What is the treatment for relapse opsoclonus-myoclonus syndrome?

Treatment of Relapse Opsoclonus-Myoclonus Syndrome

For relapsed opsoclonus-myoclonus syndrome (OMS), rituximab is the most effective treatment option, particularly as a single additional dose (375 mg/m²) for patients previously treated with full-dose rituximab therapy.

First-Line Treatment Options for Relapsed OMS

Rituximab

• Most recent evidence supports rituximab as the preferred treatment for relapsed OMS
• Dosing options:
  • Full-dose therapy: 375 mg/m²/week for 4 consecutive weeks for initial treatment 1
  • Single additional dose (375 mg/m²) for patients who previously received full-dose rituximab therapy 1
• Benefits:
  • Can provide remission lasting up to 2 years after additional single-dose treatment
  • Particularly beneficial in younger patients who wish to preserve fertility
  • No significant adverse events reported during treatment period

Alternative Immunosuppressive Regimens

Cyclophosphamide and Dexamethasone Combination

• For cases refractory to first-line treatments:
  • Cyclophosphamide pulses combined with dexamethasone pulses every 4 weeks (typically 6 cycles) 2
  • Particularly useful for chronic relapsing OMS with prolonged clinical course
  • Has shown significant improvement in OMS symptoms even after long clinical courses

Corticosteroids

• High-dose corticosteroids remain an important component of treatment
• Options include:
  • Oral prednisone (typically requiring maintenance therapy)
  • Dexamethasone pulse therapy
  • Intravenous pulse methylprednisolone for cases refractory to oral steroids 3

Treatment Algorithm for Relapsed OMS

1. First relapse after initial treatment:

   • If previously treated with rituximab full-dose therapy → Single additional dose of rituximab (375 mg/m²)
   • If not previously treated with rituximab → Full-dose rituximab therapy (375 mg/m²/week for 4 weeks)

2. For refractory cases (not responding to rituximab):

   • Combination of cyclophosphamide pulses with dexamethasone pulses every 4 weeks for 6 cycles

3. Additional options for highly refractory cases:

   • Intravenous immunoglobulin (IVIG)
   • Plasmapheresis (particularly if anticerebellar antibodies are detected) 4
   • Consider autologous stem cell transplantation (ASCT) as last resort for cases refractory to all conventional therapies 5

Monitoring and Follow-up

• Regular neurological assessments to evaluate treatment response
• Monitor for:
  • Improvement in opsoclonus (chaotic, conjugate eye movements)
  • Reduction in myoclonus (brief, involuntary jerking movements)
  • Improvement in ataxia and other neurological symptoms
• Assess for potential cognitive impairment, which can develop despite treatment of motor symptoms

Common Pitfalls and Considerations

• Delayed treatment can lead to worse neurological outcomes and cognitive impairment
• Approximately 80% of children with OMS suffer from mild to severe neurological handicaps despite treatment
• For OMS associated with neuroblastoma, tumor resection should be performed in addition to immunomodulatory therapy 6
• Long-term immunosuppression may be necessary in some cases to prevent further relapses
• Consider patient-specific factors (age, fertility concerns) when selecting between rituximab and cyclophosphamide

Special Considerations

• In very young patients or those with fertility concerns, rituximab is preferred over cyclophosphamide
• For patients with severe symptoms or rapid progression, combination therapy may be considered from the outset
• Cognitive rehabilitation should be incorporated into the treatment plan to address potential neurological sequelae