Medial branch block

Your health expert: Dr Johann Emmanuel, Consultant in Pain Medicine
Content editor review by Rachael Mayfield-Blake, March 2021
Next review due March 2024

A medial branch block is a test to see if neck and back pain comes from facet joints. Your facet joints are small pairs of joints that link the bones in your spine together. If the injections help to relieve your pain, it shows that your facet joints are the source of your pain. You may then be able to have a longer-term treatment called radiofrequency denervation.

What are medial branch block injections?

A medial branch block usually contains a local anaesthetic, which numbs the pain.

In a medial branch block, your doctor will inject the local anaesthetic over the nerves in your facet joint. These nerves send pain signals to your brain. So, this injection will temporarily stop the nerve from carrying the pain signals to your brain.

You can get facet joint pain with conditions such as osteoarthritis, which can cause your facet joints to become worn down and inflamed.

Uses of medial branch block

If you have neck or back pain, your doctor will suggest you try some other treatments before they offer you a medial branch block. These may include:

painkillers
exercise
psychological therapy

If your doctor thinks your pain could be coming from your facet joints, they may offer you a medial branch block. This is an injection that can help to find out what the source of your pain is. If the pain is coming from your facet joints, the injection will give you some temporary pain relief.

If you find that a medial branch block relieves your pain, your doctor may suggest longer-term treatment with radiofrequency denervation. In radiofrequency denervation, radiofrequency waves are used to deactivate nerves around the facet joints in your back or neck that are causing your pain. But not everyone can have radiofrequency denervation. For example, if you have a pacemaker or implantable cardioverter defibrillator, it’s not suitable. If this is the case for you, your doctor may suggest you have a facet joint injection instead.

A facet joint injection is similar to a medial branch block as it contains a local anaesthetic, but a steroid is injected too. And the injection is injected directly into your facet joint to reduce inflammation in your joint space. It may help to relieve pain for a while, anything from a few weeks to months. You’ll may then continue to have repeat facet joint injections alongside other therapies as part of a wider treatment plan.

Preparation for medial branch block

You'll need to go into hospital to have a medial branch block. You can have the injection and go home the same day. You won't need to stay overnight although you might have a sedative, which can make you feel drowsy.

Your hospital might ask you to fast before you go for the procedure. This means you shouldn’t eat anything for a certain amount of time beforehand. Your hospital will let you know in advance if you need to do this, and for how long.

Ask a friend or family member to take you to your appointment and drive you home. Ideally, you should also arrange for someone stay with you for the first night after your procedure.

Your surgeon will discuss with you what will happen before, during and after your procedure. If you’re unsure about anything, don’t be afraid to ask. No question is too small. It’s important that you feel fully informed so you feel happy to give your consent for the procedure to go ahead. You’ll be asked to do this by signing a consent form.

What happens during a medial branch block?

A pain specialist doctor will give you a medial branch block. You’ll need to lie on your front while you have the procedure. Your doctor will clean your skin, and inject a local anaesthetic to numb any pain while you're having it done. They may offer you sedation too, to help you relax.

Your pain specialist will use X-ray images to help them find the right spot on your back or neck. They may need to inject a type of dye called contrast media to help highlight where the needle needs to go.

Once the needle is in place, your doctor will inject the local anaesthetic around the nerves in your facet joint.

It will only take a few minutes to give you the injection but it may take up to half an hour to have the procedure, including having X-ray images.

Aftercare for medial branch block

You'll go to a recovery room after the procedure, where health professionals will monitor you for a short time before you can leave. They may check your blood pressure or pulse, and ask how you feel. You may feel numb, or have some weakness in your back, neck or legs at first and need some support to stand up.

You can usually go home between one and three hours after the procedure. You'll need somebody to drive you home – you won't be able to drive yourself. Ideally, you should also have someone stay with you for your first night at home after your procedure.

It’s helpful to keep a diary of your pain symptoms in the first two days so you can share this information with your pain specialist. You can continue to do all your normal activities when you get home. Your specialist may suggest you try and do some activities that you would normally find difficult. This helps you to see if the medial branch block is working. Ask them about anything you’re unsure of. For some more detail, see our section: Questions to ask your doctor.

Side-effects of medial branch block

Side-effects are unwanted but mostly temporary effects that you may get after having the procedure. The main side-effect of a medial branch block is discomfort in the area where you had the injection. This usually gets better within a few days.

Complications of medial branch block

Complications are when problems occur during or after the procedure. Possible complications of a medial branch block include:

infection
bleeding
injury to a nerve
an allergic reaction to the local anaesthetic or contrast media

If you develop a headache or fever or have ongoing weakness or numbness after you've gone home, contact the unit where you had the procedure.

Considerations for medial branch block

It’s important to discuss the procedure with your pain specialist, so you can make an informed decision about whether or not to go ahead. There are some things to consider before deciding if a medial branch block is the right treatment for you.

A medial branch block can help your doctor to find the cause of your neck or back pain. This means they may be able to offer you certain treatments that are more likely to help you. And if these treatments reduce the pain in your neck or back, it can improve your quality of life and make it easier to get about. You may find it easier to do physiotherapy or take part in an exercise programme, which may help to improve your condition in the long term.

Any pain relief you get from a medial branch block will be temporary. It’s a test used to confirm where the pain comes from, not a cure for the pain. There’s also a risk that you’ll have some problems during or after the operation. See our sections on side-effects and complications for more information.

Questions to ask your doctor

Have a think about any questions you would like to ask your doctor before you decide whether to have a medial branch block or not. Here are some example questions you might like to ask.

What can I expect to happen after I’ve had a medial branch block?
Will I be able to exercise after the injection? Are there any types of exercise it's best not to do?
How can I tell if my injection has worked to show that my neck and back pain comes from my facet joints? How long will it take until I know if it's worked?
What is the likelihood of the procedure working?
How will you reduce the risk of complications?
What treatment options do I have to relieve my pain? Should I have physiotherapy or some other rehabilitation after having my injection?

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Lumbar facet joint syndrome – injection treatment. British Association of Spine Surgeons. spinesurgeons.ac.uk, published 1 July 2018
Recommendations for good practice in the use of medial branch block (MBB) injections and radiofrequency denervation (RFD) for low back pain of lumbar facet joint origin. British Pain Society and Faculty of Pain Medicine of the Royal College of Anaesthetists. www.britishpainsociety.org, published April 2020
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Information sheet for adult patients undergoing: facet joint medial branch blocks for the treatment of pain. Faculty of Pain Medicine of the Royal College of Anaesthetists. fpm.ac.uk, reviewed September 2019
Information sheet for adult patients undergoing: facet joint rhizolysis/radio frequency lesioning (denervation) for the treatment of pain. Faculty of Pain Medicine of the Royal College of Anaesthetists. fpm.ac.uk, reviewed September 2019
Paraspinal injections – facet joint and nerve root blocks. Medscape. emedicine.medscape.com, updated 2 January 2019
Personal communication, Dr Johann Emmanuel, Consultant in Pain Medicine, 4 March 2021

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