[A case of flaccid paraplegia associated with HTLV-I infection].

A 63-year-old female began to have progressive gait disturbance at the age of 50. Neurologic examination revealed weakness and hypotonus of bilateral leg muscles. Deep tendon reflexes were hypoactive with positive Babinski sign and vibration sense was diminished in the legs. HTLV-I antibody titers were elevated both in serum (x 131,072) and in CSF (x 512). The result of nerve conduction velocities and short latency somatosensory evoked potentials suggested mild peripheral nerve lesion. Needle EMG studies showed myogenic changes in the upper limbs and also, neurogenic changes in the lower limbs. Histological examination verified mild myogenic changes in biopsied deltoid muscle and neurogenic and myogenic changes in the quadriceps femoris muscle, with ragged-red fibers. We consider that this patient has myelopathy, myopathy, peripheral neuropathy and anterior horn cell involvement associated HTLV-I infection. The relationship between HTLV-I infection and mitochondrial abnormalities of the biopsied muscles remains unclear.