What Is Hydrocephalus?

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.

If you have hydrocephalus -- that roughly means “water on 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.

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 treatment can ease its symptoms.


These 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
  • Vomiting or poor appetite

In toddlers and children, you might notice:

  • Headaches
  • Blurry vision
  • An unusually large head
  • Sleepiness or low energy
  • Bad balance or coordination
  • Lack of appetite
  • Seizures
  • Crankiness or change in mood
  • Trouble doing well in school

Adults younger than 60 may have:

  • 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

Adults 60 or older may:

  • Pee often or lose bladder control
  • Have memory loss
  • Have trouble with planning or processing skills
  • Have problems walking or poor coordination


The three main causes of hydrocephalus are:

A blockage. Tumors, cysts, birth defects, and other objects in the brain 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 fluid. In rare cases, your body makes more cerebrospinal fluid than your brain can handle.



The four main types of hydrocephalous are:

Congenital hydrocephalus. This 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 hydrocephalus. This 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.

Also, 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 they’ll recommend an imaging test to look for signs of hydrocephalus.

This test might be a magnetic resonance imaging (MRI) scan that uses powerful magnets and radio waves to make detailed images of your brain. Or it could be a computerized tomography (CT) scan, which is a series of X-rays taken from different angles that are put together to make a more complete picture of your brain.


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 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.

WebMD Medical Reference Reviewed by Neil Lava, MD on January 17, 2019



The American Journal of Clinical Nutrition. “Total body water volumes for adult males and females estimated from simple anthropometric measurements.”

Hydrocephalus Association: “Hydrocephalus,” “Classifications and Causes,” “Symptoms and Diagnosis,” “Treatment.”

National Institutes of Health: “Hydrocephalus Fact Sheet.”

American Association of Neurological Surgeons: “What Is Hydrocephalus?”

Mayo Clinic: “Hydrocephalus.”

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