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HTLV-1 associated myelopathy

Summary

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  • Chronic progressive myelopathy caused by human T-cell lymphotropic virus type 1 (HTLV-1)
  • Characterised by spastic paraparesis, bladder dysfunction, and sensory disturbances
  • MRI typically shows thoracic cord atrophy and T2 hyperintensities1

Pathophysiology

  • HTLV-1 infects CD4+ T cells, leading to:
    • Inflammatory response in the spinal cord
    • Demyelination and axonal degeneration
    • Cytokine-mediated damage to neurons and glial cells
  • Genetic factors may influence susceptibility to developing myelopathy

Demographics

  • Prevalence:
    • Endemic in Japan, Caribbean, South America, and parts of Africa
    • Estimated 5-10 million infected individuals worldwide
  • Risk factors:
    • Vertical transmission (mother to child)
    • Sexual transmission
    • Blood transfusion (rare in countries with blood screening)
  • Age of onset: typically 30-50 years
  • Female to male ratio: 2:1

Diagnosis

  • Clinical presentation:
    • Gradual onset of lower limb weakness and spasticity
    • Bladder and bowel dysfunction
    • Lower back pain and sensory disturbances
  • Laboratory tests:
    • HTLV-1 antibodies in serum and cerebrospinal fluid (CSF)
    • PCR for HTLV-1 proviral DNA
  • CSF analysis:
    • Mild pleocytosis
    • Elevated protein levels
    • Oligoclonal bands (in some cases)

Imaging

  • MRI findings:
    • Thoracic cord atrophy (most common finding)
    • T2 hyperintensities in the thoracic cord
    • Symmetrical periventricular white matter lesions (in some cases)
  • Spinal cord:
    • Preferential involvement of lateral and posterior columns
    • Minimal to no gadolinium enhancement
  • Brain:
    • Non-specific white matter lesions (in advanced cases)
    • Cerebral atrophy (rare)

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  • 55-year-old patient presented with lower limb weakness, paraesthesia and areflexia.
  • MRI showed a mildly swollen and hyperintense cervical and thoracic cord with patchy, mainly peripheral, enhancement.
  • On follow-up imaging after 2 months, the hyperintensity persisted but the swelling and enhancement resolved.

Treatment

  • No curative therapy; corticosteroids and symptomatic management. Diagnosis rests on HTLV-1 serology plus thoracic cord atrophy/T2 signal

Differential diagnosis

Differential Diagnosis Distinguishing Feature
Neuromyelitis Optica (NMO) Longitudinally extensive T2 hyperintensity spanning ≥3 vertebral segments; central cord involvement; optic nerve lesions
Multiple Sclerosis Short segment cord lesions (<2 vertebral segments); dorsolateral cord; periventricular and juxtacortical brain lesions
Transverse myelitis Acute onset cord T2 hyperintensity with swelling; may enhance; can be indistinguishable in acute phase
HIV vacuolar myelopathy Posterior and lateral column involvement; associated brain white matter changes
Subacute combined degeneration Dorsal column T2 hyperintensity on axial MRI ("inverted V" sign); may involve posterior cervical and thoracic cord
Anterior spinal artery ischaemia Anterior horn and corticospinal tract "owl-eye" or "snake-eye" pattern; diffusion restriction acutely
Hereditary spastic paraplegia Cord atrophy; lateral column involvement; no acute inflammatory lesions

  1. Bangham et al. HTLV-1-associated myelopathy/tropical spastic paraparesis. 2015. Nature reviews. Disease primers - Open in new tab. ↩