Hydrocephalus: "Water on the Brain"

Hydrocephalus is a Condition in which CSF Builds Up in the Ventricles

Hydrocephalus comes from the words hydro, which means water, and cephalus, which means head. Hydrocephalus is a common complication after head trauma. It is a condition in which there is too much fluid, called cerebrospinal fluid (CSF), inside the ventricles of the brain.

Hydrocephalus can develop quickly, but may also take up to a year to appear.

The Brain’s Ventricles

The brain has natural folds which separate it into distinct yet connected segments.

The spaces in between these segments are called ventricles. One can picture the ventricles of brain as a network of caves which are connected by small passageways. Fluid is produced in some of these caves, flows through the passageways to the other caves, and is reabsorbed when the caves/ventricles fill up and create pressure against the walls.

There are two lateral ventricles inside the right and left sides of the brain. These connect to the third ventricle via a passageway called the “interventricular foramina”. The third ventricle then connects to the fourth ventricle through a passageway called the “cerebral aqueduct”. CSF flows between all of these ventricles. From the fourth ventricle, CSF is pushed through small openings called foramina. It then flows around the outside of the brain, and down the spinal cord.

When hydrocephalus develops, it is because there is an increased amount of CSF within the ventricular spaces.

  There is a problem that doesn’t allow the fluid to drain or be re-absorbed correctly. This leads to the buildup of fluid.  

There are two broad classifications of hydrocephalus: communicating and non-communicating.

Communicating Hydrocephalus

In communicating hydrocephalus, there is a relatively equal distribution of cerebrospinal fluid between the ventricles in the brain.

The openings between the ventricles allow for adequate flow between all of the distinct spaces, and this shows up clearly on an imaging study such as an MRI.

Communicating hydrocephalus usually develops when something prevents excess CSF from being reabsorbed by the brain. After a trauma, this may be because of bleeding, damage, or obstruction of the cells that are supposed to reabsorb CSF.

Non-Communicating Hydrocephalus

When hydrocephalus is classified as non-communicating, it means that only one, or some of the ventricles have excess fluid build-up, but not all of them. This usually happens when something prevents the natural flow of CSF through all the openings. After head trauma, it might be a foreign object that has lodged itself in the brain, bleeding, or infection.

Symptoms of Hydrocephalus

Symptoms develop based on which areas of the brain are most affected by increased pressure. Some common symptoms include:

  • Changes in one’s ability to walk, such as a shuffling gait
  • Losing one’s balance
  • Having difficulty coordinating movements
  • Headache
  • Difficulty waking up, or staying awake
  • Changes in vision
  • Changes in bowel or bladder habits, with a frequent need to urinate
  • Difficulty staying focused
  • Difficulty remembering things, or staying oriented to what one is trying to accomplish
  • Seizures, in later stage hydrocephalus.

Why it Is Dangerous

In non-communicating hydrocephalus, fluid continues to build up in the ventricles. This creates pressure inside the brain which then pushes into brain tissue. As pressure increases, blood vessels are unable to stay open. This leads to decreased blood flow. Oxygen is no longer effectively delivered, and brain cells start to die.

In communicating hydrocephalus, key dangers include progressive movement and cognitive difficulties, and losing control over bladder and bowel function. If not treated within a reasonable amount of time, these can become irreversible.


First, the underlying cause of hydrocephalus needs to be determined. There may be a number of treatments necessary to address structural abnormalities, blood clots or infection. Next, the excess fluid needs to be drained.

One common treatment for hydrocephalus is the placement of a shunt.


Gliemroth, J., Käsbeck, E., & Kehler, U. (2014). Ventriculocisternostomy versus ventriculoperitoneal shunt in the treatment of hydrocephalus: A retrospective, long-term observational study. Clinical Neurology And Neurosurgery, 12292-96. doi:10.1016/j.clineuro.2014.03.022

Linnemann, M., Tibæk, M., & Kammersgaard, L. P. (2014). Hydrocephalus during rehabilitation following severe TBI. Relation to recovery, outcome, and length of stay. Neurorehabilitation, 35(4), 755-761 7p. doi:10.3233/NRE-141160

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