Muscle MRI findings of HTLV-1-associated myelopathy.

We report here the muscle MRI findings in two patients with human T-cell lymphotropic virus type I-associated myelopathy (HAM). It is known that thigh muscles are vulnerable in HAM patients, but detailed information about the affected muscles has not been available. Muscle MRI findings of these patients showed that thigh muscles, especially adductor magnus, and semimembranosus muscles were severely affected, but lower leg muscles were comparatively preserved. In these affected muscles, neurogenic changes were observed by EMG. We concluded that muscle MRI is very useful to estimate the affected muscles in HAM patients.