What is an epidural?
The term ‘epidural’ refers to the space between your spinal cord and vertebral
column (spine). All nerves pass through the epidural space as they leave the
spinal cord to different parts of the body.
Why do I need an epidural injection?
An epidural injection is one method that is used to relieve some of the pain of
‘sciatica’ (leg pain) and back pain.
A local anaesthetic and a steroid mixture are injected into the epidural space
and these bathe the nerve roots. The injection may be given as a single
treatment or as a course of treatments.
It will not necessarily cure your pain, but may relieve some or all of it for a
time, allowing you to increase your mobility and loosen stiff joints and muscles
that have not been used for a while.
The diagram below shows the position of the needle in your back during the
What happens on the day of treatment?
The procedure is carried out as a day case and hospital admission is usually
for a morning or afternoon only.
On arrival, a nurse will ask you a few brief questions. You will then be asked
to put on a theatre gown and your blood pressure and pulse will be recorded.
A doctor, usually your Pain Consultant will then discuss the procedure with
you and you will be asked to sign a consent form.
The procedure is carried out in an operating theatre. This allows for the
injection to take place in a clean environment with appropriate care and
Before entering the theatre, a small needle will be inserted into a vein in the
back of your hand. This allows the doctor to give you sedation or other
medication if needed.
The injection is performed with you lying either on your side with your legs
curled up and your head bent down or lying on your front. The doctor will
clean your back with an antiseptic fluid, which can feel very cold on the skin.
Local anaesthetic is then given into the back. This may sting initially, but the
area will soon go numb.
A needle is then inserted between two of the bones (vertebrae) in your back.
You may feel a pushing sensation and some discomfort at this stage. The
doctor may take an X-ray picture and inject some dye that will help show
whether the needle is in the correct position. Once the needle is in the correct
position, the local anaesthetic and steroid mixture is injected. You should let
the doctor know if you feel any pain. The whole procedure usually takes
around 20 minutes. A small dressing is placed over the injection site and this
should be left in place for 12 hours.
Once the injection is completed, you will be taken to the recovery area within
the theatre suite where your blood pressure will be monitored for a short
period of time. You will remain on the trolley/bed for around 1 hour. Your
ability to move your legs will be checked before you get up and you will be
asked to pass urine before you go home.
The local anaesthetic may work immediately and for a short period to relieve
some of your pain. The steroid works by reducing inflammation and ‘over
activity’ in the nerves. It may take about 2 weeks to reach its full effect.
It is important that you move normally and carry out your day to day activities
as normal to see if the injection has been helpful.
You may have a bath or shower on the same day and will be able to return to
all your usual activities the following day.
An exception to this is driving. If you have had sedation you should not drive
for 24 hours and will need a friend or relative to go home with you.
Potential complications of epidural steroid injections
Some people experience tenderness or bruising at the injection site. This
usually settles over the next few days.
As well as carrying pain messages, some of the nerves in the epidural space
carry instructions to the muscles and skin in your legs. If these nerves are
numbed, your legs can become weak and feel numb. Other nerves control the
size of blood vessels in your legs and if these nerves are numbed, your blood
pressure can fall and you may feel faint. If this happens your blood pressure
will be monitored more closely, but it is temporary and will pass.
Rarely during the injection the nerves in your back may be touched by the
needle. This may cause numbness or tingling in part of your legs. This is
usually temporary and slowly improves over a few days or weeks.
With any type of injection there is a risk of infection. Over a few days you
should observe if the area around the injection becomes painful and swollen,
red, hot to touch or ‘weepy’. If this continues and especially if you feel unwell
or concerned, you should contact the Chronic Pain Clinic. You may be
advised to come back to hospital.
Occasionally, the layer beneath the epidural space gets punctured by the
needle during the injection. This is called a ‘dural tap’ and can mean that fluid
that cushions the brain and the spinal cord leaks out which causes a
headache. If this clearly happens during your injection, you will be asked to
stay in hospital overnight to be given painkillers and intravenous fluid. If a
headache develops at home after your injection, it is advisable to take
paracetamol, drink plenty of fluids and lay flat when possible. If it continues for
several days, please contact the Chronic Pain Clinic. You may be advised to
come back to hospital.
People are often concerned about the side effects of steroids. A fairly small
dose is used in the injection and most people do not experience any side
effects, if you have any concerns please ask about these before you give your
consent for the injection.