Medial Branch Block

A medial branch block is an injection placed around the small nerves that supply the facet joints of the spine. These nerves are called the medial branches. The injection contains either local anaesthetic on its own or a mix of local anaesthetic and cortisone.

Facet joints are the small joints along your spine that help keep it stable and guide movement. When these joints become irritated or inflamed, the medial branch nerves can carry pain signals. By numbing these nerves, a medial branch block can help determine whether the facet joints are the source of your pain and, in some cases, provide short-term relief.

A medial branch block helps your doctor find out whether the facet joints are the true source of your pain. By temporarily numbing the nerves that supply these joints, the procedure shows how much of your discomfort is coming from them. If your pain drops significantly during the period of numbness, it’s a strong indication that the facet joints are involved.

Because of this, medial branch blocks are mainly used for diagnosis rather than long-term treatment. If you do experience strong temporary relief, you may be a good candidate for radiofrequency denervation, a procedure that provides longer-lasting pain reduction by disrupting the medial branch nerves more permanently.

A radiologist performs the procedure using CT guidance to ensure accurate needle placement. You will lie face down on the CT table and the skin over the injection site will be cleaned with an antiseptic solution.

A small needle is then guided to the area where the medial branch nerve sits. CT images are used to check the needle position, and a small amount of contrast dye may be injected to confirm it is in the correct place. Once confirmed, the doctor injects either local anaesthetic alone or a mix of cortisone and local anaesthetic.

You may feel some brief discomfort until the anaesthetic begins to work. The procedure usually takes about 15 to 30 minutes.

All medical procedures carry some level of risk, although complications from a medial branch block are uncommon. You may feel some discomfort at the injection site, and it’s normal to have a mild increase in pain afterward. This is usually due to temporary pressure from the injected medication.

Serious complications are very rare but can include nerve irritation or damage, infection, bleeding, or an allergic reaction to the medications used. Your radiologist will take care to minimise these risks and will discuss any concerns you may have before the procedure.

You must have someone with you to drive you home after the procedure. If the local anaesthetic provides pain relief, it will only last about four to six hours. This short period of relief is an important part of the diagnostic process, so please record how much improvement you feel. If you’re given a pain chart, complete it carefully and bring it to your next appointment with your treating doctor.

It’s normal to have mild bruising or soreness at the injection site. Ice and paracetamol can help ease these symptoms. Some people experience an initial increase in pain or stiffness, but this usually settles within 48 hours.

Avoid strenuous activity or exercise for up to a week, or follow the specific guidance from your doctor. They will let you know when it’s safe to return to your usual activities.

If you develop a fever, increasing pain, swelling, or warmth at the injection site more than 48 hours after the procedure, contact your doctor immediately.

Please let our staff know if:

• You have any allergies to medicines, local anaesthetics or X-ray contrast dye

• You have diabetes

• You are pregnant or think you might be pregnant

It’s very important we know this before your appointment so we can keep you safe and plan your care appropriately.

If you are feeling unwell on the day or need to change or cancel your appointment, please call our office as soon as you can on 08 7081 3078.