Brain magnetic resonance imaging white matter lesions are frequent in HTLV-I carriers and do not discriminate from HAM/TSP.

Human T lymphotropic virus (HTLV)-I is known to cause HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and other pronounced disease in less than 4% of those infected. However, evidence is accumulating that a proportion of HTLV-I carriers have neurological and urological symptoms without fulfilling criteria for HAM/TSP. Brain white matter (WM) lesions on magnetic resonance imaging (MRI) are frequently seen in HAM/TSP. HTLV-I carriers with MRI scans for other neurological diagnoses have WM lesions more frequently than expected. We studied 10 patients with HAM/TSP and 20 HTLV-I carriers without overt neurological disease and evaluated clinical characteristics, viral load, total, small, large, confluent WM lesion number, and lesion volume on MRI. Cerebral WM lesions were found in of 85% of HTLV-I carriers and 80% of HAM/TSP patients. Lesion number, size or location was no different between carriers and HAM/TSP. Cognitive function was lower in HAM/TSP (p = 0.045) but did not correlate with WM lesion number. Viral load and peripheral blood mononuclear cell interferon production correlated positively (p = 0.001) but did not correlate with lesion number or volume. Conventional brain MRI frequently shows WM lesions in HTLV-I-infected individuals suggesting potential early central nervous system inflammation with rare development of progressive disease.