Hydrocephalus: I. Histological and ultrastructural changes in the pre-shunted cortical mantle.

Hydrocephalus results in a reduction in the thickness of the cerebral cortical mantle which seemingly is restored by ventricular shunting. In order to determine the effect of hydrocephalus and its potential reversibility, experimental hydrocephalus was produced in adult cats by the introduction of kaolin or silicone into the basal cisterns followed by bilateral craniectomies. Microscopic and fine structural studies of these animals suggest the occurrence of significant focal axonal destruction. These studies suggest a sequence of events consisting of ventriculomegaly, disruption of the periventricular ependyma, periventricular edema, axonal destruction, secondary myelin disintegration and finally reactive astrocytosis. The damage to axons and meylin and resulting gliosis is irreversible.