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

If left untreated, hydrocephalus can be fatal.

Symptoms of hydrocephalus

The damage to the brain from hydrocephalus can cause a wide range of symptoms, including:

  • headache
  • being sick
  • blurred vision
  • difficulty walking

Different types of hydrocephalus can cause specific symptoms.

Types of hydrocephalus

There are 3 main types of hydrocephalus:

  • congenital hydrocephalus - hydrocephalus that's present at birth
  • acquired hydrocephalus - hydrocephalus that develops after birth
  • normal pressure hydrocephalus - usually only develops in older people

Hydrocephalus present from birth

Congenital hydrocephalus is when a baby is born with excess fluid in their brain.

It can be caused by a condition such as spina bifida, or an infection the mother develops during pregnancy, such as mumps or rubella (German measles).

Many babies born with hydrocephalus (congenital hydrocephalus) have permanent brain damage.

This can cause several long-term complications, such as:

  • learning disabilities
  • speech problems
  • memory problems
  • short attention span
  • problems with organisational skills
  • vision problems, such as a squint and vision loss
  • problems with physical coordination
  • epilepsy

If your child has learning disabilities, they'll need extra support from their nursery or school to ensure their needs are being met.

Hydrocephalus that develops in children or adults

Acquired hydrocephalus can affect children or adults. It usually develops after an illness or injury.

For example, it may happen after a serious head injury or as a complication of a medical condition, such as a brain tumour.

Normal pressure hydrocephalus (NPH)

Normal pressure hydrocephalus (NPH) is an uncommon and poorly understood condition that most often affects people over the age of 60.

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

Mobility problems, dementia and urinary incontinence are the main symptoms of NPH. But because these symptoms happen gradually and are similar to those of other, more common conditions, such as Alzheimer's disease, NPH can be difficult to diagnose.

Diagnosing hydrocephalus

Brain scans, such as CT scans and MRI scans, can be used to diagnose congenital and aquired hydrocephalus.

A checklist is used to help diagnose NPH. For example, how you walk, your mental ability and symptoms that affect your bladder control will be assessed.

It's important to diagnose NPH correctly because, unlike Alzheimer's disease, the symptoms can be relieved with treatment.

Treating hydrocephalus

Hydrocephalus can usually be treated using a thin tube (shunt) that's surgically implanted in the brain and drains away the excess fluid.

An endoscopic third ventriculostomy (ETV) can sometimes be used as an alternative to shunt surgery.

During this procedure, a hole is made in the floor of the brain to allow the trapped fluid to escape to the surface, where it can be absorbed.

Complications after surgery

The surgery used to treat hydrocephalus can sometimes cause complications. For example, a shunt can become blocked or infected.

Before having surgery, your surgeon should discuss the possible complications with you.

What causes hydrocephalus?

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

CSF has 3 important functions:

  • it protects the brain from damage
  • it removed waste products from the brain
  • it 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.

But if this process is interrupted, the amount of CSF can quickly build up, cause pressure in the brain.

Help and support

If you have a child with hydrocephalus, or if you've been diagnosed with the condition yourself, you may find it helpful to speak to other people affected by hydrocephalus.

Shine, the spine bifida and hydrocephalus charity, can provide you with th details of local support groups and organisations.

You can find and contact your regional Shine team or read about support for carers on the Shine website.


Hydrocephalus, or excess fluid in the brain, causes slightly different symptoms depending on the type of hydrocephalus and the age of the person affected.

Hydrocephalus from birth

Babies born with hydrocephalus (congenital hydrocephalus) often have distinctive physical features.

These can include:

  • an unusually large head
  • a thin and shiny scalp with easily visible veins
  • a bulging or tense fontanelle (the soft spot on top of a baby's head)
  • downward looking eyes

Congenital hydrocephalus can also cause:

  • poor feeding
  • irritability
  • vomiting
  • sleepiness
  • muscle stiffness and spasms in your baby's lower limbs

Congenital hydrocephalus is sometimes found before a baby is born during an ultrasound scan.

However, it's usually diagnosed soon after birth during the newborn physical examination. The condition may be suspected if your baby's head is larger than normal.

Hydrocephalus that develops in children

Hydrocephalus that develops in children or adults (aquired hydrocephalus) can cause headaches.

The headache may be worse when you wake up in the morning. This is because the fluid in your brain does not drain as well while you're lying down and may have built up overnight.

Sitting up for a while may improve the headache. However, as the condition progresses, headaches may become continuous.

Other symptoms of aquired hydrocephalus include:

  • neck pain
  • feeling sick
  • being sick - this may be worse in the morning
  • sleepiness - can progress to a coma
  • changes in your mental state, such as confusion
  • blurred vision or double vision
  • difficulty walking
  • an inability to control your bladder (urinary incontinence) and, in some cases, your bowel (bowel incontinence)

Call a GP if you think you or your child may have symptoms of hydrocephalus.

Normal pressure hydrocephalus (NPH)

The symptoms of normal pressure hydrocephalus (NPH) tend to affect older people and usually develop slowly, over many months or years.

NPH has 3 sets of distinctive symptoms. It affects:

  • how you walk (mobility)
  • the urinary system
  • mental abilities

How you walk

The first noticeable symptom of NPH is a change in how you walk (your gait). You may find it increasingly difficult to take the first step when you want to start walking.

Some people have described it as feeling as though they're frozen to the spot. You may also shuffle rather than take proper steps.

As the condition progresses, you may become increasingly unsteady on your feet and be more likely to fall, particularly when turning.

Urinary symptoms

The change in the way you walk is often followed by bouts of urinary incontinence, which may include symptoms such as:

  • a frequent need to pee
  • an urgent need to pee
  • loss of bladder control

Mental abilities

The normal thinking process also starts to slow down. For example, a person may:

  • be slow to respond to questions
  • react slowly to situations
  • be slow to process information

These symptoms may be a sign of mild dementia. They should start to improve when NPH is treated.

Who can get it

The causes of hydrocephalus (excess fluid in the brain) are poorly understood.

It's thought hydrocephalus present at birth (congenital hydrocephalus) may be the result of a brain defect restricting the flow of cerebrospinal fluid (CSF).

Hydrocephalus that develops in adults and children (acquired hydrocephalus) is often caused by an illness or injury that affects the brain.

Hydrocephalus that develops in older people (normal pressure hydrocephalus) may also be the result of an infection, illness or injury, but in many cases it's not clear what causes the condition.

Hydrocephalus from birth

Hydrocephalus present at birth (congenital hydrocephalus) can be caused by certain health conditions, such as spina bifida.

It can also develop in babies born prematurely, before week 37 of the pregnancy.

Some premature babies have bleeding in the brain, which can block the flow of CSF and cause hydrocephalus.

Other possible causes of congenital hydrocephalus include:

  • a mutation of the X chromosome - this is known as X-linked hydrocephalus
  • rare genetic disorders - such as Dandy Walker malformation
  • arachnoid cysts - fluid-filled sacs located between the brain or spinal cord and the arachnoid membrane

In many cases of congenital hydrocephalus the cause is unknown.

Hydrocephalus that develops in children

Hydrocephalus that develops in children and adults (acquired hydrocephalus) is usually the result of an injury or illness.

Possible causes of acquired hydrocephalus include:

Some people are born with narrowed passageways in their brain that restrict the flow of cerebrospinal fluid, but do not cause any symptoms until years later.

Hydrocephalus in older people

Older people can sometimes develop normal pressure hydrocephalus (NPH) after a brain injury, bleeding in the brain or an infection. But it's often not clear why NPH happens.

It may be that NPH is linked to other underlying health conditions that affect the normal flow of blood - for example, diabetes, heart disease, or having a high level of cholesterol in the blood.


Brain scans are used to diagnose hydrocephalus (excess fluid in the brain).

Congenital and acquired hydrocephalus

CT scans and MRI scans are often used in combination to confirm a diagnosis of hydrocephalus present from birth (congenital) and hydrocephalus that develops later in children and adults (acquired).

These scan the brain in detail. They can show the build-up of fluid in the brain and the increased pressure, as well as highlighting any structural defects that may be causing the problem.

Sometimes congenital hydrocephalus is detected before birth, during a pregnancy ultrasound scan.

Normal pressure hydrocephalus

Normal pressure hydrocephalus (NPH) can be difficult to diagnose because the symptoms start gradually and are similar to those of more common conditions, such as Alzheimer's disease.

It's important to make a correct diagnosis because, unlike Alzheimer's disease, the symptoms of NPH can be relieved with treatment.

Your doctors will assess:

  • how you walk (your gait)
  • your mental ability
  • symptoms that affect your bladder conrol, such as urinary incontinence
  • the appearance of your brain (using scans)

NPH may be diagnosed if you have difficulty walking, mental and bladder problems, and cerebrospinal fluid (CSF) levels that are higher than usual. However, you may not have all these symptoms.

Further tests may also be done to decide whether you would benefit from having surgery, such as a:

  • lumbar puncture
  • lumbar drainage test
  • lumbar infusion test

Lumbar puncture

A lumbar puncture is a procedure where a sample of CSF is taken from your lower spine. The pressure of the CSF sample is then checked.

Removing some CSF during a lumbar puncture may help improve your symptoms. If it does, you may benefit from having surgery.

Lumbar drainage test

You may have a lumbar drain if a lumbar puncture does not improve your symptoms.

Under local anaesthetic, a tube is inserted between the bones in your spine (vertebra) to drain a large amount of CSF. This is done over a few days, to see whether your symptoms improve.

Lumbar infusion test

During a lumbar infusion test, fluid is slowly injected into the lower part of your spine while measuring the pressure.

Your body should absorb the extra fluid and the pressure should stay low. If your body caanot absorb the extra fluid, the pressure will rise, which could indicate NPH and that surgery will be helpful.


Hydrocephalus (excess fluid in the brain) is treated with surgery.

Babies who are born with hydrocephalus (congenital) and children or adults who develop it (acquired hydrocephalus) usually need prompt treatment to reduce the pressure on their brain.

If hydrocephalus is not treated, the increase in pressure will cause brain damage.

Both congenital and acquired hydrocephalus are treated with either shunt or neuroendoscopy.

Shunt surgery

During shunt surgery, a thin tube called a shunt is implanted in your brain. The excess cerebrospinal fluid (CSF) in the brain flows through the shunt to another part of your body, usually your tummy. From here, it's absorbed into your blood.

Inside the shunt there's a valve that controls the flow of CSF, so it does not drain too quickly. You can feel the valve as a lump under the skin on your scalp.

The operation

Shunt surgery is done by a specialist in brain and nervous system surgery (neurosurgeon). It's done under a general anaesthetic and usually takes 1 to 2 hours.

You may need to stay in hospital for a few days after the operation to recover.

If you have stitches, they may dissolve or need to be removed. Some surgeons use skin staples to close the wound, which will need to be removed after a few days.

After the shunt has been installed, further treatment for hydrocephalus may be needed if the shunt becomes blocked or infected. Shunt repair surgery will then be necessary.

Endoscopic third ventriculostomy (ETV)

An alternative procedure to shunt surgery is an endoscopic third ventriculostomy (ETV).

Instead of inserting a shunt, the surgeon makes a hole in the floor of your brain to allow the trapped cerebrospinal fluid (CSF) to escape to the brain's surface, where it can be absorbed.

ETV is not suitable for everyone, but it could be an option if the build-up of CSF in your brain is caused by a blockage (obstructive hydrocephalus). The CSF will be able to drain through the hole, avoiding the blockage.

The operation

ETV is done under general anaesthetic. The neurosurgeon makes a small hole in your skull and brain, and uses an endoscope to look inside the chambers of your brain. An endoscope is a long, thin tube with a light and camera at one end.

After making a small hole in the floor of your brain to drain the fluid, the endoscope is removed and the wound is closed using stitches. The procedure takes around 1 hour.

There's less risk of infection after ETV than with shunt surgery. However, as with all surgical procedures, there are some risks.

The long-term results of ETV are similar to those for a shunt operation. As with shunts, there's a risk of a blockage happening months or years after surgery, which will cause your symptoms to return.

Normal pressure hydrocephalus (NPH)

Normal pressure hydrocephalus (NPH), which usually affects older people, can sometimes be treated with a shunt. However, not everyone with NPH will benefit from shunt surgery.

As there's a risk of complications with shunt surgery, you'll need tests to assess whether the potential benefits of surgery outweigh the risks.

Lumbar drainage or a lumbar infusion test, or both, can be used to find out if shunt surgery will benefit you.


The surgery used to treat hydrocephalus (excess fluid in the brain) can cause complications.

Shunt problems

A shunt is a delicate piece of equipment that can malfunction, usually by becoming blocked or infected.

It's estimated up to 4 in 10 shunts will malfunction in the first year after surgery.

Sometimes, a scan after the operation shows the shunt is not in the best position and further surgery is needed to reposition it.

If a baby or child has a shunt fitted, the shunt may become too small as the child grows and it will need to be replaced. As most people need a shunt for the rest of their life, more than one replacement may be needed.

There can occasionally be bleeding when a shunt is positioned. This can cause nerve problems, such as weakness down one side. There's also a small risk of fits after any type of brain surgery.

In younger children, particularly babies, cerebrospinal fluid (CSF) can run alongside the shunt rather than down it, and the fluid can leak through the skin wound. Additional stitiches will be needed to stop the leak.

Shunt blockage

A shunt blockage can be very serious as it can lead to an build-up of excess fluid in the brain, which can cause brain damage. This will cause symptoms of hydrocephalus.

Emergency surgery will be needed to replace the malfunctioning shunt.

Shunt infection

Shunt infection is also a relatively common complication after shunt surgery. The risk of infection is up to 1 in 5 in children, with a lower risk in adults. Infections are more likely to develop during the first few months after surgery.

The symptoms of a shunt infection may include:

  • redness and tenderness along the line of the shunt
  • a high temperature
  • headache
  • vomiting
  • neck stiffness
  • tummy pain if the shunt drains into your tummy
  • irritability or sleepiness in babies

Contact your care team immediately if you or your child has these symptoms.

Antibiotics may be needed to treat the infection and, in some cases, surgery may be required to replace the shunt.

Shunt alert cards

The hydrocephalus and spina bifida charity Shine has produced a series of shunt alert cards for adults and children. You carry the card with you if you've had a shunt fitted.

The card is useful in a medical emergency if you have symptoms of a blockage or infection.

The healthcare professionals treating you will be aware that you have a shunt fitted and will check whether this is causing your symptoms.

To apply for a shunt alert card, you can fill out a form on the Shine website or call 01733 555 988.

Complications of endoscopic third ventriculostomy (ETV)

An endoscopic third ventriculostomy (ETV) is surgery to create a small hole in the floor of the brain to drain the cerebrospinal fluid (CSF).

Possible complications after ETV surgery include:

  • the hole can close
  • your brain may not be able to absorb the CSF that's now draining through it
  • you may develop an infection - although this is less likely than after shunt surgery
  • you may have bleeding inside your brain - this is usually minor

If there's a problem with the hole, it may be possible to repeat the procedure, or you may need to have a shunt fitted.

Other risks of ETV include nerve problems, such as weakness down 1 side of the body, double vision or hormone imbalances. Most nerve problems will get better, but there's a small risk of permanent problems.

There's also a small risk of epilepsy, and a very small risk of an injury to a blood vessel in the brain, which may be fatal.

The information on this page has been adapted by NHS Wales from original content supplied by NHS UK NHS website nhs.uk
Last Updated: 01/04/2022 16:10:32