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Epidural injection for chronic back pain

This factsheet is for people who are considering having an epidural injection for chronic back pain. Your care may differ from what is described here because it is adapted to meet your individual needs, so it's important to follow your doctor's advice.

• Why have an epidural injection?
• Steroids
• Other uses for epidurals
• What happens before an epidural?
• What happens at the hospital?
• If you're pregnant
• The procedure
• After the epidural
• After your return home
• What are the risks?
• Further information
• Sources
• Related BUPA factsheets

Why have an epidural injection?

Epidural injections can help provide short-term pain relief for people with chronic back pain or sciatica (shooting pain down one or both legs). The injection is given by an anaesthetist. It involves injecting local anaesthetic and steroids into the epidural space that surrounds the spinal cord. Local anaesthetic drugs numb the spinal cord nerves instantly and the steroid helps by reducing swelling (inflammation).

It can take up to a week for the full benefits of an epidural injection to be felt. The effects of a successful injection can last anything from a few weeks to several months. If the injection helps reduce pain, it can be repeated every two months until the injury or cause of pain has healed.

Steroids

The Medicines and Healthcare products Regulatory Agency (MHRA) has not formally licensed the use of steroids for chronic back pain and sciatica. Doctors commonly prescribe medicines in this "off-labe" way in both NHS and private hospitals, but you should be aware that this is the case before the medicine is given.

Other uses for epidurals

Epidural injections are used to provide anaesthesia for surgery, and/or control pain after surgery. They are also used for pain relief during childbirth. This type of epidural is not discussed here.

What happens before an epidural?

Your doctor will discuss how to prepare for your treatment.

The procedure is routinely done as an out-patient or day case. You will stay awake during the procedure, but you may be offered a sedative to help you relax. Typically, you must not eat or drink for six hours before sedation. However, you may be allowed occasional sips of water until two hours beforehand.

You may be asked not to take your usual pain relief medication on the day of your procedure. This is because you need to feel and report any pain during the treatment. If you are unsure about taking your medication, please contact your doctor.

What happens at the hospital?

Your doctor will speak to you about the treatment and 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.

If you are diabetic, please tell your doctor before the treatment starts. It's possible the steroids may affect your blood sugar levels.

Generally the injection is given in the lower back. Your doctor may use X-rays to help guide the needle into the epidural space.

If you're pregnant

Please tell your doctor if you could be pregnant. Although the radiation dose being used is generally thought to be safe for adults, it may harm a developing fetus. So, X-rays are not usually done on pregnant women. If you are pregnant, your doctor will discuss alternatives to the procedure.

The procedure

The procedure usually takes 10 to 20 minutes.

You may be asked to change into a hospital gown that opens at the back.

You will be helped onto an X-ray table and asked to lie face down or on your side with your knees drawn up and chin tucked in. This position helps to open up the space between the vertebrae.

If you are having sedatives, these will be injected into a vein in the back of your hand. You will quickly feel relaxed and drowsy.

Your doctor will carefully select a point to inject by feeling for specific bones in the spine and hips. The injection point will be marked with a pen.

A small amount of local anaesthetic is injected into the skin. After a minute or so, when the skin is numb, the anaesthetist will insert the larger epidural needle through the skin and towards the epidural space.

At this point, your doctor may take X-ray pictures to help guide the needle into the correct spot. You may find the procedure uncomfortable because the needle is being put into an area that is already painful.

When the needle reaches the correct spot, a fine plastic tube (cannula) is inserted through the centre of the needle. The needle is then removed, leaving the tube in the epidural space running through the skin to the outside.

The anaesthetic and/or steroids are injected directly into the epidural space through the tube. When the treatment is complete, the tube is taken out and the area covered with a plaster.

While the doctor is preparing your back for the injection and especially whilst the epidural needle is being inserted, it is very important to stay still, as any movement makes positioning the needle more difficult.

After the epidural

Your blood pressure may be monitored for 15 to 20 minutes. When you feel ready, you will be able to go home. You will need someone to drive you home.

Before you go home, your nurse will give you a telephone number for the hospital and a date for a follow-up appointment. This is usually two to six weeks later.

After your return home

If you had sedation you should have someone stay with you for the first 24 hours. Sedatives can temporarily affect your co-ordination and reasoning skills, so you should not drive, drink alcohol, operate machinery or sign legal documents for at least 24 hours after your procedure. If you are in doubt about driving, please contact your motor insurer so that you are aware of their recommendations, and always follow your doctor's advice.

You should take it easy for 48 hours after the injection. Try to keep active by doing some gentle walking. This can help reduce stiffness and discomfort. Follow your doctor's advice about returning to work.

What are the risks?

An epidural for chronic back pain is a commonly performed and generally a safe procedure. 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.

Side-effects are the unwanted but mostly temporary effects of a successful procedure. These can include the following.

• A drop in blood pressure - after the epidural drug is given, you will have your blood pressure monitored for about 20 minutes. If your blood pressure falls, then it may be necessary to give drugs and more fluids through a drip.
• A drop in blood sugar levels - if you have diabetes, your doctor will check your sugar levels after the epidural, but you must also keep a close check on sugar levels when you go home.
• Loss of leg strength or control of the leg muscles - this wears off with the anaesthetic.
• The injection area may feel sore.
• Back or leg pain may actually get worse, before it begins to get better.

Complications are when problems occur during or after the procedure. Most people are not affected. The main complications specific to epidural injections are listed here.

• Headache - if the epidural needle nicks the covering of the spinal cord, there may be a small leak of fluid from around the cord, which can cause a severe headache lasting for up to a week.
• Bleeding - there are many blood vessels around the spinal cord and occasionally one will be pricked as the epidural needle goes in. This requires careful observation in hospital.
• Infection - this is uncommon because the skin is cleaned before the (sterile) needle is inserted. However, if there is an infection, drainage of the infected area and antibiotics may be necessary.
• Long-term numbness - some people have patches of numbness lasting up to three months. Permanent damage, such as paralysis (complete loss of sensation and movement) is very rare.
• Allergic reaction - it's possible to have an allergic reaction to the drugs or the contrast dye. If you feel itchy or have difficulty in breathing tell your doctor immediately. Medicines are available to treat any allergic reaction.
• No effect - it's important to realise that epidural injections do not work for every person. Some people may find their back pain does not improve.

You should ask your doctor to explain how these risks apply to you. The exact risks will differ for every person. This is one of the reasons why we have not included statistics here.

Further information

• Spine-health.com
  www.spine-health.com

Sources

• Epidural corticosteroids for back pain. Bandolier systematic review.
  www.jr2.ox.ac.uk/Bandolier
  accessed 3 May 2006
• Effective health care: Acute and chronic low back pain. NHS Centre for Reviews and Dissemination, University of York. 2000; volume 6: bulletin number 5.
  www.york.ac.uk
  accessed 3 May 2006

Related BUPA factsheets

• Epidural injection for surgery and pain relief
• Local anaesthetic or sedation

Published by BUPA's health information team, healthinfo@bupa.com, July 2006.

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