[Movement disorders in HTLV-I associated myelopathy (HAM)]

Periodic movements in sleep (nocturnal myoclonus) are characterized by a triple flexion of the ankle, knee and hip, which are particularly evident during 1-2 and 2-3 sleep stages. Iijima et al (1991) reported these movements in 5 out of 7 HAM patients, suggesting that nocturnal myoclonus is not rare in HAM. L-dopa and bromocriptine are reported to be the most effective. Spinal myoclonus (SM) is characterized by symmetric, rhythmic involuntary contractions of muscle groups supplied by one or several contiguous segments of the spinal cord. There has been only one case report of SM by Kanda et al (1988). Clonazepam and tetrabenazine are reported to be the most effective. Tremor is characterized by a sinusoidal oscillatory movement produced by synchronous or alternating contractions of reciprocally innervated antagonist muscles. Postural finger tremor was seen in about 40% of HAM patients (Suwazono et al, 1989). Painful, paroxysmal muscle contractions of the lower limbs were reported in only one patient with HAM by Ikeda et al in 1990. Based on electrophysiological findings, they were thought to be caused by reciprocal excitation in the spinal cord.