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Brain & Nervous System


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Hydrocephalus is a brain condition that happens when cerebrospinal fluid (CSF) — the clear, watery fluid that surrounds and cushions the brain and spinal cord — cannot drain from the brain. It then pools, causing a buildup of fluid in the skull. Hydrocephalus gets its name from the Greek words for water (hydro) and head (cephalus), and sometimes is called “water on the brain.”

Hydrocephalus can cause babies’ and young children’s heads to swell to make room for the excess fluid. Older kids, whose skull bones have matured and fused together, have painful headaches from the increased pressure in the head.

If it’s not treated, hydrocephalus can lead to brain damage, a loss in mental and physical abilities, and even death. With early diagnosis and timely treatment, though, most children recover successfully.


When everything is working normally inside the brain, CSF flows through narrow passageways called ventricles and exits the brain through a small reservoir at the base of the brain called the cistern. CSF delivers nutrients to the brain; it also takes waste away from its sensitive areas to be absorbed into the bloodstream.

If there’s a blockage in any of the ventricles, CSF backs up and causes hydrocephalus. This excess of fluid in the brain also can happen when the choroid plexus (the area of the brain that produces CSF) is in overdrive or if the waste products aren’t properly absorbed by the bloodstream.

hydrocephalus illustration

Congenital hydrocephalus means a baby is born with the condition. This is often due to problems like spina bifida (abnormal development of the spinal cord) or aqueductal stenosis (the narrowing of a small passageway, the “aqueduct of Sylvius,” that connects two major ventricles in the brain).

Acquired hydrocephalus happens after birth and can affect people of any age. It’s usually caused by bleeding in the brain. This can happen in premature babies or people who’ve had traumatic head injuries. Some kids can develop hydrocephalus due to a tumor or infection in the brain. Some cases have no known cause.

Signs in Babies

Symptoms of hydrocephalus vary depending on the age of a child.

Babies under the age of 1 year will have heads that appear very swollen. Their skull bones — thin, bony plates that have not yet fused together — are connected by fibrous tissue called sutures. These sutures, or “soft spots,” have not yet hardened and therefore stretch and expand to store the excess CSF. As a result, a baby with hydrocephalus will appear to have an oddly shaped head — usually much larger than other babies the same age.

Other signs to look for include:

  • bulging at the soft spots
  • “split” sutures — a gap can be felt between skull bones
  • rapid increase in head circumference
  • swollen veins that are easily seen with the naked eye
  • downward cast of the eyes (called “sunsetting”)

Depending on how severe the condition is, babies also may seem excessively sleepy, fussy, and vomit or have seizures. Young children with hydrocephalus also may miss developmental milestones or may revert to earlier developmental stages. In extreme cases, a child also may experience “failure to thrive” and miss growth milestones.

Signs in Older Kids

Older children will not have the easily recognizable symptom of an enlarged head because their skull bones have fused together and can’t expand to make room for the excess fluid. In these cases, added pressure on the brain can cause severe headaches that may wake a child in the middle of the night or early in the morning.

Kids also might have:

  • nausea/vomiting
  • sleepiness
  • problems with balance and motor skills
  • double vision
  • squinting and/or other repetitive eye movements
  • seizures

Changes in personality, loss of new developmental abilities (like speaking or walking), and memory loss can happen in more advanced cases.


A child who shows any of the signs and symptoms mentioned above should see a doctor right away. The doctor will perform examinations, which may include a medical history and diagnostic tests — like ultrasound, CT (computed tomography) scan, or MRI (magnetic resonance imaging) — to get a clear picture of the inside of the brain.

Treatment Options

It is important to treat hydrocephalus right away. Untreated hydrocephalus can get worse and cause further problems in the nervous system.

Treatment for hydrocephalus varies depending on the age of the child, the cause of the CSF buildup (whether from a blockage, overproduction of fluid, or another problem), and the child’s overall health.

Ventriculostomy and Coagulation

Endoscopic third ventriculostomy (ETV) with choroid plexus coagulation (CPC) is a relatively new procedure that is becoming common for kids who need surgery. This minimally invasive approach involves placing a small, lighted camera (called an endoscope) inside the brain so that surgeons can see the surgical site on a computer monitor. Then, using very small instruments, surgeons make a tiny hole in the bottom of the third ventricle of the brain.

This creates an “evacuation route” that lets fluid drain from the brain and bypass any blockages that are causing a backup. The body then absorbs the CSF back into the bloodstream as it normally would.

After the ventriculostomy, surgeons cauterize (burn slightly) parts of the choroid plexus, the area of the brain that produces CSF. This is done to reduce the amount of CSF that the brain makes.

This surgical approach has a higher success rate than shunting (implanting a tube in the brain to drain the fluid), which used to be the standard surgery for kids with hydrocephalus. It’s performed in kids ages 1 and up, but may be available to younger kids in the future.

Kids who have ventriculostomies and coagulation need to follow up with their care team often. If they develop hydrocephalus again, doctors usually have to do a shunting procedure because a repeat ventriculostomy is not likely to work.

Shunt Procedure

Shunt procedures, which have been done for decades, involve surgery to place one end of a catheter (flexible tube) into a ventricle of the brain and place the other end in the abdominal cavity, chambers of the heart, or space around the lungs. Fluid drains from the brain into these places and is absorbed by the bloodstream. A valve (flap that opens and closes) in the shunt system regulates the flow to prevent over-draining and under-draining.

While shunting has been an effective treatment for hydrocephalus, the long-term success rate of a shunt isn’t great. There is a high chance of failure and complications after a shunt is implanted, with almost half of all shunts failing to work well within the first year. When this happens, a child needs to have surgery again to replace a catheter or valve or replace the entire shunt. Most kids who undergo shunting will require future operations over their lifetimes to deal with shunt problems.

Infections are another side effect of shunting. Most infections develop within the first few months after a shunt procedure and require temporary removal of the device while a child receives IV (given through a vein) antibiotics for up to 2 weeks.

Because of the drawbacks of shunting, these procedures are done less and less these days. Doctors use shunting as an alternative when ventriculostomies and coagulation can’t or don’t work.


With timely treatment, many kids with hydrocephalus go on to lead normal lives.

Those with more complex medical problems, like spina bifida or bleeding in the brain from prematurity, may have more health problems due these conditions. In these kids, early treatment by developmental specialists, physical therapists, and occupational therapists can make recovery much more likely and greatly improve their outcomes.

Reviewed by: Manish Shah, MD, and Rupal Christine Gupta, MD
Date reviewed: September 2014
Originally reviewed by: Jeffrey W. Campbell, MD