Strokes & ruptures aneurysm

When an area of the brain is deprived of oxygen as a result of obstruction by a blood clot in the artery that feeds the brain, it is referred to as an ischemic stroke.
Conversely, when a small artery bleeds inside the brain, it causes a hematoma which may impact the brain ventricles, limiting the flow of CSF and thereby causing hydrocephalus, this is referred to as a hemorrhagic stroke.

Finally, aneurysms, that is, small pockets that deform the walls of the main arteries to the brain, resulting in weakness, may suddenly rupture, which is known as a ruptured aneurysm.
In such cases, a large volume of blood will spread around the brain and block the resorption of CSF. Ruptured aneurysms are thus the primary cause of adult-acquired hydrocephalus.