In noncommunicating hydrocephalus, CSF cannot get to the subarachnoid space because its flow is blocked by gliosis of the aqueduct, fibrosis of the foramina of Luschka and Magendie or a colloid cyst of the third ventricle. In spite of the fact that CSF pathways are blocked CSF is formed at a normal rate so the ventricles have to dilate at the expense of the white matter particularly but also the grey matter since the CSF has no place to be resorbed. Hydrocephalus is often an accompaniment of a meningomyelocoele or Arnold-Chiari malformation. It can also be caused by isolated stenosis of the Aqueduct of Sylvius due to in utero viral infection. Meningitis can cause communicating hydrocephalus.
Ventricles show loss of ependyma.
Infants have large heads as well ventricles because of their flexible skull. Older children and adults develop headache and signs of increased intracranial such as lethargy or a dilated pupil. Must place a shunt tube into the lateral ventricles and extend it to the peritoneal cavity or atrium of the heart to drain excess fluid. Children with hydrocephalus if unshunted are retarded. Robbins Pathologic Basis of Disease.