Gross enlargement of the lateral and third ventricles, with superior bowing of the markedly thinned corpus callosum. The fourth ventricle is normal in calibre. Centrally, the cerebral aqueduct has a focal membrane/web without any convincing flow on CSF flow studies.
No evidence of tectal plate mass. The cerebral white matter volumes are diffusely reduced, presumably related to a longstanding hydrocephalus, which is associated with the typical skull findings. No periventricular hyperintensity to suggest transependymal oedema.
Conclusion: Gross hydrocephalus sparing the fourth ventricle due to aqueductal stenosis.