[HTLV-I-associated myelopathy]

Following our proposal of a new clinical entity, HTLV-I-associated myelopathy (HAM), at least 270 cases have now been diagnosed in Japan. The geographical distribution resembles that of adult T-cell leukemia-lymphoma. Our laboratory has now identified 85 cases (27 males and 58 females aged 18-75 [mean 52] yrs. with age at onset 6-75 [mean 37] yrs.). The illness duration ranged from 4 mos. to 55 yrs. (mean 15.6 yrs.). Of the 85 cases, 81 lived in Kagoshima, where about 16% of the population have HTLV-I antibodies. Previously, we recognized a subgroup of cases who had frequent histories of blood transfusion, and from our recent data, 18 (21%) had the same history. The group with no history of transfusion was younger at onset of HAM (33 [SD 18] yrs. vs 49 [12] yrs.; p less than 0.05). From the latter, we have also recognized another subgroup consisting of 6 young cases (under 15 yrs.) whose mothers were positive for HTLV-I antibody titer. This group has been labeled mother-to-child or vertical transmission. Notably, the progression of symptoms was slower in the vertically transmitted group when compared to the group with a history of transfusion. We also reported the effectiveness of corticosteroids in 4 HAM cases and from the present data, 65 cases have been followed up for treatment response. Based on a 14-grade disability scoring, excellent response was noted in 20%, good in 37%, fair in 34% and no response in 9% of the total 65 cases. Compared with the vertically transmitted group, the group a history of blood transfusion appeared to have a better response to corticosteroids.