Hydrocephalus, sometimes called “water on the brain,” is a condition where extra fluid builds up inside the brain. This fluid is called cerebrospinal fluid (CSF). Every hour, a certain amount of CSF is produced, and a certain amount of CSF is reabsorbed. When there is an imbalance to this production or reabsorption, too much CSF puts pressure on the surrounding brain. This decreases overall blood and oxygen flow to the surrounding brain, which can lead to long-term developmental issues or be life-threatening.

Hydrocephalus can be present at birth (congenital), found during pregnancy, or develop later in life (acquired). With early diagnosis, treatment, and ongoing care, many children with hydrocephalus grow up to live healthy, active lives.

What is hydrocephalus?

The brain and spinal cord are surrounded by a clear fluid called cerebrospinal fluid (CSF). This fluid cushions the brain and spinal cord, delivers nutrients, and removes waste. Normally, the body makes and absorbs CSF in a balanced way that ensures the right amount of fluid.

Hydrocephalus happens when:

• CSF flow is blocked inside the brain
• The body doesn’t absorb CSF the way it should
• The brain makes too much CSF

When this balance is off, CSF builds up and causes pressure inside the skull. 

Causes of hydrocephalus

Hydrocephalus has many possible causes. In children, it may develop because of: 

• Birth differences such as spina bifida
• Bleeding in the brain, especially in premature babies
• Infections like meningitis
• Head injuries
• Brain tumors or cysts
• Unknown causes in some cases

Before birth

With advanced prenatal imaging, doctors can often detect enlarged ventricles and fluid buildup in the brain before a baby is born. This is called ventriculomegaly. It can lead to hydrocephalus after birth. 

How fetal ventriculomegaly is diagnosed

• Prenatal ultrasound: Ventriculomegaly may be suspected if the brain’s fluid spaces (ventricles) look enlarged.
• Fetal MRI: This provides a more detailed picture of the baby’s brain and helps identify the cause. Ultrafast fetal MRI techniques were refined here at CHOP, and our fetal imaging team performs more than 600 fetal MRIs every year, experience that helps ensure the most accurate diagnosis.
• Monitoring during pregnancy: Doctors track changes in the baby’s head size and brain development over time, and sometimes this is how fetal ventriculomegaly is diagnosed. 

Prenatal management at CHOP

At Children’s Hospital of Philadelphia, our Center for Fetal Diagnosis and Treatment provides specialized care for babies diagnosed with hydrocephalus before birth. Families may receive: 

• Detailed prenatal evaluation with ultrasound and fetal MRI
• Genetic counseling to check for related conditions
• Pregnancy management with maternal-fetal medicine specialists
• Delivery planning at CHOP’s Garbose Family Special Delivery Unit (SDU), where the baby can receive expert care immediately after birth 

Treatment for hydrocephalus happens after the baby is born. Prenatal diagnosis is important because it allows doctors and families to plan ahead for delivery and immediate newborn care.

Symptoms of hydrocephalus

Hydrocephalus symptoms depend on your child’s age and how quickly the fluid builds up. 

In babies:

• Unusually fast head growth
• Bulging or firm soft spot on the top of the head (fontanelle)
• Vomiting
• Sleepiness or irritability
• Poor feeding
• Eyes that look downward (sometimes called “sunsetting eyes”) 

In older children:

• Headaches
• Nausea and vomiting
• Blurred or double vision
• Trouble with balance, walking, or coordination
• Learning difficulties or memory problems
• Irritability or behavior changes 

If you notice any of these signs, tell your child’s pediatrician and they can help guide you on next steps.

How hydrocephalus is diagnosed

Doctors use several tools to check for hydrocephalus after a child is born:

• Ultrasound: Often used in newborns to see fluid around the brain
• MRI or CT scans: Provide detailed pictures of the brain to confirm a diagnosis
• Physical exams: Includes tracking head growth and checking reflexes and development 

Treatment for hydrocephalus

Hydrocephalus treatment in babies and children can depend on many factors, including the type of hydrocephalus, rate of progression, age and severity.

Treatment is focused on reducing pressure in the brain by draining the extra fluid.

• aShunt system: This is the most common treatment for hydrocephalus. A thin, flexible tube is placed in the brain to carry fluid to another part of the body (such as the belly), where it can be absorbed. Shunts can stay in place for many years. Sometimes they need to be replaced.
• Endoscopic third ventriculostomy (ETV): A minimally invasive surgery where doctors make a small opening inside the brain to allow CSF to flow more freely. In some cases, ETV is combined with a procedure called choroid plexus cauterization (CPC) to reduce CSF production. 

Your child’s neurosurgery team will recommend a treatment plan based on the child’s age, symptoms, and overall health.

Living with hydrocephalus

Many children live full, active lives after treatment for hydrocephalus. Most will need lifelong follow-up care to make sure their shunt or ETV continues to work. 

Parents should watch for signs of shunt problems, which can include:

• Sudden headaches
• Nausea or vomiting
• Sleepiness or irritability
• Vision changes
• Trouble with balance 

If you notice these symptoms, call your doctor right away. 

Early therapies (such as physical, occupational, and speech therapy) and school supports can also help children who have developmental challenges.

Frequently asked questions about hydrocephalus

Can hydrocephalus improve before birth?
In some cases, ventricular enlargement (fluid buildup) may remain stable during pregnancy or appear less severe later. However, most babies with fetal ventriculomegaly will still need evaluation and possible treatment after birth.

Does fetal ventriculomegaly mean my baby will have brain damage? 
Not always. The outcome depends on the cause, the amount of fluid, and whether there are other medical conditions. Some children develop normally, while others may need therapies and support as they grow. 

What is the survival rate for babies with hydrocephalus?
Most babies with hydrocephalus survive, especially with early diagnosis and treatment. Outcomes depend on the cause, severity, and how quickly treatment begins. 

Will my baby need surgery right after birth?
Not all babies need surgery immediately. Some are monitored closely after delivery, while others may need shunt placement or another procedure in the newborn period. Your baby’s care team will create the safest plan.

Where should I deliver my baby if they have hydrocephalus? 
For babies diagnosed before birth, delivery in a hospital with specialists in fetal and neonatal care — like CHOP’s Garbose Family Special Delivery Unit — ensures both mother and baby have access to immediate expert care.

Can a child with hydrocephalus live a normal life?
Yes. With treatment and regular medical care, many children with hydrocephalus grow up to attend school, play sports, and enjoy daily activities like other kids.

Is hydrocephalus lifelong?
Hydrocephalus is usually a lifelong condition that requires ongoing care. Children with shunts or ETVs may need additional surgeries as they grow. 

Will my child have developmental delays?
Some children with hydrocephalus may experience learning or motor challenges. Early intervention and therapy services can make a big difference. 

How do I know if my child’s shunt is failing?
Warning signs include sudden headaches, vomiting, unusual sleepiness, or behavior changes. If you see these, call your child’s doctor immediately. 

Why choose Children’s Hospital of Philadelphia for hydrocephalus care?

At CHOP, we have one of the largest pediatric hydrocephalus programs in the country. Your child will receive expert care from before birth through delivery and beyond from leading fetal medicine experts and one of the nation’s leading neurosurgery and neurology teams. We offer:

• Advanced imaging and prenatal diagnosis for hydrocephalus
• Expertise in shunt placement and minimally invasive surgery (ETV/CPC)
• Lifelong support, from infancy through adolescence and beyond 

Our team partners with families to create personalized care plans that support medical needs and overall quality of life.