Experimental hydrocephalus and hydrosyringomyelia in the cat. Radiological findings.

Fourty-six cats were made hydrocephalic and hydromyelic by means of an intracisternal kaolin injection. In 17 other cats hydrocephalus and syringohydromyelia were achieved by operative occlusion of the foramina Luschkae of the fourth ventricle. In both the kaolin treated animals and the animals whose outlets of the fourth ventricles were operatively obstructed a progressive dilatation of the ventricles and central canal occurred, which could be demonstrated and followed in 30 animals by ventriculography, myelography and/or contrast filling of the hydromyelic central canal. Coinciding with the dilatation of the central canal the clinical picture of a raised intracranial pressure due to obstructive hydrocephalus improved. The presented results suggest that the dilated central canal acts as a kind of natural by-pass between the ventricles and the spinal subarachnoid space. In order to determine the role of spinal kaolin arachnoiditis on spinal cyst formation and central canal dilatation in 13 animals, kaolin was locally applied in the lower thoracic region. The local spinal kaolin arachnoiditis had no influence on central canal dilatation or cyst formation.