Normal pressure hydrocephalus

In normal pressure hydrocephalus, hydrocephalus can be broken down into “hydro” which means water and “cephalus” which means head.

Hydrocephalus, which is also termed as “water on the brain”, is an excessive buildup of cerebrospinal fluid within the brain.

Even though the pressure on lumbar puncture is expected to be increased, in this case, it’s normal, which is why it’s termed as “normal pressure” hydrocephalus.

Let's start with some relevant anatomy. The brain has four interconnected cavities in the brain called ventricles, and each one contains a structure called a choroid plexus.

The choroid plexus is made up of ependymal cells which produces cerebrospinal fluid - a fluid that helps provide buoyancy and protection, as well as metabolic fuel for the brain.

Highest up, are two C-shaped lateral ventricles that lie deep in each cerebral hemisphere.

The two lateral ventricles drain their cerebrospinal fluid into the third ventricle, which is a narrow, funnel-shaped, cavity at the center of the brain.

The third ventricle makes a bit more cerebrospinal fluid and then sends all of the cerebrospinal fluid to the fourth ventricle via the cerebral aqueduct.

The fourth ventricle is a tent-shaped cavity located between the brainstem and the cerebellum.

After the fourth ventricle, the cerebrospinal fluid enters the subarachnoid space, which is the space between the two inner linings of the brain - the arachnoid and pia mater.

Now, the arachnoid mater protrudes into the outermost covering, called dura mater, at various points.