Possible etiologies for tropical spastic paraparesis and human T lymphotropic virus I-associated myelopathy

The epidemiology of tropical spastic paraparesis/human T lymphotropic virus I (HTLV-I)-associated myelopathy (TSP/HAM) is frequently inconsistent and suggests environmental factors in the etiology of these syndromes. The neuropathology corresponds to a toxometabolic or autoimmune process and possibly not to a viral disease. Some logical hypotheses about the etiology and physiopathology of TSP and HAM are proposed. Glutamate-mediated excitotoxicity, central distal axonopathies, cassava, lathyrism and cycad toxicity may explain most cases of TSP. The damage caused to astrocytes and to the blood-...