🧠 Neuromyelitis optica (NMO), also known as Devic’s disease, is a severe autoimmune disorder of the CNS.
Unlike Multiple Sclerosis (MS), which primarily targets myelin, NMO is an astrocytopathy, driven by antibodies against aquaporin-4 on astrocytes.
It mainly affects the optic nerves and spinal cord, causing recurrent attacks of optic neuritis and transverse myelitis.
📌 About
- Distinct relapsing demyelinating CNS disease, separate from MS.
- Most common in young females.
- Associated with systemic autoimmune conditions (e.g. Sjögren’s, SLE).
⚠️ Aetiology
- Autoantibodies (anti-AQP4 IgG) target astrocytes in the CNS.
- ~20% are associated with anti-MOG (myelin oligodendrocyte glycoprotein) antibodies.
🌟 Key Features
- Severe myelopathy with longitudinally extensive cord lesions (>3 vertebral segments on MRI).
- Optic neuritis – often bilateral, severe, with optic disc swelling or chiasm involvement.
- Intractable hiccups, nausea, vomiting >2 days → due to medullary (area postrema) lesions.
🩺 Clinical Presentation
- UMN weakness below lesion level.
- Sensory level and sphincter dysfunction (urinary/faecal).
- Visual loss, RAPD (afferent pupillary defect).
- Brainstem symptoms: persistent nausea, vomiting, hiccups.
- Positive Romberg’s and Lhermitte’s phenomenon.
📍 Affected Areas
- Optic nerves & spinal cord (hallmark).
- Area postrema (dorsal medulla).
- Brainstem, diencephalon, periependymal regions, corpus callosum, internal capsule.
🔬 Investigations
- Bloods: Hyponatraemia may occur (SIADH).
- Serology: Anti-AQP4 autoantibodies (major biomarker, predicts relapsing course).
- Anti-MOG antibodies: Seen in ~20% of cases, especially in children.
- MRI: Cord lesions extending ≥3 segments, central, often enhancing with contrast.
- VEP: Evidence of optic neuropathy.
- CSF: Typically absent oligoclonal bands (contrast with MS).
🆚 Comparing MS and NMO
- Course: NMO often monophasic or relapsing-severe; MS typically relapsing-remitting.
- Severity: NMO relapses are more disabling and leave residual deficits.
- MRI: NMO – long cord lesions; MS – shorter, patchy white matter plaques.
- CSF: OCB usually absent in NMO, present in MS.
- Antibodies: NMO → anti-AQP4 / anti-MOG; MS has no disease-specific antibody.
- Treatment: Interferon-β (effective in MS) can worsen NMO.
📑 Wingerchuk Diagnostic Criteria
- Required:
- Optic neuritis
- Acute transverse myelitis
- Plus ≥2 of 3 supportive criteria:
- Spinal cord lesion ≥3 vertebral segments
- Brain MRI not meeting MS criteria
- AQP4-IgG seropositivity
💊 Management
- Acute attacks: IV methylprednisolone 1g daily × 5 days ± oral taper.
- Plasma exchange (PLEX): For severe or steroid-refractory relapses (5–7 exchanges).
- Maintenance therapy: Azathioprine, mycophenolate, or rituximab (anti-CD20).
- Supportive care: Neurorehabilitation, pain control, spasticity management (e.g. carbamazepine for tonic spasms).
📚 Reference
