Hydrocephalus is a build-up of fluid on the brain. The excess fluid puts pressure on the brain, which can damage it.

The damage to the brain can result in a wide range of symptoms, including:

  • headache
  • being sick
  • blurred vision
  • difficulty walking

Read more about the symptoms of hydrocephalus.

Hydrocephalus can usually be treated using a piece of equipment known as a shunt. A shunt is a thin tube that's surgically implanted in the brain and drains away the excess fluid.

Read more about how hydrocephalus is treated.


In the past, hydrocephalus was often referred to as ‘water on the brain’. However, the brain is not surrounded by water but by a special fluid called cerebrospinal fluid (CSF).

CSF has three important functions, it:

  • protects the brain from damage
  • removes waste products from the brain
  • provides the brain with the nutrients it needs to function properly

The brain constantly produces new CSF (about a pint a day), while old fluid is released from the brain and absorbed into the blood vessels. However, if this process is interrupted, the level of CSF can quickly build-up, placing pressure on the brain.

Read more about the causes of hydrocephalus.

Types of hydrocephalus

There are three main types of hydrocephalus:

  • hydrocephalus that's present at birth (congenital hydrocephalus)
  • hydrocephalus that develops after birth (acquired hydrocephalus)
  • hydrocephalus that usually only develops in older people (normal pressure hydrocephalus or NPH)

These are briefly described below.

Congenital hydrocephalus

Congenital hydrocephalus is present in babies when they're born and can be caused by birth defects, such as spina bifida, or as a result of an infection the mother develops during pregnancy, such as mumps or rubella (German measles).

It's estimated that spina bifida affects one baby in every 1,000 born in Britain. Most of them will have hydrocephalus.

Congenital hydrocephalus carries the risk of long-term mental and physical disabilities as a result of permanent brain damage.

Read more information about complications of hydrocephalus.

Acquired hydrocephalus

Acquired hydrocephalus can affect children or adults. It usually develops after an injury or illness. For example, it may occur after a serious head injury or as a complication of a medical condition, such as a brain tumour.

Read more about the causes of hydrocephalus.

Normal pressure hydrocephalus

Normal pressure hydrocephalus (NPH) is a poorly understood condition that usually only affects people over 50 years old.

It can sometimes develop after an injury or a stroke, but in most cases the cause is unknown.

The average age of people with NPH is 75, although it's a rare condition. In 2009-2010, there were just under 1,000 recorded cases in England. However, the true number may be higher.

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