What is Devic's disease (Neuromyelitis Optica)?

Devic's Disease (Neuromyelitis Optica)

Devic's disease, also known as neuromyelitis optica (NMO), is a distinct autoimmune disorder characterized by inflammation and demyelination primarily affecting the optic nerves and spinal cord, caused by antibodies targeting aquaporin-4 water channels in the central nervous system.

Clinical Characteristics

Primary Features

• Optic neuritis: Often bilateral or rapidly sequential, causing visual loss and pain with eye movement 1
• Transverse myelitis: Typically longitudinally extensive (spanning ≥3 vertebral segments) 1
• Relapsing course: Most common pattern, with poor prognosis if untreated 2

Common Symptoms

• Visual impairment or blindness
• Limb weakness (often severe)
• Balance problems
• Sensory disturbances
• Bladder and bowel dysfunction 2, 3
• Breathing difficulties in severe cases 4

Pathophysiology

• Autoimmune mechanism: Mediated by NMO-IgG antibodies that target aquaporin-4 (AQP4), the dominant water channel in the CNS 3, 5
• Humoral immunity: Characterized by perivascular deposition of IgG and complement in the perivascular space 3
• Inflammatory infiltrates: Granulocytes and eosinophils (distinct from MS) 3
• Vascular changes: Hyalinization of vascular walls 3

Diagnostic Criteria

Key Diagnostic Tests

1. MRI imaging:

   • Spinal cord: Longitudinally extensive transverse myelitis spanning ≥3 vertebral segments 1
   • Brain: May show lesions atypical for MS, often in regions around the third and fourth ventricles 1
   • Optic nerves: Long lesions, often involving posterior portions and chiasm 1

2. Serum biomarkers:

   • AQP4-IgG (NMO-IgG) antibody testing: High sensitivity and specificity 2, 3
   • MOG-IgG testing to rule out MOG encephalomyelitis 6

3. CSF analysis:

   • May show mild-to-moderate abnormalities (50-70%) 1
   • Important to exclude infectious causes 1
   • Typically lacks oligoclonal bands (unlike MS) 6

Differential Diagnosis

• Multiple sclerosis (MS)
• MOG encephalomyelitis
• Acute disseminated encephalomyelitis (ADEM)
• Infectious myelitis
• Systemic lupus erythematosus with neuropsychiatric manifestations 1, 6

Treatment Approach

Acute Attacks

• High-dose intravenous methylprednisolone: 1 gram daily for 3-5 consecutive days 2
• Plasma exchange: Recommended if response to steroids is poor 1, 2
• Early intervention: Critical to prevent irreversible damage, should be initiated within hours of symptom onset 1

Long-term Management

• Immunosuppressive therapy: Required for all patients with NMO to prevent relapses 2
  • First-line options: Azathioprine, mycophenolate mofetil, methotrexate
  • Second-line option: Rituximab
  • Typically continued for approximately 5 years after attack 2

Rehabilitation

• Physical therapy: Critical for improving mobility, strength, and coordination 4
• Occupational therapy: For fine motor deficits and activities of daily living 4
• Speech therapy: If swallowing or speech difficulties are present 4

Prognosis and Monitoring

• Poor prognosis if untreated, with accumulating disability from each attack 2, 5
• Regular MRI monitoring: To assess disease activity and treatment response
• Relapses: Common (50-60%) during corticosteroid dose reduction, highlighting need for maintenance therapy 1
• Factors associated with severe outcomes: Extensive MRI lesions, reduced muscle strength, sphincter dysfunction at presentation, antiphospholipid antibodies, and delayed treatment 1

Historical Context

Devic's disease was first named in 1894 by Eugène Devic and Fernand Gault, though earlier cases were documented, including a notable report from 1876 describing a 30-year-old woman with simultaneous bilateral optic neuritis and transverse myelitis 7.

The recognition of NMO as distinct from MS was solidified in 2004 with the discovery of the NMO-IgG antibody targeting aquaporin-4, establishing it as a separate disease entity rather than a variant of MS 7.