Shunts and NPH

Treatments for NPH involve surgery. For most people this will mean insertion of a ventricular shunt, for a smaller number of people a procedure called an Endoscopic Third Ventriculostomy (ETV) might be offered instead. It is thought that, as the fluid-filled chambers inside the brain (ventricles) enlarge, brain tissue above becomes distorted, which results in the difficulties with walking, bladder control and dementia many people experience. The aim of treatment is to help reduce the size of the ventricles by draining CSF from the ventricles. Early diagnosis is key to how well treatment work, but even those with long-standing symptoms can improve with treatment.

For some patients, having a series of lumbar punctures can be used as a temporary treatment to reduce symptoms.


Ventricular shunts

Shunts are the most commonly used treatment for NPH. They are thin silicon catheters that drain excess CSF from the head or spine and divert it to another part of the body for reabsorption/removal. Silicon is long-lasting, and very few people are allergic to it. Some shunts are made with antibiotics inside the silicon to help reduce infection after surgery e g Codman Bactiseal®. Most shunts placed in people with NPH are ventriculo-peritoneal (VP) shunts that drain CSF from the ventricles to the peritoneum (abdominal space).

Tests are usually carried out to see whether improvements in NPH signs and symptoms, can be expected before offering shunt surgery, after which around 80% of patients will experience improvement in the symptoms of their condition. Improvement is often quite rapid after surgery but it can take weeks or months to see the full benefit. 

Ventricular shunts have a valve (3 in the diagram below), which opens when the pressure in the head reaches a certain level. There are several different types of valves. For example, fixed pressure valves open when the pressure reaches a certain pressure and can’t be altered, programmable valves can be adjusted to open at higher or lower pressures, and gravitational valves have different settings for standing and lying down, to adjust for the effects of gravity on shunt drainage. Some shunts have several of these features.


  1. Proximal catheter: A short tube which drains CSF out of the ventricles. The proximal catheter is inserted through the brain via through a hole made in the skull and runs for a short distance under the skin. 
  2. Reservoir: This is a soft, domed structure that can usually be felt through the skin. It can be used to measure pressure, to remove CSF samples for testing, and can be injected with fluid to test the flow and function of the shunt.  
  3. Valve: This controls the pressures and opens to allow CSF to flow through the shunt tubing to regulate the pressures or reduce the amount of CSF in the ventricles. The valve lies just the skin, usually on the back or the top of the head, or behind the ear. 
  4. Distal catheter: A longer tube which runs under the skin and drains CSF from the valve to elsewhere in the body, usually the abdominal space, but occasionally to the heart or other drainage site.

Effects of shunt treatment:

Generally the greatest benefits seen from shunt treatment relate to walking.  

Video used with permission from Miethke. 

Shunt complications in older adults are relatively uncommon due to lower rates of blockage and infection and shunt revisions (surgery to replace part or all of a shunt) are much less common in adults compared with children (from The UK Shunt registry)

Despite their relative robustness, complications do occur. Complications needing surgery include:

  • Malfunction/blockage 
  • Infection 
  • Subdural haematoma 

The return of NPH symptoms that were experienced before having a shunt fitted could be a sign of blocked or malfunctioning shunt.

Symptoms of shunt failure in NPH include the following (not all of these symptoms need to be present): 

  • Increasing difficulty walking 
  • Increased cognitive impairment (memory problems, difficulty thinking, organising, speaking) 
  • Urinary symptoms: frequency / urgency / incontinence 
  • Swelling or redness along the shunt tract 
  • Fever (infection) 

Subdural haematoma (SDH) 

Subdural haematoma (SDH) is a potentially serious complication of shunt surgery in NPH. The blood vessels and brain tissue of older people and of those with NPH are fragile due to changes in the compliance (springiness) of the brain as we age and as part of how NPH develops.

Lowering the pressure in the head too rapidly when a shunt is put in can pull the firm brain tissue away from its coverings (meninges). This leads to bleeding into the space between the layers of meninges. The blood clot (haematoma) that forms puts pressure on the brain causing the following symptoms: 

If you experience these symptoms then you should urgently attend accident and emergency for assessment and treatment. Take your Shunt Alert Card and Hospital Passport if already completed but do not wait to fill them in if not.

The highest risk for SDH is in the immediate postoperative period and the first 3 months. It’s rare for it to occur outside of this window, especially with programmable shunts, but it’s worth just being aware of symptoms.

Treatment for SDH may involve drilling a hole in the skull (Burr hole) to relieve the pressure. 

Shunt function and adjustments 

Programmable shunts are often the first choice for NPH so that more or less CSF can be removed according to your needs. As NPH progresses in many people it may become necessary to adjust the setting on the valve to reduce the pressures further and further, in response to return of the original symptoms.

Shunt over-drainage may result in low pressure headaches, especially when upright for long periods, and will often be relieved by lying down.

Body position: Shunt drainage is affected by gravity and tend to drain less when lying down. Patients may benefit from sleeping with extra pillows, or with the head of the bed propped up a couple of centimetres.

Weight gain or loss especially around your middle, can affect shunt drainage. If you gain or lose a significant amount of weight you may need to have your shunt adjusted to allow it to drain more or less CSF and compensate for changes in pressure in your abdomen.

Bowel enlargement, e.g. due to constipation or gas, reduces abdominal space and reduces the ability of your shunt to drain CSF. Constipation should be treated promptly and it’s important to eat balanced, fibre-rich diet to keep your bowels moving.  

Strong magnets can affect the function of some programmable shunts but fixed-pressure valves are completely unaffected. Many newer models of shunt are designed so they cannot be unintentionally reset by environmental magnets e.g. electronic devices, and some can even resist being reset by the MRI scanner (‘MRI-resistant’). It’s important to know what type and model of shunt you have so that you know what precautions to take, if any. Your shunt alert card is a useful place to record and keep your shunt details. Read more: Know your shunt

Shunt alert cards and hospital passports 

Shine can provide free Shunt Alert Cards for adults with NPH. They are available in digital and hardcopy format and ideally should be carried at all times by anyone with a shunt.  

The card explains that if you are experiencing a return of your symptoms prior to shunt placement that you should seek an appointment with your neurosurgical team for assessment and shunt adjustment where needed. 

Shunt alert cards and NPH patient information leaflets are available to order online or ordered from Shine by calling 01733 555988, or emailing

Should you ever be taken into hospital, a hospital passport contains all the key information professionals will need to give you the best possible care.  You can fill it out online and save it to your mobile device for ease of access. You can download your hospital passport here.

Endoscopic third ventriculostomy (ETV) 

In rare cases where NPH is a result of blockage in CSF flow between the third and fourth ventricles of the brain, the main treatment is bypassing the blockage. To do this a hole can be made in the floor of the third ventricle using an endoscope. This procedure is called an ETV and the hole made gives an alternative route for the CSF to flow out of the ventricles.  



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