NMO — formerly called Devic's disease — causes severe attacks of optic neuritis and transverse myelitis. Unlike MS, it can cause permanent blindness and paralysis. Dr. Anand Karnam explains the diagnosis and the AQP4 antibody test.
Key Points
- NMO (Neuromyelitis Optica Spectrum Disorder) is an autoimmune attack on the optic nerve and spinal cord — distinct from MS.
- Hallmarks: severe visual loss in one eye AND transverse myelitis causing limb weakness — often severe and bilateral.
- AQP4-IgG antibody test in blood confirms the diagnosis in 75% of NMO cases.
- NMO relapses are often severe and leave permanent disability — aggressive immunosuppression must start immediately.
- Treatment is different from MS — some MS drugs (natalizumab, interferon) worsen NMO.
75%
of NMO patients are AQP4-IgG antibody positive
Source: NCBI
90%
of NMO patients have severe residual disability without immunosuppression
Source: Lancet Neurology
5×
more common in women than men — peak age 35–45
Source: NHS
"NMO and MS look similar on first presentation — but the treatment is different and getting it wrong is devastating. A patient with severe vision loss AND severe myelitis, especially if bilateral, gets my full antibody panel immediately. Correct diagnosis saves function."
Neuromyelitis Optica Spectrum Disorder (NMOSD), formerly Devic's disease, is an autoimmune inflammatory disease of the central nervous system that predominantly attacks the optic nerves (causing optic neuritis — vision loss in one or both eyes) and the spinal cord (causing transverse myelitis — limb weakness, sensory loss, and bladder dysfunction). Unlike MS, NMO attacks tend to be more severe, leave more residual disability, and are mediated by a specific antibody — anti-AQP4 (aquaporin-4) — that distinguishes NMO from MS.
Clinical Features
Optic neuritis in NMO: More severe than MS-associated optic neuritis — typically bilateral or sequential; severe vision loss; poor recovery. Transverse myelitis in NMO: Longitudinally extensive (involving 3 or more vertebral segments on MRI — LETM) — this length is a key distinguishing feature from MS. Produces severe bilateral leg weakness, sensory level, and severe bladder/bowel dysfunction. NMO attacks can cause permanent blindness or paraplegia — prevention of attacks is paramount.
Diagnosis
Anti-AQP4 antibody (serum or CSF): positive in 70–80% of NMOSD patients — highly specific. Anti-MOG antibody (AQP4-seronegative NMOSD is partially distinct — MOG antibody disease): positive in a significant proportion of seronegative cases. MRI brain (often normal or non-MS-like) and MRI spine (LETM). CSF: pleocytosis (white cells in the CSF — more so than typical MS).
Treatment
Acute attack: High-dose IV methylprednisolone (1g/day for 5 days); plasma exchange for severe attacks not responding to steroids. Maintenance prevention: Rituximab (anti-CD20 monoclonal antibody — depletes B cells that produce the AQP4 antibody) — most commonly used in India; azathioprine; mycophenolate mofetil; newer approved agents: eculizumab, inebilizumab, satralizumab. NOTE: MS immunomodulatory drugs (interferons, natalizumab, fingolimod) can worsen NMO — correct diagnosis before treatment is critical. Sri Anand CNC, Chanda Nagar, Hyderabad. Call +91 90633 66983.
Dr. Anand Karnam
DrNB Neurology · Sri Anand CNC, Chanda Nagar Hyderabad · Sri Anand Child and Neuro Center
DrNB-qualified Neurologist, Fellow of the World Headache Society (FWHS), and Headache Specialist with 12+ years of experience treating epilepsy, stroke, migraine, and movement disorders. Practices at Sri Anand Child and Neuro Center, Chanda Nagar, Hyderabad.
References & Sources
- 1.Neuromyelitis Optica — NCBI StatPearls — NCBI StatPearls
- 2.Neuromyelitis Optica — NHS — NHS UK
- 3.Multiple Sclerosis and Related Disorders — WHO — World Health Organization
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