What are epidural injections?

The vertebral column is made up of vertebrae (see number 1 in figure 1) in between which can be found the so-called intervertebral discs, which allow the vertebrae to move against one another. At the back of the vertebra are the so-called spinous processes (number 2 in the figure) and inside the vertebra is the vertebral canal. The vertebral canal contains the spinal cord (number 3 in the figure) that is surrounded by cerebrospinal fluid that, in turn, is surrounded by a hard membrane called the dura (number 4 in the figure). The space between this hard membrane and the bone of the vertebra is called the epidural space (number 5 in the figure); we call them epidural injections since it is here that we want to inject drugs.



Figure 1. Cervical vertebra seen from above (see text). The needle at the bottom (6) is used for epidural injections.


In order to inject medication into the epidural space, a needle is advanced in between the two spinous processes (number 2 in the figure) until only the very tip of the needle enters this space. Corticosteroids are then injected with this needle into the epidural space in order to reduce local inflammation. Epidural injections are only done in the thoracic vertebrae and the lumbar vertebrae, and not in the cervical vertebrae.

When will I need an epidural injection?

If you have lower back pain, with or without radiation to one or both legs, that has not responded to other means of treatment and, after examining you, your pain physician thinks that the intervertebral disc is the main cause of your pain symptoms, then he may decide to give you an epidural injection.


What should I be aware of before undergoing an epidural injection?

Any of the following situations should be reported to your pain specialist if he proposes an epidural injection:

  • If you are pregnant: since X-ray equipment is used, pregnant women may not undergo epidural injection.
  • If you are ill or have a fever on the day of treatment you cannot undergo epidural injection, in which case a new appointment will have to be made.
  • If you are allergic to iodine, plasters, anaesthetics or contrast fluids, you should notify your pain specialist before the appointment for treatment is made.
  • If you are taking blood thinners, you should notify that your pain specialist before the appointment for treatment is made. He will then consider whether the use of certain medications should be ceased temporarily.

How should I prepare for an epidural injection?

  • No special preparations, such as an overnight bag, are necessary because the treatment is carried out on an outpatient basis.
  • You may eat before treatment and take your normal medication.
  • N.B.: this does not include blood thinners, as mentioned above.
  • Make sure you have someone to take you home, because you may not drive for 24 hours.

How does an epidural injection work?

  • The treatment will be performed in the surgical day-care centre, where you will be asked to change into a surgical gown. This gown closes at the back.
  • A nurse will escort you to the treatment room, where there is a treatment table, an X-ray machine and television monitors.
  • During treatment, you will be seated on the table with your legs hanging to the side.
  • Your pain specialist will estimate the correct place for the epidural injection.
  • For an epidural injection into the lower back or thoracic spine, you will be asked to bend forward as far as possible so that there is sufficient space between the spinous processes (see 2 in the figure).
  • You will be asked to relax as much as possible and to breath quietly.
  • The area around the injection site is then disinfected with a cold, red liquid. The pain specialist covers the site with sterile drapes.
  • After a local anesthetic has been applied to the skin, the pain specialist, by means of fluoroscopy (via the television monitor), will insert the needle in the correct place.
  • When the needle is in the correct place, a small amount of local anesthetic will be injected together with corticosteriods.
  • This numbness may last for several hours and is sometimes accompanied by a feeling of paralysis in both legs, which will disappear spontaneously.
  • You will have to lie flat for two hours in order to give the medication the opportunity to be properly distributed throughout the epidural space (see 5 in the figure).
  • You will then be asked to get dressed and to make an appointment with your own pain specialist in order to evaluate the effects of the treatment and to discuss further treatment possibilities.
  • On the day of treatment you should take it easy and you are advised not to drive for 24 hours.

What are the dangers and side effects of epidural injections?

  • Occasionally an allergic reaction to the injected substances can occur.
  • If you suffer from diabetes, your blood sugar level can become deregulated.
  • It is important to inform your pain specialist about this before the treatment is planned.
  • After an epidural injection, your blood sugar level must be controlled by your GP or treating internist.
  • Occasionally contact is made with a nerve, and then the pain can persist for longer.
  • In such a case, you should contact the pain nurse or specialist, who will provide you with extra pain medication.
  • In women, due to the corticosteroids, hot flushes can occur and the menstrual cycle may be disrupted briefly.
  • In very rare cases, headaches can develop due to a tiny hole being made by the needle in the dura (see 4 in the Figure), resulting in the leakage of brain fluid.
  • If you experience such a headache, you should contact the pain clinic without delay for further treatment.
  • There is a small chance of bleeding in the epidural space, which can give rise to the following symptoms:
    • Increased weakness in the legs
    • Increased numbness in the legs
    • Inability to urinate
  • In such cases, you should contact the pain clinic without delay for further treatment of these complaints.
  • In very rare cases, a local infection can occur at the site where the needle was inserted. This infection can spread around the dura (see 6 in the Figure) and result in an abscess.
  • In this case, the following symptoms may occur:
    • Increased local pain
    • Increased local redness
    • Increased local swelling at the site where the needle was inserted.
  • In such cases, you should contact the pain clinic without delay for further treatment of these complaints.

When can I expect pain relief after the treatment?

  • Afterpains can occur as the result of an epidural injection. These may last for a week but will eventually disappear.
  • The optimum results of treatment will be seen after two weeks.
  • Around this time, an appointment will have been planned with your pain specialist.


Figuur 1. Nekwervel van boven af gezien (zie tekst). De onderste naald (6)

wordt gebruikt voor epiduraal injecties.

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