What is hydrocephalus?

Hydrocephalus is a condition where there is a build-up of cerebrospinal fluid (CSF) within the normal fluid-filled chambers within the brain (ventricles). You may know the term ‘hydrocephalus’ as ‘water on the brain’. Hydrocephalus can exist from birth (congenital) such as in patients with spina bifida, or can develop later as a result of other conditions, such as trauma, brain tumours, brain haemorrhage, scarring within the fluid flow pathways or meningitis. It can also develop into older age, when the exact cause is unclear.

Diagram of brain and normal CSF pathways

Types of hydrocephalus

Raised pressure hydrocephalus

Raised pressure hydrocephalus is a serious life threatening condition. It requires immediate attention and an emergency or urgent treatment plan.


  • Headache
  • Vomiting
  • Deterioration in conscious level
  • Poor coordination
  • Behavioural changes and visual deterioration

Normal pressure hydrocephalus 

Normal pressure hydrocephalus is a long-term condition, which causes a build-up of fluid within the brain. The difference is that it does not cause an increase in pressure, but can adversely affect quality of life over time.


  • Unsteadiness and decline in mobility
  • Memory issues
  • Problems controlling your bladder (incontinence)

Idiopathic intracranial hypertension (IIH)

This is a condition where there is a build-up of pressure within the brain, which can cause loss of vision. This is not due to hydrocephalus, but can be treated in a similar way to hydrocephalus, so this leaflet may have relevant information. Some patients with IIH may need a shunt inserted in order to help with the symptoms of high pressure.

How is hydrocephalus diagnosed?

The main tests used to confirm hydrocephalus include:

  • CT Scan (Computerised Tomography) – X-ray images of the brain which show the size and shape of the ventricles and other abnormalities.
  • MRI (Magnetic Resonance Imaging) – MRI  shows  the size and shape of the ventricles using magnetic fields to create computer images. MRI also gives detailed images of soft tissue structures and is often particularly useful to help identify the specific cause of hydrocephalus.
  • Lumbar puncture – a small needle is inserted into the lower part of the spine (lumbar spine) under local anaesthetic to obtain a small sample of cerebrospinal fluid (CSF) and to measure CSF pressure.
  • Lumbar drain – flexible tubing inserted into the lumbar spine connected to a drain. A measured amount will be drained over 2-3 days to help your doctor to determine whether a permanent shunt would be beneficial.

What are the treatment options?

Currently there is no cure for hydrocephalus. The condition can be controlled by diverting fluid (CSF) away from the brain or by diverting the fluid around an obstruction of flow within the brain. Both of these techniques require surgery:

Treatment with shunts

A shunt is a device that is surgically inserted permanently to control hydrocephalus. It drains the excess CSF from the ventricles of the brain.
The type of shunt and its placement is based on what your neurosurgeon determines is most appropriate for you, influenced by the type of hydrocephalus and any other existing medical conditions.

The most common type of shunt used is the ventriculo-peritoneal (VP) shunt but ventriculo-atrial (VA) shunts and lumbar peritoneal (LP) shunts are also used. 

Ventriculo-Peritoneal (VP) shunt

The surgical procedure involves draining the excess CSF via a pressure valve implanted in the head above the ear. It then travels down a catheter (tube) that is tunnelled under the skin to the abdominal cavity, where it is reabsorbed by the lining (peritoneum). A second catheter runs between the pressure valve into one of the ventricles of the brain.

Ventriculo-peritoneal (VP) shunt


Ventriculo-atrial (VA) shunt

Ventriculoatrial shunts drain from the ventricles into the heart. They are less commonly used than VP shunts.

Lumbar-peritoneal (LP) shunt

Lumbar peritoneal shunts drain from the CSF space around the lumbar spine to the abdomen. This type of shunt is used for draining CSF where there is no blockage through the ventricles, but not enough CSF is being absorbed, such as in communicating hydrocephalus, and idiopathic intracranial hypertension (IIH). 

Endoscopic third ventriculostomy 

Some patients may be offered an endoscopic third ventriculostomy rather than a shunt. In this operation, a small endoscope is passed surgically into the ventricle and a hole is opened at the base of one of the ventricles. This allows the CSF to bypass the obstruction and flow out of the ventricles.

Ommaya reservoir

In some patients, a ventricular access device, also known as an Ommaya reservoir, is inserted. This usually sits under the skin on the right side of the head, and is connected to a short catheter that joins the reservoir to the ventricle.
CSF may be aspirated (drawn off) from the reservoir if your shunt stops working. A reservoir can also be used to measure the pressure in the brain and to help confirm that a shunt is working properly.

Alternative treatments

Hydrocephalus almost always requires some form of surgical treatment. Untreated it can lead to a rise in the pressure inside the brain, which is often life-threatening, or to long-term cognitive/memory changes, balance and bladder disturbances. There are some rare instances where hydrocephalus is chronic and does not cause symptoms. In this situation your neurosurgeon may keep you under close follow-up or arrange additional tests. 

What are the risks of treatment?

The risk and benefits will be explained by your neurosurgical team and this procedure will only be carried out in your consultant’s best opinion. There will be an opportunity to ask any questions at the time of gaining your consent before going ahead with any procedure. If you have any concerns or questions regarding how you will feel following the procedure then you should always discuss these with the doctor.

There is a small risk of infection to the wound or deeper into the shunt itself.

There may be some bruising around the surgical wound site. There is some risk of bleeding inside the brain from the operation. There is also a small risk of a blood clot which may be a serious complication

Some pain may be felt from where the shunt has been inserted or at the wound sites. This is normally well controlled with simple pain relief. Some people may experience a headache post-op due to adjusting to pressure changes in the brain. This usually gets better with simple pain relief, rest and plenty of fluids.

Brain injury/seizures: as with any surgery on the brain, the risk of this is extremely small. You may require ‘one-off’ or long term treatment to control this depending on the circumstances. 

Shunt failure
A shunt is a mechanical device, that in most patients, is able to work very well. They consist of a tube into the brain (ventricular or proximal catheter), a valve to regulate the flow of CSF, and tube into the abdomen (peritoneal or distal catheter). 

These tubes can become blocked, kinked or snap with time. If this occurs the shunt can stop working and the symptoms of hydrocephalus return. You must seek urgent medical attention if any of your symptoms of hydrocephalus return.

After the operation

There will likely be metal clips (staples) to the wound but you may also have sutures or steristrips. If not removed on the ward, then these will need to be removed by the practice nurse at your GP surgery. You will be advised when these need to be removed when you leave hospital.

Observe the wounds for any sign of infection, unusual redness or pain, swelling, heat or discharge. Please contact your Hydrocephalus Nurse Practitioner if you notice any of these symptoms.

You will need to inform the Driving and Vehicle Licensing Agency (DVLA) of your shunt. At present, there is a minimum restriction of 6 months off driving. However, this can be longer if there are other influencing medical conditions or disabilities.

An outpatient appointment will be sent to you by post after having your shunt inserted. Please contact the secretary of your Consultant Neurosurgeon or the Hydrocephalus Nurse Practitioner Team if you do not receive this.

Frequently asked questions

What are the signs I should look out for?

  • Headaches
  • Nausea and vomiting
  • Visual disturbances
  • Drowsy, sleepy, hard to wake
  • Temperature
  • Worsening memory
  • Balance problems or unsteady on feet
  • Worsening concentration
  • Return of pre-shunt issues

These signs may mean that your shunt is infected or blocked.

If you get any or all of these you should contact your Hydrocephalus Nurse Practitioner or GP without delay. If out of hours, please go to your nearest Emergency Department informing them that you have a shunt.

How long will I have to stay in hospital?

You will usually be discharged within one day of surgery. Initially you will need a period of recovery before going back to work. It would be useful to discuss this with your employer.
Will the shunt be visible after the operation?

A bump can be felt under the skin surface behind the ear. This is due to the valve which is an essential part of the shunt system. However, it is not usually visible under hair. 

Does a shunt last forever?

As a man-made device, a shunt will not last forever. It can last from a few days to many years. In adults, we have seen them last for as long as 35 years. Over time the plastic tube can corrode and disintegrate so you will need a replacement. The valve itself can also block and so can the tube that is in the ventricle of the brain itself.

Will it affect me at work?

The shunt is under the skin and as such there is usually only minimal external evidence that it is there. The shunt itself will not affect academicperformance or achievement. As mentioned above, it is usual to have 2-4 weeks off work to recover from shunt surgery, but this will depend on your occupation.

Can I fly?

There are no reasons why you should not travel by air after treatment for hydrocephalus. There are no cases that we know of where this has been harmful. However, if a shunt has been inserted that has an adjustable valve, we usually recommend avoiding electromagnetic scanning devices such as handheld security scanners because they may change the shunt valve setting.

Will I be able to have an MRI scan?

Currently the most commonly used programmable shunts are adjusted with a magnetic device. This can mean that occasionally some types can be accidentally reset by magnetic fields coming close to the valve area, or by powerful magnets such as those in MRI scanners. If you are asked to have a MRI scan, please make sure that the radiographer is aware that you have a programmable shunt – this shunt setting will need to be checked following your scan. 

Will I be able to go back to my normal activities?

We encourage you to return to your normal activities as soon as you are able. 


Hickey, J.V. (2003) The Clinical Practice of Neurological and Neurosurgical Nursing.
5th edition. Lippincott Williams & Wilkins, Philadelphia.
Lindsay, K.W. & Bone, I. (2004) Neurology and Neurosurgery Illustrated. 
4th edition. Churchill Livingstone, London.

Images reproduced with the permission of Medtronic Ltd.

NHS Constitution: information on your rights and responsibilities

Additional information

Shine Hydrocephalus Charity

Hydrocephalus association (American site)

This edition published November 2020. Review due November 2022. NBT002071