Abstract
A personal series of 12 patients with benign aqueduct stenosis has been surveyed. A review of the radiographs has shown that in chronic aqueductal stenosis there is axial enlargement of the 3rd ventricle and displacement of the brain-stem. When these two features are pronounced, blockage of the basal cisterns will occur. We propose that when unsatisfactory flow of fluid through the basal cisterns may be inferred, then ventriculocisternostomy should be avoided. Evidence that the ventricular drainage is continuing satisfactorily after operation may be obtained either by echoencephalography, or by radiography, or by both means.