What is the initial treatment for Paediatric Myelin Oligodendrocyte Glycoprotein (MOG) antibody disease?

Initial Treatment for Paediatric MOG Antibody Disease

Initiate high-dose intravenous methylprednisolone (IVMP) at 1000 mg/day (or 20-30 mg/kg/day, maximum 1000 mg) for 3-5 days immediately upon diagnosis, as this is the first-line treatment for acute MOG-antibody associated disease in children. 1, 2, 3

Acute Phase Treatment Protocol

First-Line Therapy

• Administer IVMP as the primary acute treatment, which was used in 88% of reported pediatric MOGAD cases and leads to favorable outcomes in the majority of patients 2, 3
• Follow the initial IVMP course with an oral corticosteroid taper extending up to 3 months (not just 2-3 weeks) to maintain treatment benefit and suppress disease activity, as shorter tapers are associated with higher relapse risk 3, 4
• Corticosteroid treatment duration ≥5 weeks is independently associated with a 6.7-fold reduction in odds of relapsing disease (OR 0.15,95% CI 0.03-0.80) 4

Second-Line Therapies (If Inadequate Response After 3-5 Days)

• Proceed to plasma exchange (5-7 exchanges) or intravenous immunoglobulin (IVIG) at 2 g/kg if there is insufficient response to IVMP after 3-5 days 1, 3
• Plasma exchange was reported in 33% of pediatric studies and is particularly effective in severe, steroid-refractory cases 2, 3
• IVIG was used in 66% of reported cases and constitutes an alternative second-line option 2, 3

Critical Timing Considerations

Early Treatment Reduces Relapse Risk

• Initiating immunotherapy within 7 days of symptom onset is independently associated with a 6.7-fold reduction in odds of relapsing disease course (OR 0.15,95% CI 0.03-0.61) 4
• This finding emphasizes the importance of rapid diagnosis and treatment initiation, even before MOG-IgG confirmation if clinical suspicion is high 1

Maintenance Treatment Decision-Making

When to Initiate Long-Term Immunosuppression

• Start maintenance treatment after the first relapse to prevent further attacks and permanent sequelae, as 40-50% of pediatric MOGAD patients will experience relapses 3, 4
• The European Paediatric MOG Consortium identifies four first-line maintenance options: rituximab, azathioprine, mycophenolate mofetil, or monthly IVIG 3
• Rituximab shows particularly good responses, with relapses occurring immediately after B-cell re-emergence, making it a preferred option for relapsing disease 1

Predictors of Relapsing Disease

• Children older than 8 years have shorter time to first relapse (median 4 months) compared to younger children (median 18 months) 4
• Presentation with optic neuritis is more common in older children (57.6% in >8 years vs 21.4% in ≤8 years) and may indicate different disease trajectory 4
• Abnormal optic nerves on onset MRI are paradoxically associated with 12.5-fold reduced odds of relapse (OR 0.08,95% CI 0.01-0.50), suggesting monophasic disease 4

Common Pitfalls to Avoid

Steroid Tapering Errors

• Do not taper corticosteroids too rapidly, as 50-60% of patients experience relapses during dose reduction 1
• Avoid the standard 2-3 week taper used in other conditions; extend to at least 5 weeks and up to 3 months 3, 4

Inappropriate MS Therapies

• Never use interferon-beta or natalizumab, as these multiple sclerosis disease-modifying therapies can worsen MOG-positive disease and increase relapse rates 1
• MOG-antibody disease requires distinct treatment strategies from MS protocols 5

Diagnostic Confirmation

• Ensure MOG-IgG was detected by cell-based assay using full-length human MOG as the target antigen, as this is the gold standard 1
• Serum is the preferred specimen, not CSF, since MOG-IgG is produced extrathecally 1
• Retest MOG-IgG antibodies at 3 months after onset: persistent positivity suggests relapsing disease, while antibody disappearance may indicate monophasic course 4, 6

Age-Specific Considerations

Younger Children (≤8 Years)

• More commonly present with acute disseminated encephalomyelitis (ADEM) phenotype (66.7% vs 30.3% in older children) 4
• Longer time to first relapse if disease recurs 4
• Longitudinally extensive transverse myelitis is frequently present at disease onset (80% in pediatric MOG-EM) 7

Older Children and Adolescents

• More commonly present with isolated optic neuritis (57.6% vs 21.4% in younger children) 4
• Shorter interval to first relapse (median 4 months) 4
• May require earlier consideration of maintenance therapy given higher relapse risk 4

Outcome Monitoring

Disability Assessment

• Each 1-point increment in worst EDSS at onset is associated with 6.7-fold increased odds of final disability (EDSS ≥1) (OR 6.65,95% CI 1.33-33.26) 4
• Patients with relapsing disease have higher rates of final disability (37.5%) compared to monophasic disease (12.8%) 4
• Monthly IVIG treatment may prevent further attacks in relapsing cases with a favorable side effect profile 6