Health A to Z
Hydrocephalus is a build-up of fluid on the brain. The excess fluid puts pressure on the brain, which can damage it.
If left untreated, hydrocephalus can be fatal.
This page covers:
The damage to the brain can cause a wide range of symptoms, including:
Different types of hydrocephalus can cause specific symptoms.
Read more about the symptoms of hydrocephalus.
There are three main types of hydrocephalus:
Congenital hydrocephalus is when a baby is born with excess fluid on the brain.
It's estimated spina bifida affects one baby in every 1,000 born in Britain. Most of them will have hydrocephalus.
Many babies born with hydrocephalus (congenital hydrocephalus) have permanent brain damage.
This can cause a number of long-term complications, such as:
If your child has learning disabilities, they'll need extra support from their nursery or school to ensure their needs are being met.
Read more about special educational needs (SEN).
Acquired hydrocephalus can affect children or adults. It usually develops after an illness or injury.
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 they come on gradually and are similar to the symptoms of other, more common conditions, such as Alzheimer's disease, it can be difficult to diagnose.
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.
Read more about diagnosing hydrocephalus.
Hydrocephalus can usually be treated using a shunt, a thin tube 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 CSF to escape to the surface, where it can be absorbed.
Read more about how hydrocephalus is treated.
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.
Read more about the complications of surgery for hydrocephalus.
In the past, hydrocephalus was often referred to as water on the brain. However, the brain isn't surrounded by water but by a fluid called cerebrospinal fluid (CSF).
CSF has three important functions:
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 level of CSF can quickly build up, placing pressure on the brain.
Read more about the causes of hydrocephalus.
Hydrocephalus, or fluid on the brain, causes slightly different symptoms depending on the type of hydrocephalus and the age of the person affected.
Babies born with hydrocephalus (congenital) often have distinctive physical features.
These can include:
Congenital hydrocephalus can also cause:
Congenital hydrocephalus is sometimes picked up before a baby is born during an ultrasound scan.
However, it's usually diagnosed soon after birth during the newborn physical examination. The problem may be suspected if your baby's head is larger than normal.
Hydrocephalus that develops in adults or children (acquired) can cause headaches.
The headache may be worse when you wake up in the morning because the fluid in your brain doesn't drain so well while you're lying down and may have built up overnight.
Sitting up for a while may improve your headache. However, as the condition progresses, the headaches may become continuous.
Other symptoms of acquired hydrocephalus include:
Call your GP or NHS 111 if you think you or your child may have symptoms of hydrocephalus.
The symptoms of normal pressure hydrocephalus (NPH) tend to affect older people and usually develop slowly, over the course of many months or years.
NPH has three sets of distinctive symptoms. It affects:
See your GP if you have any of the symptoms described below.
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.
The change in the way you walk is often followed by bouts of urinary incontinence, which may include symptoms such as:
The normal thinking process also starts to slow down. This can take the form of:
These symptoms may indicate that you have mild dementia. They should start to improve when NPH is treated.
Read more about how NPH is treated.
The causes of hydrocephalus are poorly understood.
It's thought hydrocephalus present at birth may be the result of a brain defect restricting the flow of cerebrospinal fluid (CSF).
Hydrocephalus that develops in adults and children is often caused by an illness or injury that affects the brain.
Normal pressure hydrocephalus (NPH) that develops in older people may also be the result of an infection, illness or injury, but in many cases it's not clear what causes the condition.
Congenital hydrocephalus can also occur 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:
In many cases of congenital hydrocephalus, the cause is unknown.
Hydrocephalus that develops in adults or children (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 don't cause any symptoms until years later.
Hydrocephalus that develops in older people (normal pressure hydrocephalus, or NPH) can occur after a brain injury, bleeding in the brain or an infection. However, in most cases, there's no clear reason.
Brain scans are used to diagnose hydrocephalus, or fluid on the brain.
These scan the brain in greater detail. They can show the build-up of fluid on 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 an ultrasound scan.
Normal pressure hydrocephalus (NPH) can be difficult to diagnose because the symptoms come on 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:
NPH may be diagnosed if you have walking, mental and bladder problems, and cerebrospinal fluid (CSF) levels are higher than usual. However, you may not have all of the above symptoms.
Further tests may also be carried out to decide whether you would benefit from having surgery, such as a:
A lumbar puncture is a procedure where a sample of CSF is taken from your lower back. The pressure of the CSF sample is then checked.
Removing some CSF during a lumbar puncture may help improve your symptoms.
If this is the case, it's a good indication that you may benefit from treatment with surgery – see treating hydrocephalus to find out more.
You may have a lumbar drain if a lumbar puncture doesn't improve your symptoms.
A tube is inserted between your back bones to drain a large amount of CSF. This is carried out over a few days to see whether your symptoms improve. The procedure is usually carried out under local anaesthetic.
During a lumbar infusion test, fluid is slowly injected into your lower back while measuring the pressure.
Your body should absorb the extra fluid and the pressure should stay low. If your body can't absorb the extra fluid, the pressure will rise, which could indicate NPH and that surgery will be beneficial.
Hydrocephalus (fluid on the brain) is treated with surgery.
Babies born with hydrocephalus (congenital) and adults or children who develop it (acquired) usually need prompt treatment to reduce the pressure on their brain.
If hydrocephalus isn't treated, the increase in pressure will cause brain damage.
Both congenital and acquired hydrocephalus are treated with either shunt surgery or neuroendoscopy.
During shunt surgery, a thin tube called a shunt is implanted in the brain. The excess cerebrospinal fluid (CSF) in the brain flows through the shunt to another part of the body, usually the tummy. From here, it's absorbed into your bloodstream.
Inside the shunt there's a valve that controls the flow of CSF and ensures it doesn't drain too quickly. You can feel the valve as a lump under the skin of your scalp.
Shunt surgery is carried out by a neurosurgeon, a specialist in brain and nervous system surgery. The procedure is carried out under general anaesthetic and usually takes one to two 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 it becomes blocked or infected. Shunt repair surgery will then be necessary.
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 the brain to allow the trapped CSF to escape to the brain's surface, where it can be absorbed.
ETV isn't 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.
ETV is carried out under general anaesthetic. The neurosurgeon makes a small hole in your skull 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.
A small hole is made inside your brain with the help of the endoscope. After removing the endoscope, the wound is closed using stitches. The procedure takes around one hour.
There's less risk of infection after ETV than with shunt surgery. However, as with all surgical procedures, there are some risks.
Read more about the complications of hydrocephalus.
The long-term results of treatment with ETV are similar to those for a shunt operation. As with shunts, there's a risk of a blockage months or years after surgery, which will cause your symptoms to return.
Normal pressure hydrocephalus (NPH), which usually affects older people, can sometimes be treated with a shunt, although not everyone with the condition 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.
The surgery used to treat hydrocephalus (fluid on the brain) can cause complications.
A shunt is a delicate piece of equipment that can malfunction, usually by becoming blocked or infected.
It's estimated up to 4 out of 10 shunts will malfunction in the first year after surgery.
Sometimes a scan after the operation shows the shunt isn't 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.
Bleeding can occasionally occur when shunt tubes are positioned. This can result in nerve problems, such as weakness down one side. There is 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 stitches will be needed to stop the leak.
A shunt blockage can be very serious as it can lead to an excess build-up of fluid on the brain, which can cause brain damage. This will cause the symptoms of hydrocephalus.
Emergency surgery will be needed to replace the malfunctioning shunt.
Shunt infection is also a relatively common complication after shunt surgery. The risk of infection is around 3-15% and is more likely to occur during the first few months after surgery.
The symptoms of a shunt infection may include:
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.
Shine, the hydrocephalus and spina bifida charity, 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 either fill out a form on the Shine website or call 01733 555 988.
An endoscopic third ventriculostomy (ETV) is a surgical procedure to create a small hole in the floor of your brain.
Possible complications after this type of surgery include:
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 one 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 one of the blood vessels in the brain, which may be fatal.