Venous sinus stents (for the treatment of venous sinus stenosis and idiopathic intracranial hypertension)

Venous sinus stenosis is a narrowing of the large veins (the venous sinuses) on the surface of the brain. These veins drain the blood from the brain. Narrowing or stenosis in these sinuses is commonly seen in IIH.

IIH is a condition where the pressure inside the head is higher than normal without a clear cause, such as a mass. The exact causes of IIH are not fully understood. All treatments are aimed at reducing the pressure. It is not clear whether the stenosis results in the raised pressure or the stenosis is caused by the raised pressure.

IIH is quite rare, and most patients get better after a few months on medication or by draining a small amount of cerebrospinal fluid (CSF). This is done by inserting a needle into the space around the spine. Draining CSF in this way is called a lumbar puncture (see alternative treatments).

IIH can cause headache. In some cases, these headaches can be prolonged and become very severe and disabling. In extreme cases, the pressure on the nerves at the back of the eyes can lead to blindness if left untreated.

A stent is a tiny tube made of a metallic mesh. It is placed into the blood vessels to open up the narrowing and improve blood flow. There is growing evidence that opening up the narrowed vein can reduce the pressure inside the head and relieve the symptoms.

All treatments and procedures have risks, and we will talk to you about the risks of venous sinus stents. No two venous sinus stenosis are the same: The risks of stenting vary from one venous sinus to the next according to the size, position, and configuration of the vessels. Sometimes it is not possible to stent the venous sinus stenosis safety. The procedure will take place under a general anaesthetic. Your anaesthetist will discuss the risks of general anaesthesia with you.

Problems that may happen straightaway

During a venous sinus stenting, a contrast agent will be injected into your veins; this allows the Interventional Neuroradiologist (INR) to see the blood vessels and the stent when an X-ray is taken. Contrast agents are considered safe drugs. However, as with all drugs, they have the potential to cause an allergic reaction. The department and team are well equipped to deal with reactions in the rare event of this happening.

Problems that may happen later

The contrast agent used during the procedure is iodine-based contrast and is excreted through the kidneys, this may affect your kidney function. You will have a blood test to test your kidney function beforehand to ensure it is safe for you to have contrast. The risk of you having contrast will be weighed against the benefit of having this treatment and is decided by the team referring you. For further information on the use of iodine-based contrast agents please see the information leaflet ‘Contrast Agents for X-ray, Fluoroscopy, CT and Angiography Examinations: An Information Guide’ or alternatively visit the trust website.

Problems that are rare, but serious

Venous sinus stentings are difficult and complex procedures: serious complications are unlikely but are always present. Like all procedures involving the blood vessels of the brain, a venous sinus stenting carries a risk of stroke which results from either a blockage of a blood vessel or from a haemorrhage. This can range from a minor problem which improves over time to a severe disability involving movement and balance or may even be a threat to life. The percentage level of this risk can only really be discussed on a case-by-case basis and depends on size, position and configuration of the stenosis itself.

On our current evidence, we would estimate that about 1 person in 100 will experience a complication like this. The problem is almost always apparent during or immediately after the procedure or within the next few days whilst you remain in hospital.

The type of stent devices we are using have been used elsewhere in the body for over 20 years with good long-term results. Their use in the venous sinuses is quite new and therefore we do not yet know how they will behave in the long term. Based on experience in other hospitals around the UK and the rest of the world, delayed problems seem to be very rare.

Other Problems that occur

A haematoma, bruising or vessel damage around the groin puncture site may also occur. Occasionally there is bruising and sometimes bleeding in the groin. It is rarely serious but can go on for a few hours. Very occasionally there is damage to the blood vessel requiring a further surgical operation.

Increased risk of bleeding

You will need to take tablets to make the blood less likely to clot in the days leading up to the procedure and for many months afterwards. These tablets can increase the risk of bleeding in other areas of the body and can irritate the stomach. It is important to tell your consultant if you have had a stomach ulcer in the past.

Radiation Risk

The use of X-rays during the procedure presents a very small risk of hair loss, skin erythema (reddening) or very rarely the development of cancers in the future. Our state-of-the-art imaging equipment and modern techniques help to ensure the radiation dose is as low as possible. In addition, your doctor will have made a judgement about your risk and benefit before agreeing to the procedure, including the risk to your health of not having the procedure.

Female patients of childbearing capacity between the ages of 12 and 55 years are required by law to be asked about possible pregnancy when undergoing examinations involving X-ray.

Patients who either are or think they may be pregnant must inform the Neuroradiology department as soon as possible. In some urgent cases the procedure may still go ahead but with additional precautions in place. To reduce the risk for early and unknown pregnancies, venous sinus stenting is usually performed within the first ten days of the menstrual cycle when pregnancy is much less likely.

The Interventional Neuroradiologist performing the procedure will discuss all possible risks with you and give you the opportunity to ask questions.

It is important that you fully understand the procedure, the risks and benefits and any alternative treatments available. There is clearly no obligation to follow the advice given. A decision not to choose this treatment will not affect any other aspect of your care. Also, it is entirely reasonable to seek a second opinion if you still have concerns.

If we think you will benefit from venous sinus stenting we will offer you this procedure, but the final decision whether or not to have this procedure is entirely yours. To decline the procedure will not affect your personal care. However, it may mean that your doctor cannot be as certain or specific about any future treatment or procedures and it may affect some clinical decision making.

Certain patients with multiple risk factors or who have very complex venous stenosis, for which treatments would be considered high risk, may have conservative management of their venous stenosis instead. This would involve interval imaging and clinical assessment to monitor the progression of the narrowing. Some patients may be able to take medication to reduce symptoms they experience from their venous sinus stenosis and idiopathic intracranial hypertension.

Usually, treatments for venous stenosis and IIH are offered according to the severity of the symptoms. They are offered in the following order:

Medication: A medicine called acetazolamide is the most common first line treatment. This is often effective, but side effects are quite common and often limit its use.

Lumbar puncture: For patients with rapidly progressive symptoms who do not respond to tablet treatment, the pressure in the head can be reduced by drainage of some of the fluid around the brain and spinal cord. This is done by passing a fine needle through the back into the lower spine to drain cerebrospinal fluid (CSF).

This probably will already have been performed at the beginning of your treatment to confirm the pressure is indeed raised.

Neurosurgery: For a longer-term solution, there are two surgical options: Optic nerve sheath fenestration is performed if loss of vision is the main problem. The skull is opened, and a hole is made in the sheath (covering) around the nerve at the back of the eye to relieve the pressure here. CSF-shunting procedures are performed where headache is the main symptom. A tube is passed through the skull into one of the fluid spaces within the brain under a general anaesthetic to drain the CSF and relieve the pressure.

Both operations carry the risks of general anaesthetic, damage to brain or nerves during the procedure or subsequent infections. It is likely that these other treatments will have been considered or perhaps previously performed without completely solving the problems.

You will be given a course of anti-platelet medication for 5 days prior to your venous sinus stent treatment. This course will involve taking oral aspirin, which is used to thin the blood, these are given to reduce the likelihood of your blood clotting and potentially causing a stroke, during or shortly after the procedure. The neurovascular clinical nurse specialists will contact you before your treatment to advise on these medications. You should take all your other medications as normal.

You will be asked to arrive at the hospital the day before or on the morning of your procedure. If you are arriving the morning of your procedure, you will be asked to arrive at 8am to the ward specified by the admission officer in contact with you.

Your procedure may take place at any time during the day due to emergency cases, but we will endeavour to keep you informed and perform your procedure as early in the day as possible.

The procedure is performed by specialist doctors called Interventional Neuroradiologists (INR). The INR will see you on the ward to explain the procedure and any associated risks. Please feel free to ask any questions at this time.

The procedure is performed under a general anaesthetic, which means you will be unconscious or ‘asleep’ throughout. Your anaesthetist will talk to you about the anaesthetic, and what you can expect when having a general anaesthetic both in clinic before the procedure and again briefly on the ward the day of your procedure. You will need to fast for six hours before your procedure. Your anaesthetist will confirm with you a specific time you must stop eating and drinking. You should still take all of your usual medications at the normal times throughout this period with a sip of water, unless advised otherwise.

You will be asked to change into a hospital gown and disposable underwear. A member of staff, usually the nurse caring for you, will accompany you to the radiology department.

It is important that you are involved in all the decisions about your care and treatment. If you decide to go ahead with treatment, by law we must ask for your consent and will ask you to sign a consent form. This confirms that you agree to have the procedure and understand what it involves. Staff will explain all the risks, benefits, and alternatives before they ask you to sign a consent form. If you are unsure about any aspect of your proposed treatment, please don’t hesitate to speak with a senior member of staff.

The procedure is performed by an Interventional Neuro-radiologist (INR), in an operating theatre located in the radiology department. It usually takes between one and three hours. A dedicated team of radiologists, radiographers, anaesthetists, and nurses will be in the operating theatre. They will be monitoring you closely throughout the procedure.

After the anaesthetic has commenced, the INR uses X-ray and/or ultrasound guidance to pass a thin, flexible, plastic tube (catheter) into the femoral vein. This is the large vein in the groin. The catheter is passed up through the body and into the jugular vein in the neck.

A second smaller catheter is inserted inside the first, past the narrowing in the vein. The collapsed stent is pushed through the tip of the smaller catheter. The catheter is then pulled back to allow the stent to expand in the vessel. Sometimes it is necessary to inflate a tiny balloon in the vein to open the narrowing. Often this immediately reduces the pressure inside the head, sometimes it can take a few days to settle.

Once the INR is satisfied with the result, all the tubes are removed, leaving just the stent in the vein. You will be moved to the recovery ward where you will be closely monitored as you recover from the anaesthetic. Afterwards you may spend some time in the high dependency unit for monitoring and control of your blood pressure and to ensure you are recovering as expected.

After the procedure you will spend some time in the recovery unit or high dependency unit (HDU) before being transferred back to your ward. These units provide a high level of monitoring. You will be on bed rest for at least a few hours following the procedure to ensure the entry site of the catheters in your groin begin to heal and that you are neurologically stable.

You can expect to remain in hospital for a minimum of three to four days after the procedure, until you are walking around and feeling back to normal. You should plan to take some time off work, at least a week or two and you should arrange to have someone to stay with when you first return home. Everyone is different and people recover from these procedures at different rates.

It is common to experience headaches in the days or weeks afterwards. You will be given pain killing drugs to help with this.

If this headache becomes severe or you experience nausea, vomiting, drowsiness or severe stiffness in your neck you should go to your nearest Accident and Emergency Department (A& E, Casualty) where a CT scan will be performed. The local A & E doctors will contact us for further advice.

You may also experience some pain or bruising at your groin where the catheters were placed, this should reduce over a few days.

For any other issues, you should contact the Neurovascular Specialist Nurses.

The stent itself will remain in your body for the rest of your life. It will gradually be covered by the normal linings inside the vein over time. It will not set off metal detectors at airports and is safe for you to have an MRI scan of any part of the body, including the brain, under certain conditions.

• The Brain & Spine Foundation UK
  Telephone: 0808 808 1000
• Idiopathic Intracranial Hypertension UK

UCLH cannot accept responsibility for information provided by other organisations.

• Iihuk. 2012. Idiopathic Intracranial Hypertension: Working to relieve the pressure!. [Online]. [27 July 2020]. Available from: http://www.iih.org.uk/iih.php
• Morita et al.. 2016. Incidence and Predictors of Catheterization-Related Cerebral Infarction on Diffusion-Weighted Magnetic Resonance Imaging. BioMed Research International. [Online]. 2016(6052125), . [1 November 2021]. Available from: https://www.hindawi.com/journals/bmri/2016/6052125/
• Khatri et al.. 2006. Ischemic Strokes After Cardiac Catheterization Opportune Thrombolysis Candidates?. Archive Neurology. [Online]. 63(6), 817-821. [1 November 2021]. Available from: https://jamanetwork.com/journals/jamaneurology/fullarticle/791524

Lysholm Department of Neuroradiology

National Hospital of Neurology and Neurosurgery, Queen Square, London, WC1N 3BG

Direct line: 020 344 83444

Switchboard: 0845 155 5000 / 020 3456 7890

Extension: 83444 / 83446

Fax: 020 344 84723

Email: uclh.referrals.neurorad@nhs.net

Website: www.uclh.nhs.uk/nhnn

Neurovascular Clinical Nurse Specialists

National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG

Direct line: 020 344 83523

Switchboard: 0845 155 5000 / 020 3456 7890

Extension: 83523

Email: uclh.neurovascularnurse@nhs.net

The Lysholm Department of Neuroradiology reception is located in Chandler wing, on the lower ground floor of the National Hospital for Neurology & Neurosurgery, Queen Square.

Please turn left when you exit the Chandler wing lifts on the lower ground floor to find our main departmental reception.