Anaesthetics - Regional Anaesthesia (Nerve Block) for Limb Surgery

Introduction

Pain is expected after surgery. There are different ways to provide good pain relief. One method of providing excellent pain relief is an injection of local anaesthetic around a large nerve.  You may hear this referred to as a nerve block.

This leaflet provides information about nerve blocks, and it is important that you understand the risks and benefits involved with this procedure. If you have any questions, your anaesthetist will be able to answer them on the day of surgery.

What is regional anaesthesia (‘nerve block’)?

Nerve blocks aim to give you the best possible pain relief after your surgical procedure. It involves an injection of local anaesthetic agent near the nerves in your neck, arm, hand or leg depending on the type of surgery you are having. An anaesthetist will perform the injection prior to your surgical procedure.

To perform effective nerve blocks, your anaesthetist will usually use an ultrasound machine to identify the relevant nerves prior to injection. After the injection is performed, you may notice that the affected area of the body will gradually go numb and pain free. This will hopefully last for some hours after the surgery.

What will happen on the day of surgery?

On the day of surgery, an anaesthetist will come and speak with you. They will ask questions about your medical history and your medications, some of which you may have been asked before.  They will explain the intended anaesthetic to you in detail, including any nerve blocks they intend to perform.

After speaking with your anaesthetist, you will get changed into a hospital gown and wait in the pre-operative area. This will either be a ward or an area of the day care unit. When it is time for your surgery, you will be brought into a room next to the operating theatre called the anaesthetic room or a similar area where these nerve blocks are performed.

Your anaesthetist will be there as well as the anaesthetic assistant who is a nurse or operating departure practitioner. There may be more than one anaesthetist, usually for training purposes.

A cannula will be inserted into a vein in your arm. You will be attached to monitors for your heart, lungs and blood pressure. This is routine practice for any type of anaesthetic, and you are now ready for a nerve block.

How is a nerve block performed?

The skin around the proposed injection site is cleaned with an antiseptic. A small amount of local anaesthetic may be given to numb the skin before the nerve block is administered.

Your anaesthetist will identify the underlying nerves using either an ultrasound machine and/or a nerve stimulator. The nerve stimulator, if used, will twitch the muscles in your arm or leg when the needle is close to the nerve. The ultrasound machine allows your anaesthetist to see the nerves as well as the needle and the spread of the local anaesthetic around the nerve.

When your anaesthetist has identified the correct nerve, he/she will insert a fine needle through the skin. When your anaesthetist is satisfied that the needle is in the right place, they will inject some more local anaesthetic. During the injection, you may feel a tingling sensation as well as pressure. This is normally well tolerated with minimal discomfort. It is important that you stay as still as possible whilst the injection is being given. It can sometimes take more than one attempt to place the needle in the right place.

As the local anaesthetic starts to work, you may feel a tingling sensation that is followed by the arm or leg becoming warm, heavy, and numb. This usually happens within a few minutes of the injection and sometimes during the injection itself. It is common to feel that the numb arm or leg doesn’t belong to you as it becomes very heavy and weak.

The entire procedure should take about 5-10 minutes to perform, but sometimes can take slightly longer if it is a more complex procedure. It will then take a further 20-40 minutes for the limb to get anaesthetised completely. The doctor will use a cold spray to confirm that the surgeon can proceed with the operation.

After your nerve block

Your nerve block may be given alone or in addition to a general anaesthetic.

If you are not having a general anaesthetic, you will be taken directly to the operating theatre on a trolley. A member of staff will sit with you during the operation. Please feel free to bring your own music player with headphones if you would like to listen to music during the operation. You may be given oxygen through a light plastic face mask if necessary.

If you are having a general anaesthetic too, another anaesthetist will administer it in an adjacent anaesthetic room. You will not remember anything. When you wake up the nerve block ensures that you have adequate pain relief.

Benefits of having a nerve block

• Excellent pain relief after surgery which can last up to 24 hours
• You should not need strong pain killers and therefore you feel less drowsy or sick after the operation
• Your recovery from surgery should be quicker and you are often able to leave hospital earlier

Side effects and complications

Serious complications from nerve blocks are very rare. However, it is important you are aware of the risks and side effects associated with this procedure.

Common side effects of having a nerve block include:

• Pain during injection – you should tell your anaesthetist immediately if you feel any pain or pins and needle in your arm while the nerve block is being performed. This may indicate irritation/damage to a nerve and the needle may need to be repositioned
• Numbness and heaviness after the injection – it will be difficult for you to control the movement of your arm or leg after the injection. This will slowly wear off over the subsequent 24 hours
• Inadequate effect of nerve block – Sometimes one or more nerves can escape the local anaesthetic drug. The anaesthetist will test the block prior to surgery and, if they are not completely satisfied with the effect of block, may either perform additional local anaesthetic injections or ask the surgeon to supplement this by injecting more local anaesthetic at the site of operation. Alternatively, if the nerve block is deemed ineffective, the anaesthetist may give you a general anaesthetic. This is unusual and the anaesthetist will ensure you will not be in any pain during the surgery.

As with any invasive procedure, there is a risk of bruising and infection.

There are some serious complications it is important you are aware of. These complications are thankfully very rare:

Nerve damage

Many people worry about the possibility of nerve damage during a nerve block. If a nerve is damaged, you may have a temporary loss of sensation or persistent pins and needles. Sometimes there is muscle weakness. Nerve damage happens to less than one in ten patients.
 
If there is any nerve damage, in most people it is evident within days to short weeks:

• Any symptoms will resolve within 4 to 6 weeks in 92-97% of affected patients
• 99% of patients will recover within one year

Permanent nerve damage is rare. Based on available evidence, the risk is estimated at between 1 in 2000 and 1 in 5000 nerve blocks.  Nerve damage post-operatively may also be due to other causes, including the actual surgical procedure itself.

Systemic toxicity

If a large dose of local anaesthetic is inadvertently injected directly into a blood vessel, seizures, loss of consciousness and severe depression of heart function can occur. This is an extremely rare event and will be managed by your anaesthetist.

Pneumothorax (lung puncture)

Nerve blocks done in the neck may rarely lead to a punctured lung. This may need insertion of a chest drain and hospital admission for a few days until resolution of the pneumothorax.

There will be specific risks depending on the type of nerve block you are having. Your anaesthetist will discuss these with you and any other questions you may have on the day of your operation.

Aftercare

You will be given a sling/ brace to support and protect your arm/ leg from pressure and injury. It should be worn until sensation and control of your limb returns.

You should avoid use of any machinery or domestic appliances. You must be careful around heat sources such as fires and radiators as injuries are possible while you cannot feel your limb.

Start taking your pain killers regularly as prescribed even if you don’t have any pain. This is important as the pain can appear suddenly, and it is then harder to manage.

It is likely you will go home with the area numb. If the numbness persists after 72 hours, please contact the anaesthetic team:

Rochdale Infirmary - 01706 517401

Royal Oldham Hospital - 0161 627 8385

You may receive a phone call from hospital on the day after your discharge to enquire about your well-being.

If you have any questions please ask your anaesthetist, surgeon or nurses on the ward before you leave the hospital.

Feedback

We appreciate and encourage feedback, which helps us to improve our services. If you have any comments, compliments or complaints to make about your care, please contact the PALS team (Patient Advice and Liaison Service) on 0161 604 5987 between 9:30am and 4:30pm Monday to Friday or email pals@nca.nhs.uk

Contact information

If you have any questions about the nerve block, please ask your anaesthetist for more information.

Anaesthetic Department

Rochdale Infirmary - 01706 517401
Royal Oldham Hospital - 0161 627 8385

Further information

Further information about regional anaesthesia can be found on the following websites:

Regional Anaesthesia UK
Website: www.ra-uk.org

The Royal College of Anaesthetists
Website: www.rcoa.ac.uk/patientinfo

Sources:
https://www.rcoa.ac.uk/sites/default/files/documents/ 2022-06/13- NerveDamagePeripheralNB2019web.pdf