Abstract
RIHSA cisternography was abnormal in all of 24 patients with supratentorial tumours. The most common finding was asymmetry caused by ipsilateral obstruction of the sylvian fissure and the subarachnoid space around the convexity. Another frequent finding was partial or total obstruction at the tentorial notch, often in combination with reduced or absent activity along the superior sagittal sinus. These disturbances of CSF flow may explain the pathogenesis of raised CSF pressure with cerebral tumours.