Cisternal abnormalities produced by clinical tumours in the posterior cranial fossa. II. Fourth ventricle tumours.

A detailed analysis of the distortion of the subarachnoid cisterns produced by intraventricular tumours of the fourth ventricle was carried out on a clinical material of 30 patients examined with pneumography. The cisternal distortions in cases with a tumour originating from the roof of the ventricle have been compared with those in tumours originating from the floor, and the typical appearances for each group of tumours are recorded. The results should be applicable when analysing cisterns examined not only with pneumography but also with other radiologic methods, such as computer tomography and cisternography with positive contrast media.