HTLV-1 Associated Neurological Complex. What is Hidden below the Water?

The human T-cell lymphotropic virus type 1 (HTLV-1) infects 5-10 million people worldwide and causes fatal and disabling diseases in a significant proportion of them. A chronic myelitis named HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) is the typical neurological manifestation of HTLV-1. However, other neurological syndromes can be either associated with HAM/TSP or occur in isolation in the HTLV-1 infected individual. Although this fact has been widely described over the years, it has been somewhat neglected by the mainstream literature, which has been largely focused on HAM/TSP. Cognitive dysfunction, encephalopathy, neurogenic bladder, motor neuron disease, inflammatory myopathies, polyneuropathy, and dysautonomia can also occur in the HTLV-1 infected patient and may remain unnoticed to the unsuspecting physician. In the present review, we intend to draw attention, primarily to the infectious disease specialist and to the general practitioner, to the fact that HTLV-1 has a broader neurological spectrum than the designation HAM/TSP suggests and that infected individuals may harbor other neurological syndromes in addition to HAM/TSP.