HYDROCEPHALUS

Water brain

Hydrocephalus is defined as the accumulation of excessive CSF within the brain’s ventricular system. Let’s break it down further.

Communicating hydrocephalus

The granulations that drain CSF become clogged. Something is blocking the CSF’s exit (resorption through the subarachnoid space), which can be caused by meningitis or subarachnoid hemorrhage. The entire ventricular system enlarges. Causes high brain pressures! 

Non-communicating hydrocephalus

A tumor or malformation compresses one of the ventricles, obstructing the flow of CSF from one ventricle to another. The most common clog site is the long and narrow cerebral aqueduct. Distinguishing Feature: not all of the ventricles are big. Causes high brain pressures!

Hydrocephalus ex vacuo

Brain tissue adjacent to a ventricle dies. So CSF leaks out of the ventricle and into the dead tissue, to fill the vacuum left behind. Pressure in the CSF is normal.

Increased CSF production

Rare. Low yield. There's an excess of CSF because too much CSF is made. Caused by a choroid plexus tumor.

Normal pressure hydrocephalus

The patient has large ventricles, normal ICP but no cortical atrophy. Cause: Unclear! One theory is that patients have a transient impairment of CSF resorption, which causes a communicating hydrocephalus, which normalizes in pressure after some time. Typical patient: elderly patient with gait disturbance, urinary incontinence and dementia (Wet, Wacky, Wobbly). It can be reversible early on in the disease.