acute attack, an urgent neurological evaluation should be performed.8
Information for healthcare professionals only.

Prompt treatment of acute attacks is crucial to prevent the physical impairment in NMOSD that accumulates with each relapse9 and to improve clinical outcomes.10,11

Irreversible damage may be prevented by reducing the acute inflammation.12

Dependent on the clinical presentation, below steps may be considered by the treating physician:

  1. High-dose intravenous steroids may be used promptly to control attacks.1,13,22
  2. If improvement is not immediate or if neurological impairment is severe, plasma exchange may be implemented early in order to optimise recovery.1,10,13 Plasma exchange usually consists of five treatments performed every other day.13
  3. Plasma exchange may also be used in combination with steroids.12,14
  4. Intravenous immunoglobulin (IVIgG) treatment has been used but supporting data are scarce.15
A number of diseases can mimic some of the clinical characteristics of NMOSD because they involve the optic nerves and/or the spinal cord.18,19 These diseases include stroke, infections and other neurological and systemic autoimmune diseases (e.g. multiple sclerosis (MS) and systemic lupus erythematosus).18,19 Other potential differential diagnoses are compression and toxic or metabolic causes.20,21

A differential diagnosis is therefore important to confirm the presence of NMOSD, particularly as this has important treatment implications.
A patient with NMOSD may be receiving certain medications which can increase their susceptibility to meningococcal infection.19 Physicians should be alert to the possibility that a patient’s symptoms may be due to a meningococcal infection.19
1. Broadley S, Khalili E, Heshmat S, et al. Neuromyelitis optica spectrum disorder. ACNR 2017;17:11–4. 2. Campbell A, Ogundipe OA. Neuromyelitis optica spectrum disorder presenting in an octogenarian. BMJ Case Rep 2018;2018:bcr2018225601.  3. Huda S, Whittam D, Bhojak M, et al. Neuromyelitis optica spectrum disorders. Clin Med (Lond) 2019;19:169–76. 4. Du Q, Shi Z, Chen H, et al. Mortality of neuromyelitis optica spectrum disorders in a Chinese population. Ann Clin Transl Neurol 2021;8:1471–9. 5. Papadopoulos MC, Verkman AS. Aquaporin 4 and neuromyelitis optica. Lancet Neurol 2012;11:535–44. 6. Papadopoulos MC, Verkman AS. Aquaporin water channels in the nervous system. Nat Rev Neurosci 2013;14:265–77. 7. Ma X, Kermode AG, Hu X, et al. Risk of relapse in patients with neuromyelitis optica spectrum disorder: recognition and preventive strategy.Mult Scler Relat Disord 2020;46:102522. 8. Jarius S, Aktas O, Ayzenberg I, et al. Update on the diagnosis and treatment of neuromyelits optica spectrum disorders (NMOSD) – revised recommendations of the Neuromyelitis Optica Study Group (NEMOS). Part I: Diagnosis and differential diagnosis. J Neurol 2023;270:3341–68. 9. Kleiter I, Gahlen A, Borisow N, et al. Neuromyelitis optica: evaluation of 871 attacks and 1,153 treatment courses. Ann Neurol 2016;79:206–16. 10. Bonnan M, Valentino R, Debeugny S, et al. Short delay to initiate plasma exchange is the strongest predictor of outcome in severe atta cks of NMO spectrum disorders. J Neurol Neurosurg Psychiatry 2018;89:346–51. 11. Kleiter I, Gahlen A, Borisow N, et al. Apheresis therapies for NMOSD attacks: a retrospective study of 207 therapeutic interventions. Neurol Neuroimmunol Neuroinflamm 2018;5:e504. 12. Chu YC, Huang TL. What's new in neuromyelitis optica spectrum disorder treatment? Taiwan J Ophthalmol 2022;12:249–63. 13. Sherman E, Han MH. Acute and chronic management of neuromyelitis optica spectrum disorder. Curr Treat Options Neurol 2015;17:48. 14. Siritho S, Nopsopon T, Pongpirul K. Therapeutic plasma exchange vs conventional treatment with intravenous high dose steroid for neuromyelitis optica spectrum disorders (NMOSD): a systematic review and meta-analysis. J Neurol 2021;268:4549–62. 15. Contentti EC, Lopez PA, Pettinicchi JP, et al. Assessing attacks and treatment response rates among adult patients with NMOSD and MOGAD: Data from a nationwide registry in Argentina. Mult Scler J Exp Transl Clin 2021;7:20552173211032334. 16. Yang X, Li X, Lai M, et al. Pain symptoms in optic neuritis. Front Pain Res (Lausanne) 2022;3:865032. 17. Wingerchuk DM, Lennon VA, Lucchinetti CF, et al. The spectrum of neuromyelitis optica. Lancet Neurol 2007;6:805–5. 18. Kim SM, Kim SJ, Lee HJ, et al. Differential diagnosis of neuromyelitis optica spectrum disorders. Ther Adv Neurol Disord 2017;10:265–89. 19. Lana-Peixoto MA, Talim N. Neuromyelitis optica spectrum disorder and anti-mog syndromes. Biomedicines 2019;7:42. 20. Hoorbakht H, Bagherkashi F. Optic neuritis, its differential diagnosis and management. Open Ophthalmol J 2012;6:65–72. 21. Jacob A, Weinshenker BG. An approach to the diagnosis of acute transverse myelitis. Semin Neurol 2008;28:105–20. 22. Kuempfel T, Giglhuber K, Aktas O et al. Update on the diagnosis and treatment of neuromyelitis optica spectrum disorders (NMOSD) – revised recommendations (NEMOS Group) J of Neurology 2024;271:141-176