Neurosurgery - Hydrocephalus and Shunts

Natalie Williams
Hydrocephalus/CSF Clinical Nurse Specialist – 0161 206 7679

NHS No: ______________________________   

Hospital No: ______________________________        

Consultant Neurosurgeon: ______________________________      

Type of shunt valve: ______________________________       

Insertion of shunt: ______________________________       

What is Hydrocephalus?

You may have heard the term Hydrocephalus being described as ‘water on the brain’, but the ‘water’ is cerebrospinal fluid (CSF). Hydrocephalus is a condition in which there are enlarged fluid cavities, due to a build-up of excess CSF in the ventricles (fluid filled spaces) that are within the brain.

The ventricles are a network of communication spaces (or cavities) filled with CSF. There are 2 lateral ventricles, the third ventricle, the cerebral aqueduct and the fourth ventricle.

Normally the body produces about 500mls of CSF per day, with about 125mls at any one time produced within ventricles flowing
freely between them, and around the brain and spinal cord (acting as a cushion), before being reabsorbed by the body. Hydrocephalus tends to happen when there is a problem causing a blockage of flow, or a problem with the reabsorption of the CSF. The build-up of excess fluid may cause increased pressure on the brain from within, which in turn can cause damage to the brain tissue and lead to:

• Headache
• Neck pain
• Nausea and/or vomiting
• Sleepiness/reduction in consciousness
• Confusion
• Blurred/double vision
• Difficulty walking/weakness to limbs
• Urinary incontinence
  
  

Types of Hydrocephalus

Congenital - This means that hydrocephalus is present at birth, a baby already has a build-up of excess CSF present in the brain caused by a blockage of flow/ drainage or reabsorption of CSF, leading to an increase in the size of the ventricles and the pressure inside the brain to rise (also known as raised intracranial pressure or raised ICP). The causes of congenital hydrocephalus are not always found but known causes can include:

• Aqueduct Stenosis - Complete or partial obstruction of CSF flow through a narrow channel connecting the third and fourth ventricle
• Spina Bifida - A type of defect where the spine and spinal cord does not develop properly in the womb
• Genetic causes and cysts
• Maternal Infections - i.e., Rubella, Syphilis, Group B Streptococcus

Acquired - This type of hydrocephalus develops in adults and children and can often be caused by:

• Brain Haemorrhage - Blood and damage following a haemorrhage can disrupt the production, drainage, and reabsorption of CSF
• Prematurity - Premature babies are at high risk of suffering haemorrhage due to their very fragile blood vessels within their brains
• Meningitis - Blockage of flow of CSF caused by inflammation and debris from the infection
• Brain Tumours and Colloid Cysts - Block the flow of CSF

Normal Pressure Hydrocephalus - Normal pressure hydrocephalus, or NPH, is characterised by memory problems/ confusion, decreased mobility and urinary incontinence, and is normally seen in people over the age of 60. The cause of normal pressure hydrocephalus (NPH) is usually unknown. In this type of hydrocephalus pressure does not build, but the ventricles are enlarged and disturbed brain function occurs.

LOVA (Long-standing Overt Ventriculomegaly of Adults) – Some people may only be found to have large ventricles as an adult, although this may have been present their whole lives and never caused a problem. In some people, later in life, large fluid cavities can lead to difficulties such as memory impairment, headaches, problems with mobility and bladder problems. Many of the symptoms are similar to NPH but tend to occur in a younger group of people.

Other terms you may hear

Communicating Hydrocephalus

Communicating hydrocephalus is when the flow of CSF is blocked after it exits the ventricles, but the passages between the ventricles remain open and the CSF builds up ‘behind’ the blockage. This also relates to the reduced flow and reabsorption of CSF into the arachnoid villi when a patient has, for example, a subarachnoid haemorrhage.

Non-communicating (or Obstructive) Hydrocephalus

Non-communicating hydrocephalus is when one or more of the passages between the ventricles is blocked, for example, aqueductal stenosis.

Hydrocephalus Ex-vacuo

Hydrocephalus Ex-vacuo occurs when the brain is damaged from stroke or injury. The ventricles become larger as a result of the brain tissue shrinking.

Idiopathic Intracranial Hypertension (IIH)

This is a condition where the pressure in the brain is increased, but an increase in the size of the fluid cavities does not occur. It is closely related to other hydrocephalus conditions as in rare cases it may need treated with a shunt. It may present with swelling behind the eyes and severe headaches. Other treatments include weight loss, medications such as Acetazolamide, venous sinus stenting, or optic nerve sheath fenestration (ONSF).

Treatment options

Shunt insertion

One of the main treatments for hydrocephalus is a shunt. A shunt is a thin tube inserted in one of the fluid filled chambers in the brain (ventricles) to drain away the excess CSF usually to the peritoneum (the ‘empty’ sac that surrounds the bowels in the abdomen) where it can be absorbed into the bloodstream.

The ventricular shunt systems consist of a valve that regulates the flow of CSF along it. They can either be set at a fixed pressure setting or be adjustable valves that means the setting can be reset after surgery to change the amount of CSF drainage according to your symptoms.

Endoscopic Third Ventriculostomy (ETV)

Another treatment option is an endoscopic third ventriculostomy (ETV). It involves an operation where a small hole is made in the bottom of the third ventricle using a small camera to divert the flow of CSF so that it can be absorbed in the usual way and bypass any obstruction to CSF flow. However, not everybody with hydrocephalus is suitable for this operation, and there is a chance that it won’t work, and a shunt will have to be fitted.

Diagnostic Tests

CT scan

A CT scan (also known as a CAT scan) is an X-ray based scan that shows us the anatomy of the ventricles. If you have a shunt, this may be performed to check on the size of the ventricles as it will show if the shunt has stopped working (known as shunt malfunction).

MR scan

An MR scan is a type of scan that uses strong magnetic fields and radio waves to produce detailed images of the inside of the body. It is a noisy scan, and patients can feel claustrophobic in the scanner. Please make your consultant aware if:

• You suffer from claustrophobia
• You have previously had a shunt inserted (as this can affect the pressure settings in certain shunt valves)
• You have a pacemaker
• You have had any metalwork inserted surgically

Lumbar puncture

A lumbar puncture is where a thin needle is inserted between the bones in your lower spine, and it is carried out in hospital by a doctor or specialist nurse. The pressure within the spinal canal is measured, and then some of the CSF is removed. The fluid is removed to both reduce the pressure and so that samples can be sent to the laboratory for testing. After the procedure, you will be tested to see if your symptoms have improved after the removal of the CSF. This procedure is usually carried out with patients with normal pressure hydrocephalus (NPH) or idiopathic intracranial hypertension (IIH).

Shunt series X-rays

X-rays may be requested of your skull, neck, chest, and abdomen in order to check the shunt tubing. This can identify whether the shunt itself has become disconnected or broken and is still draining to the correct place. Certain skull X-rays that are focused over the valve, they can help show us the setting of the shunt, if your shunt is programmable.

Complications that can occur following Shunt surgery

Infection - As the skin is being cut, there is a risk of infection. This may simply need to be treated with antibiotics or sometimes deeper infections can occur. As a shunt is a foreign body, shunt infections can occur which might necessitate antibiotic treatment and sometimes removal of the shunt. In people who are shunt- dependent (i.e., they become very ill without a shunt) an external drain may need to be inserted while a shunt infection is treated. An external ventricular drain (EVD) is a temporary drainage tube that is inserted into the ventricles and drains into an external bag where the drainage is monitored. This is normally used until a new shunt can be inserted.

Bleeding/bruising - Some bruises can occur around surgical wounds but may also occur along the path of the shunt. There is also a risk of bleeding inside or outside of the brain caused by operation. These risks are small should bleeding occur this could cause stroke like symptoms or could potentially be life- threatening.

Shunt blockage - Although a shunt may be working when it is initially placed, there is the risk that it can later get blocked, or break (fracture) or even migrate to the wrong position. If this happened then symptoms of a blocked shunt can occur which can include headache, vomiting and drowsiness in some people.
Often the symptoms recur that first led to the diagnosis of hydrocephalus. If any of these symptoms should occur, then medical attention should be sought urgently.

Pain - There may be pain present along the path of the shunt and from the surgical wounds. This can usually be controlled by simple painkillers like paracetamol. The operations themselves are not particularly painful procedures. Some people may experience headache after a shunt because of a change in the pressure inside their head.

Brain injury - The risk is extremely small, but important to understand. It may be seen in the form of a weakness or paralysis like a stroke and could be temporary or permanent. If something like this were to occur the neurosurgeon would investigate to find out why it happened and explain this to you.

Fits/Epilepsy - Fits are possible but relatively uncommon after shunt surgery or a third ventriculostomy or any neurosurgical operation. Long-term treatment may or may not be required depending on the circumstance. The risk of having fits is the reason that you will be asked not to drive for a period of time after your shunt operation.

Risk to life - This is usually extremely small but is partially dependent on your age, and general health. The risk is there because this is surgery to the brain and as it involves a general anaesthetic.

Frequently Asked Questions

Can I drive after the operation?

No, the current DVLA guidance is that you must not drive after a ventricular shunt or third ventriculostomy operation. You must inform them that you have been in hospital and have had an operation. They will contact us for details and inform you when you can drive again. The usual time period is 6-months suspension from the date of surgery provided you do not suffer any epileptic fits.

Can I fly?

There are no reasons why you should not fly after treatment for hydrocephalus. There are no cases that we know of where this has been harmful.

How long will it take to recover?

You will usually be discharged within 1-3 days of surgery. Initially you will need to plan to have 2-4 weeks off work to recover from the operation.

What do I do if I have to have an MRI scan?

Inform the doctor that you have had a shunt inserted, some shunts can be affected by the magnetic field and change the setting of the shunt valve, so this will need to be checked after the scan has been done.

I have a swelling on my scalp that wasn’t there before my operation, is this normal?

At the time of the shunt surgery a valve is implanted under the skin that connects to the shunt tubing. This may be a programmable (which allows us to change the pressure with a magnet) or fixed pressure. There is also a small reservoir which may be part of or separate from the shunt valve. One or both of these can be felt as firm lumps under the skin after the operation. This is completely normal and allows us to access CSF directly from the shunt or check that the shunt is working.

Useful Links

Brain and Spine Foundation
0808 808 1000
www.brainandspine.org.uk

Shine – Spina Bifida and Hydrocephalus
42 Park Road Peterborough PE1 2UQ 01733 555988
www.shinecharity.org.uk

Department of Work and Pensions (DWP)
020 7712 2171
www.dwp.gov.uk

Citizens Advice Bureau
0207 833 2181
www.citizenadvice.org.uk

DVLA
Driver Vehicle Licensing Authority, Drivers Medical Group, DVLA, Swansea, SA99 1DL
0300 790 6806
www.dvla.gov.uk
 
Headway
0808 800 244
E-mail: enquiries@headway.org
Website: www.headway.org.uk

Miethke
www.miethke.com/en/hydrocephalus/about-hydrocephalus

Integra (Codman)
www.integralife.com/our-patients