Clinical neurophysiological comparative study on HTLV-1 associated myelopathy/tropical spastic paraparesis

In order to determine the neurophysiological characteristics of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) throughout the world, we analyzed and compared the most common clinical neurophysiological studies (CNPS) performed in this entity from those places with a high prevalence and interesting regional differences were noted. African patients showed a noteworthy involvement of the peripheral nervous system (PNS). Chilean patients displayed a more circumscribed abnormality around the spinal cord. The migrants from the West Indies to England showed important visual, and somatosensory evoked potential (SSEP) alterations in the upper limbs (UL). Japanese patients also presented some involvement of the PNS, but their illness duration was less protracted than that observed in other countries. The differences found in visual pathways and PNS involvement among these groups were statistically significant (p < 0.05). Thus, this study shows not only a widespread subclinical involvement in both central and PNS in HAM/TSP, but also strongly supports the idea that the lesion distribution and progression of this disease are different among countries. Such differences could likely be due to the action of the so-called environmental co-factors present in each of these areas which should be promptly investigated.