ABSTRACT
Cerebral herniations were successfully produced in experimental animals during the expansion of intracranial balloon or laminaria. Visualizing structures deep in the brain, cat's heads were instantaneously frozen with liquid nitrogen and were sectioned in the midline longitudinally. The cerebral herniations were assessed by measureing the distance between parts of various anatomical structures on the brain in mid-sagittal sectional plane. Transtentorial rostrocaudal herniation of the brain stem was evident and more marked in the group of bilateral lesions than in the groups of frontal and temporal lesions. Infratentorial lesions produced transtentorial upward herniation of a part of anterior cerebellar vermis and downward herniation of the cerebellar tonsil through the foramen magnum. The risk of brain herniation was noted to be greater in rapid expanding lesions with balloon than the more slowly developing lesions with laminaria.