[Cervical collar therapy for juvenile muscular atrophy of distal upper extremity (Hirayama disease): results from 38 cases].

Juvenile muscular atrophy of distal upper extremity is a peculiar type of cervical myelopathy affecting young people characterized by localized amyotrophy in the forearm and hand that is initially progressive, and then stabilized in a few years. The anterior horn cell damage may be induced by forward displacement of the lower cervical dural sac and spinal cord on neck flexion. We proposed that the forward displacement was one of pathogenic factors, and reported that therapeutic intervention using a cervical collar in order to minimize neck flexion halted the progressive weakness in some patients.To examine effectiveness of cervical collar treatment for this disease and to investigate clinical and radiological profiles that predict a favorable outcome before treatment.Thirty-eight patients who had progressive illness within 5 years after onset underwent cervical collar therapy (treatment group). Forty-five patients in a previous case series without any therapeutic intervention made up a control group. The duration of progressive phase of illness was compared between the two groups. In the treatment group, the time interval from onset and the measurements of cervical cord atrophy and its flattening on neck flexion at the introduction of treatment by CT-myelography or MRI were analyzed with respect to prognosis.All the patients in the treatment group showed no further progression after introduction of treatment. The duration of the progressive period was shorter in the treatment group (mean 1.8 +/- 1.2 years) than in the control group (mean 3.2 +/- 2.3 years) (p < 0.005). In the treatment group, 15 of 31 patients within 2.5 years after the onset showed not only stabilization but also improvement of muscular weakness or cold paresis. Five of 7 patients who had no or mild cord atrophy at the introduction showed improvement after treatment.Cervical collar therapy induces a premature arrest of this disease. Improvement is expected in patients who have shorter duration of illness and have mild cord atrophy in a neutral neck position. Early diagnosis and therapeutic intervention may minimize the functional disability of young patients.