What lab studies are recommended for diagnosing transverse myelitis?

Recommended Laboratory Studies for Diagnosing Transverse Myelitis

MRI of the spine with and without contrast is the essential first-line diagnostic test for transverse myelitis, followed by lumbar puncture for CSF analysis and comprehensive blood tests to rule out other causes. 1, 2

Imaging Studies

• MRI of the spine with thin axial cuts through the region of suspected abnormality is essential to detect T2-weighted hyperintense lesions that may appear wedge-shaped on axial views and cigar-shaped on sagittal views 1, 2
• MRI helps rule out compressive lesions and evaluate for nerve root enhancement/thickening 3
• Brain MRI should be performed to evaluate for demyelinating lesions suggestive of multiple sclerosis or other CNS disorders 3, 4
• For patients with suspected neuromyelitis optica spectrum disorder (NMOSD), look for longitudinally extensive transverse myelitis (LETM) affecting ≥3 vertebral segments 3, 2

Cerebrospinal Fluid Studies

• Lumbar puncture should be performed to analyze: 1, 4
  • Cell count (often shows pleocytosis with elevated WBCs) 3
  • Protein (typically elevated) 3
  • Glucose
  • Oligoclonal bands (to distinguish from MS) 1
  • Cytology (particularly important in patients with cancer) 3
  • Viral PCRs 1
  • IgG index 4

Blood Tests

• Aquaporin-4 IgG antibodies (to evaluate for NMOSD) 3, 1
• MOG-IgG antibodies (myelin oligodendrocyte glycoprotein) 3
• Autoimmune panel: 1, 2
  • Antinuclear antibodies (ANA)
  • Anti-Ro/La antibodies
  • Antiphospholipid antibodies
• Infectious disease screening: 1, 2
  • HIV
  • RPR (for syphilis)
• Metabolic and nutritional screening: 1, 2
  • Vitamin B12 levels
  • Thyroid function tests (TSH)
• In cases with suspected Guillain-Barré syndrome variants, test for serum antiganglioside antibodies (e.g., anti-GQ1b for Miller Fisher variant) 3

Electrophysiological Studies

• Electrodiagnostic studies (EMG/NCS) should be considered to evaluate for polyneuropathy and distinguish from peripheral nerve disorders 3, 5

Diagnostic Algorithm

1. First-line testing (perform immediately): 1, 4

   • MRI spine with and without contrast
   • Lumbar puncture for CSF analysis
   • Basic blood tests (CBC, CMP, B12, folate, TSH)

2. Second-line testing (based on clinical suspicion): 3, 1

   • Aquaporin-4 IgG and MOG-IgG antibodies
   • Brain MRI with and without contrast
   • Expanded autoimmune panel
   • Infectious disease screening

3. Third-line testing (for atypical presentations): 3, 5

   • Electrodiagnostic studies
   • Specialized antibody testing
   • Additional imaging as indicated

Clinical Pearls and Pitfalls

• The presence of increased deep tendon reflexes is a key distinguishing feature of transverse myelitis compared to conditions with flaccid paralysis (like Guillain-Barré syndrome) 2
• Longitudinally extensive transverse myelitis (≥3 vertebral segments) should raise suspicion for NMOSD 3, 2
• Normal MRI does not rule out transverse myelitis - in cases of "myelopathy with normal MRI," consider repeat imaging and comprehensive CSF analysis 5
• Distinguishing between acute complete transverse myelitis (ACTM) and acute partial transverse myelitis (APTM) is important for determining etiology and relapse risk 4
• Testing for NMO-IgG antibodies is particularly important in patients presenting with clinical features of acute complete transverse myelitis 4

Special Considerations

• For patients with immune checkpoint inhibitor therapy, consider immune-related adverse events as a potential cause of transverse myelitis 3
• In patients with suspected paraneoplastic syndromes, test for onconeural antibodies in CSF 1, 5
• Evaluation for urinary retention and constipation is important as these are common autonomic manifestations of transverse myelitis 1, 2