In Hydrocephalus ex vacuo, the compensatory enlargement of ventricles and an increase in CSF volume due to brain atrophy is seen in-
Hydrocephalus ex vacuo

Insignificant cortical atrophy, there is compensatory ventricular enlargement secondary to loss of parenchyma → Hydrocephalus ex vacuo.
This can be seen in Alzheimer disease and Pick disease. - Anderson 10th/ep. 2740.
Alzheimers diseae
Picks diseases
Both
None of the above