本文报道了２１例小儿外伤性外部性脑积水。其ＣＴ表现为双侧额顶部蛛网膜下腔增宽、大脑纵裂前部增宽、脑沟裂增宽加深、脑室系统及脑底池轻度扩大。通过ＣＴ动态观察发现，这种改变出现在外伤后不久，且短期内可增多、减少或消失。文中对本病的发生机制、ＣＴ表现及与脑萎缩的鉴别进行了讨论 This article reports 21 cases of pediatric traumatic external hydrocephalus. The CT showed the top of the bilateral frontal subarachnoid widened, the front of the brain widened longitudinal cleft crack wider and deeper brain ventricles and cerebrospinal fundus slightly enlarged. By CT dynamic observation found that such changes occur shortly after trauma, and short-term increase, decrease or disappear. The pathogenesis of this disease, CT findings and identification of brain atrophy were discussed