[Subdural effusion following radical surgery for chiasmal region tumors in children--report of 4 cases (author's transl)].

Four cases of subdural effusion following radical surgery for the chiasmal region tumors in childhood were presented in this report. Three out of four cases were craniopharyngioma and the remaining one was optic glioma. The pathogenetic mechanisms of this disorder were explained probably and at least partly by a change from internal to external hydrocephalus or craniocerebral disproportion due to cerebral atrophy in two of the four cases and unclear in the remaining two cases. In all four cases meningitis did not supervene postoperatively. The subdural effusion may be divided into two types according to symptomatology, i.e., "serious type" which presents with severe symptoms and "mild-type" which is virtually asymptomatic. The serious type required immediate surgical procedure, such as continuous subdural drainage and subduroperitoneal shunt, while the mild type should be carefully monitored for the course of subdural effusion by CT scan.