Neuropathology of human and experimental TSP/HAM: a critical review

Tropical Spastic Paraparesis/HTLV-1 Associated Myelopathy (TSP/HAM) is clinically characterized by chronic insidious spastic paraparesis associated with variable sensory impairment and sphincter symptoms. Neuropathological studies of this condition are based on a few autopsied cases, and on experimental animal models. However, divergent aspects exist between human and experimental animal neuropathology of TSP/HAM, namely, the site of lesions in the spinal cord, the involvement of peripheral nerves and roots, the nature of histological abnormalities, and the cellular reactions. Moreover, unanswered questions as to the preferential site of spinal affection, the temporal inflammatory picture, the selective damage of the corticospinal tract, the sparing of lower motor neurons, the inconsistent affection of sensory tracts, and the involvement of the brain, are outlined. A long-term, chronological, correlated clinical and neuropathological study in HAM experimental animals is suggested.