Hydrocephalus is a condition that occurs when fluid builds up in the skull and causes brain swelling. The name means “water on the brain.”

Cerebrospinal fluid (CSF) usually moves within the brain’s cavities, also known as ventricles. But during hydrocephalus, excess fluid causes the ventricles to expand, putting pressure on other parts of the brain.

Brain damage can occur as a result of this fluid buildup. This can lead to developmental, physical, and intellectual impairments. It requires prompt treatment to prevent serious complications.

Hydrocephalus mainly occurs in children and adults aged over 60 years, but younger adults can get it too. The National Institute of Neurological Disorders and Stroke estimates that 1 to 2 of every 1,000 babies is born with hydrocephalus.

Hydrocephalus can cause permanent brain damage, so it’s important to recognize the symptoms of this condition and seek medical attention. It’s most common in children but can develop in people of any age.


Early signs of hydrocephalus in infants include:

  • bulging fontanel, which is the soft spot on the surface of the skull
  • a rapid increase in head circumference
  • eyes that are fixed downward
  • seizures
  • extreme fussiness
  • vomiting
  • excessive sleepiness
  • poor feeding
  • low muscle tone and strength

Toddlers and older children

Symptoms or signs that affect toddlers and older children include:

  • short, high-pitched cries
  • personality changes
  • changes in facial structure
  • crossed eyes
  • headaches
  • muscle spasms
  • delayed growth
  • trouble eating
  • extreme sleepiness
  • irritability
  • loss of coordination
  • loss of bladder control
  • larger-than-average head
  • trouble staying awake or waking up
  • vomiting or nausea
  • seizures
  • problems concentrating

Young and middle-aged adults

Symptoms in young and middle-aged adults include:

Normal pressure hydrocephalus (NPH)

This form of the condition usually begins slowly and is more common in adults over the age of 60. One of the earliest signs is falling suddenly without losing consciousness. Other common symptoms of normal pressure hydrocephalus (NPH) include:

What does hydrocephalus look like?

Below, we compare a CT image of a brain with hydrocephalus to one without.

Swollen ventricles in the brain cause hydrocephalus.

To understand how hydrocephalus develops, it’s important to understand the function of CSF in the brain, how too much can cause adverse effects right across the body, and what can cause hydrocephalus.

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Hydrocephalus occurs when cerebrospinal fluid builds in the ventricles in the brain, causing increased pressure in the brain.
Illustration by Antonio Jimenez

Why is cerebrospinal fluid important?

CSF usually flows through your brain and spinal cord. This vital fluid protects the brain and spinal cord, acting as a cushion that absorbs the shock from impact or injury. It also helps by transporting waste products away from the central nervous system, helping it work at full capacity.

Your brain and spinal cord support:

  • muscle movement
  • organ function
  • cognitive processes, like memory

Why do cerebrospinal fluid levels increase?

Under certainconditions, the amount of CSF in your brain increases. The amount of CSF can increase when:

  • a blockage develops that prevents CSF from flowing in its usual way
  • there’s a decrease in the ability of blood vessels to absorb it
  • your brain produces an excess amount of it

Too much of this fluid puts your brain under too much pressure. This increased pressure can cause brain swelling, which can damage your brain tissue and lead to some of the functional and cognitive issues that occur due to hydrocephalus.

Hydrocephalus from birth

In some cases, hydrocephalus starts before a baby is born. This can result from:

  • a birth irregularity in which the spinal column doesn’t close
  • a genetic anomaly
  • certain infections that occur during pregnancy, like rubella

Hydrocephalus in children/young adults

This condition can also occur in infants, toddlers, and older children due to:

  • central nervous system infections like meningitis, especially in babies
  • bleeding in the brain during or shortly after delivery, especially in babies born prematurely
  • injuries that occur before, during, or after delivery
  • head trauma
  • central nervous system tumors

Hydrocephalus in older adults: Normal pressure hydrocephalus

When hydrocephalus occurs in adults (usually those over 60 years of age), CSF levels rise, but the amount of pressure is usually normal. But it still causes the brain to swell and can lead to impaired functioning. In adults, this condition usually results from conditions that prevent CSF from flowing.

But in some cases, there’s no known cause. You might be at higher risk if you’ve experienced any of the following:

Here’s what to expect when seeing a doctor about hydrocephalus.

Physical examination

If you suspect that you or your child has hydrocephalus, your doctor will perform a physical exam to look for signs and symptoms. In children, doctors check for:

  • eyes that are sunken in
  • slow reflexes
  • a bulging fontanel
  • a head circumference that’s larger than usual for their age

Ultrasound scan

Your doctor may also use an ultrasound to get a closer look at the brain. These tests use high-frequency sound waves to create images of the brain. This type of ultrasound can only be done in babies whose fontanel (soft spot) is still open.

Magnetic resonance imaging (MRI) scans

These can indicate signs of excess CSF. MRIs use a magnetic field and radio waves to make a cross-sectional image of the brain.

Computerized tomography (CT) scans

These can also help diagnose hydrocephalus in children and adults. CT scans use several different X-rays to form a cross-sectional image of the brain. These scans can show enlarged brain ventricles that result from too much CSF.

Hydrocephalus can be fatal without treatment. Interventions may not reverse all brain damage that’s already occurred, but its goal is to restore the flow of CSF and prevent further brain damage. Your doctor may explore either of the following surgical options.

Shunt insertion

In most cases, a surgeon surgically inserts a shunt.

The shunt is a drainage system consisting of a long tube with a valve. The valve helps CSF flow at a normal rate and in the right direction. Your doctor inserts one end of the tube in your brain and the other end into your chest or abdominal cavity.

Excess fluid then drains from the brain and out the other end of the tube, where it becomes easier to absorb. A shunt implant is typically permanent and requires regular monitoring.


A surgeon can perform a procedure called a ventriculostomy as an alternative to shunt insertion. This involves making a hole at the bottom of a ventricle or in between ventricles, allowing CSF to leave the brain and relieving pressure.

The outlook for someone with hydrocephalus depends largely on the extent of their symptoms and how soon they receive treatment.

Outlook for children

Many children experience lifelong brain damage after hydrocephalus. Their outlook will depend on:

  • how the condition progresses
  • how long a child had symptoms before receiving treatment
  • any complications, including infections

By working with a range of healthcare professionals, children can learn to manage their disability and lessen the lifelong effects. These may include:

Outlook for adults

Adults with severe symptoms of hydrocephalus might need to work with occupational therapists. Others may require long-term care.

Some might need the care of medical specialists who focus on dementia.

The long-term effects of this condition vary widely, depending on individual circumstances. Talk with your doctor about the outlook for your presentation of hydrocephalus.

You can’t prevent hydrocephalus, but you can lower your risk and your child’s risk for developing the condition in the following ways:

  • Prenatal care. Make sure you get prenatal care during pregnancy. This can help reduce your chance of going into premature labor, which can lead to hydrocephalus.
  • Vaccinations. Getting vaccinations can help prevent illnesses and infections that are linked to hydrocephalus. Having regular screenings can also ensure that you get prompt treatment for illnesses or infections that could increase your risk of hydrocephalus.
  • Safety equipment. Use safety equipment, like helmets, to prevent head injuries when doing activities like riding a bike. You can also lower your risk of head injuries by always wearing a seat belt.
  • Buying safe gear for younger children. It’s essential to secure young children in a car seat. You can also prevent head injuries by making sure your baby equipment, like strollers, meets safety standards.

By taking steps to hydrocephalus, you can reduce your risk for permanent disability, as well as that of your child.