HTLV-1 Associated myelopathy (Tropical Spastic Paraparesis)

Also known as Tropical Spastic Paraparesis (TSP), HAM/TSP is a chronic, progressive spastic paraparesis due to HTLV-1 infection. It mainly affects the lower limbs and bladder, causing significant disability over time.

🧬 About

• HTLV-1 Associated Myelopathy (HAM) = slowly progressive neurological disorder with spastic weakness.
• Long latency after infection with HTLV-1 retrovirus (same virus can also cause adult T-cell leukaemia/lymphoma).
• Endemic in Caribbean, South America, Africa, and parts of Asia 🌍.
• Only ~2–3% of HTLV-1 carriers develop HAM/TSP.

⚠️ Aetiology

• Transmission: blood transfusion, sexual contact, breastfeeding, needle sharing.
• Not all infected develop HAM/TSP — host genetics and immune response influence risk.

🧠 Pathophysiology

• Chronic immune-mediated inflammation of the spinal cord (esp. thoracic cord).
• Demyelination + degeneration of corticospinal tracts → spastic paraparesis.
• Tomacula and inflammatory infiltrates seen in pathology.

🩺 Clinical Features

• Progressive spastic paraparesis 🦵 (classical feature).
• Scissor gait, brisk reflexes, clonus, and extensor plantar responses (Babinski).
• Bladder dysfunction: urgency, frequency, incontinence.
• Mild distal sensory changes (numbness, tingling) possible.
• Upper limb or cognitive features = rare in advanced cases.

🔬 Investigations

• Serology or PCR for HTLV-1 in blood/CSF → diagnostic.
• MRI spine: often normal early; later shows cord atrophy or T2 hyperintensity.
• CSF: mild pleocytosis, ↑ protein, sometimes oligoclonal bands.
• EMG/NCS: exclude peripheral neuropathy.

🔎 Differentials

• Cervical/thoracic cord compression (must exclude on MRI).
• Vitamin B12 deficiency → subacute combined degeneration.
• Multiple sclerosis → MRI brain lesions, relapsing course.
• Other infectious myelopathies: HIV, syphilis.

💊 Management

• No curative therapy → symptomatic & supportive care.
• Spasticity: baclofen, tizanidine, dantrolene; botulinum toxin in refractory cases.
• Bladder: oxybutynin or intermittent catheterisation.
• Experimental: corticosteroids, interferon-α, plasmapheresis (variable benefit).
• Physiotherapy: gait, mobility, contracture prevention.
• Multidisciplinary support: neurologist, physio, OT, urologist, psychologist.

📉 Prognosis

• Slowly progressive; most eventually require walking aids or wheelchair.
• Life expectancy usually preserved, but QoL impaired.
• Complications: recurrent UTIs, thromboembolism, immobility-related issues.

Cases — HTLV-1 Associated Myelopathy (HAM/TSP)

• Case 1 — Slowly Progressive Spastic Paraparesis 🌴: A 42-year-old woman from the Caribbean presents with 2 years of gradually worsening stiffness and weakness in both legs. Exam: spastic paraparesis, brisk reflexes, extensor plantar responses, and mild urinary urgency. Sensory exam: reduced vibration sense in feet. Diagnosis: HAM/TSP due to HTLV-1 infection. Management: Supportive — physiotherapy, baclofen for spasticity, bladder management, counselling about transmission.
• Case 2 — Blood Transfusion-Associated HAM 🩸: A 55-year-old man who received multiple blood transfusions in South America 20 years ago presents with progressive difficulty walking, leg cramps, and erectile dysfunction. Exam: spastic gait, ankle clonus, patchy sensory loss. HTLV-1 serology positive. Diagnosis: HTLV-1 Associated Myelopathy from prior transfusion exposure. Management: Symptomatic — muscle relaxants, pain relief, rehabilitation; screening family members.
• Case 3 — Co-Infection with Strongyloides 🦠: A 38-year-old woman from West Africa presents with slowly worsening leg weakness and bladder urgency. Exam: bilateral pyramidal signs in the legs. Bloods: HTLV-1 antibodies positive. She is also found to have Strongyloides stercoralis infection. Diagnosis: HAM/TSP in the context of HTLV-1 + Strongyloides co-infection. Management: Supportive care for HAM; ivermectin for Strongyloides (important since HTLV-1 predisposes to hyperinfection).

Teaching Commentary 🧠

HTLV-1 Associated Myelopathy is a chronic, progressive demyelinating disease of the spinal cord, usually affecting the thoracic cord. Transmission: vertical (breastfeeding), sexual, and blood transfusion. Clinical picture: slowly progressive spastic paraparesis, sphincter dysfunction, mild sensory loss. Unlike MS, there are no remissions, and onset is more insidious. Diagnosis: positive HTLV-1 serology in blood/CSF, exclusion of MS and structural cord disease. Management: largely supportive (physio, spasticity control, bladder/bowel care). Corticosteroids or interferon may be tried in selected cases, but evidence is limited. Screening for associated conditions (e.g. adult T-cell leukaemia/lymphoma, Strongyloides) is essential.