Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune disease of the central nervous system that primarily attacks the optic nerves and the spinal cord. For many years it was mistaken for a severe form of multiple sclerosis (MS), but we now understand that NMOSD is a separate condition — with its own antibody, its own appearance on MRI, and its own treatments. Getting that distinction right is one of the most important jobs in neuroimmunology, because several medications used for MS can actually make NMOSD worse.
If you have recently been told you may have NMOSD, there is real reason for optimism. In 2026, NMOSD has changed from a condition with very limited options to one with several purpose-built therapies that powerfully reduce the risk of relapse. With an accurate diagnosis and modern treatment, most people achieve long periods of stability.
What is NMOSD?
In most people with NMOSD, the immune system produces an antibody against a protein called aquaporin-4 (AQP4) — a water channel found on astrocytes, the support cells of the brain and spinal cord. When this antibody binds to AQP4 it triggers inflammation and damage, most often in the optic nerves and spinal cord. Because the target is different from MS (which attacks the myelin coating of nerves), the disease behaves differently and responds to different drugs.
NMOSD is rare — far less common than MS — and can affect people of any age, including children and older adults. It is more common in women, and in people of Asian, African and Indigenous backgrounds.
Symptoms of NMOSD
Attacks (relapses) tend to be more severe than in MS and may include:
👁️ Optic neuritis
Painful loss of vision in one or both eyes, sometimes severe. NMOSD optic neuritis is more likely to affect both eyes, or to recur, than in MS.
🦴 Transverse myelitis
Inflammation of the spinal cord causing weakness, numbness, and bladder or bowel problems. In NMOSD this often involves a long segment of the cord (longitudinally extensive transverse myelitis).
🤢 Area postrema syndrome
Episodes of intractable hiccups, nausea or vomiting caused by a lesion in a specific part of the brainstem. This is a characteristic and easily-missed clue to NMOSD.
🧠 Brainstem and brain syndromes
Less common, but recognised.
Why the distinction from MS matters: some effective MS drugs can make NMOSD worse. Testing for the AQP4 antibody before starting any long-term treatment protects you from the wrong medication.
How NMOSD differs from multiple sclerosis
| Feature | How NMOSD differs |
|---|---|
| The antibody | NMOSD is usually AQP4-IgG positive; MS is not. |
| MRI pattern | NMOSD spinal cord lesions are typically long; MS cord lesions are short. Brain lesions differ too. |
| Spinal fluid | Oligoclonal bands are usually absent in NMOSD, but present in around 95% of people with MS. |
| Attack severity | NMOSD relapses are often more severe, so preventing them is the priority. |
How NMOSD is diagnosed
Diagnosis follows international criteria and combines:
🧪 AQP4-IgG antibody test
A blood test using a sensitive cell-based assay. A positive result, together with a typical clinical syndrome, confirms NMOSD.
🧲 MRI of the brain and spinal cord
MRI (magnetic resonance imaging) looking for the characteristic long cord lesion, optic nerve involvement, or an area postrema lesion.
🔬 MOG antibody test
To check for MOG antibody disease, a separate condition that can look similar.
💧 Lumbar puncture and blood tests
To support the diagnosis and exclude mimics.
Modern treatment of NMOSD
Treating an acute attack
Relapses are treated promptly with high-dose intravenous corticosteroids and, for severe attacks, plasma exchange (PLEX), which removes the harmful antibody from the blood. Early treatment improves recovery.
Preventing relapses
This is where care has been transformed. For AQP4-positive NMOSD, preventive treatment in Australia is structured by line of therapy:
| Therapy | How it works | Place in therapy |
|---|---|---|
| Rituximab | Depletes CD20 B-cells | First-line preventive therapy |
| Ravulizumab (Ultomiris) | Blocks complement (C5), long-acting | Second-line, as per PBS criteria |
| Eculizumab (Soliris) | Blocks complement (C5) | Complement-inhibitor option |
Choosing between these therapies — and arranging access and monitoring — is a subspecialty decision based on your antibody status, how active the disease is, other health conditions, and your preferences. Access arrangements in Australia change over time; general patient information is available through MS Australia.
* Satralizumab (Enspryng, an IL-6 receptor blocker) and inebilizumab (Uplizna, a CD19 B-cell depleter) are purpose-built NMOSD therapies used overseas, but at present they are not clinically available in Australia outside a clinical trial.
Reassuring: with one of these modern preventive treatments, the great majority of people with NMOSD have far fewer relapses — and many have none for years at a time.
Pregnancy and NMOSD
NMOSD can be more active around pregnancy and after birth, and treatment choices need careful planning. If you are considering pregnancy, raise it early so your treatment can be optimised before and after delivery, working alongside your obstetrician.
Outlook
Because NMOSD damage accumulates with each relapse, the goal of treatment is simple: prevent relapses. Thanks to modern therapies, that goal is now achievable for most people, and the long-term outlook has improved dramatically compared with even a decade ago.
NMOSD care at East Neurology
Dr Tal Koren provides subspecialty neuroimmunology care for NMOSD at East Neurology in Bondi Junction — from antibody testing and diagnosis through to selecting and monitoring modern preventive therapy, and coordinating acute relapse treatment. He works alongside Dr Ron Granot and the wider team.
Frequently asked questions
Is NMOSD the same as MS?
No. They can look similar at first, but NMOSD has a different cause (the AQP4 antibody), a different MRI pattern, and different treatments. Distinguishing them is essential, because some MS drugs can worsen NMOSD.
Can NMOSD be cured?
There is no cure yet, but modern preventive therapies are highly effective at stopping relapses — which is what protects long-term function.
What if my antibody test is negative?
A proportion of people are AQP4-negative. Diagnosis then depends on the clinical picture, MRI, and excluding MOG antibody disease and MS. Subspecialty assessment is particularly valuable in these cases.
Related reading
- Neuroimmunology — overview of conditions and team
- Multiple sclerosis — how NMOSD differs
- MOG antibody disease (MOG-AD)
- Dr Tal Koren — Consultant Neurologist (Neuroimmunology)
External resources
- MS Australia — information and support
This page is general information about NMOSD and is not personal medical advice. Please contact the practice to discuss your individual situation.
Book an appointment
To arrange a consultation about NMOSD with Dr Tal Koren, ask your GP or specialist for a referral, then get in touch — new patients and second opinions are welcome.
Or call 02 9388 0615. East Neurology is a private practice; we do not bulk bill (including DVA cardholders) — Medicare claims are processed for you on the day.