Medically Reviewed by Christopher Melinosky, MD on August 23, 2022
7 min read

Hydrocephalus -- which roughly means “water on the brain” -- is the buildup of fluid in the cavities (ventricles) deep within the brain. This fluid doesn’t flow or get absorbed the way it should. That can lead to backups and blockages that put pressure on your brain.

You’ve probably heard that the human body is mostly water. That’s true. From your blood to the fluids that flow in and around your tissues and organs, liquid makes up about 70% of your body.

Your head is no different. Your skull is filled with a fluid that surrounds your brain’s folds and lobes. It’s called cerebrospinal fluid, and it cushions your brain from injuries and has nutrients and proteins that help keep it healthy and working.

Cerebrospinal fluid also:

  • Allows the relatively heavy brain to float within the skull

  • Removes waste products of the brain’s metabolism

  • Flows back and forth between the brain cavity and spinal column to regulate pressure in the brain

Hydrocephalus happens most often in infants or in adults older than 60, but you can have it at any age. It can’t be cured, but with early diagnosis and treatment, people can live active lives. 

Symptoms of hydrocephalus can be different depending on your age. In babies, they include:

  • An unusually large head that gets bigger quickly

  • The soft spot on top of a baby’s head is firm or bulging

  • Eyes that are focused downward (sometimes called “sunsetting of the eyes”)

  • Crankiness or irritability

  • Vomiting or poor feeding

  • Seizures

  • Poor muscle tone and strength

  • Less responsive to touch

  • Poor growth

Symptoms of hydrocephalus in toddlers and children:

  • Headaches

  • Eyes that are focused downward (sometimes called “sunsetting of the eyes”)

  • Blurry vision

  • An unusually large head

  • Sleepiness or low energy

  • Nausea or vomiting

  • Bad balance or coordination

  • Problems with gait (walking)

  • Lack of appetite

  • Seizures

  • Peeing often or loss of bladder control

  • Crankiness or change in mood

  • Change in personality

  • Trouble doing well in school

  • Delays or problems in already acquired skills, such as walking and talking


Symptoms of hydrocephalus in adults younger than 60:

  • Headaches

  • Tiredness

  • Poor balance or coordination

  • Peeing often or loss of bladder control

  • Changes in vision

  • A drop-off in memory or concentration that causes problems at work

Symptoms of hydrocephalus in adults older than 60:

  • Peeing often or loss of bladder control

  • Memory loss

  • Trouble with planning or processing skills

  • Problems walking or poor coordination

  • Dementia

  • General slowing of movements

The three main causes of hydrocephalus are:

  • A blockage. Tumors, cysts, birth defects, brain injury, or stroke can block or affect the normal flow of cerebrospinal fluid.

  • Poor fluid absorption. Inflammation, injuries, or infections like bacterial meningitis can keep your brain tissues from taking in cerebrospinal fluid.

  • Too much fluidIn rare cases, your body makes more cerebrospinal fluid than your brain can handle, often due to  infection like meningitis.

The four main types of hydrocephalus are:

  • Congenital hydrocephalusThis is when someone is born with hydrocephalus.

  • Compensated hydrocephalus. This shows up early in life -- sometimes before birth -- but doesn’t cause symptoms until later in life.

  • Acquired hydrocephalus. This is caused by a tumor, cyst, head injury, or a brain infection.

  • Normal pressure hydrocephalusThis usually shows up in older adults and leads to a swelling in the small, open areas of the brain but without any change in pressure. Doctors aren’t sure what causes this type.

Some experts refer to hydrocephalus as either “communicating” -- meaning the cerebrospinal fluid is flowing freely -- or “non-communicating,” which is when there’s a blockage.

Your doctor will start with a physical examination and ask about your symptoms, then recommend tests to look for signs of hydrocephalus. Tests may include:

  • Neurological exam to check muscle strength, reflexes, coordination, balance, vision, eye movement, hearing, mental functioning, and mood

  • Magnetic resonance imaging (MRI), a scan that uses powerful magnets and radio waves to make detailed images of your brain

  • Computerized tomography (CT) scan, a series of X-rays taken from different angles that are put together to make a more complete picture of your brain

  • Spinal tap, when a doctor inserts a needle into the lower back in order to remove and test some of the fluid

  • Intracranial pressure monitoring (ICP), which uses a small monitor inserted into the brain to measure how much swelling is there; intracranial pressure can also be measured by EVD (external ventricular drain) or lumbar drain (like a lumbar puncture but a small catheter stays in place to measure pressure and to drain fluid).

  • Fundoscopic exam, which looks at the nerve behind the eye to see if swelling is present

If your symptoms are mild, you may not need treatment. If they’re serious, your doctor probably will recommend surgery to put a flexible plastic tube called a shunt in your brain to redirect the cerebrospinal fluid into another part of your body, like your belly. The shunt typically isn’t ever removed, and regular checkups are important to make sure it’s working.

In some cases, hydrocephalus can be treated without using a shunt. One type of surgery, endoscopic third ventriculostomy, opens a pathway in your brain so the fluid can flow freely, while the other closes off the part of your brain that makes cerebrospinal fluid. If your hydrocephalus is due to a tumor, the tumor can be removed; if it is due to a stroke, the skull may be opened to relieve pressure and swelling. Some medications help slow the production of CSF, such as acetazolamide (Diamox).

Many people with hydrocephalus find help through therapy and education. Specialists may provide:

  • Occupational therapy to help children and adults with life skills

  • Developmental therapy to help children learn social behaviors

  • Special education for learning disabilities

  • Mental health care or social workers to provide emotional support and help families find services

  • Dementia care

It’s important to get medical help right away if anything goes wrong after treatment for hydrocephalus.

Complications of shunt systems can happen when the shunt is blocked and stops working or when an infection occurs. This can cause cerebral spinal fluid to build up again. Signs and symptoms may include:

  • Headache

  • Double vision or sensitivity to light

  • Nausea or vomiting

  • Soreness of the neck or shoulder muscles

  • Seizures

  • Redness or tenderness along the shunt tract

  • Low-grade fever

  • Sleepiness or tiredness

  • Return of hydrocephalus symptoms

The most common complication of ETV surgery is when the pathway created by the surgery closes and it leads to infection. Signs of such  problem may include:

  • Fever

  • Bleeding

  • Short-term memory loss

  • Temporary problems with the endocrine system, which regulates hormones

If any previous symptoms of hydrocephalus symptoms come back, it’s a sign of a complication. Other things to look for include:

  • Trouble waking up or staying awake. Get urgent care for this symptom because it may lead to a coma.

  • Swelling or redness along shunt tract

  • Fever

  • Prominent scalp veins in babies

Some, but not all causes of hydrocephalus can be prevented.

  • Safety gear such as helmets can help prevent head injuries while playing sports, riding a bike, and other activities.

  • Car seats and seatbelts can help protect children in the car.

  • Regular health care during pregnancy can help lower the chances of problems during pregnancy, including infection and premature birth.

  • Meningitis was once a common cause of hydrocephalus. Ask your doctor about a vaccine.

The long-term effects of hydrocephalus vary widely and depend on the cause and the extent of symptoms. 

Without treatment, hydrocephalus will get worse over time, but with surgery, therapy, and education, many people live relatively active lives. The earlier it's diagnosed, the better the chances for successful treatment and recovery.