Hydrocephalus is a condition in which the cerebrospinal fluid (CSF) within the ventricles of the brain does not drain properly or at all. The condition can lead to a build-up of pressure in the ventricles and the surrounding brain tissue, and an enlargement of the head due to excess CSF. Hydrocephalus can sometimes be a result of a brain tumour or a congenital obstruction to flow of spinal fluid. Frequently, intraventricular hemorrhage, which is bleeding in the ventricles of the brain, is a cause of hydrocephalus.

What is CSF?

CSF is produced in the chambers or spaces in the brain called ventricles. It surrounds the brain and spinal cord, acting as a cushion. CSF is constantly produced; it bathes the brain and spinal cord and then gets reabsorbed into the blood vessels over the top of the brain. CSF travels inside the brain and spinal cord in a special pathway. Some of the functions of CSF are:

  • to protect the brain and spinal cord from injury
  • to nourish brain cells, which helps with brain functioning
  • to carry away waste products from brain cells

A baby’s enlarging head can be the first indication of hydrocephalus. Also, any baby at risk of brain injury will have a head ultrasound or several head ultrasounds, which may also spot hydrocephalus before the head is visibly enlarged. Although CSF can be drained off with a needle to relieve pressure, the long-term solution is the surgical placement of a shunt.


A shunt is a soft flexible tube that acts as a drain from the ventricles. It provides another pathway for CSF to be drained away from the brain. One end of the shunt is placed in one ventricle. The shunt is then threaded under the skin, like a tunnel, to another part of the body. Usually it goes to the abdomen, but sometimes it goes to the chest and rarely to the heart. The CSF is drained and reabsorbed into the bloodstream.

The shunt tube is attached to a valve in some shunts. The valve controls the flow of fluid. You can’t see a shunt because it is under the skin, but you can feel the shunt valve and tubing under the skin with your fingers. In children who are thin, it may be more noticeable under the skin.

There are many different kinds of shunts. The shunt is inserted during a simple operation which takes about three hours.

Shunt complications

Occasionally, there can be problems with the shunt. For example, it can be blocked or infected, or the tubing may become too short and disconnected as the child grows. If a shunt is not working well, your baby will need to have an operation to fix the problem. The surgeon will either clear the blockage or replace the shunt. If the shunt is infected, your child will need to have the shunt removed, have an external ventricular drain placed temporarily, and take antibiotics.


View the original article by Hilary Whyte, MSc, MB, BCh, BAO, MRCPI, FRCPC  here.

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