Quantitative assessment of subclinical spasticity in human T-cell lymphotropic virus type I infection

Objective: To compare human T-cell lymphotrophic virus type I(HTLV-I) serop ositive and seronegative women for symptoms and signs of spasticity. Backgr ound: Infection with HTLV-I causes tropical spastic paraparesis/HTLV-I-asso ciated myelopathy (TSP/HAM). Certain populations, including female commerci al sex workers (FSW), are at increased risk of developing this infection. F ewer than 5% of HTLV-I-seropositive persons develop TSP/HAM, which is typic ally associated with spasticity. Methods: Cross-sectional study of 255 regi stered FSW in Callao, Peru, involving a questionnaire detailing demographic s and neurologic symptoms, standard neurologic examination, quantitative as sessment of spasticity (QSA) of muscle tone, and serologic testing for HTLV -I. Participants and examiners were blinded to serology results. Results: O n the questionnaire and neurologic examination, none of the 32 HTLV-I-serop ositive or 223 seronegative women had signs or symptoms of spasticity. Howe ver, mean values on QSA were significantly higher among seropositive women (27.1 Newton-meters/radian [N-m/r]) than among seronegative women (21.6 N-m /r, p = 0.01), indicating a subclinical increase in lower extremity tone. W ith values of QSA divided into tertiles, and the first tertile serving as t he comparison group, the odds ratio for seropositivity was 1.4 (95% confide nce interval [CI] 1.0 to 2.0) in the second and 3.1 (95% CI 2.2 to 4.3) in the third tertile, after adjusting for age and place of birth. Conclusions: Although a standard neurologic evaluation could not distinguish beta een w omen with and without HTLV-I infection, QSA indicated significantly increas ed lower extremity tone in those with infection. Long-term follow-up will d etermine whether these subclinical findings in asymptomatic women progress to overt TSP/HAM.