Intrinsic third ventricle craniopharyngiomas with normal pressure hydrocephalus.

Two observations of intrinsic third ventricle craniopharyngiomas, both involving males in the fifth decade, are reported. Histologically, the tumours, one entirely solid and the other one chiefly cystic, were composed of squamous epithelium with microcysts and no calcifications. In the literature primary third ventricle craniopharyngiomas are considered to be exceedingly rare. However, if a more precise preoperative diagnosis, using computerised axial tomography, were made as a matter of routine, to verify third ventricular masses, it might demonstrate that these tumours are more common than previously believed. In both cases striking clinical pictures of normal pressure hydrocephalus were observed. The relations between intracranial pressure, CSF circulation and ventricular size are discussed. On mechanical grounds, it is very difficult to explain the poastoperative reduction in ventricular size, since there was no significant change in intracranial pressure.