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1Risks associated with your anaesthetic v Information for Patients: The Royal College of Anaesthetists

Section 11:Nerve damage (2)

What is a spinal injection?

A needle is inserted between the bonesof your back, through ligaments andthen through the dura. The dura is amembrane which encloses the nervesand spinal cord. Spinal injections areusually performed near the lowest partof the spine. At this level, the spinal corditself has ended and a bundle of nervesis present which supplies the legs andgenital area. Nerves in this area arebathed in cerebro-spinal fluid (CSF). Asingle injection of local anaesthetic isgiven and the needle is removed. Thisinjection makes you feel numb in thelower part of the body for about twohours.

You can find out more about having aspinal injection in the leaflets AnaesthesiaExplained and Your spinal anaesthetic on

the Royal College of Anaesthetists website(www.rcoa.ac.uk).

What is an epidural?

A needle is used to introduce a finecatheter (tube) into your back. Theneedle is passed between the bones,through ligaments and into a spaceoutside the dura. The catheter is passedthrough the needle into this space and the

needle is removed. The catheter is tapedsecurely to your skin. Local anaestheticcan be given through this catheter for aperiod of time perhaps several days.

An epidural is used for operations which

are longer than two hours or when painrelief is needed for several days.

You can find out more about havingan epidural in the leaflets AnaesthesiaExplained and Your epidural forpain relief on the Royal College ofAnaesthetists website (www.rcoa.ac.uk).

Risks and benefits

You can find general information aboutthe risks and benefits of spinal andepidural injections in the leaflets namedabove. Your anaesthetist will be able totell you more about your individual risksand benefits. He/she will also be able todescribe alternative treatments, which willalso have benefits and risks.

This article describes nerve damageassociated with spinal and epidural

injections. It is aimed at patients havingall kinds of operations. If you areplanning to have an epidural or a spinalfor childbirth you can find additionalinformation at www.oaa-anaes.ac.ukInformation for Mothers section.

What types of nerve damage canhappen?

Nerve damage is a rare complication of

spinal or epidural anaesthesia. Nervedamage is usually temporary. Permanentnerve damage resulting in paralysis (lossof the use of one or more limbs) is very

Your anaesthetist may suggest that you have a spinal or epidural injection. Theseinjections can rarely be associated with nerve damage. This section gives youinformation about:

Risks associated with your anaesthetic

Section 11: Nerve damage associated with

a spinal or epidural injection

4 spinal and epidural injections

4 how nerve damage can happen

4 what the symptoms are

4 how likely this is

4 what recovery can be expected.


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rare. More figures are given at the end ofthis section.15

4A single nerve or a group of nervesmay be damaged. Therefore the area

affected may be small or large.4 In its mildest form you can get a small

numb area or an area of pins andneedles on your skin.

4 There may be areas of your body thatfeel strange and painful.

4 Weakness may occur in one or moremuscles.

4 The most severe (and very rare) casesgive permanent paralysis of one or

both legs (paraplegia) and/or loss ofcontrol of the bowel or bladder.

The majority of people make a fullrecovery over a period of time betweena few days and a few weeks. Permanentdamage is very rare.

How does nerve damage happen?

The ways in which nerve damage can becaused by a spinal or epidural injection

are listed here and explained below.4 Direct injury caused by the needle or

the catheter.

4 Haematoma (a blood clot).

4 Infection.

4 Inadequate blood supply.

4 Other causes.

Direct injury

This can occur if the epidural or spinalneedle or the epidural catheter damagesa single nerve, a group of nerves or thespinal cord.

Contact with a nerve may cause pins andneedles or a brief shooting pain. Thisdoes not mean that the nerve is damaged,but if the needle is not repositioned,damage can occur. If this happens youshould try to remain still and tell your

anaesthetist about it. The anaesthetistwill change the position of the needleand the sensations will usually improveimmediately.

Most cases of direct damage are to a single

nerve and temporary. Injecting drugs

right into the nerve rather than into the

area surrounding it can also cause direct

damage.

Haematoma

This is a collection of blood near the

nerve, which collects due to damage to a

blood vessel by the needle or the catheter.

Small amounts of bleeding or bruising are

common, and do not cause damage to the

nerve. A large haematoma may press on

a nerve or on the spinal cord and cause

damage. Occasionally an urgent operationis required to remove the haematoma and

relieve the pressure.

If your blood does not clot normally or

you take a blood-thinning medicine (anti-

coagulants) such as warfarin or heparin,

you are more likely to get a haematoma.

You will need to stop these medicines

before you can have an epidural or spinal

injection. It is important that you tellyour anaesthetist about any problems with

blood clotting that you have had in the

past as you may not be able to have an

epidural or spinal injection. See below for

more details about anti-coagulants.6,7

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 an abscess (a collection of

pus) or meningitis. These infections are

very serious and require urgent treatment

with antibiotics and/or surgery to prevent

permanent nerve damage.

If you already have a significant infection

elsewhere, or if you have a weak immune

system, you have a higher risk of these

serious infections. You may not be

offered an epidural or spinal injection.


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Inadequate blood supply

Low blood pressure is very common whenyou have an epidural or spinal injection.This can reduce the blood flow to nerves

and, rarely, this can cause nerve damage.Anaesthetists are aware of this risk anduse both drugs and intravenous fluid toprevent large drops in blood pressure.

Other causes

There have been cases of the wrongdrug being given in an epidural or spinalinjection. This is an exceptionally rareevent.

What else can cause nerve damage?If you have nerve damage, you should notassume that it is caused by the epidural orspinal injection. The following list showsother causes of nerve damage related tohaving an operation. You can find moreabout these causes in Section 10 in thisseries.

4 Your nerves can be damaged by thesurgeon. During some operations, thismay be difficult or impossible to avoid.If this is the case, your surgeon shoulddiscuss it with you beforehand.

4 The position that you are placed in forthe operation can stretch a nerve anddamage it.

4 The use of a tourniquet to reduceblood loss during the operation willpress on the nerve and may damage it.

4 Swelling in the area after the operation

can damage nerves.4 Pre-existing medical conditions,

such as diabetes or atherosclerosis(narrowing of your blood vessels), canmake damage more likely.

What is done to prevent nervedamage?

Anaesthetists are trained to be aware ofnerve damage. Steps taken to prevent

each kind of damage are described here.

Direct injury

4All anaesthetists performing epidural

and spinal injections are trained inthese techniques.

4 Spinal injections are placed below theexpected lower end of the spinal cord.

This should prevent damage to thespinal cord itself.

4 Spinal injections are usually performedwhile you are awake or lightly sedated.If there is pain or tingling due tocontact with a nerve, you will be ableto warn the anaesthetist.

4 Your anaesthetist may wish to doyour epidural injection while you areawake. Direct nerve injury after an

epidural injection is rare, and so thereis no clear evidence about whether it issafer to do the epidural while you areawake or after the general anaesthetichas been given. Anaesthetists varyin their views on this matter and youshould discuss your preference aboutthis with your anaesthetist.

Haematoma

4 If you take an anti-coagulant (a

drug which thins the blood, such aswarfarin), you will be asked to stop itseveral days before surgery IF yourdoctors think it is safe to do so. Theanaesthetist and surgeon together willdecide if and when the drug should bestopped.5 A blood test will allow youranaesthetist to decide if it is safe tohave a spinal or epidural injection. Ifyour anti-coagulation cannot be safely

stopped, then you will not be able tohave an epidural or spinal injection.

4 If you take aspirin, you can have anepidural or spinal injection. However,your surgeon may ask you to stoptaking the aspirin to help preventbleeding during or after the operation.

Infection

All epidural and spinal injections are

performed under sterile conditions,similar to those used during the operation.

Your back should be kept clean and

regularly checked over the next few days.


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General care

If you have an epidural or spinal injection,the nurses will make regular checks untileverything returns to normal. This should

help spot possible nerve damage veryearly and if treatment is needed it can bestarted immediately.

If I think I have nerve damage, whatcan be done about it?

Your anaesthetist or surgeon may arrangefor you to see a neurologist (a doctorspecialising in nerve diseases). Tests maybe done to try and find out exactly where

and how the damage has occurred. Thismight involve:

4 nerve conduction studies (very smallelectrical currents are applied to theskin or muscles and recordings madefurther up the nerve. This showswhether the nerve is working or not)

4 Magnetic Resonance Imaging (MRI)

4 Computed Tomography (CT) scanning.

The neurologist will suggest a treatment

plan, which might include physiotherapyand exercise. If you have pain, drugsthat relieve pain will be used. This mayinclude drugs that are normally used fortreating epilepsy or depression becauseof the way that they change electricalactivity in nerves. Drug treatment is notalways successful in relieving pain.

Occasionally an operation can be done,either to repair a nerve or to relieve

pressure on a stretched nerve.

How likely is permanent nervedamage?

A large national audit of majorcomplications from spinal or epiduralinjections performed in the UK waspublished in 2009 by the Royal Collegeof Anaesthetists and is available on theCollege website.4 The audit estimated

that just over 700,000 central nerve blocksare done each year in the UK in NHShospitals. 45% are epidural injectionsand about 40% are spinal injections. The

report describes the risks and benefits ofthese injections in great detail and givesspecific information on the risk of nervedamage. The number of people knownto have nerve damage is very small. Thefollowing figures are a guide:

Estimated frequency (cases per spinal/epidural injection):

The risk of damage to nerves is between1 in 1,000 and 1 in 100,000.

In many of these cases the symptomsimprove or resolve within a few weeks ormonths.

The risk of longer lasting problems is4 Permanent harm

1 in 23,500 to 50,500

4 Paraplegia or death1 in 54,500 to 1 in 141,500

Summary

Nerve damage is a rare complication ofspinal or epidural injection.

In the majority of cases, a single nerve is

affected, giving a numb area on the skinor limited muscle weakness. These effectsare usually temporary with full recoveryoccurring within days or a few weeks.

Significant permanent nerve damageresulting in the loss of the use of your legsis very rare.

Some people have a higher risk ofpermanent damage. Your anaesthetistwill balance this against the benefits of an

epidural or spinal injection.Your anaesthetist will be able to tellyou about the benefits and risks of anepidural or spinal injection for you as anindividual. He/she will also be able todescribe the alternatives.


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AuthorsDr Sachin Rastogi, FRCASpecialist Registrar in AnaesthesiaNorth West Deanery

Dr Justin Turner, FRCALead Consultant Anaesthetist for Acute PainHope Hospital, Salford

EditorDr Barrie Fischer, FRCAConsultant AnaesthetistAlexandra Hospital, Redditch

President, European Society of RegionalAnaesthesia (GB&I zone) and ESRA BoardMember 19972004.

References1 Wheatley RG, Schug SA, Watson D. Safety and

efficacy of postoperative epidural analgesia. Br JAnaesth 2001;87:4761.

2 Auroy Y, et al. Serious complications related to

regional anesthesia. Anesthesiology 1997;87:479486.

3 Horlocker T, Wedel D. Neurological complicationsof spinal and epidural anesthesia. Reg Anesth PainMedJanFeb 2000;25(1):8398.

4 Cook TM, Counsell D, Wildsmith JAW. Majorcomplications of central neuraxial block: reporton the Third National Audit Project of the RoyalCollege of Anaesthetists. Br J Anaesth 2009;102(2):179190.

5 de Seze MP et al. Severe and long-lastingcomplications of the nerve root and spinal cordafter central neuraxial blockade. Anesth Analg

2007;104:975979.6 Bombeli T, Spahn DR. Updates in perioperative

coagulation. Br J Anaesth 2004;93:275287.

7 www.asra.com. Second consensus statement onneuraxial blockade and anti-coagulation: 2002.

The material from this article may be copied for the purpose of producing information materials for

patients. Please quote the RCoA as the source of the information. If you wish to use part of the

article in another publication, suitable acknowledgement must be given and the RCoA logo must be

removed. For more information or enquiries about the use of this leaflet please contact:

The Royal College of Anaesthetists

website: www.rcoa.ac.uk

email: [email protected]

This leaflet will be reviewed three years from the date of publication.The Royal College

of Anaesthetists

The Royal College of AnaesthetistsRevised edition2009

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