MRI demonstrates marked dilatation of the supratentorial ventricular system noted with associated enlarged 4th ventricle, associated with webs at the distal portion of the aqueduct, causing marked tight distal stenosis and with proximal funnelling. This is associated with decreased mamillopontine distance (3 mm) and periventricular T2/FLAIR hyperintensity reflecting associated transependymal permeation. Webs are also noted at the 4th ventricular outlet foramina, notably the median foramen of Magendie, with consequent supratentorial ventricular dilatation and prominent 4th ventricle
Dynamic CSF flow study and ultra-thin 3D T2 Sagittal sequences revealed: multiple webs at the distal portion of the aqueduct with consequent tight aqueductal stenosis and at 4th ventricle outlet foramen. Very poor/absent CSF flow signal across the aqueduct at cine phase sequences matching the markedly tight focal aqueductal stenosis.