Nerve damage after epidural injection

What is an epidural injection?

An epidural injection is given into the space that surrounds your spinal cord (called the epidural space). A spinal injection is given directly into the fluid that surrounds your spinal cord (called the cerebrospinal fluid). The injection can be a local anaesthetic or a medicine to relieve pain.

What are the symptoms of epidural nerve damage?

Nerve damage is a rare complication of spinal or epidural injections. A single nerve or a group of nerves may be damaged. Therefore, the area that is affected will vary and may be small or large.

The symptoms will depend on the nature of the nerve damage and which type of nerves have been affected. Nerves may be sensory nerves, which help you to feel light touch, pain or whether something is hot or cold. The other main type of nerves are the motor nerves, which take nerve impulses to the muscles in your body and so control movement.

Nerve damage is usually temporary. In its mildest form the nerve damage may cause just a small numb area or an area of 'pins and needles' on your skin. There may be areas of your body that feel strange and painful. You may also get some weakness in one or more muscles.

Most people with this type of nerve damage make a full recovery over a period of time, usually between a few days and a few weeks.

Permanent nerve damage resulting in loss of the use of one or more limbs (paralysis) and/or loss of control of your bladder or bowel is very rare.

What causes epidural nerve damage ?

The main ways in which nerve damage can be caused by a spinal or epidural injection are by:

• Injury caused by the needle or the catheter.

• Blood clot (haematoma).

• Infection.

• Inadequate blood supply.

Direct injury

The epidural or spinal needle or the epidural catheter may, rarely, damage a single nerve, a group of nerves or the spinal cord. Contact with a nerve may cause 'pins and needles' or a shooting pain. This doesn't mean that the nerve is damaged; however, damage may occur if the needle is not immediately moved to another position.

If you do suddenly feel an area of pain, numbness or pins and needles, try to stay still and tell the anaesthetist about it. The anaesthetist will change the position of the needle and the sensations will usually improve immediately.

Most cases of direct damage are to a single nerve and are temporary. Injecting medication into the nerve rather than into the area surrounding it can cause more severe damage to the nerve.

Haematoma

A collection of blood (a haematoma) may collect near to the nerve, due to damage to a blood vessel, caused by the needle or the catheter. A large haematoma may press on a nerve or on the spinal cord and so cause damage. This is a very rare problem but you may need an urgent operation to remove the haematoma and relieve the pressure.

If your blood does not clot normally (or you take a blood-thinning medicine such as warfarin), you are more likely to get a haematoma. You will usually be asked to stop these medicines before you have an epidural or spinal injection. If the epidural or spinal injection is needed more urgently then you may not be able to have the spinal or epidural injection - in which case you will be advised on an alternative.

Infection

Most infections related to a spinal injection or an epidural are local skin infections and do not cause nerve damage. Very rarely, an infection can develop close to the spinal cord and major nerves. There may be a serious infection such as a collection of pus (an abscess) or meningitis. These infections need urgent treatment with antibiotics and sometimes an operation to prevent permanent nerve damage.

You have a higher risk of a serious infection if you already have a significant infection elsewhere (such as a chest infection or skin infection), or if you have a weak immune system.

Inadequate blood supply

Low blood pressure is very common when you have an epidural or spinal injection. This can reduce the blood flow to nerves and this may, rarely, cause nerve damage. Medicines and intravenous fluid may be needed to prevent large drops in blood pressure.

What else can cause nerve damage?

If you have nerve damage, you should not assume that it is caused by the epidural or spinal injection. The surgical operation may be the cause of the nerve damage.

If you have a medical condition that interferes with blood supply (for example, diabetes) or nerve function (for example, multiple sclerosis), this can make damage more likely or make it more difficult to know exactly what has caused the nerve damage.

How do anaesthetists prevent nerve damage?

Epidural and spinal injections are performed by anaesthetists, who are very highly trained at performing these procedures. They are also trained to be aware of nerve damage and the steps that are required to prevent nerve damage.

If you have an epidural or spinal injection, the nurses in hospital will make regular checks until everything returns to normal. This should help to spot any possible nerve damage very early so treatment can be started immediately if needed.

Direct injury

• All anaesthetists performing epidural and spinal injections are trained in these techniques.

• Spinal injections are placed below the expected lower end of the spinal cord. This should prevent damage to the spinal cord itself.

• Spinal injections are usually performed while you are awake or lightly sedated. If there is pain or tingling due to contact with a nerve, you will be able to warn the anaesthetist who will then be able to adjust.

Haematoma blood clot

• If you take a medicine (an anticoagulant) to thin your blood, such as warfarin, you will be asked to stop it several days before surgery if your doctors think it is safe to do so.

• If you take clopidogrel (another medicine which thins the blood by its effect on platelets), you will usually be asked to stop it several days before planned surgery. For urgent surgery, your doctors will think about whether it is safer for you to have or to avoid a spinal or epidural injection.

• If you take aspirin, you can have an epidural or spinal injection.

Infection

All epidural and spinal injections are performed under 'aseptic conditions' (this means using special precautions to make the procedure as clean as is possible), similar to those used during the operation. Your back should be kept clean and regularly checked over the following few days.

General care

If you have an epidural or spinal injection, the nurses will make regular checks until everything returns to normal. This should help spot any possible nerve damage very early so that treatment can be started immediately if needed.

What are the treatment options for nerve damage?

If you are concerned you may have nerve damage then you will be seen by a doctor, who may refer you to see a doctor who specialises in nerve problems (a neurologist). Tests may be done to try to find out exactly where and how the damage has occurred. These tests might include:

• Nerve conduction studies (very small electrical currents are applied to the skin or muscles and recordings made further up the nerve. This shows whether the nerve is working or not).

• Magnetic resonance imaging (MRI): a form of body scan.

• Computed tomography (CT): a form of body scan.

If any treatment is needed then this may include physiotherapy and following any advice about regular exercises that will help. If you have any pain then medicines can be used to relieve the pain. See the separate leaflet called Neuropathic Pain for more information.

Occasionally an operation is necessary, either to repair a nerve or to relieve the pressure on a nerve.

What can be done if you might have nerve damage?

The nerve damage may not be due to the epidural or spinal injection and other causes need to be considered. The cause of the nerve problem will determine whether the nerve function returns, and how quickly.

Can something else cause nerve damage?

If you have nerve damage, you should not assume that it is caused by the epidural or spinal injection. There are other possible causes of nerve damage involving the operation itself:

• Your nerves can be damaged by the surgery. During some operations, this may be difficult or impossible to avoid. If this is the case, your surgeon should discuss it with you beforehand.

• The position that you are placed in for the operation can stretch a nerve and damage it.

• The use of a tourniquet to reduce blood loss during the operation will press on the nerve and may damage it. Tourniquets are used for many orthopaedic arm and leg operations. Swelling in the area after the operation can damage nerves.

The problems with the nerves may also be due to a health condition you already have, such as a condition that interferes with blood supply (for example, diabetes) or with nerve function (for example, multiple sclerosis).

What tests can be done if you might have nerve damage?

If you are concerned you may have nerve damage from an epidural or spinal injection, it is important your anaesthetist knows about it. Your anaesthetist will be able to assess you. Your anaesthetist may arrange for you to see a doctor specialising in nerve diseases (a neurologist). Tests may be done to try to find out exactly where and how the damage has occurred. This might involve:

• Nerve conduction studies (very small electrical currents are applied to the skin or muscles and recordings made further up the nerve. This shows whether the nerve is working or not).

• MRI scanning: a form of body scan.

• CT scanning: a form of body scan.

If necessary, the neurologist will suggest a treatment plan, which might include physiotherapy and exercise. If you have pain, medicines that relieve pain will be used. This may include medicines that are normally used for treating epilepsy or depression because of the way they change electrical activity in nerves. Treatment with medication is not always successful in relieving pain.

Occasionally an operation is necessary, either to repair a nerve or to relieve pressure on a stretched nerve.

How likely is permanent nerve damage?

Permanent damage to nerves is very rare. The risk of longer-lasting problems after a spinal or epidural injection is:

• Permanent harm occurs between 1 in 23,500 and 1 in 50,500 spinal or epidural injections.

• Nerve damage to both legs (paraplegia) or death occurs between 1 in 54,500 to 1 in 141,500 spinal or epidural injections.

These figures can only give you a rough idea of the risks and theyare based on an audit of these procedures in the UK (available in Further Reading below). The risk may be higher or lower depending on your general health and the reasons for you having the spinal or epidural injection.