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Tropical Spastic Paraparesis/HTLV-1–Associated Myelopathy (TSP/HAM)

By

Michael Rubin

, MDCM, New York Presbyterian Hospital-Cornell Medical Center

Last full review/revision Jan 2020| Content last modified Jan 2020
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Tropical spastic paraparesis/HTLV-1–associated myelopathy (TSP/HAM) is a slowly progressive viral immune-mediated disorder of the spinal cord caused by the human T-lymphotropic virus 1 (HTLV-1). It causes spastic weakness of both legs. Diagnosis is by serologic and polymerase chain reaction tests of serum and cerebrospinal fluid and MRI. Treatment includes supportive care and possibly immunosuppressive therapies.

The HTLV-1 retrovirus is transmitted via sexual contact, IV drug use, or exposure to infected blood or from mother to child via breastfeeding. It is most common among prostitutes, IV drug users, hemodialysis patients, and people from endemic areas such as equatorial regions, southern Japan, and parts of South America.

TSP/HAM affects < 2% of HTLV-1 carriers. It is more common among women; this finding is consistent with the higher prevalence of HTLV-1 infection in women. HTLV-2 may cause a similar disorder.

The virus resides in T cells in blood and cerebrospinal fluid (CSF). CD4+ memory T cells, CD8+ cytotoxic T cells, and macrophages infiltrate the perivascular areas and parenchyma of the spinal cord; astrocytosis occurs. For several years after onset of neurologic symptoms, inflammation of spinal gray and white matter progresses, causing preferential degeneration of the lateral and posterior columns. Myelin and axons in the anterior columns are also lost.

Symptoms and Signs

Spastic weakness develops gradually in both legs, with extensor plantar responses and bilateral symmetric loss of position and vibratory sensation in the feet. Achilles tendon reflexes are often absent. Urinary incontinence and urgency are common.

Symptoms usually progress over several years.

Diagnosis

  • Serologic and polymerase chain reaction (PCR) tests of serum and CSF

  • MRI

Tropical spastic paraparesis/HTLV-1–associated myelopathy is suggested by typical neurologic deficits that are otherwise unexplained, particularly in patients with risk factors.

Serum and CSF serologic tests, PCR tests, and spinal cord MRI are indicated. If CSF-to-serum ratio of HTLV-1 antibodies is > 1 or if PCR detects HTLV-1 antigen in CSF, the diagnosis is very likely. Protein and Ig levels in CSF may also be elevated, often with oligoclonal bands; lymphocytic pleocytosis occurs in up to 50% of patients. Spinal cord lesions often appear hyperintense on T2-weighted MRI.

Treatment

  • Immunomodulatory or immunosuppressive therapies

No treatment has proved effective for tropical spastic paraparesis/HTLV-1–associated myelopathy, but interferon alfa, IV immune globulin, and oral methylprednisolone may have some benefit.

Treatment of spasticity is symptomatic (eg, with baclofen or tizanidine).

Key Points

  • Tropical spastic paraparesis/HTLV-1–associated myelopathy (TSP/HAM) affects < 2% of HTLV-1 carriers and occurs more commonly in women.

  • Symptoms include gradually developing spastic weakness in both legs, extensor plantar responses, bilateral symmetric loss of position and vibratory sensation in the feet, and absent Achilles tendon reflexes.

  • Diagnose using serum and CSF serologic tests, PCR tests, and MRI.

  • Interferon alfa, IV immune globulin, and oral methylprednisolone may have some benefit; treat spasticity with baclofen or tizanidine.

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