Sequential morphological and functional changes in kaolin-induced hydrocephalus.

An experimental model of kaolin-induced hydrocephalus in the dog was studied in order to evaluate the progress of ventricular dilatation and the communications between the ventricular system and the subarachnoid space. Skull and spine radiological studies were obtained after metrizamide intraventricular injection, and the baseline ventricular pressure and cerebral pulse pressure amplitude were measured in anesthetized animals. Intracranial compliance and resistance to drainage of cerebrospinal fluid were calculated by means of bolus injection test. Light and scanning electron microscope studies were done at different developmental stages of hydrocephalus. With these experimental parameters, two successive phases were seen: an initial acute hypertensive hydrocephalus (H1) with high resistance, low compliance, severe ependymal damage, and subependymal edema; and a late chronic normotensive hydrocephalus (H2) with little resistance increase, normal compliance, epithelial regeneration, and subependymal gliosis. Both the H1 and H2 stages showed an increase in the cerebral pulse pressure amplitude.