Those health incidents can sometimes cause a blockage in the CSF absorption or the CSF circulation inside or around the brain and spinal cord, potentially creating an acquired or secondary hydrocephalus.
For instance, a tumor ingrowth could block one of the CSF pathways. A bleed forming clots inside the brain can block the sagittal sinuses, where CSF is normally absorbed, A trauma to the head can damage some of the structures responsible for CSF circulation and/or absorption.