青少年上肢远端肌萎缩症,又称平山病、良性单肢肌萎缩症,是一种青少年期自限性的下颈段脊髓前角病变,好发于15~25岁之间,男性多发,男女之比为7~20∶1,呈慢性隐袭起病,数年后停止进展,预后良好。迄今全世界报道共约l500例左右,绝大部分病例由日本和印度报道,但近年来欧美等国家 Adolescent upper limb distal muscular atrophy, also known as Pingshan disease, benign limb muscle atrophy, is a juvenile self-limited cervical spine anterior horn lesions occur in 15 to 25 years old, multiple men, The ratio of men to women is 7 ~ 20: 1, was chronic insidious onset, stopped progress after a few years, the prognosis is good. So far around the world reported about l500 cases, the vast majority of cases reported by Japan and India, but in recent years, Europe and the United States and other countries