ACUTE HYDROCEPHALUS IN POSTERIOR-FOSSA INJURY

This is the first known report of the use of computerized tomography ( CT) scanning to examine acute hydrocephalus in posterior fossa injury. Of the 1802 patients with acute head trauma treated at Funabashi Muni cipal Medical Center, 53 (2.9%) had suffered injury to the posterior f ossa. Of these, 12 patients (22.6%) had associated acute hydrocephalus : nine patients with acute epidural hematoma (AEH) and three with intr acerebellar hematoma and contusion (IWC). There was a significant rela tionship between cases of AEH with hydrocephalus and supratentorial ex tension, hematoma thickness of 15 mm or more, and abnormal mesencephal ic cisterns. In cases of IH/C, bilateral lesions and no visible fourth ventricle were significant causes of hydrocephalus. According to thes e results, possible mechanisms of acute hydrocephalus in posterior fos sa injury may be as follows: in cases of AEH, hematoma that extends to the supratentorial area compresses the aqueduct posteriorly and cause s hydrocephalus; in cases of IH/C, hematoma and contusional lesions ma y directly occlude the fourth ventricle and cause acute hydrocephalus. Seven patients suffering from AEH with acute hydrocephalus underwent evacuation of their hematoma without external ventricular drainage. In these cases, CT scanning showed that the hydrocephalus improved immed iately after evacuation of the hematoma. Two patients suffering from W C with hydrocephalus underwent a procedure for evacuation of the hemat oma and external ventricular drainage. The authors do not believe that ventricular drainage is necessary in treating posterior fossa AEH. Ho wever, both evacuation of the hematoma and ventricular drainage are ne cessary in cases of IH/C with hydrocephalus to provide the patient wit h every chance for survival. There was no significant difference in mo rtality rates when cases of AEH with acute hydrocephalus (0%) were com pared with cases of AEH without hydrocephalus (7.7%). The observed mor tality rates in cases of IH/C with hydrocephalus and those without hyd rocephalus were 100% and 15.4%, respectively; this is statistically si gnificant.