What is Congenital Hydrocephalus?

Hydrocephalus is a condition in which too much fluid builds up in the brain. The name comes from a combination from Greek words meaning “water” and “head.” “Congenital” means a person is born with it.

The liquid that builds up isn’t water. It’s cerebrospinal fluid (CSF). It circulates through the brain, bringing important nutrients and flushing away waste products from tissues. Normally, it’s absorbed into the bloodstream.

With hydrocephalus, there’s an imbalance between how fast fluid is made and how quickly it’s absorbed. The result is that it builds up. This can cause the head to enlarge and increase pressure around the brain.

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There are treatments to help, depending on the underlying cause.


In general, an imbalance can happen for any one of three reasons:

  • The ventricles – spaces in the brain where CSF is made -- produce too much fluid.
  • Something blocks the normal flow of fluid and causes it to build up.
  • The bloodstream can’t absorb all the fluid.

Congenital hydrocephalus can be genetic or caused by something else that occurred during pregnancy.

Common reasons for congenital hydrocephalus include:

  • Aqueductal stenosis, a type of blockage. The passageway between two of the ventricles in the brain is narrow or blocked, and fluid can’t circulate. The path may be cut off because of an infection, a tumor, or a hemorrhage.
  • Neural tube defects. Among these is spina bifida, in which a baby is born with part of the spinal cord exposed. In some cases, the flow of CSF out of the skull may be blocked.
  • Arachnoid cysts , a type of growth in the brain that can block the flow of fluid.
  • Dandy-Walker syndrome, a condition in which parts of the brain don’t develop as they should. Among other issues, one ventricle of the brain becomes enlarged because the pathways out are very narrow or closed.
  • Chiari malformations, conditions that affect the spot where the brain and spinal cord join. The lower part of the brain pushes down into the spinal column, causing a blockage.


Routine ultrasound tests during pregnancy may be able to pick up problems with your baby’s brain development, such as enlarged ventricles or spaces within the brain.

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If a problem shows up on ultrasound, further tests can help diagnose the issue more clearly.

Because some babies with hydrocephalus also have other serious health issues, your doctor will want to get a full picture of your baby’s overall condition. So you might get other tests, such as an MRI – which can provide more details on your baby’s brain development.

Your doctor may also take a sample of your amniotic fluid, to check on your baby’s chromosomes. Your doctor will also want to know about your family’s health history, especially if any of your relatives have had any neural tube defects.


Even though doctors can diagnose hydrocephaly in the womb, treatment generally doesn’t begin until your baby is born.

The most common treatment for congenital hydrocephaly is a shunt system. A surgeon will place a flexible plastic tube in the baby’s brain to drain the extra fluid. The other end of the tube goes under the skin and into the belly, or another place in the body where the excess CSF can be absorbed.

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Another possible treatment is called ETV (endoscopic third ventriculostomy), which uses fiber-optic technology. A doctor guides a small camera into a baby’s brain and, with a tool, opens a hole in a ventricle, bypassing a blockage. The brain fluid then drains through that hole and is absorbed into the bloodstream.

What to Expect

The outlook for babies born with hydrocephalus varies and depends in part on the cause of the condition.

Shunt systems have to be watched carefully. Your child might need more than one procedure. Among the problems that can crop up:

  • Infections
  • Clogged lines
  • Mechanical problems
  • Shunt needs to be longer

ETV also has some risks. The opening in the ventricle could close suddenly, which can be life-threatening. Infection, fever and bleeding also could occur.

Even when it’s treated, congenital hydrocephalus can affect physical and intellectual development. Your child may need rehabilitation and special education, but a normal life with just a few limitations is possible.

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