What is a nerve block?
A nerve block is an injection of local anaesthetic around the nerves carrying pain sensation. Local anaesthetic numbs the nerves to provide anaesthesia for surgery or reduces postoperative pain from the surgical site. A small injection is done around the nerves resulting in a numb feeling and an immobile limb, depending on the location of the nerve block and the amount (concentration) of local anaesthetic used.
Why you have been asked to consider it?
You are having an operation on your lower limb and your anaesthetist is planning to perform this as a sole anaesthetic or for pain relief after surgery as it is one of the most effective methods of relieving pain in the first 12 to 24 hours after the surgery.
What should you expect to happen?
The nerve block will be performed in the operating theatre while you are awake, sedated or when you are under general anaesthesia. Your anaesthetist will discuss with you what is best suited for you. The nerves are located using an ultrasound machine or by using a small electric device which passes a tiny electrical current through a special needle to locate the nerve. When this needle is next to a nerve, the muscles to which the nerve goes will twitch - a surprising sensation, but not one that is usually painful. As long as the nerve block lasts your leg will feel numb and heavy. Once the nerve block wares off, the limb will return back to normal. The nerve block can last for 12-24 hours. As the block wears off you may experience a tingly sensation and pain at the site of surgery
Potential benefits are:
Excellent pain relief for first 12 to 24 hours after the surgery. You will need less Morphine based opioid pain killers resulting in reduced sickness. Also, you will be able to eat and drink earlier and potentially be able to go home sooner.
Side effects and complications
There are occasional problems from this procedure, as with anything we do in medicine. Most of these last only as long as the local anaesthetic lasts. Following are some of the side effects and complications. Your anaesthetist will tick those which apply to you before giving this leaflet to you.
Temporary nerve injury ☐
Permanent nerve injury ☐
Block failure ☐
Limb weakness ☐
Risk of falling ☐
Protect insensate limb ☐
Injury to vital organ ☐
Occasionally the block is unsuccessful. You will then be given an alternative anaesthetic and another form of pain relief after the operation.
Alternatives to nerve block:
Pain can also be controlled by local anaesthetic infiltration by the surgeon or by using Morphine based pain killers.
What do you need to do?
While the block is effective you will have reduced sensation and weakness in your leg. Therefore you should avoid hot or cold items near the blocked limb or surgical site. Please do not drive or use any machinery till the block has completely worn off. Orally taken pain killers take some time to work. Please take your oral pain killers as instructed even if you are not experiencing any pain. This will help control the pain when the block wears off. Please contact the hospital or the anaesthetist if you have any concerns or if the block has not worn off after 24 hours.
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Cambridge University Hospitals
NHS Foundation Trust
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