Microsurgery of tumours of diencephalic region.

A report about the microsurgical treatment of large tumours involving or displacing the diencephalon (craniopharyngiomas 150, pituitary adenomas 450 out of 1100, meningiomas 200, and rare tumours as epidermoids and gliomas of the third ventricle). It is mandatory to save the floor of the third ventricle, the pituitary stalk and even the small vessels. The technical procedure is described in detail depending on the extent of the tumour. Craniopharyngiomas can be within the sella and above it, suprasellar and extraventricular or combined intraventricular and extraventricular. In each case the origin and extent of the tumour decide the approach, which can be unilateral or bilateral frontal, subtemporal, transtentorial, transventricular or any combination of these. In intraventricular tumours the approach by incising the lamina terminalis proved to be the best procedure in 50 cases. Radical removal was possible in 80%, but with a high mortality of 17%. In giant adenomas with involvement of the third ventricle the approach through the lamina terminalis is dangerous. In doing an intracapsular removal of the "intraventricular" portion of the tumour it is of great assistance to use a stomatological reverse mirror. The mortality of giant adenomas could be reduced from 30% to 11%. In meningiomas of the medial third of the sphenoidal wing and tuberculum sellae the microsurgical separation of the floor of the third ventricle and the stalk is the most important problem and has become possible in most cases. Some gliomas of the third ventricle can be separated completely via the lamina terminalis or the foramen of Monro without touching the floor of the third ventricle.