Key takeaways

  • Hydrocephalus occurs when cerebrospinal fluid (CSF) builds up in the brain’s ventricles, causing swelling and increased pressure that can damage brain tissue. This happens when a blockage prevents CSF from flowing normally, blood vessels can’t absorb it properly, or the brain produces too much.
  • Symptoms vary by age and may include bulging soft spots and rapid head growth in infants, headaches and coordination problems in children and young adults. Older adults with normal pressure hydrocephalus (NPH) may experience walking difficulties and memory issues.
  • Treatment typically involves surgically inserting a shunt to drain excess fluid or performing a ventriculostomy to create a drainage hole. Early treatment is essential to prevent permanent brain damage, and many people require ongoing care from healthcare professionals.

Hydrocephalus is a condition that involves the buildup of fluid in the skull and causes brain swelling. The name means “water on the brain.” It rarely develops on its own. Usually, it develops as a complication of neurological conditions such as a brain tumor or infection.

Cerebrospinal fluid (CSF) usually flows around the brain and spinal cord and 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, leading to developmental, physical, and intellectual impairments. It requires prompt treatment to prevent serious complications.

Hydrocephalus mainly occurs in children and adults over 60 years of age, but younger adults can also develop it. The Hydrocephalus Association estimates that roughly 1 in 770 babies in the United States develop 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.

Infants

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 may appear in 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 age 60 years. One of the earliest signs of the condition is falling suddenly without losing consciousness.

Chronic alcohol use is a common cause of NPH. Older adults who already have brain atrophy may develop NPH instead of increased pressure if they experience conditions that would typically cause increased CSF pressure due to blocked CSF flow. These conditions include brain tumor, blood in the brain, or inflammation.

Other common symptoms of normal pressure hydrocephalus (NPH) include:

  • changes in the way you walk
  • impaired mental functions, including memory problems
  • trouble controlling urine

What does hydrocephalus look like?

Below, we show two different MRI scans of brains with hydrocephalus.

Hydrocephalus involves increased CSF in the brain, which leads to enlargement of the ventricles.

To understand how hydrocephalus develops, it’s important to understand the function of CSF in the brain and what can cause hydrocephalus.

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

Why is cerebrospinal fluid important?

CSF flows around your brain and spinal cord and within the ventricles. 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 certain conditions, the amount of CSF in your brain increases. The amount of CSF can increase when any of the following happens:

  • 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.
  • The brain tissue shrinks, leaving space for the fluid to fill.

When there is excess CSF in the brain, the fluid pushes against the brain tissue. This increased pressure 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

The 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), it can cause increased pressure. But in some cases, the pressure remains normal.

Increased CSF buildup due to meningitis, encephalitis, brain tumor, or bleeding places pressure on the brain tissue. Sometimes excess fluid can build up due to atrophy, or the shrinking of the brain. This usually causes normal pressure hydrocephalus.

In these situations, the fluid builds up due to excess space in the skull, and the fluid takes up the space that used to be filled by brain tissue. Therefore, the fluid doesn’t necessarily cause pressure, and the symptoms occur due to brain atrophy. The fluid is a sign of atrophy that’s detected based on brain imaging.

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 or your child has neurological symptoms, your doctor may check for signs of hydrocephalus. 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.

While a CT scan can detect hydrocephalus, an MRI will usually be used to help identify the cause. MRI can more clearly visualize tumors, inflammation, and blockages in the flow of CSF.

Hydrocephalus can be fatal without treatment. Interventions may not reverse all brain damage that’s already occurred, but the 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 into 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. This type of shunt — a peritoneal shunt — is used when doctors believe hydrocephalus will continue to recur if the fluid isn’t regularly drained. A shunt implant is typically permanent and requires regular monitoring.

Ventriculostomy

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 between ventricles, allowing CSF to leave the brain and relieving pressure.

Tumor removal

If hydrocephalus occurs due to a brain tumor, doctors will perform surgery to remove the tumor that’s causing obstruction in CSF flow.

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 team 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 a stroller, meets safety standards.
  • Limit alcohol use: Chronic alcohol use can contribute to brain atrophy, which may lead to normal pressure hydrocephalus, so it’s important to avoid overuse and get treatment for alcohol misuse.

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