[Chronic unilateral distal juvenile muscular atrophy localized to the upper extremity (Hirayama type). A European...

A 40 year-old Frenchman had had for 12 years, an amyotrophy of one upper limb. Clinical features were similar to those previously reported in Japan and India i.e. atrophy limited to one hand and forearm, with mild functional discomfort, and slow progression for 2 years after which the disorder did not progress. Electromyography showed disturbances of anterior horn cell type. The cause of this syndrome is unknown, no pathological case has yet been reported. The prognosis appears to be good.