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  • Updated 06.19.2023
  • Released 04.03.2001
  • Expires For CME 06.19.2026

HTLV-1 associated myelopathy/Tropical spastic paraparesis



The author’s update of this article on HTLV-1-associated myelopathy is an essential tool for physicians and virologists alike. HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is essentially a disease of persons of Caribbean and Japanese origins, which has spread among a number of other ethnic groups. Through horizontal transmission, HTLV-1 infection has started to become recognized among Caucasians and, thus, HAM/TSP. The author expands on the criteria for diagnosis and stresses their practical value. He brings to the world’s attention the fact that HTLV-1 pandemy is affecting Canadian Natives of the Northwest Pacific as well as immigrants from Eastern Iran and that the disease is starting to appear among Caucasians. The author defines the similarities and differences between primary progressive multiple sclerosis and HTLV-1-associated myelopathy. He describes the main features of the disease, highlighting the progress made in the biology, epidemiology, and clinical as well as MRI phenotyping. Unfortunately, treatment of the disease has remained disappointing. His clinical experience of the disease, bench work, and insights from many scientific publications will benefit clinicians faced with diagnosing and treating this virally induced inflammatory myelopathy.

Key points

• HTLV-I associated myelopathy is a retroviral disease specific to certain ethnic groups and transmitted in a manner similar to HIV. It is the model of virally induced inflammatory demyelinating myelopathies.

• Clinically, it mimics spinal cord primary progressive multiple sclerosis, and one must think about it as a differential; otherwise, it will be missed. Brain and cord MRI with serology and PCR will make the diagnosis.

• The evolution is progressive and leads to disability and death over a matter of years to decades. There is only symptomatic treatment for inflammation and spasticity, but no specific etiologic treatment.

• A working group has been formed, and clinical trials will hopefully be coordinated and marshal clinical improvement.

Historical note and terminology

It was in 1984 that A Gessain demonstrated that blood samples from patients with “tropical spastic paraparesis” in the island of Martinique (French Western Indies) reacted with the HTLV-1 virus (21). The results were immediately convincing: the great majority of the samples contained antibodies to the HTLV-1 virus and, thus, pinpointed the etiologic agent responsible for this disorder. The HTLV-1 virus had just been isolated by R Gallo from a leukemia patient living in the Pacific Northwest of North America, probably a West Coast Native (54).

In 1986, Osame and coworker proposed the term “HTLV-1-associated myelopathy” (53). Criteria for diagnosis have been updated and modernized by introducing intrathecal antibody secretion as a diagnostic criterion (14). It appears that the most solid argument for the diagnosis of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in the presence of spasticity comes from quantitative polymerase chain reaction (QPCR), which reveals high proviral load in blood and CSF lymphocytes of patients with HAM/TSP compared to a lower viral load in carriers (20).

Cases of “tropical spastic paresis” that are clinically indistinguishable from HTLV-1-associated myelopathy, but without antibody or a positive PCR, are frequently found in endemic areas (59; Oger J, personal experience). A high degree of suspicion exists that these cases could be due to a defective virus or a virus similar to HTLV-1, but not yet identified. These cases should, however, retain the designation of “tropical spastic paresis.” This author wants to stress that the diagnosis of “HTLV-1-associated myelopathy” should be reserved to cases where there is evidence of myelopathy and where the presence of the virus has been proven by finding antibodies to HTLV-1 or by PCR amplification. The denomination "tropical spastic paraparesis," or even better "chronic inflammatory myelopathy,” would be more appropriately saved for those cases where the etiologic proof is lacking.

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