例1，男，1岁半，因生后四肢松软无力来诊.体检神清，发有营养欠佳，方依，前囟未闻，约1cm×1cm，心肺正常，肝脾不大，双侧睾丸下降，脊柱无畸形。抬头无力，双手托头不能和躯干保持在一个轴上。仰卧呈蛙式，直立托起似要滑脱感，水平托起头和四肢下垂。肌肉萎缩不明显，两手 Example 1, male, 1 and a half years old, due to post-natal limb weakness to visit. Physical examination clear, poor nutrition, according to Fang, before the fontanel not heard, about 1cm × 1cm, normal heart and lungs, Side of the testicles decreased, no deformity of the spine. Crane looked weak, hands and head can not be maintained on a shaft with the trunk. Supine was a frog-like, upright support seems to feel slipping off, the level of support and limbs drooping. Muscle atrophy is not obvious, both hands