Neuromyelitis Optica Symptoms and Treatment
Neuromyelitis optica (NMO) is characterized by severe inflammatory attacks primarily targeting the optic nerves and spinal cord, causing vision loss and transverse myelitis, with a relapsing course that requires prompt diagnosis and aggressive immunosuppressive treatment to prevent disability.
Clinical Presentation
Optic Neuritis
- Acute, often painful visual loss that can be unilateral or bilateral 1
- Visual field defects including central or arcuate defects 1
- Optic disc edema visible in 30-40% of cases 1
- Severe visual outcomes with only 30% of patients maintaining visual acuity better than 20/25 1
- Often more severe than optic neuritis seen in multiple sclerosis, with vision potentially deteriorating to light perception or worse 2
Transverse Myelitis
- Rapidly evolving spinal cord inflammation 1
- Signs of motor dysfunction including spasticity, hyperreflexia (upper motor neuron) or flaccidity and hyporeflexia (lower motor neuron) 1
- Reduced muscle strength and sphincter dysfunction 1
- Sensory disturbances 1
- Longitudinally extensive lesions spanning three or more spinal cord segments, which is characteristic of NMO 1
Other Manifestations
- Area postrema syndrome with intractable nausea, vomiting, or hiccups 3
- Brainstem syndromes 2
- Simultaneous occurrence of optic neuritis and myelitis in approximately one-third of cases 1
Diagnostic Evaluation
Imaging
- MRI of orbits with and without contrast is essential, showing abnormal enhancement of the optic nerve in 95% of optic neuritis cases 1
- MRI of the head should be performed to evaluate for intracranial demyelinating lesions and to differentiate from multiple sclerosis 1
- MRI of the complete spine is crucial to detect longitudinally extensive transverse myelitis, a hallmark of NMO 1
- T1-weighted post-contrast images with fat suppression are particularly useful for identifying optic nerve enhancement 1
Laboratory Testing
- Testing for serum NMO-IgG (aquaporin-4) antibodies is essential for diagnosis, with approximately 75% sensitivity 2
- CSF analysis often shows mild-to-moderate abnormalities (50-70% of cases) but is non-specific 1
- Microbiological studies of CSF are important to exclude infectious myelitis 1
Treatment Approach
Acute Attack Management
- High-dose intravenous methylprednisolone (1 gram daily for 3-5 consecutive days) should be initiated promptly 4
- Plasma exchange is recommended for patients who do not respond adequately to steroids 5, 4
- Treatment should be initiated within hours of symptom onset, as delay (>2 weeks) is associated with severe neurological deficits 1
Preventive Treatment
- All patients with confirmed NMOSD should receive long-term immunosuppressive therapy 4
- First-line immunosuppressive options include:
- Newer FDA-approved targeted therapies include:
- Maintenance therapy is typically recommended for at least 5 years after an attack 4
Monitoring
- Regular visual field testing to monitor for progression or improvement 6
- OCT monitoring of retinal nerve fiber layer thickness 6
- Regular neurological examinations to assess for new symptoms 4
Prognosis and Complications
- Without treatment, NMO has a poor prognosis with severe disability from recurrent attacks 4
- Relapses are common (50-60%) during corticosteroid dose reduction, emphasizing the need for maintenance immunosuppressive therapy 1
- Factors associated with severe neurological deficits include:
Important Considerations
- NMO is distinct from multiple sclerosis and requires different treatment approaches 5
- Early and accurate diagnosis with appropriate immunosuppressive treatment is crucial for preventing disability 5
- Patients with isolated optic neuritis who have severe visual loss should be evaluated for NMO, as approximately half of NMO patients initially present with isolated optic neuritis 2
- TNF antagonists should be avoided in patients with demyelinating diseases like NMO 1