The spinal cord central canal in kaolin-induced hydrocephalus

Abstract

To study the cause of the great individual variations in kaolin-induced hydrocephalus, the lower brain stem and upper spinal cord were examined histologically in a series of young rabbits that received injections of kaolin into the cisterna magna. Animals with complete occlusion of the outlets from the 4th ventricle into the subarachnoid space showed only a moderate ventricular dilatation; cases with marked hydrocephalus also had plugs of kaolin in the caudal part of the 4th ventricle. The intraventricular kaolin was adherent to the roof of the 4th ventricle by strands of connective tissue, and the plugs perhaps served as valves that initially occluded the opening of the central canal and were then lifted away as the ventricle dilated and the roof moved posteriorly. The animals with marked hydrocephalus also had extensive dilatation of the central canal with cleft formation in the posterior columns. In hydrocephalus the central canal may serve as an alternative resorption route for the CSF through communication with the spinal subarachnoid space.