What is the treatment for myelitis?

Treatment for Myelitis

For acute inflammatory myelitis, initiate high-dose intravenous methylprednisolone (1 gram daily for 3-5 days) immediately after excluding infectious causes, and strongly consider adding intravenous cyclophosphamide for severe cases or IVIG (2 g/kg over 5 days) for refractory disease. 1

Immediate Diagnostic Priorities

Before initiating immunosuppressive therapy, you must rapidly exclude infectious etiologies that require antimicrobial treatment rather than immunosuppression:

• Obtain urgent contrast-enhanced spinal cord MRI to exclude cord compression (surgical emergency) and detect T2-weighted hyperintense lesions, which appear in 70-93% of inflammatory myelitis cases 1
• Perform lumbar puncture for cell count, protein, glucose, Gram stain, culture, viral PCRs (especially HSV), and oligoclonal bands 1
• Check serum aquaporin-4 (NMO-IgG) antibodies if longitudinal myelopathy involves more than three spinal cord segments, as this indicates possible neuromyelitis optica requiring different management 1
• Obtain blood work: B12, HIV, RPR, ANA, Ro/La, TSH, ESR, CRP 1

First-Line Treatment Algorithm

For Inflammatory/Autoimmune Myelitis (Infection Excluded)

Mild cases (Grade 1):

• Permanently discontinue any immune checkpoint inhibitors if applicable 1
• Methylprednisolone 2 mg/kg IV daily 1

Moderate cases (Grade 2):

• Methylprednisolone 1 gram IV daily for 3-5 days 1
• Strongly consider adding IVIG 2 g/kg over 5 days 1

Severe cases (Grade 3-4) or SLE-associated myelitis:

• Pulse methylprednisolone 1 gram IV daily for 3-5 days PLUS intravenous cyclophosphamide - this combination is most effective when initiated within the first few hours of presentation 1
• Neurological response paralleled by MRI improvement typically occurs within days to 3 weeks 1
• Add IVIG 2 g/kg over 5 days if oligoclonal bands present or if symptoms progress despite corticosteroids 1

For Infectious Myelitis

If CSF resembles bacterial meningitis or HSV encephalitis:

• Initiate antimicrobial/antiviral therapy immediately (IV acyclovir for suspected HSV) 1
• High-dose glucocorticoids may be given early while awaiting MRI confirmation, but continue antimicrobials until infection definitively ruled out 1

Maintenance Therapy

Critical consideration: Relapses occur in 50-60% of patients during corticosteroid dose reduction, making maintenance immunosuppression essential 1

• Azathioprine is the standard maintenance agent following cyclophosphamide induction 1
• For SLE-associated myelitis, continue maintenance immunosuppressive therapy indefinitely given high relapse rates 1

Refractory Disease Management

If no improvement after initial high-dose corticosteroids and IVIG:

• Plasma exchange therapy has been used successfully in severe cases 1
• Consider rituximab if positive for autoimmune encephalopathy antibodies and limited improvement with standard therapy 1
• For immune checkpoint inhibitor-induced myelitis that relapses, consider plasmapheresis as third-line therapy 2

Special Populations

Antiphospholipid-Positive Myelopathy

• Add anticoagulation therapy in addition to immunosuppression, as this combination shows good results for ischemic/thrombotic myelopathy 1

Neuromyelitis Optica Spectrum Disorder (NMOSD)

• If aquaporin-4 antibodies positive, consider cyclophosphamide-based conditioning protocols possibly associated with rituximab 1
• Standard myelitis treatment alone is often insufficient for NMOSD 1

Prognostic Factors and Timing

Factors associated with severe neurological deficit:

• Extensive spinal cord MRI lesions 1
• Reduced muscle strength or sphincter dysfunction at presentation 1
• Antiphospholipid antibodies 1
• Delay >2 weeks in initiation of therapy - this is the most modifiable poor prognostic factor 1

Critical Pitfalls to Avoid

• Never delay treatment beyond 2 weeks - this significantly worsens neurological outcomes 1
• Do not taper corticosteroids too rapidly - 50-60% relapse rate during dose reduction necessitates slow taper and maintenance therapy 1
• Do not assume improvement on imaging is required early - clinical symptoms and inflammatory markers are more important than radiographic changes in the first 4-6 weeks 1
• Do not use corticosteroids alone for severe cases - combination with cyclophosphamide or IVIG significantly improves outcomes 1
• Do not miss concurrent bacteremia - if present, clear bacteremia before adding rifampin or other adjunctive agents to prevent resistance 3, 4

Monitoring Response

• Repeat MRI to assess for improvement, though clinical response precedes radiographic improvement 1
• Monitor ESR/CRP levels to guide treatment response 3
• Assess for urinary retention and constipation requiring management 1
• Continue follow-up for at least 6 months after treatment completion to detect relapses 3