Hydrocephalus is a buildup of fluid inside the skull that leads to the brain pushing against the skull.

Hydrocephalus means "water on the brain."

Water on the brain

Hydrocephalus is due to a problem with the flow of the fluid that surrounds the brain. This fluid is called the cerebrospinal fluid, or CSF. The fluid surrounds the brain and spinal cord and helps cushion the brain.

CSF normally moves through the brain and around the spinal cord, and then is absorbed into the bloodstream. CSF levels in the brain can rise if:

• The flow of CSF is blocked.
• The fluid does not get properly absorbed into the blood.
• The brain makes too much of the fluid.

Too much CSF puts pressure on the brain. This pushes the brain up against the skull and damages brain tissue.

Hydrocephalus may begin while the baby is growing in the womb. It is common in babies who have a myelomeningocele, a birth defect in which the spinal column does not close properly.

Hydrocephalus may also be due to:

• Genetic defects
• Certain infections during pregnancy

In young children, hydrocephalus may be due to:

• Infections that affect the central nervous system (such as meningitis or encephalitis), especially in infants.
• Bleeding in the brain during or soon after delivery (especially in premature babies).
• Injury before, during, or after childbirth, including subarachnoid hemorrhage.
• Tumors of the central nervous system, including the brain or spinal cord.
• Injury or trauma.

Hydrocephalus most often occurs in children. Another type, called normal pressure hydrocephalus, may occur in adults and older people.

Symptoms of hydrocephalus depend on:

• Age
• The amount of brain damage
• What is causing the buildup of CSF fluid

In infants, hydrocephalus causes the fontanelle (soft spot) to bulge and the head to be larger than expected. Early symptoms may also include:

• Eyes that appear to gaze downward
• Irritability
• Seizures
• Separated sutures
• Sleepiness
• Vomiting

Symptoms that may occur in older children can include:

• Brief, shrill, high-pitched cry
• Changes in personality, memory, or the ability to reason or think
• Changes in facial appearance and eye spacing
• Crossed eyes or uncontrolled eye movements
• Difficulty feeding
• Excessive sleepiness
• Headache
• Irritability, poor temper control
• Loss of bladder control (urinary incontinence)
• Loss of coordination and trouble walking
• Muscle spasticity (spasm)
• Slow growth (child 0 to 5 years)
• Slow or restricted movement
• Vomiting

The goal of treatment is to reduce or prevent brain damage by improving the flow of CSF.

Surgery may be done to remove a blockage, if possible.

If not, a flexible tube called a shunt may be placed in the brain to reroute the flow of CSF. The shunt sends CSF to another part of the body, such as the belly area, where it can be absorbed.

Other treatments may include:

• Antibiotics if there are signs of infection. Severe infections affecting the shunt may require the shunt to be removed.
• A procedure called endoscopic third ventriculostomy (ETV), which relieves pressure without replacing the shunt.
• Removing or burning away (cauterizing) the parts of the brain that produce CSF.

The child will need regular check-ups to make sure there are no further problems. Tests will be done regularly to check the child's development, and to look for intellectual, neurological, or physical problems.

Visiting nurses, social services, support groups, and local agencies can provide emotional support and help with the care of a child with hydrocephalus who has serious brain damage.

Without treatment, up to 6 in 10 people with hydrocephalus will die. Those who survive will have different amounts of intellectual, physical, and neurological disabilities.

The outlook depends on the cause. Hydrocephalus that is not due to an infection has the best outlook. People with hydrocephalus caused by tumors will often do very poorly.

Most children with hydrocephalus who survive for 1 year will have a fairly normal lifespan.

The shunt may become blocked. Symptoms of such a blockage include headache and vomiting. Surgeons may be able to help the shunt open without having to replace it.

There may be other problems with the shunt, such as kinking, tube separation, or infection in the area of the shunt.

Other complications may include:

• Complications of surgery
• Infections such as meningitis or encephalitis
• Intellectual impairment
• Nerve damage (decrease in movement, sensation, function)
• Physical disabilities

Seek medical care right away if your child has any symptoms of this disorder. Call 911 or the local emergency number or go to the emergency room if emergency symptoms occur, such as:

• Breathing problems
• Extreme drowsiness or sleepiness
• Feeding difficulties
• Fever
• High-pitched cry
• No pulse (heartbeat)
• Seizures
• Severe headache
• Stiff neck
• Vomiting

You should also contact your child's provider if:

• The child has been diagnosed with hydrocephalus, and the condition gets worse.
• You are unable to care for the child at home.

Protect the head of an infant or child from injury. Prompt treatment of infections and other disorders associated with hydrocephalus may reduce the risk of developing the disorder.

Published Date: October 01, 2025
Published By: Charles I. Schwartz, MD, FAAP, Clinical Assistant Professor of Pediatrics, Regional Medical Director of Penn Medicine Primary and Specialty Care, Perelman School of Medicine at the University of Pennsylvania, General Pediatrician at PennCare for Kids, Phoenixville, PA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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