Changes in the components and content of biological water in the brain of experimental hydrocephalic rabbits

Changes in biological water components and their respective content in the cortical gray matter and periventricular white matter were studied in rabbits rendered hydrocephalic by intracisternal kaolin injection. There was no change in either total water content or free or bound water content in the cortical gray matter at the various stages of hydrocephalus development. While there was no significant change in total water content in the periventricular white matter at any stage of hydrocephalus, free water content was significantly elevated and bound water content was decreased at the acute and subacute stages, with a return to relatively normal levels at the chronic stage. It is concluded that in the periventricular white matter, free water enters the brain across the ependymal lining during the acute and subacute stages of experimental hydrocephalus with a simultaneous reduction in the bound water and that there is some recovery at the chronic stage. It is suggested that alternative drainage pathways may develop in chronic hydrocephalus allowing drainage of free water in the periventricular white matter, which in turn permits bound water to return to relatively normal levels.