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Nerve root block injection

Published by Bupa's health information team, September 2009.

This factsheet is for people who are having a nerve root block injection, or who would like information about it.

A nerve root block is a combination of local anaesthetic and a steroid, which is injected into your spine to help relieve nerve root or back pain.

Your care will be adapted to meet your individual needs and may differ from what is described here. So it's important that you follow your doctor's advice.

About nerve root block injection
What are the alternatives?
Preparing for your procedure
About the procedure
What to expect afterwards
What are the risks?
Questions and answers
Related topics
Further information
Sources

About nerve root block injection

Nerve root block injections are used to relieve persistent nerve root and/or back pain. Nerve root pain is pain that spreads out along a nerve from your spine, into a leg or arm.

Nerve root block injections can also be used to help diagnose your back pain, when other tests have been unable to find the cause.

The nerve root block is a combination of a local anaesthetic and a steroid, which is injected around one of the nerves in your spine. The local anaesthetic will numb the nerve in your spine immediately and if necessary, can be used to confirm the cause of your back pain. If your pain improves after the treatment, the nerve blocked by the injection is most likely to be the cause of your pain. If your pain stays the same, then that nerve is unlikely to be causing your pain.

The steroid is used to reduce inflammation around the nerve root and disc between your vertebrae, and give long-term pain relief. As inflammation is often the cause of the pain, a nerve root injection with steroid can sometimes completely cure the pain, other times it just lessens it.

X-ray images are usually used during the procedure to help guide the injection to the correct nerve. However, your doctor may prefer to use CT (computerised tomography) for the procedure. A CT scan uses X-rays to make a three-dimensional image of the body or part of the body.

The procedure can be done as an out-patient procedure or as a day case if you are having it under sedation. A sedative helps you to relax and reduces anxiety, and can be used in this procedure if your doctor thinks it necessary. The procedure may be carried out by a radiologist (a doctor specialised in using imaging procedures to diagnose medical conditions), a specialist pain management anaesthetist or an orthopaedic surgeon.

What are the alternatives?

Exercise therapies, pain treatment programmes and pain relief medicines may help to relieve your lower back pain. Your doctor will only recommend a nerve root block injection if other treatments haven't been effective.

Preparing for your procedure

Your hospital will tell you if there are any specific instructions you need to follow before your procedure. For instance, if you have a sedative, you may need to follow fasting instructions.

If you take anticoagulant medicines, like warfarin, aspirin or clopidogrel, you may be asked to stop taking these a few days before the procedure. If you're unsure about any medicine you're taking, ask your doctor.

When you arrive for your treatment, you may be asked some questions about your health, experience of surgery, allergies and any medicines you are taking. You may have your heart rate and blood pressure checked.

If you have diabetes, tell your doctor before the treatment starts. It's possible the steroid in the injection may affect your blood sugar levels. You should also tell your doctor if you could be pregnant. A nerve root block with X-ray guidance isn't recommended for pregnant women.

You will be asked to sign a consent form. This confirms that you understand the risks, benefits and possible alternatives to the procedure and have given your permission for it to go ahead.

About the procedure

The procedure usually takes about 20 minutes. You may be asked to change into a hospital gown that opens at the back.

You will be taken to an X-ray room, CT room or operating theatre and asked to lie face down on a table. A machine called a fluoroscope may be used which shows 'live' X-ray images during the procedure. The table will be positioned under the X-ray machine, or inside the CT scanner.

A sterile antiseptic wipe is used to clean the area over the injection site. Local anaesthetic is then injected into your skin so that you don't feel the needle going into your back.

A thin hollow needle is then carefully inserted into your back. You won't feel the needle going in. However, once the needle has reached your spine, it can feel uncomfortable.

Once the needle is in place, your doctor will inject a contrast agent (a liquid that shows up on X-ray) and take X-ray images. This is to ensure the needle is correctly placed close to the nerve root. When the needle is in the right place, the local anaesthetic and steroids are injected into the nerve root.

Afterwards, your doctor will remove the needle and may cover the injection site with a plaster.

What to expect afterwards

You will be helped to get up slowly from the table. If you have had a sedative, you may remember little of the procedure. You will be taken to a recovery area to be monitored.

You will usually be able to go home when you feel ready, but you will need someone to drive you home.

Some people will know whether the injection has worked within 15 minutes of the procedure. However, other people may find that their pain does not improve until a few days after the procedure. If your pain has not got any better within two weeks of the injection, then it hasn't worked.

In some people, the injection may cure the pain but in others, the pain relief may last a couple of weeks to a few months. If the treatment has helped with your pain, you may be able to have it again. Your doctor will tell you how often you can have the procedure.

What are the risks?

Nerve root block is commonly performed and generally safe. However, in order to make an informed decision and give your consent, you need to be aware of the possible side-effects and the risk of complications for this procedure.

Side-effects

These are the unwanted but mostly temporary effects you may get after having this procedure. After having a nerve root block injection, you may feel weak, dizzy or faint. The injection area may feel sore. You may also get a type of headache called a post-dural puncture headache. This may go away on its own, but can sometimes be severe and need further treatment.

The pain in your back or legs may get temporarily worse, before it begins to get better.

The steroid in the injection may affect your blood sugar levels. If you have diabetes, you will need to monitor your blood sugar levels closely after the procedure.

Complications

This is when problems occur during or after the procedure. Most people aren't affected.

The main complications specific to having a nerve root injection are listed here.

The treatment reaching further than intended and going into your spinal cord. This can cause a drop in your blood pressure or widespread numbness. The theatre team and your doctor will monitor you constantly and will provide appropriate care if this happens.
Bleeding. There are many blood vessels around your spinal cord and there is a risk the needle may puncture one. You may need an operation to treat this.
Infection. This is uncommon because your skin will be cleaned before the sterile needle is inserted. However, if you get a high temperature, contact the hospital immediately.
Having an allergic reaction to the steroid or the contrast agent. If you feel itchy or have difficulty in breathing, tell your doctor immediately. Medicines are available to treat an allergic reaction.

The exact risks will differ for every person, so we haven't included statistics here. Ask your doctor to explain how these risks apply to you.