Coil embolisation in the treatment of cerebral aneurysms

A cerebral (brain) aneurysm is an out pouching or sack like structure protruding from the blood vessel wall. Aneurysms are known as flow-diverting phenomena as they usually occur at a point in the blood vessel where blood flow suddenly changes direction or speed, i.e. where the blood vessel branches (think of a fork in the road when you are driving). The blood vessel wall can become weakened at this point and forms this out pouching over time.

Hypertension or high blood pressure is often the cause for aneurysms. Some people will have strong family history of cerebral aneurysms meaning they are more prone to these. Lifestyle choices can also play a role in aneurysms forming e.g. heavy smoking or drug usage. You may have been referred for a coil embolisation as you previously suffered an aneurysmal subarachnoid haemorrhage (aSAH) or have experienced symptoms of aneurysms such as visual disturbances (seeing double or loss of vision), headaches or neurological deficit. Some patients have asymptomatic aneurysms that have been identified on imaging or investigations as ‘incidental findings.’

The aim of a coil embolisation is to prevent blood from entering the aneurysm and therefore prevent the risk of it bursting. A coil is made of very fine metallic wire with a smooth coating. Coils can come in various sizes and shapes and can be manipulated to fit exactly within an aneurysm.

Coils act as a plug within the aneurysm, reducing the blood flow within it and preventing any further bleeding. Some aneurysms are difficult to pack due to their shape. Occasionally we will use other equipment in combination with intracranial coils to help pack the aneurysm like stents (a wire tube which lines the vessel wall).

All treatments and procedures carry risks and we will discuss the risks of having a coil embolisation with you. Each case carries a different risk and we will try to estimate your personal risk in our discussions with you prior to your treatment. The procedure will take place under a general anaesthetic. Your anaesthetist will discuss the risks of general anaesthesia with you. It is important to tell your doctor if there is a possibility you may be pregnant.

Problems that may happen straight away

During your procedure a contrast agent will be injected into to the arteries to visualise the aneurysm for treatment. Contrast agents are safe drugs; however as with all drugs, they have the potential to cause an allergic reaction. The department is equipped to deal with reactions in the rare event of this happening. If you have known hyperthyroidism, previous kidney problems or kidney failure or are currently taking a medication called metformin, please contact Neuroradiology prior to your treatment, as we may need to provide you with further instructions before having a contrast enhanced procedure.

Problems that may happen later

You may experience some headaches or tiredness following your procedure. These are quite common after aneurysm treatments, probably due to clotting inside the aneurysm as part of the healing process and may go on for some time. A mild painkiller, rest and drinking plenty of water will help. We will give you pain medication to help. As you may require a stent for treatment of your aneurysm, you will need to take tablets to make the blood thinner and less likely to clot in the days leading up to the procedure and for many months afterwards. You may be at a higher risk of bleeding than normal. 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.

The contrast agent used during a coil embolisation 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’.

Problems that are rare, but serious

Whilst serious complications remain very unlikely, there are some risks evident. Like all procedures involving the blood vessels of the brain, a coil embolisation carries a small risk of stroke. This can range from a minor problem which improves over time to a severe disability involving movement, balance, speech or vision or may even be a threat to life.

On our current evidence, we would estimate that about 5 people in 100 will experience these problems. Such a problem is usually apparent during or immediately after the procedure, or during the next few days whilst you are still in hospital.

Other problems that may occur

Haematoma, bruising or vessel damage around the groin puncture site may also occur. Usually a stitch is placed in the femoral (in the groin) artery after the tube has been removed to stop the bleeding. If the wrist (radial artery) is used for access, a compression band will be applied to the wrist after the procedure. Often there is bruising, and less often bleeding. It is rarely serious but can go on for a few hours if unnoticed. Very occasionally there is damage to the blood vessel requiring a further surgical operation.

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 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).

Patients of child bearing 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, treatments are 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.

Your case will have been discussed by a multidisciplinary team of interventional neuroradiologists, neurosurgeons and neurologists. The treatment offered is based on the agreement of the team as to what is the best course of action. If you chose not to have this treatment it will mean the aneurysm is not protected from bleeding in the future. It is important that you fully understand the procedure, what it means for you and any alternative treatments available. You are under no obligation to follow the advice given.

If you are unhappy about the treatment being offered, a full discussion with members of the team can be arranged. It is entirely reasonable to seek a second opinion if you still have concerns. Whatever decision you reach it will not affect the standard of care you receive. We will continue to offer you the best care possible, based on the best current evidence we have available.

There are several options available for the treatment of aneurysms. However the location, size and shape of the aneurysm can dictate which treatment is the safest. It is likely that these other treatments will be considered as higher risk than the treatment offered. Your consultant or a senior member of their team will talk through all options with you. Alternative treatments for cerebral aneurysms include:

Conservative treatment

On occasion, treatment consists of clinical follow-up and Magnetic Resonance Imaging (MRI) or Computerised Tomography (CT) scans. This is done in conjunction with blood pressure control and advising on any appropriate lifestyle changes (such as giving up smoking). This option carries a risk of the aneurysm bleeding or causing other problems in the future.

Surgical treatment

Some aneurysms can be treated surgically by placing a metal clip across the neck of the aneurysm (narrow part of the aneurysm), this is called ‘clipping’. This procedure is performed under a general anaesthetic and involves opening the skull to reach the aneurysm.

Other radiological techniques

Occasionally, aneurysms are treated by implanting a WEB device inside the aneurysm, or a flow diverting stent across the aneurysm neck. Both are made of very fine mesh. These may be more challenging due to the size or shape of the aneurysm to be treated as these devices are only available in limited sizes and shapes and are manipulated in a different manner from coils.

You will be given a course of anti-platelet medication for 5 days prior to your treatment. This course will involve taking oral aspirin and prasugrel, which are 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, unless advised otherwise.

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 surgical reception unit (SRU) or 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 a specialist doctor called an Interventional Neuroradiologist (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 (this means you will be unconscious or ‘asleep’ throughout). Your anaesthetist will talk to you about the anaesthetic, pain relief 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 medications at the normal times throughout this period with a sip of water. A member of staff, usually the nurse caring for you, will accompany you to the radiology department.

You will be given a general anaesthetic in the anaesthetic room prior to transfer to the angiography suite. The procedure is performed by an INR in the angiography suite (operating theatre) located in the neuroradiology department. It usually takes between one and three hours. A dedicated team of radiologists, radiographers, anaesthetists and nurses will be in the angiography suite. They will be monitoring you closely throughout the procedure.

Once the procedure has commenced, the INR uses X-ray guidance to place a thin, flexible plastic tube (catheter) into the femoral (in the groin) or radial (in the arm) artery. The catheter passes through the main artery in the body called the aorta and finally into an artery supplying the brain. A second smaller catheter is inserted inside the first. The second catheter goes into the aneurysm.

The coils are pushed through this catheter and into the aneurysm until it is fully packed. This usually reduces the amount of blood getting into the aneurysm immediately. It is usually necessary to place multiple coils into the aneurysm to get the best results. Once the INR is satisfied with the result, the catheters are removed and bleeding form the blood vessel is sealed by a stich (in the groin) or compression band (at the wrist).

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 can expect to remain in hospital for at least a day 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. You may experience some pain or bruising at your groin or arm, depending where the catheter was placed, this should reduce over a few days. It is also common to experience headaches in the days or weeks following the procedure. This is related to the aneurysm shrinking. You will be given pain killing drugs to help.

If this headache becomes severe or you experience nausea, vomiting, drowsiness or severe stiffness in your neck go immediately to your nearest Accident and Emergency Department (A & E, Casualty) where a CT scan will be performed. For any non-urgent questions or concerns you may have following your procedure, please contact the neurovascular nurse specialists.

• The Brain & Spine Foundation UK - 0808 808 1000
• NHS direct also provides helpful information

UCLH cannot accept responsibility for information provided by other organisations.

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

Neurovascular clinical nurse specialists
The National Hospital for Neurology and Neurosurgery
Queen Square, London
WC1N 3 BG

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.