Hydrocephalus ex vacuo also refers to an enlargement of cerebral ventricles and subarachnoid spaces, and is usually due to brain atrophy (as it occurs in dementias), post-traumatic brain injuries, and even in some psychiatric disorders, such as schizophrenia. As opposed to hydrocephalus, this is a compensatory enlargement of the CSF-spaces (leading to the allusion of more "water" in the head, which makes the head look more "empty" on imaging) in response to brain parenchyma loss; it is not the result of increased CSF pressure.