Cisternal abnormalities produced by clinical tumours in the posterior cranial fossa. III. Tumours of the brain stem and pontine angle.

The pneumographic appearances of the subarachnoid cisterns have been analysed in detail in a clinical series of 17 patients with brain stem tumours and in 40 with pontine angle tumours. The cisternal distortions may be used to distinguish tumours in the pons from tumours in the medulla oblongata and also to distinguish tumours of the pontine angle with different modes of growth, e.g. tumours mainly indenting the cerebellar hemisphere from those mainly indenting the brain stem. The results should be applicable also for an analysis of cisternal pathology by other methods such as computer tomography and cisternography with positive contrast media.