What is a medial branch block?
A medial branch block is an injection over the tiny nerve to a facet joint – a small joint that links the bones of the spine together. The facet joints allow movement and stabilise the spine. Wear and tear, inflammation and injury to the facet joints may cause pain in some people. The injection provides information about whether pain is coming from your facet joints.
Usually, several injections are undertaken during the same procedure. The injection contains local anaesthetic sometimes with a small amount of steroid. It is used for localised back pain where simpler measures have not helped. It can help your pain by reducing some of the pain signals from the joint.
Though pain relief is usually short-lived, some people can get significant and more long lasting pain relief from these injections. The injection is usually undertaken alongside other treatments such as physiotherapy.
Is this the right treatment for me?
Other treatment options will be discussed with you before deciding to go ahead with the injection(s) and your consent is needed. The decision on whether or not to go ahead with the injection(s) is a shared decision between you and your doctor. Pain injections are not life-saving procedures, so there is always an option of “no treatment” or continuing with the conservative management.
If you want to go ahead, your doctor will be able to provide you with up-to-date information about the likelihood of this being a successful treatment for you and how this treatment fits into the best pathway of care. If you are undecided about whether or not to have injection(s) then further advice and information to make this informed decision can be provided. Please speak to your doctor for more information.
If your health has changed, it is important to let your doctor know:
- If you have an infection in your body or on the skin of your back – your doctor will postpone the treatment until the infection is cleared.
- If you have been started on anticoagulant or antiplatelet medicines that “thin the blood” such as warfarin, heparin or clopidogrel – this may require extra preparation.
- If you suffer from diabetes – the use of steroids during injections may cause your blood sugar to change requiring monitoring and adjustment of your diabetic medication.
- If you have any allergies.
You must also inform the doctor if there is any chance that you could be pregnant.
Finally, if you are planning to fly or travel abroad within two weeks after the injections, please let your doctor know as it may be best to change the date of the injections.
I have heard that steroids are unlicensed, what does this mean?
Steroids have been used for a long time with only small risks. Around a quarter of medicines used in pain medicine are unlicensed – this means that the medicine has not been approved by a regulatory body for the purpose for which they are to be used. Therefore, these steroids cannot be marketed by the pharmaceutical industry.
Medicines will only be licensed if there is a need for a pharmaceutical company to do this as the process of licensing is very expensive. Your doctor can discuss this with you further.
What will happen to me during the treatment?
Before the injection, your doctor will discuss the procedure with you. Your doctor will either obtain your consent before the injection or confirm this consent if it was previously given.
The treatment will take place in a dedicated area with trained personnel. An X-ray machine (or other forms of image guidance) will be used to enable accurate injection.
The following usually happens:
- You will be prepared for the procedure as per local protocol.
- Observations such as blood pressure and pulse rate may be made.
- You will be carefully positioned and the skin around the injection site(s) will be cleaned with an antiseptic solution or spray; this can feel very cold.
- X-ray (or an alternative way of guiding the needles) will be used.
- You will feel a stinging sensation as local anaesthetic is injected to numb the skin and
surrounding tissues. Your doctor will warn you of this first. - The doctor will direct the injections to the area(s) suspected to be a source of pain. When the injections are made; you may feel pressure, tightness or a pushing sensation. If there is any discomfort, let the doctor know.
What will happen to me after the injections?
You may be assisted to sit up and your blood pressure and pulse may be checked. You will be advised when to get dressed and be given assistance to help to ensure that you can stand safely after the procedure.
When will I be able to go home from hospital after my injections?
You will usually be able to return home soon after the injection. Please ensure that you have made arrangements for someone to collect you after the procedure. It is unsafe for you to drive home immediately after the procedure. If you do so your motor insurance will be invalid.
What can I do after my procedure?
Ideally, you should arrange for someone to stay with you for 24 hours but, failing that, you should at least have access to a telephone.
When can I return to work after the procedure?
This will vary between individuals and may depend on the nature of your work. It is difficult to give general advice and so you should discuss this with your doctor.
Will I experience any side effects?
As with any procedure, side effects may occur. These are usually minor but there are risks with this procedure.
Side effects may include:
- Mild local tenderness and/or bruising at the site of the injection, that usually settles over the first few days.
- The local anaesthetic may rarely spread causing some numbness and/or weakness in your legs and other areas. Should this occur, the effect is temporary and will rapidly resolve over minutes or rarely hours.
- Infection is rare. You should seek medical help if there is local warmth or redness over the site of injection with tenderness and/or you feel hot and unwell. This may require antibiotic treatment.
- There are important nerves in the spine, but serious nerve injury is extremely rare (less than 1 in 10,000 cases).
- Injection treatments are not always effective and may not help your pain.
- Injury or collapse of the lung (pneumothorax) (injections in thoracic area only). This is very rare. If you get chest pain or breathlessness, you should seek immediate medical help.
What can I expect in the days afterwards?
You may experience some soreness or aching at the injection site. Do not worry if your pain feels worse for a few days as this sometimes happens.
Take your regular pain killers and medications as normal and this should settle down. Try to keep on the move about the house whilst avoiding anything too strenuous.
What should I do in the weeks after the injections?
As your pain decreases, you should try to gently increase your exercise. Simple activities like a daily walk, using an exercise bike or swimming on your back will help to improve your muscle tone. It is best to increase your activities slowly.
Try not to overdo things on a good day so that you end up paying for it with more pain the following day.
What follow-up will be arranged?
A letter will be sent to your GP and your doctor will advise on what to do after the procedure. You will be also sent a letter with a review appointment.
Is there anything else I need to consider before the procedure?
- Please bring your glasses if you need them for reading.
- Always bring a list of all current medication.
- Continue to take your medication as usual on the treatment day.