[Small hand muscle atrophy as an initial sign in HTLV-I associated myelopathy].

A 68-year-old female had been well until the age of 52 when she noticed weakness and atrophy of her right small hand muscles. She began to have gait disturbance at the age of 63. On admission, neurological examinations revealed atrophy and weakness of the small hand muscles on both sides as well as spastic paraparesis. As the antibody titer for human T-lymphotropic virus type I (HTLV-I) was elevated both in the serum and CSF, a diagnosis of HTLV-I associated myelopathy (HAM) was made. Electrophysiological studies showed neurogenic changes and suggested anterior horn cell involvement. After oral administration of prednisolone, her spasticity and gait disturbance improved slightly. Small hand muscle atrophy can be one of the initial signs of HAM, and may mimic amyotrophic lateral sclerosis and cervical spondylosis.