Hydrocephalus is the buildup of cerebrospinal fluid (CSF) in spaces called ventricles deep within the brain. This buildup can make the ventricles larger and put pressure on the brain.

Cerebrospinal fluid usually flows through the brain ventricles and around the brain and spinal column. When there's too much fluid, the pressure can harm brain tissue and lead to changes in thinking, movement and other functions.

There are several types of hydrocephalus:

• Congenital hydrocephalus. This type starts before birth. It can happen because the brain doesn't develop as expected in the womb or due to changes in genes.
• Communicating hydrocephalus. In this type, fluid flows through the brain's ventricles without being blocked. But the body either doesn't absorb it properly or makes too much of it.
• Noncommunicating hydrocephalus. Also called obstructive hydrocephalus, this happens when something blocks the flow of fluid inside the brain. The fluid builds up behind the blockage, causing the nearby ventricles to get bigger and raising pressure inside the skull.
• Normal-pressure hydrocephalus. Most common in older adults, this type causes the brain's ventricles to enlarge, but the pressure of the fluid stays within a typical range. It can affect walking, memory and bladder control.
• Hydrocephalus ex vacuo. This type happens after brain tissue is lost, often due to a stroke, head injury or another condition. As the brain shrinks, extra space is left behind. Fluid fills the space, making the ventricles look larger, but pressure in the brain usually stays in the typical range.

Hydrocephalus can happen at any age, but it occurs more often among infants and among adults 60 and older. Surgery can help drain the extra fluid and control pressure. Therapies can manage symptoms resulting from hydrocephalus.

The symptoms of hydrocephalus can vary by age.

Infants

Common symptoms of hydrocephalus in infants include:

Changes in the head

• A head that is larger than usual.
• A rapid increase in the size of an infant's head.
• A bulge or tense soft spot on the top of the head.

Physical symptoms

• Nausea and vomiting.
• Sleepiness or sluggishness, known as lethargy.
• Irritability.
• Poor eating.
• Seizures.
• Eyes fixed downward, known as sunsetting of the eyes.
• Issues with muscle tone and strength.

Toddlers and older children

Among toddlers and older children, hydrocephalus symptoms might include:

Physical symptoms

• Headache.
• Blurred or double vision.
• Unusual eye movements.
• Enlargement of a toddler's head.
• Sleepiness or sluggishness.
• Nausea or vomiting.
• Trouble with balance.
• Poor coordination.
• Poor appetite.
• Loss of bladder control or urinating often.

Behavioral and cognitive changes

• Irritability.
• Change in personality.
• Decline in school performance.
• Delays or difficulty with earlier gained skills, such as walking or talking.

Young and middle-aged adults

Common hydrocephalus symptoms in young and middle-aged adults include:

• Headache.
• Sluggishness.
• Loss of coordination or balance.
• Loss of bladder control or needing to urinate often.
• Vision problems.
• Decline in memory, concentration and other thinking skills that may affect job performance.

Older adults

Among adults 60 and older, the more common symptoms of hydrocephalus are:

• Loss of bladder control or needing to urinate often.
• Memory loss.
• Progressive loss of other thinking or reasoning skills.
• Trouble walking, often described as shuffling or the feeling of the feet being stuck.
• Poor coordination or balance.

When to see a doctor

Seek emergency medical care for infants and toddlers with these symptoms:

• A high-pitched cry.
• Difficulty with sucking or feeding.
• Vomiting that happens again and again with no clear cause.
• Seizures.

Seek prompt medical attention for other hydrocephalus symptoms in any age group.

More than one condition can cause the symptoms associated with hydrocephalus. It's important to get a timely diagnosis and appropriate care.

In many cases, the cause of hydrocephalus isn't clear. But it can result from medical conditions or from issues that affect brain development before birth.

Newborns

Hydrocephalus that begins before or shortly after birth is called congenital hydrocephalus. In newborns, it may be caused by:

• Development of the central nervous system in a way that blocks the flow of cerebrospinal fluid.
• Bleeding inside the brain. This is a possible complication of premature birth.
• An infection in the uterus during pregnancy, such as rubella or syphilis. An infection can cause swelling in the brain tissues of an unborn baby.

Other causes at any age

Hydrocephalus also can develop later in life due to health issues or injuries. These may include:

• Brain or spinal cord tumors.
• Infections in the brain or spinal cord, such as meningitis or mumps.
• Bleeding in the brain caused by a stroke or head injury.
• Other types of brain injury that affect how CSF flows or is absorbed.

Often, hydrocephalus gets worse over time if it's not treated. Lack of treatment can lead to serious issues, such as learning delays, physical or developmental disabilities, or even death. If hydrocephalus is mild and treated early, many people have few or no long-term complications.

Hydrocephalus can't always be prevented. In many cases, the cause is unknown or happens before birth. But certain steps may lower the risk, especially for conditions that lead to hydrocephalus later in life.

During pregnancy

• Get regular prenatal care. Routine checkups help catch infections and other issues that may affect brain development. Prenatal care also can help lower the risk of preterm birth, which is linked to bleeding in the brain and a higher chance of hydrocephalus.
• Avoid infections. Rubella, syphilis and other infections during pregnancy can increase hydrocephalus risk. Vaccination and good hygiene can help prevent them.

At any age

• Protect against infections. Vaccines for illnesses such as meningitis can reduce the risk of brain infections.
• Prevent head injuries. Use car seats, helmets and seat belts to protect the brain from trauma.
• Treat brain infections early. Quick treatment for infections such as meningitis or encephalitis can help prevent complications.
• Manage health conditions. Strokes, tumors and certain injuries can lead to hydrocephalus. Taking care of overall health, such as managing blood pressure, may help reduce risk.

Should you be vaccinated against meningitis?

Ask your healthcare professional if you or your child should receive a vaccine against meningitis, once a common cause of hydrocephalus. The Centers for Disease Control and Prevention recommends meningitis vaccination for preteen children and boosters for teenagers.

Vaccination also is recommended for younger children and adults who might be at increased risk of meningitis for any of the following reasons:

• Traveling to countries where meningitis is common.
• Having an immune system disease called terminal complement pathway deficiency.
• Having a damaged spleen or having had the spleen removed.
• Living in a college dormitory.
• Joining the military.

A diagnosis of hydrocephalus is usually based on:

• Your symptoms.
• A general physical exam.
• A neurological exam.
• Brain imaging tests.

Neurological exam for hydrocephalus

The type of neurological exam depends on age. A healthcare professional may ask questions and use simple tests to check muscle strength, movement, balance, and senses such as touch or vision.

Brain imaging for hydrocephalus

Imaging tests can help diagnose hydrocephalus and also may find what's causing symptoms. Common tests include:

• Ultrasound. This is often the first test for babies because it's simple and low risk. The device is placed on the soft spot, also called the fontanelle, on top of the baby's head. Ultrasound also may detect hydrocephalus before birth during a routine prenatal scan.
• MRI. This test uses radio waves and a magnetic field to create detailed images of the brain. It's painless but noisy and requires lying still. MRI can show enlarged ventricles and help find the cause of hydrocephalus or related symptoms. Some children might need medicine to help them feel calm, known as mild sedation, but some hospitals use a faster MRI that usually doesn't require it. This is the test of choice for adults with hydrocephalus.
• CT scan. This imaging test uses special X-ray technology to create cross-sectional views of the brain. It's fast and painless, but it involves a small amount of radiation. CT scans show less detail than MRI, so they're usually used in emergency situations.

With the help of therapies and educational services, many people with hydrocephalus live with few limitations.

If you have a child with hydrocephalus, there are many resources available to provide emotional and medical support. Children with developmental disabilities might be eligible for government-sponsored healthcare and other support services. Check with your state or county social services agency.

Hospitals and organizations serving people with disabilities are good resources for emotional and practical support. Members of your healthcare team also can help. Ask for help connecting with other families who are living with hydrocephalus.

Adults living with hydrocephalus might find valuable information from organizations dedicated to hydrocephalus education and support, such as the Hydrocephalus Association.

The timing of diagnosing a child with hydrocephalus can depend on the symptoms are and when they appeared. It also may depend on whether there were risk factors for hydrocephalus during pregnancy or delivery. Sometimes hydrocephalus can be diagnosed at birth or before birth.

Well-baby visits

It's important to take your child to all regularly scheduled well-baby visits. Healthcare professionals monitor your child's development in key areas, including:

• Head size, rate of head growth and overall body growth.
• Muscle strength and tone.
• Coordination.
• Posture.
• Age-appropriate motor skills.
• Sensory abilities such as vision, hearing and touch.

Questions you should be prepared to answer during regular checkups might include:

• What concerns do you have about your child's growth or development?
• How well does your child eat?
• How does your child respond to touch?
• Is your child reaching certain milestones in development, such as rolling over, pushing up, sitting up, crawling, walking or speaking?

Preparing for other healthcare visits

You'll likely start by seeing your child's healthcare professional or your healthcare professional. You may then be referred to a doctor who specializes in brain and nervous system conditions, known as a neurologist.

Be prepared to answer the following questions about your symptoms or your child's symptoms:

• What symptoms have you noticed? When did they begin?
• Have these symptoms changed over time?
• Do these symptoms include nausea or vomiting?
• Have you or your child had any vision issues?
• Have you or your child had a headache or fever?
• Have you noticed personality changes, including increased irritability?
• Has your child's school performance changed?
• Have you noticed new issues with movement or coordination?
• Is your child having trouble sleeping or lacking in energy?
• Has your infant had seizures?
• Has your infant had difficulty with eating or breathing?
• In older children and adults, have symptoms included loss of bladder control and urinating often?
• Have you or your child had a recent head injury?
• Have you or your child recently begun a new medicine?