Surgery to remove fluid in the brain

Fluid can build up in your brain and cause the pressure inside your head to increase. This is called hydrocephalus. Treatments for hydrocephalus include:

  • shunt surgery
  • endoscopic third ventriculostomy (ETV) 

What is hydrocephalus?

The brain and spinal cord are surrounded by a clear fluid called cerebrospinal fluid (CSF). The CSF supports and protects the brain and the spinal cord.

Some brain tumours block the normal circulation of the CSF. The fluid can’t drain away. So it builds up inside the brain and increases the pressure inside the head (intracranial pressure).

This increased pressure can cause symptoms, such as headaches and feeling sick. It can also damage the brain if left untreated.

Treatment for hydrocephalus

Treatment for hydrocephalus is usually surgery. There are 2 main types of surgery that you can have:

  • shunt surgery
  • endoscopic third ventriculostomy (ETV)

You might have surgery for hydrocephalus at the same time you have surgery to remove your tumour. Or you may have a separate operation.

Having brain surgery might sound like a frightening procedure, but it is quite safe. Doctors who carry out these surgeries are very skilled specialists. Talk to your doctor or cancer nurse specialist if you are worried.

Shunt surgery

A shunt is a thin tube that drains away the extra CSF from the ventricles of the brain. The shunt drains the CSF to other parts of the body, where it is absorbed.

Shunts are usually plastic and small, about 0.3cm (3mm) across. They have valves so that fluid can flow down from the brain but not back the other way. Shunts are also called ventricular catheters.

You have shunt surgery under a general anaesthetic. This means that you will be asleep and won’t feel anything. A specialist team of doctors does your surgery. They are called neurosurgeons.

The most common type shunt is the ventriculoperitoneal shunt. This is a tube from the brain ventricles into the abdomen (tummy). Other types of shunts drain the fluid into the chest.

Diagram showing a brain shunt

You can’t see the shunt from outside the body. Some people have a shunt for a short period of time and then the surgeon removes it. Others have them for much longer.

Possible problems with shunts

The most common problems with shunts are blockage and infection. Shunts that drain into the tummy can also cause a hole in the bowel (perforation), but this is rare.


Doctors don’t know for sure why some shunts become blocked. A blockage may cause symptoms of increased pressure inside the head. Symptoms include:

  • headaches
  • feeling or being sick
  • drowsiness
  • unconsciousness
  • neck stiffness

A shunt blockage can be serious. You usually need an urgent operation to replace it. 


Shunt infections are more common in the first few weeks after having shunt surgery. If your shunt is infected, you might have:

  • headaches
  • high temperature (fever)
  • a reddening of the skin over the path of the shunt (a red area tracking down your neck and chest for example), but this is rare

You usually have antibiotics if this happens.

Contact your doctor or cancer nurse specialist if you have any of these symptoms. They can check your shunt and give you treatment.

Endoscopic third ventriculostomy (ETV)

ETV involves making a tiny hole inside your brain to allow the extra CSF to drain into another part of the brain, where it is absorbed.

ETV isn’t suitable for everyone. You might have it if your hydrocephalus is caused by a blockage.

You usually have an ETV under general anaesthetic. This means that you will be asleep and won’t feel anything.

Your surgeon carefully makes a small hole into the skull. They put an endoscope through the hole and into the ventricles. The ventricles are spaces inside the brain filled with CSF.

Diagram showing where the ventricles are in the brain

An endoscope is a long tube with a light and a camera at one end. This allows your doctor to see inside the brain and make the tiny hole inside the ventricles.

Possible problems with ETV

ETV is a safe procedure and complications are usually rare. Possible problems of ETV include:

  • bleeding in the brain
  • damage to other parts of the brain
  • infection
  • a hole in the membranes that cover the brain (meninges) which may cause the CSF to leak
Talk to your doctor about the possible complications of ETV if you are worried.


It can be upsetting to learn that you have hydrocephalus and need to have brain surgery. Talk to your doctor or cancer nurse specialist about what to expect during an operation to treat hydrocephalus. Ask them about the side effects you might have and the support that will be available to you.

For support and information, you can call the Cancer Research UK information nurses on freephone 0808 800 4040, from 9am to 5pm, Monday to Friday. They can give advice about who can help you and what kind of support is available.
  • Brain tumours (primary) and brain metastases in adults
    National Institute for Health and Care Excellence (NICE), 2018

  • Primary brain tumours in adults
    S Lapointe, A Perry and N Butowski
    Lancet, 2018. Vol 392, Pages 432-446 

  • Ventriculoperitoneal shunt complications: A review
    M Paff and others
    Interdisciplinary Neurosurgery 2018 Volume 13 pages  66–70

  • Complications of Endoscopic Third Ventriculostomy
    T Bouras and S Sgouros
    World Neurosurgery 2013 Volume 79, Issue 2, Supplement Pages S22.e9-S22.e12

  • Neuro-Oncology Essentials for Clinicians 
    European Society for Medical Oncology (ESMO), 2017

  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. Please contact with details of the particular issue you are interested in if you need additional references for this information.

Last reviewed: 
31 Mar 2023
Next review due: 
31 Mar 2026

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