Hydrocephalus, illustration. Example of congenital hydrocephalus in which there is an excessive amount of intracranial cerebrospinal fluid (CSF). This results in dilated lateral ventricles filled with CSF and in comparison to the gray matter of the cerebral cortex, the white matter is markedly diminished. A common cause is atresia (abnormal development/obstruction) of the aqueduct of Sylvius resulting in obstructed flow of CSF and ventricular dilation. In utero the head may attain a huge size. Convulsions, blindness, motor impairment are common as is death. From Bollinger, O. 1901 Atlas und Gundriss der Pathologischen Anatomie, vol 2. Lehmann, Munich.