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# HTLV-1-associated myelopathy / tropical spastic paraparesis

A slow, inflammatory disease of the [spinal cord](https://durgical.com/en/anatomy/spinal-cord/) caused by the HTLV-1 virus, giving stiff weak legs, back pain and bladder problems.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Spinal cord](https://durgical.com/en/anatomy/spinal-cord/)
- [T10 vertebra](https://durgical.com/en/anatomy/t10/)
- [T9 vertebra](https://durgical.com/en/anatomy/t9/)
- [T11 vertebra](https://durgical.com/en/anatomy/t11/)
- [T12 vertebra](https://durgical.com/en/anatomy/t12/)
- [Mid-back nerve roots](https://durgical.com/en/anatomy/anterior-root-of-spinal-nerve-spine-and-pelvis/)
- [Conus medullaris](https://durgical.com/en/anatomy/conus-medullaris/)
- [Dura (dural sac)](https://durgical.com/en/anatomy/spinal-dura/)

## Why it happens

- [Chronic inflammation: causes, cells and features](https://durgical.com/en/general-pathology/chronic-inflammation-causes-cells-and-features/)
- [Oncogenic viruses and H. pylori: the table to know](https://durgical.com/en/general-pathology/oncogenic-viruses-and-h-pylori-the-table-to-know/)
- [Upper versus lower motor neuron lesions](https://durgical.com/en/physiology/upper-versus-lower-motor-neuron-lesions/)

## What it is

A chronic inflammatory myelopathy, abbreviated HAM/TSP, that develops in a small proportion of people infected with human T-lymphotropic virus type 1 (HTLV-1). It mainly damages the thoracic spinal cord and produces slowly progressive spastic weakness of the legs with bladder dysfunction. The same virus causes adult T-cell leukaemia/lymphoma, which is covered with non-Hodgkin lymphoma.

## Who gets it

Between 5 and 10 million people are estimated to live with HTLV-1, with endemic areas in southern Japan, the Caribbean, sub-Saharan Africa, Iran, Melanesia and South America. In Colombia the Pacific coast (for example Tumaco in Nariño) is a well-known endemic focus, where the disease was described as tropical spastic paraparesis. About 2% of infected people develop HAM/TSP during their lifetime, more often women, usually in their forties or fifties.

## Causes

- Infection with HTLV-1, a retrovirus that infects CD4 T lymphocytes
- Transmission through breastfeeding (mother to child)
- Sexual transmission
- Transfusion of unscreened cellular blood products and shared needles
- Organ transplantation from an infected donor

## Risk factors

- Birth or residence in an endemic area such as the Colombian Pacific coast
- Prolonged breastfeeding by an infected mother
- Female sex
- High proviral load
- Infection acquired through transfusion (shorter latency)

## Pathophysiology

HTLV-1 integrates into the DNA of CD4 T cells as a provirus. Infected cells and virus-specific cytotoxic T cells cross into the spinal cord, where they release inflammatory cytokines. This "bystander" damage produces perivascular inflammation, demyelination and axonal loss, mostly in the lateral columns of the lower thoracic cord. The corticospinal tracts are hit hardest, explaining spastic paraparesis, while the posterior columns and autonomic pathways explain sensory symptoms and bladder dysfunction. A high proviral load and a strong immune response are linked to disease.

## Symptoms and signs

- Slowly progressive stiffness and weakness of both legs, with a spastic gait
- Low back pain
- Urinary urgency, frequency, incontinence or retention; constipation
- Erectile dysfunction
- Mild sensory symptoms: tingling, burning, reduced vibration sense in the feet
- Brisk reflexes, clonus and extensor plantar responses; arms usually spared
- Associated conditions: uveitis, dry eyes, infective dermatitis, arthritis

## Red flags

- Rapid progression over weeks (consider cord compression or another cause)
- Clear sensory level or severe back pain (exclude compression)
- Lymphadenopathy, skin lesions or high calcium in an HTLV-1 carrier (adult T-cell leukaemia/lymphoma)
- Disseminated strongyloidiasis in an infected person given corticosteroids

## Diagnosis

**Clinical**
Suspected in a person from an endemic area with slowly progressive spastic paraparesis and bladder symptoms, without a compressive lesion.

**Tests**
HTLV-1 antibodies in serum confirmed by Western blot or PCR, and antibodies in the CSF. CSF may show mild lymphocytosis, raised protein and intrathecal antibody production; proviral load in blood and CSF can support the diagnosis. Tests to exclude B12 deficiency, syphilis and HIV. Stool testing or serology for Strongyloides before any immunosuppression.

**Imaging**
MRI of the [spine](https://durgical.com/en/anatomy/region/spine/) excludes compression; it is often normal or shows atrophy of the thoracic cord, and occasionally swelling and enhancement in early, active disease. Brain MRI may show [white matter](https://durgical.com/en/anatomy/white-matter-of-telencephalon/) lesions.

## Differential diagnosis

- Compressive myelopathy (disc, tumour, spondylosis, tuberculosis)
- Primary progressive multiple sclerosis
- Subacute combined degeneration (vitamin B12 or copper deficiency)
- HIV vacuolar myelopathy and neurosyphilis
- Hereditary spastic paraplegia
- Neuromyelitis optica and transverse myelitis

## Goal of treatment

There is no cure; treatment aims to slow inflammation in active disease, reduce spasticity and bladder symptoms and preserve walking.

## Treatment

**Medical**
Corticosteroids are the most used disease-modifying treatment, especially in rapidly progressive or inflammatory phases; interferon alfa is an alternative in some centres. Antiretrovirals have not shown clear benefit.

**Medical**
Symptomatic drugs: antispasticity agents (baclofen, tizanidine), anticholinergic bladder drugs and neuropathic pain treatment.

**Follow-up**
Rule out and treat Strongyloides before corticosteroids. Nursing priorities: bladder scanning and intermittent catheterisation, prevention of urinary tract infections, bowel programme, fall prevention and [skin](https://durgical.com/en/anatomy/skin/) care.

**Rehabilitation**
Physiotherapy for spasticity and gait, walking aids, orthoses and occupational therapy.

## Complications

- Loss of independent walking and wheelchair dependence
- Neurogenic bladder with recurrent urinary tract infections
- Falls and fractures
- Pressure injuries
- Co-existing adult T-cell leukaemia/lymphoma or severe strongyloidiasis

## Prognosis

The course is slowly progressive over years; many patients need a walking aid within about a decade. Faster progression is seen with older age at onset, transfusion-acquired infection and high proviral load. Life expectancy is shortened mainly by infections and immobility.

## Prevention

- Screening of blood and organ donors for HTLV-1
- Condom use and safe injection practices
- In infected mothers, avoiding or shortening breastfeeding with access to safe alternatives
- Antenatal HTLV-1 screening in endemic areas (there is no vaccine)

## Test yourself

Think of the answer, then tap the question to see it.

## A woman from Tumaco has slowly progressive spastic paraparesis, back pain and urinary urgency with a normal spinal MRI. What is the likely diagnosis?

HTLV-1-associated myelopathy / tropical spastic paraparesis.

## What is the main route of HTLV-1 transmission from mother to child?

Breastfeeding.

## Which part of the spinal cord is mainly affected?

The lateral columns (corticospinal tracts) of the lower thoracic cord.

## Which parasitic infection must be excluded before giving corticosteroids to an HTLV-1 carrier?

Strongyloidiasis, which can become disseminated (hyperinfection).

## Which haematological malignancy is also caused by HTLV-1?

Adult T-cell leukaemia/lymphoma.

[Add to my cards (5)](https://durgical.app/estudiar/?add=/en/conditions/htlv-1-associated-myelopathy-tropical-spastic-paraparesis/)

## Related conditions

- [Non-Hodgkin lymphoma](https://durgical.com/en/conditions/non-hodgkin-lymphoma/)
- [Strongyloidiasis](https://durgical.com/en/conditions/strongyloidiasis/)
- [Multiple sclerosis](https://durgical.com/en/conditions/multiple-sclerosis/)
- [Subacute combined degeneration (vitamin B12)](https://durgical.com/en/conditions/subacute-combined-degeneration/)
- [Transverse myelitis](https://durgical.com/en/conditions/transverse-myelitis/)
- [HIV infection and AIDS](https://durgical.com/en/conditions/hiv-infection-and-aids/)
- [Syphilis](https://durgical.com/en/conditions/syphilis/)
- [Malignant spinal cord compression](https://durgical.com/en/conditions/malignant-spinal-cord-compression/)
- [Uveitis](https://durgical.com/en/conditions/uveitis/)
- [Spinal tuberculosis (Pott disease)](https://durgical.com/en/conditions/spinal-tuberculosis/)
- [Lumbar spinal stenosis](https://durgical.com/en/conditions/lumbar-spinal-stenosis/)
- [Neuromyelitis optica spectrum disorder](https://durgical.com/en/conditions/neuromyelitis-optica-spectrum-disorder/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Human T-lymphotropic virus-1](https://www.who.int/news-room/fact-sheets/detail/human-t-lymphotropic-virus-type-1) (World Health Organization, 2025).

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Source: https://durgical.com/en/conditions/htlv-1-associated-myelopathy-tropical-spastic-paraparesis/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/htlv-1-associated-myelopathy-tropical-spastic-paraparesis/