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Section 10: Nerve damage (1)

Risks associated with your anaesthetic Section 10: Nerve damage associated with an operation under general anaesthetic

ignificant nerve damage is uncommonly associated with a general anaesthetic S(less than 1 in 1,000 patients). This article gives information about how nerves can be damaged during an operation under , what kinds of nerve damage can happen, how likely this is, and what recovery can be expected.

What is the ? 4 The Peripheral Nervous System The nervous system consists of: l The peripheral nerves include motor nerves (controlling muscles) and 4 The sensory nerves (bringing information l The , which acts as the about touch, pain, and other ‘central processor’ of the system. sensations). l The spinal cord. This carries l Some nerves are mixed nerves – electrical signals away from the partly motor and partly sensory. brain to nerves supplying muscles What symptoms can be caused by and organs. It also carries signals nerve damage? from nerves which supply the organs towards the brain. These Peripheral nerve damage signals allow you to feel touch, 4 If sensory nerves are damaged, you pain, position and hot or cold. may feel numbness, tingling or pain. The pain can be a continuous aching pain or a sharp shooting pain. You Brain may also get inappropriate warm or cold sensations. Spinal cord 4 If motor nerves are damaged, there may be weakness or paralysis (loss of movement) of muscles in that area. 4 If mixed nerves are damaged, there will be a mixture of the symptoms given above. Peripheral 4 The area varies according to the nerves nerves affected, from a very small patch of numbness, to most of a limb being affected. Spinal cord damage 4 Damage to the spinal cord usually affects both muscle power and sensation, depending on where the The Nervous damage has happened. Unfortunately, System spinal cord damage is often extensive, with pain being a frequent feature.

1 Risks associated with your anaesthetic v Information for Patients: The Royal College of Anaesthetists Section 10: Nerve damage (1)

Control of the bowels and the bladder be done to try and find out exactly where can also be affected. and how the damage has occurred. This might involve: How long do these effects last? 4 nerve conduction studies (very small Peripheral nerves electrical currents are applied to the 4 This is variable. skin or muscles and recordings made 4 If the changes you notice are slight, further up the nerve. This shows they may resolve within a few days, whether the nerve is working or not) but often it will take several weeks. 4 Most symptoms resolve within three Magnetic Resonance Imaging (MRI) months. 4 Computed Tomography (CT) scanning. 4 Full recovery can sometimes take up The neurologist will suggest a treatment to a year or even longer. plan, which might include physiotherapy 4 Rarely, (less than 1 in 10,000 general and exercise. If you have pain, anaesthetics) nerve damage occurs that relieve pain will be used. This may that is permanent. include drugs that are normally used for Spinal cord treating epilepsy or depression. These 4 Unfortunately, damage caused by an drugs help because of the way in which injury to the spinal cord is usually they change electrical activity in nerves. permanent. This is very rare, treatment is not always successful in occurring in less than 1 in 50,000 anaesthetics (see later for more relieving pain. Occasionally an operation information on the risk). can be done, either to repair a nerve or to relieve pressure on a stretched nerve. What are the most common nerve injuries? How does peripheral nerve damage 4 The ulnar nerve at the elbow. happen? 4 The common peroneal nerve at the The ways in which nerve damage can knee. happen are listed here and explained The ulnar nerve of the arm is by far the below.7 most commonly reported nerve injury.1–4 4 Compression. It can be compressed at the elbow, where 4 it is very close to the skin. Ulnar nerve Stretching. 4 damage causes numbness in the fourth Surgical damage. and fifth fingers and/or weakness of the 4 Inadequate supply. hand muscles. 4 Insertion of a cannula. 4 Not known. The common peroneal nerve can be damaged on the outside of the leg, just Compression and stretching below the knee. This can cause foot During the operation, you will be placed drop (an inability to raise the foot off the in a certain position to allow the operation ground), and/or numbness on the front of to be done. For example, you may need the foot.5,6 to lie on your front to allow surgery on your back. If a nerve is stretched or What can be done if there is nerve compressed (pressed on or squashed), damage? there can be nerve damage. If you were Your anaesthetist or surgeon may arrange awake, you would feel this and move for you to see a neurologist (a doctor to relieve the discomfort. During an specialising in nerve diseases). Tests may anaesthetic, you cannot do this.

2 Risks associated with your anaesthetic v Information for Patients: The Royal College of Anaesthetists Section 10: Nerve damage (1)

If a tourniquet is used to reduce surgical What is done to prevent peripheral bleeding there can be nerve damage due nerve damage? to compression. The pressure of the Your anaesthetist, surgeon and theatre tourniquet and the time it is used should staff take care to try and prevent nerve be carefully controlled to reduce the damage. They share the responsibility of chance of this happening. minimising the risks by: Very rarely, the nerves to your tongue can 4 careful padding of vulnerable areas be compressed by the tube used to ensure 4 positioning you in a way which avoids your airway is clear, or by the process stretching nerves as much as possible used to place the tube. You can find out 4 surgical awareness of the risk more about this in Section 4 in this series. 4 avoiding prolonged bed rest. Surgical damage What increases the risk of nerve The surgeon might cut a nerve, or damage? injure it with the diathermy (cautery) 4 Certain positions required for the instrument used to stop bleeding. Surgical operation, for example: instruments can also compress and/or l lying on your front for an stretch a nerve. During some operations, operation on your back this may be difficult or impossible to l lying on your side for some avoid. If this is likely, the surgeon should operations on the chest or kidney discuss it with you beforehand. l lying on your back with your Local anaesthetic injections including spinal legs raised and separated – for and epidural injections operations in the genital area (this is called the lithotomy position) This is discussed in Sections 11 and 12 in l your arm being placed in position this series. for some shoulder operations. Inadequate blood supply 4 Certain operations, including: Every nerve is supplied by blood vessels l operations on the spine or brain which keep it healthy. If these blood l cardiac or vascular operations (on vessels are damaged during the operation, the heart or major blood vessels) or if the blood supply is reduced due to l operations on the neck or parotid pressure or stretching, the nerve can be (a gland in the face) starved of oxygen. This type of damage is l some kinds of breast operation slightly more likely if you have narrowing l operations where a tourniquet is of your blood vessels generally – you may used to reduce bleeding (knee, know that you have coronary heart disease foot, hand operations mainly). 4 or narrowed blood vessels elsewhere. Previous disease – here are a few examples. Insertion of a cannula or a ‘drip’ l Diabetes Nerves can be damaged by needles used to l Rheumatoid or osteo-arthritis place an intra-venous cannula (‘your drip’) l Atherosclerosis (hardening and/or or a cannula into large veins or arteries. narrowing of the arteries). 4 Increasing age. Cause unknown 4 Being very overweight or extremely Unfortunately, the mechanism of injury thin. is unclear in the majority of cases of 4 Being male – men have a higher risk nerve injury2 associated with surgery and of ulnar nerve damage. The reason for general anaesthesia this is not known.

3 Risks associated with your anaesthetic v Information for Patients: The Royal College of Anaesthetists Section 10: Nerve damage (1)

How does spinal cord damage If you have disease of your blood vessels happen? elsewhere (for example coronary heart Spinal cord damage is very rare. disease) the risk of this happening is Unfortunately, compared to peripheral higher. But the risk remains very rare nerve injury, it is more likely to result (see later for estimated figures). Your in permanent serious disability. This is anaesthetist can adjust your anaesthetic because the spinal cord cannot grow back to keep your blood pressure at a level that and heal, unlike peripheral nerves which he/she considers safe. can re-grow. Compared to peripheral nerve injury, How likely is peripheral nerve and spinal cord damage is: spinal cord damage? 4 much more rare The exact risk of nerve damage is not 4 more likely to be disabling known. The following figures are the best 4 more likely to be permanent information available. 4 more often associated with pre-existing 4 disease. The risk of a significant peripheral nerve injury lasting more than three How does it happen? months, is estimated to be less than The main cause of spinal cord damage 1 in 2,000 patients having a general associated with a general anaesthetic is an anaesthetic.7 Permanent damage, inadequate blood supply to the spinal cord. lasting more than a year, is estimated Other causes of spinal cord damage during an to be less than 1 in 5,000. operation are not related to the anaesthetic 4 Spinal cord damage occurs in less than and happen during surgery on or near the 1 in 50,000 patients having a general spine itself. anaesthetic.8 Inadequate blood supply to the spinal cord 4 More minor symptoms may occur This can happen due to: much more frequently, perhaps as 4 low blood pressure high as 1 in 100 people having a general anaesthetic, but most recover 4 a clot blocking the blood vessels completely. 4 compression or stretch of blood 4 Who should I go to for help if I think vessels, making them narrower. I may have nerve damage and I have These may cause oxygen starvation of the left hospital? spinal cord, leading to damage. l Your GP. The ‘anterior spinal artery syndrome’ is l Your surgeon. caused by one or more of these factors l Your anaesthetist. reducing blood flow in the anterior spinal You should go to your GP initially, who artery. If the flow of blood in this artery may refer you back to your surgeon or to is very low, the front part of the spinal your anaesthetist, depending on the area cord becomes starved of oxygen and may affected. be damaged. If this is not corrected, nerve cells will die. This will result in permanent lower limb paralysis.

4 Risks associated with your anaesthetic v Information for Patients: The Royal College of Anaesthetists Section 10: Nerve damage (1)

More detailed information about the risk of nerve and spinal cord damage

The risk of significant and disabling only a general anaesthetic, without peripheral nerve damage occurring in any kind of peripheral . association with surgery and anaesthesia Some were thought to be associated in the United Kingdom is unknown. with the position of the arm during the Many cases of nerve damage have been anaesthetic, but the exact cause of reported, but the denominator is not many injuries was not known. usually known. This means that although l Just over a tenth of the injuries (84 we know that there are a certain number out of 670, or 13%) were spinal cord of reports of problems, we do not know injuries. Those affected were more how many anaesthetics there were during likely to have had a spinal or epidural the same time without problems, so we injection than a general anaesthetic don’t know how frequently the damage is alone. There were 23 people with occurring. spinal cord damage who had only had From the USA, a report of closed claims a general anaesthetic, but about half of (cases which have been settled in a these people were having operations on court of law) gives some indication of the their spine. overall risks in the USA.2 Between 1975 It is helpful to remember that: and 1995, there were 670 closed claims in the USA involving nerve damage and l Many millions of anaesthetics were anaesthesia. These cases include all given in this 20 year period. types of anaesthetic – general anaesthetic, l This information only includes cases peripheral nerve blocks, spinal and reported and settled in a court of law. epidural injections. You can find out l The information is now quite old, and more about nerve damage and local considerable improvements have been anaesthetic injections in Sections 11 and made in the care given during and after 12 in this series. operations. Of these closed claims: l Most UK anaesthetists and surgeons l Just over half of the injuries (373 out would consider the risks now to be less of 670, or 55%) were to nerves in the than those quoted here, but this view arm. The majority of these involved remains to be proven.

5 Risks associated with your anaesthetic v Information for Patients: The Royal College of Anaesthetists Section 10: Nerve damage (1)

Author References Dr Sean Tighe, MRCS, LRCP, FRCA 1 Warner MA et al. Ulnar neuropathy in medical Consultant Anaesthetist patients. 2000;92:613–615. The Countess of Chester Hospital Foundation NHS 2 Cheney FW et al. Nerve injury associated with Trust, Chester . A closed claim analysis. Anesthesiology 1999;90:1062–1069. Editor 3 Warner MA Warner ME, Martin JT. Ulnar Dr Barrie Fischer, FRCA neuropathy. Incidence, outcome and risk factors Consultant Anaesthetist in sedated or anesthetized patients. Anesthesiology Alexandra Hospital, Redditch 1994;81:1332–1340. 4 Warner MA et al. Ulnar neuropathy in surgical President, European Society of Regional patients. Anesthesiology 1999;90:54–59. Anaesthesia (GB&I zone) and ESRA Board Member 1997–2004. 5 Warner MA et al. Lower-extremity motor neuropathy associated with surgery performed on patients in a lithotomy position. Anesthesiology 1994;81:6–12. 6 Warner MA et al. Lower extremity neuropathies associated with lithotomy position. Anesthesiology 2000;93:938–942. 7 Sawyer RJ et al. Peripheral nerve injuries associated with anaesthesia. Anaesthesia 2000;55:980–991. 8 Borgeat A, Ekatodramis G. Nerve injury associated with regional anesthesia. Curr Top Med Chem 2001;1:199–203.

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

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