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Section 12: Nerve damage (3)

Risks associated with your anaesthetic Section 12: Nerve damage associated with peripheral nerve block

our anaesthetist may suggest that you have a peripheral nerve block. YThis is an injection placed near to a nerve or group of nerves. Rarely, there may be damage to nerves. This section gives you information about: 4 what a peripheral nerve block is 4 how likely this is 4 how nerve damage can happen 4 what recovery can be expected 4 what the symptoms are

A peripheral nerve block is not the same as an epidural or spinal injection, which are described in Section 11.

What is a peripheral nerve block? Risks and benefits This is an injection of local anaesthetic Benefits of a nerve block may include a near to the nerves which go to the area shorter recovery period, and better of your operation, making the area feel relief after your operation. This allows numb. The injection may be used on its you to be mobile more quickly after your own, as the anaesthetic, or you may operation. You may not need as many receive or a strong pain relieving medicines such as as well. You can find out more about morphine. This will help reduce your risk these choices in the booklet ‘Anaesthesia of the side effects associated with these Explained’ which you will find on the medicines, which include nausea (feeling Royal College of Anaesthetists website sick) and drowsiness. (www.rcoa.ac.uk). This article describes nerve damage after a peripheral nerve block. Your anaesthetist Types of nerve block will be able to tell you about other risks. There are many types of nerve block, each one aimed at a different group of nerves. Nerve damage Your anaesthetist will tell you if there is a Permanent nerve damage is a rare block suitable for your operation. Having complication of peripheral nerve block. talked about the benefits, risks and your Nerve damage is usually temporary, and preferences, you can decide together most patients with nerve damage make a 1–4 whether you would like a nerve block. full recovery within a few days or weeks.

How long does the block last? How does it feel to have nerve damage? What recovery can I A nerve block can give pain relief for two expect? to 18 hours depending on the site and on the drugs used. Sometimes a catheter Some people have mild changes in (a very thin tube) can be passed through sensation (feeling). There may be an area the needle and left in place. More local of numbness or ‘pins and needles’. anaesthetic can then be given for a longer Sometimes there may be strange period – perhaps up to a few days. sensations or there may be pain.

1 Risks associated with your anaesthetic v Information for Patients: The Royal College of Anaesthetists Section 12: Nerve damage (3)

Uncommonly, there may be in other precautions to avoid nerve damage. one or more muscles. He/she will be able to explain these to you. Most nerve are temporary, and will recover over a period of about three Intra-neural injection (injecting drugs months. Permanent does occur on directly into the nerve rather than very rare occasions. In the most serious cases near to the nerve) can also cause nerve there can be severe pain or permanent damage. This would cause feelings paralysis of the area involved. similar to those described above. The anaesthetist may use a nerve stimulator (a How does nerve damage happen? small electrical gadget which is connected What is done to prevent nerve to a sticky pad on your and to the damage? needle) to help find the correct spot for injection and to help avoid intra-neural The ways in which a nerve can be injection. Your anaesthetist may also use damaged are listed here, and explained an ultrasound machine to show the nerve below. and nearby structures on a screen. This 4 Direct injury caused by the needle or can help to find the nerve and to place the catheter. local anaesthetic near to the nerve. 4 Haematoma (a blood clot). Haematoma 4 Inadequate blood supply. This is a collection of blood near the nerve 4 Infection. due to damage to a by the 4 Other causes. needle or the catheter. Small amounts All anaesthetists performing nerve blocks of bleeding or bruising are common, are trained in the technique and will take and do not cause damage to nerves. A steps to prevent these types of nerve large haematoma may press on a nerve damage. and cause damage. Rarely, an urgent operation is required to remove the Direct injury haematoma and stop it pressing on the This may happen if the needle or catheter nerve. damages the nerve. Contact with the If you take blood-thinning medicines nerve may cause ‘pins and needles’ or a such as warfarin or clopidogrel, you are brief shooting pain. This does not mean more likely to get a haematoma. Your the nerve is damaged but if the needle is anaesthetist will take this into account not repositioned damage can occur. before he/she offers you a nerve block. If you are having a peripheral nerve Inadequate blood supply block and a general anaesthetic, your anaesthetist may wish to do the nerve Every nerve is supplied by blood vessels, block while you are awake, before giving which keep it healthy. If the blood supply the general anaesthetic. This allows you is damaged or reduced, the nerve may be to report any tingling or shooting starved of oxygen, which leads to damage. that you feel. If you notice these, you Infections should tell the anaesthetist immediately. These are very rare. They are slightly The anaesthetist will reposition the needle more likely if a catheter is left in place. and the feelings should disappear. Sterile conditions similar to those used If you have the nerve block after you are for the operation itself are used to help anaesthetised, the anaesthetist will take prevent infection. If a catheter is used

2 Risks associated with your anaesthetic v Information for Patients: The Royal College of Anaesthetists Section 12: Nerve damage (3) the site should be kept clean and checked further up the nerve. This shows regularly by a nurse. If you have infection whether the nerve is working or not) elsewhere or a weak , you 4 Magnetic Resonance Imaging (MRI) are more likely to get an infection. The 4 Computed Tomography (CT) scanning. anaesthetist will take this into account The neurologist will suggest a treatment before he/she offers you a nerve block. plan, which might include physiotherapy and exercise. If you have pain, drugs What else can cause nerve damage? that relieve pain will be used. This may If you have nerve damage, you should include drugs that are normally used for not assume that it is caused by the nerve treating epilepsy or depression because block. The following list shows other of the way that they change electrical causes of nerve damage related to having activity in nerves. Drug treatment is an operation. You can find out more not always successful in relieving pain. about these causes in Section 10 in this Occasionally an operation can be done, either to repair a nerve or to relieve series. pressure on a stretched nerve. 4 Your nerves can be damaged by the surgeon. During some operations, this How likely is permanent nerve may be difficult or impossible to avoid. damage? If this is the case, your surgeon should There have been many studies looking discuss it with you beforehand. at how often nerve damage happens in 4 The position that you are placed in for various peripheral nerve blocks.1–6 the operation can stretch a nerve and 4 damage it. Nerve damage occurs in less than 3 out of every 100 nerve blocks (<3%). 4 The use of a tourniquet to reduce The risk varies between the different blood loss during the operation will blocks. The vast majority of those press on the nerve and may damage it. affected (92–97%), recover within four 4 Swelling in the area after the operation to six weeks. 99% of these people can damage nerves. If it is a limb, have recovered within a year. elevation of the limb will help reduce 4 Permanent nerve damage is rare and any swelling. precise numbers are not available A 4 Pre-existing medical conditions, possible estimate from the information such as or atherosclerosis that we do have suggests it might (narrowing of your blood vessels), can happen in between 1 in 5,000 and 1 in 30,000 nerve blocks. A recent review make damage more likely. of 16 large studies reported only 1 case If I think I have nerve damage, what of permanent nerve damage. can be done about it? Summary Your anaesthetist or surgeon may arrange Permanent nerve damage after a for you to see a neurologist (a doctor peripheral nerve block is very rare. The specialising in nerve diseases). Tests may most common type of nerve damage be done to try and find out exactly where causes an area of numb skin which is very and how the damage has occurred. This likely to resolve within a few weeks. might involve: 4 nerve conduction studies (very small electrical currents are applied to the skin or muscles and recordings made

3 Risks associated with your anaesthetic v Information for Patients: The Royal College of Anaesthetists Section 12: Nerve damage (3)

Authors References Dr Sharmistha Saha, FRCA 1 Liguori GA. Complications of regional . Specialist Registrar in Anaesthetics J Neurosurg Anesth 2004;16:84–86. North Western Region 2 Ben-David B. Complications of peripheral nerve blockade. Anesthesiol Clin N A 2002;20:457–469. Dr Justin Turner, FRCA 3 Fischer B. Complications of Regional Anaesthesia. Lead Consultant Anaesthetist for Acute Pain Anaesth Intens Care Med 2004;4:125–128. Hope Hospital, Salford 4 Auroy Y et al. Serious complications related to regional anesthesia. 1997;87:479– Editor 486. Dr Barrie Fischer, FRCA 5 Brull R et al. Neurological complications after Consultant Anaesthetist regional anesthesia: contemporary estimates of risk. Alexandra Hospital, Redditch Anesth Analg 2007;104(4):965–974. President, European Society of Regional 6 Neal JM et al. ASRA Practice advisory on Anaesthesia (GB&I zone) and ESRA Board neurologic complications in regional anaesthesia Member 1997–2004. and pain medicine. Reg Anesth Pain Med 2008;33(5):404–415.

The Royal College of Anaesthetists Revised edition 2009 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.ukT email: [email protected] The Royal College of Anaesthetists This leaflet will be reviewed three years from the date of publication.

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