[Two cases of atypical HTLV-I associated myelopathy (HAM)]

We report two cases of HTLV-I associated myelopathy (HAM) who showed high HTLV-I antibody titers with clinically atypical neurological symptoms compared with typical HAM originally reported by Osame et al. Case 1 is a 59 year-old-woman who showed Shy-Drager syndrome-like symptoms such as a slowly progressive gait disturbance, pyramidal and extra-pyramidal symptoms, an orthostatic hypotension and a sweating disturbance. The anti HTLV-I antibody titer was highly positive in both her serum and cerebrospinal fluid (CSF), and there was also a high level of oligoclonal immunoglobulin in her CSF. These symptoms improved slightly with steroid therapy. Therefore, it was suspected that this neurological condition was associated with HTLV-I, which means that HTLV-I can be associated not only with myelopathy but also with various other neurological symptoms. The second case is a 52-year-old woman who had a myelopathy with a slowly progressive course. She had suffered from a transient optic neuritis 5 years before admission that had improved completely with steroid therapy. She had highly positive anti HTLV-I antibody in both her serum and CSF, and also showed a high level of oligoclonal immunoglobulin in her CSF. With administration of steroids, the sensory disturbances and abnormal findings in the CSF improved slightly. Koprowski et al reported that in some MS patients they found positive anti HTLV-I antibody and furthermore proved the presence of CSF cells which hybridized with a HTLV-I probe. They suggested the presence of an unknown HTLV-related agent which may be a pathogenic factor in some subtypes of MS. The transient optic neuritis responding to steroid therapy and the following transverse myelopathy, as seen in case 2, are highly characteristic of MS. Thus, some clinical features of HAM may be very similar to MS.