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This patient information aims to answer some of the questions you may have about having a CT guided facet joint/nerve root injection. It explains what you need to do to prepare for the scan, what you can expect when you come to hospital and what happens after. If you have any further questions please speak to your consultant or the imaging department.
What is a CT guided facet joint/ nerve root injection?
CT stands for Computered Tomography and it takes a series of pictures of your body using multiple x-rays to show cross-sections or ‘slices’ of the part of interest. Facet joint injections/ nerve block injections are performed to treat pain – most commonly in the neck, back and legs. The procedure involves an injection either directly into the joint or to the small nerve near the joint. The injection consists of a mixture of local anaesthetic (to numb the area) and a corticosteroid. The corticosteroid reduces inflammation at the site, and therefore reduces pain and other symptoms caused by the inflammation. The effect of these injections is different for each individual.
The use of the CT scan for the injection is to guide a radiologist precisely to the area that needs to be treated to ensure accuracy.
What are the benefits of having a CT guided facet joint/ nerve root injection?
These injections help reduce the pain associated with the compression or aggravation of nerves commonly in your neck, legs or back.
Are there any risks with this procedure?
A CT scan uses radiation, so it is always considered if the benefit of the procedure outweighs the risk. The level of radiation used is very small.
This is a common procedure and very safe when performed in a controlled setting. However, with any interventional procedure there are risks, side effects and a possibility of complications. The radiologist will go through this in more detail on the day.
If you are or if you think you could be pregnant, if you have had any allergic reaction to corticosteroids or local anaesthetic in the past, you must tell your referring doctor and the Imaging team.
Are there any alternatives?
Your doctor has considered the options and believes a CT guided injection is the best/ most accurate option. An alternative is a fluoroscopy guided injection, however this does not provide the same level of accuracy when compared to CT.
Consent – asking for your consent
The radiologist will ask you if you are happy for the scan to go ahead. This is called ‘verbal consent’ and you will be asked to sign a consent form which states you agree to have the injection and understand what it involves. If you do not wish to have the scan or are undecided, please tell the radiographer/ radiologist.
It is your decision and you can change your mind at any time. Please bear in mind that not having the scan may delay your pain management. Please remember that you can ask the radiographer any questions you have at any time before, during or after your scan.
What do I have to do to prepare for the scan?
In many cases you do not need to do anything to prepare for the scan. If you are taking any medication, please check when booking the appointment if you can continue booking this procedure.
What do I need to wear?
Please wear clothes that are easy to remove as you will be required to change into a hospital gown before you have your injection. This is to ensure a sterile procedure.
What happens during the procedure?
Before the scan takes place, you will be given the opportunity to ask the radiographer any questions you have. You will be asked to get changed into a hospital gown and remove any clothing around the site being injected. The radiologist will go through a consent form, check any allergies and explain the procedure and answer any questions you may have.
You will then lie down on the bed, on your back for an injection in your neck or on your front for an injection to your back. We aim to make you as comfortable as possible because it is very important to not move until the end of your procedure. The scanner is open at the back and the front, allowing you to see out. The technologist will always be able to see and hear you during your exam.
A marker grid is placed on the skin and a planning scan will be taken to find the correct position for the injection. The injection site is then marked with a pen and the area cleaned.
The radiologist will then inject a small amount of local anaesthetic to numb the area. Once this has taken effect, a needle will be placed into the site and another planning scan is taken. The needle may need repositioning and another scan may need to be taken. Once the radiologist is happy that the tip of the needle is in the correct place, the injection will be given.
How long will the procedure take?
The procedure usually takes between 30 and 40 minutes, however it is patient dependant. We will ask you to stay in the department for about 30 minutes after your injection as well, so that we can make sure you feel comfortable enough to go home.
Will there be anyone with me during the scan?
The radiographer and radiologist will talk to you through what’s going on during the procedure. The radiologist will be in the room most of the time. Unfortunately as CT uses radiation it is not advisable for a relative/ friend to accompany you while the procedure is going on. However, they can join for the consent and explanation.
Can I bring my children?
Unfortunately we are not able to offer childcare facilities and your children cannot go into the scan room with you. If you need to bring your children with you, please bring along an adult who can look after them while you are having the examination.
What happens afterwards?
Immediately after the nerve block injection, you may feel that your pain has gone or is significantly reduced. This is due to the local anaesthetic and will last for a few hours. You may resume normal activity as soon as you feel able. However, you may feel numbness and tingling on the affected side for up to 12 hours after the procedure. For this reason you must not drive for 24 hours after your procedure.
After the local anaesthetic has worn off you may experience a worsening of your usual symptoms, which may last for a few days. This is called a steroid flare and is common. Most people start noticing pain relief three to five days after the procedure when the steroid begins to take effect.
If the temporary flare-up caused by the injection persists beyond this time, an anti-inflammatory drug, such as ibuprofen can be helpful at relieving this pain.
The patient specific response to having a CT-guided nerve block injection is variable and ranges from no benefit to improvement in symptoms for over six months. If the injection does not alleviate your pain, please speak to the doctor who referred you.