Intermittent hydrocephalus due to cysts of the septum pellucidum: a study of three cases.

Three male patients with posturally induced, intermittent hydrocephalus were found on pneumoencephalography to have cavum septi pellucidi and cavum vergae. The clinical presentation resembled that of colloid cyst of the third ventricle. Remission followed excision of the septal walls in 2 cases, but relapse of symptoms occurred when the caves reformed. It is postulated that intermittent obstruction to the lateral ventricular outflow by the cavum septum pellucidum and cavum vergae was the basis of the symptomatology. Transcaval shunting may prove to be the simplest reliable form of treatment.