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Normal pressure hydrocephalus specialist service

Patient information A-Z

This information is for patients with suspected normal pressure hydrocephalus who may benefit from surgical treatment. This information summarises a typical patient pathway, including all services and tests that a patient may receive.

Normal pressure hydrocephalus

Cerebrospinal fluid (CSF) is produced in the fluid spaces in your brain. It then circulates through these spaces to the spinal canal and back up again to the brain in a loop. Fluid is then reabsorbed in the brain. This cycle normally takes place three times a day.

Hydrocephalus is a build-up of CSF in the brain. The excess fluid puts pressure on the brain, which can damage it. Hydrocephalus can be caused by many reasons, and normal pressure hydrocephalus (NPH) is one of the main types of hydrocephalus.

NPH is a still poorly understood condition that most often affects people over the age of 60. It can sometimes develop because of a known cause such as a trauma or a bleed in the brain (secondary NPH), but in most cases the cause is unknown (idiopathic NPH). Walking and thinking difficulties, as well as urinary incontinence are the three main symptoms of NPH. Not all NPH patients have issues in all three NPH typical symptoms. Since these symptoms happen gradually and are similar to those of other conditions, such as Alzheimer's disease, NPH can be difficult to diagnose. It is important to diagnose NPH correctly because, unlike other forms of dementia, the symptoms can be relieved with treatment.

Addenbrooke's hospital has built a unique NPH Specialist Service that involves a comprehensive, holistic assessment of this condition, using innovative diagnostic tools, which help us make more accurate diagnosis and offer appropriate treatment faster.

Initial appointment

Your initial appointment with the NPH specialist service may be in person at our outpatient NPH clinic, or over the phone. You will be seen by a neurosurgeon or a clinical nurse specialist, who will ask for details of your medical history, your level of independence to carry out activities of daily living, and have an initial discussion with you about your condition and possible investigations and treatments.

You may also be seen by a neuropsychologist and a neuro-physiotherapist for NPH-relevant clinical examinations and assessments. A neuropsychologist will perform specific cognitive assessments that help with the diagnosis of cognitive changes that are usually associated with NPH. A neuro-physiotherapist will carry out specific physical examinations and tests of your gait and balance, that will help us determine whether any issues with these could be related to NPH.

Based on findings from this initial appointment we may be able to offer you further clinical and surgical investigations as described below.

Clinical and surgical investigations

Several investigations are usually needed to help us make a more accurate diagnosis and offer you possible treatment options. Imaging investigations may include CT and / or MRI head scans. Surgical investigations may include a lumbar infusion study and / or an extended lumbar drain. Details about each of these surgical procedures are described below.

Lumbar infusion study

A lumbar infusion study involves the slow, controlled injection of saline fluid (made of water and salts) into the fluid spaces of your spinal canal in the lower back. At the same time, we take pressure measurements that help us determine how efficiently your CSF loop is working.

Before the procedure

For most patients, the procedure will be done on an outpatient basis and you can go home the same day. Occasionally, admission on the previous day will be suggested.

Before the infusion study, you may be seen by a neuropsychologist and a neuro-physiotherapist, who will perform relevant cognitive and physical assessments if you have not had them before.

During the procedure

The test is done under local anaesthesia. You will need to lie on your side, with your legs curled up to your chest. Through a lumbar puncture a needle is inserted into the fluid spaces in your spinal canal in the lower back. The saline fluid that is slowly injected in this space, is connected to monitoring devices which allow us to take pressure measurements. We also withdraw some CSF fluid before completing the procedure, to see whether this leads to any relief in your symptoms within a period ranging from a few hours up to a few days following the test. Generally, once the needle is placed in the back, the test takes about 30-45 minutes.

After the procedure

Once the needle is removed, you will have to rest by lying down on a bed for about 30 minutes. Two to four hours after the end of the test, you will be asked to complete two very short cognitive tests and three very short physical assessments to determine whether you notice any improvement in your symptoms following the extraction of some CSF. You will usually be able to go home on the same day of the procedure. If you feel quite unwell, you may have to stay overnight but this is very unlikely.

You should be able to eat and drink as normal, but you will need to drink plenty of fluids over the following 24 hours. You will also be given information about things to watch out for that might be early signs of problems (for example, infection). You should be able to resume your normal activities the next day.

You will be asked to complete a very short questionnaire on changes in your symptoms at day 1, 3 and 7 after your infusion study.

Extended lumbar drain

An extended lumbar drain involves the insertion of a small flexible tube into the fluid spaces in your spinal canal in the lower back, which is attached to an external drainage system in a closed sterile temporary system. The system drains excess CSF with the aim of establishing and maintaining a lower, normal pressure, within the CSF system, usually for 3 to 5 days.

Before and during the procedure

This procedure will be performed as an inpatient, at the bedside or in a surgical theatre. You will be admitted in hospital, usually for 3 to 5 days.

Before the procedure, you may be seen by a neuropsychologist and a neuro-physiotherapist, who will perform relevant cognitive and physical assessments if you have not had them before.

During your stay

Your nurse will check the status of the drain regularly, however, if you have any concerns in between the nurse’s visits please call them as soon as possible. Your nurse will also perform a neurological observation and will need to check your vital signs frequently.

For safety reasons, you and or your relatives should not touch any part of the drainage system at any time. You must not go out of the ward while you have the drain inserted. If for any reason you are to go off the ward for clinical reasons, you will be accompanied by a trained staff member.

Your lumbar drain will usually be clamped most of the time and unclamped at specific intervals (often every 4 hours). You will have to maintain your posture at all times when your drain is unclamped. This is to minimise the risk of over drainage (too much) or under drainage (too little) as the drain works by gravity.

You will be asked to complete a very short questionnaire on changes in your symptoms 1, 3 and 7 days after the day of insertion of the lumbar drain.

Medication before surgical investigations

Please tell the team about all the medicines you normally take, either prescribed by a doctor or bought over the counter. During your hospital stay, you will be able to continue taking your medication either by nurse administration or self-medicating. The nursing staff will be able to confirm which drug administration meets your needs.

IMPORTANT: You should not take Aspirin as pain relief prior to your procedure. If you are on blood thinners such as Rivaroxaban, Edoxaban, Apixaban, Dabigatran, Warfarin, Aspirin, Clopidogrel or Di-Pyridamole, please let your clinical team know and they will advise you when to stop taking the medications if it is safe to do so.

Benefits, risks, and alternatives to surgical investigations


To assess if you have NPH, which can be improved with a CSF shunt operation.


  • Nerve damage – it is rare to cause nerve damage by doing a lumbar puncture in the lower spine. At this level, the nerve rootlets float freely in a sac of fluid. However, if you know that you have a spinal abnormality, please let us know about this.
  • Bleeding – sometimes the lumbar puncture may cause bleeding from veins in the spinal canal. This rarely causes a severe problem unless you are on blood-thinning medication. Please advise us of this and stop your medication seven days before the test to be safe.
  • Infection – an infection can occur related to any puncture of the skin.
  • Discomfort – sometimes a lumbar puncture can be uncomfortable. This is alleviated by giving local anaesthesia. You will also be able to talk to us during the procedure.
  • Headaches – we drain fluid as part of the test and encourage you to drink fluids to replenish this loss afterwards. However, you may experience a headache due to loss of fluid. This usually improves over the next day or so as your body produces more fluid.
  • Inconclusive test results – sometimes even if the test goes smoothly, the results may be inconclusive. We will discuss the implications of the test with you at your next clinic or phone appointment.


  • Some patients are not able to have a lumbar infusion study or extended lumbar drain. In these cases, some patients may be offered continuous monitoring of the pressure in your brain (intracranial pressure monitoring). This would be done in a surgical theatre under general anaesthetic. It consists of the insertion of a pressure sensor in your brain, through a small hole in your skull, which is connected to a pressure monitoring device. The monitoring is usually done overnight, but occasionally it may take longer.
  • If we think that you have NPH and you do not wish to proceed to have surgery, there is no need for you to have any type of infusion study or lumbar drain at all. Please discuss this with your doctor.

Results appointment

Your results appointment may take place either in person at our outpatient NPH clinic, or over the phone. Based on the results from your investigations, your symptoms, and your medical history, we will be more certain about your diagnosis, as well as be able to discuss the treatment options available with you. You may be offered CSF shunt surgery, as summarised below.

CSF shunt surgery

CSF shunt surgery is an operation to divert excess CSF in the fluid spaces of your brain and spine into other body cavities where it can be reabsorbed.

A separate patient information leaflet will be provided if you are offered CSF shunt surgery. A brief summary of the procedure is provided below.

Before the procedure

You will either be admitted to hospital the day before or on the day in preparation for the operation. Your doctor will discuss the length of stay with you.

This procedure involves the use of general anaesthesia. You will see an anaesthetist before your procedure.

During the procedure

A shunt procedure is done under general anaesthetic and involves making a hole in the skull, usually at the front of the head, on the right side, as well as passing both a small plastic tube (catheter) into the fluid space within the brain (ventricles) and a valve that sits under the scalp. The valve underneath the skin is only visible if the patient is balding. These are connected to another catheter which drains the excess fluid into another cavity within the body, usually the tummy (peritoneum), where it can be easily absorbed.

After the procedure

Once your surgery is completed you will usually be transferred to the recovery unit where you will be looked after by specialist trained nurses, under the direction of your anaesthetist. The nurses will monitor you closely until the effects of any general anaesthetic have adequately worn off and you are fully conscious. You may be given oxygen via a facemask, fluids through an intravenous drip, and appropriate pain relief, until you are comfortable enough to return to your ward.

Post-surgical follow-up

You will be followed up about 3 months and about 1 year following hospital discharge from your shunt operation.

At these appointments you will have a comprehensive assessment to determine the scale of change to your symptoms after your shunt procedure. This will include your level of independence to carry out activities of daily living, cognition and your gait and balance.

Contacts and further information

For any further information please telephone 01223 596412. Alternatively you can email CSF infusion studies or email REVERT.

References / sources of evidence

Privacy and dignity

Same sex bays and bathrooms are offered in all wards except critical care and theatre recovery areas where the use of high-tech equipment and / or specialist one to one care is required.

We are smoke-free

Smoking is not allowed anywhere on the hospital campus. For advice and support in quitting, contact your GP or the free NHS stop smoking helpline on 0800 169 0 169.

Other formats

Help accessing this information in other formats is available. To find out more about the services we provide, please visit our patient information help page (see link below) or telephone 01223 256998.

Contact us

Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151