What is the treatment for longitudinally extensive transverse myelitis (LETM)?

Treatment of Longitudinally Extensive Transverse Myelitis (LETM)

High-dose intravenous methylprednisolone (1g daily for 3-5 days) followed by oral steroids is the first-line treatment for LETM, with intravenous immunoglobulin (IVIG) or plasma exchange recommended for patients with severe symptoms or inadequate response to steroids. 1

Diagnostic Workup

Before initiating treatment, a comprehensive diagnostic evaluation is essential:

• Neurologic consultation - Required for all suspected LETM cases

• MRI of spine - With thin axial cuts through suspected abnormality areas

• MRI of brain - To evaluate for associated brain lesions

• Lumbar puncture - To analyze:

  • Cell count, protein, glucose
  • Oligoclonal bands
  • Viral PCRs
  • Cytology
  • Onconeural antibodies

• Blood tests:

  • B12, HIV, RPR
  • ANA, Ro/La, TSH
  • Aquaporin-4 IgG (NMO-IgG)
  • MOG antibodies 1

• Evaluation for urinary retention and constipation

Treatment Algorithm

First-Line Treatment:

1. High-dose corticosteroids:
   • Methylprednisolone 1g IV daily for 3-5 days 1
   • Follow with oral prednisone taper

Second-Line Treatment (for inadequate response to steroids):

1. IVIG:

   • 2g/kg over 5 days 1

   OR

2. Plasma exchange:

   • Particularly for patients with positive autoimmune encephalopathy antibodies or limited improvement with steroids 1

For Severe Cases (Grade 3-4):

• Combination therapy:
  • Pulse corticosteroids (methylprednisolone 1g IV daily for 3-5 days)
  • PLUS IVIG 2g/kg over 5 days 1
  • Consider rituximab in consultation with neurology for refractory cases

Treatment Based on Etiology

LETM has multiple potential causes, and treatment should address the underlying etiology:

1. NMO-spectrum disorder (AQP4-positive):

   • Long-term immunosuppression after acute treatment
   • Consider rituximab or other immunosuppressants

2. MOG antibody-associated disease:

   • Steroids as first-line therapy
   • Consider IVIG for maintenance in recurrent cases 1

3. Infectious causes (e.g., tuberculosis):

   • Combination of anti-infectious therapy with corticosteroids
   • For tuberculous LETM: standard anti-TB regimen plus steroids 2, 3

Monitoring and Follow-up

• Regular neurological assessment
• Follow-up MRI to evaluate treatment response
• Monitor for urinary retention and constipation
• Rehabilitation therapy for motor deficits

Common Pitfalls and Caveats

1. Misdiagnosis: LETM is not exclusively associated with neuromyelitis optica. Multiple other etiologies including infectious, autoimmune, and neoplastic causes must be considered 4, 5.

2. Delayed treatment: Early and aggressive immunomodulatory therapy is crucial for better outcomes 6.

3. Inadequate diagnostic workup: Failure to test for AQP4 and MOG antibodies may lead to misdiagnosis and inappropriate treatment 1.

4. Paradoxical worsening: In infectious causes like tuberculosis, LETM can develop as a paradoxical response to antimicrobial treatment, requiring addition of corticosteroids 2.

5. Overlooking infectious causes: Particularly in endemic areas, tuberculosis and other infections should be considered as potential causes of LETM 2, 3.

The prognosis of LETM varies widely depending on the underlying etiology, timing of treatment initiation, and response to therapy. Early diagnosis and prompt, aggressive treatment significantly improve outcomes and reduce long-term disability.