neurologic disorders
HTLV 1–Associated Myelopathy Tropical Spastic Paraparesis (HAM TSP)
Introduction
HTLV-1–associated myelopathy/tropical spastic paraparesis (HAM/TSP) 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. (See also Overview of Spinal Cord Disorders .) 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 sex workers, IV drug users, hemodialysis patients, and people from endemic areas such as equatorial regions, southern Japan, and parts of South America. HAM/TSP 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. 