Dr Toni B. S. Hundle MBChB FRCA FFPMRCA Consultant Anaesthetist
Dr Toni B. S. Hundle MBChB FRCA FFPMRCAConsultant Anaesthetist

Consent - Nerve Blocks




Some surgery can be performed under nerve blocks alone. This is different from local anaesthesia surgery which may be performed by the surgeon themselves. Nerve blocks are usually used to block a region of the body, such as a limb, in order to perform surgery with the patient either fully conscious or drowsy with the aid of a mild sedative.

Nerve block only surgery is possibly one of the most difficult anaesthetic techniques to master. Because of variations in human anatomy and difficulty visualising the nerves this technique has a higher failure rate (approx. 10%). It can also only be used in patients who are fully compliant and co-operative because they will need to sit very still for the duration of the surgery.


Over 18 years of clinical practise I have used many different techniques and technologies to improve the success and safety of nerve blocks for awake surgery and post-operative pain relief. Currently I use the latest ultrasound machines to visualise the nerves and the most advanced needles and drugs available to perform my blocks.


Most of the nerve blocks I perform (>90%) are for post-operative pain relief and are usually performed with the patient asleep. They just need to be reminded that when they wake up from their general anaesthesia, they will not be able to move their "blocked" limb for up to 24 hours.


If the patient is having awake "block-only" surgery, then the procedure is as follows. Similar monitoring to a general anaesthetic is applied in the form of a blood pressure cuff, ECG heart rate monitoring and oxygen saturation level monitoring. The area around the injection site is prepared with antiseptic solution. A small amount of local anaesthetic is injected to anaesthetise the skin before an ultrasound scan is taken of the local anatomy. A deeper injection is then administered around the visible nerves to create a "block". this starts straight away but can sometimes take up to 45 minutes to reach peak effect. Rest assured that no surgery will be allowed to start until both the patient and anaesthetist are satisfied that the nerve block is working adequately.



Nerve blocks may provide the gold standard for post-operative pain relief

They reduce mental and physical stress during and after surgery.

This in turn puts less strain on the heart, lung and brain systems.

Nerve blocks are better for controlling blood pressure both during and after surgery.

By reducing opiate pain-killers patients are less drowsy and nauseous immediately after surgery and the better pain control allows for a speedier discharge home.

As the limb is usually completely numb then the depth of anaesthesia can be reduced slightly allowing for a faster wake up and discharge after general anaesthesia.



After the nerve block wears off the patient may experience significant pain which they have not been anticipating. 

Some patients do not like the numb limb feeling.

As it is numb, they must be careful not to injure the limb on the way home otherwise burns and trauma may occur without the patient being aware until the block wears off.

Heaviness of the chest wall can result in a sensation of breathlessness which although temporary can result in an overnight stay depending on oxygen levels.



Any procedure which involves breaking the skin has the potential to result in superficial infection, bleeding, and bruising. These are rare complications of any injection. Depending on where the injection is being performed determines the possible additional side-effects from the nerve block. For example, nerve blocks around the shoulder may cause temporary hoarse voice, breathlessness, stuffy nose, and droopy eyelid on the same side as the nerve block. This is because of the local anaesthetic spreading beyond its immediate area of need and temporarily anaesthetising other nerves in the vicinity. All these side-effects are well known and understood, they are also temporary and will disappear when the nerve block wears off.

A particularly rare but devastating complication of nerve blocks is direct nerve trauma or injury from the needle itself. I have read in the anaesthesia textbooks and journals of cases where direct injury to the nerve has led to permanent paralysis or pain in the affected limb. The recorded incidence of temporary injury is estimated to be about 1 in 5000 nerve blocks. Most issues will resolve within 3 months. There has however been recorded cases of permanent harm that has failed to completely resolve after nerve block injury. This has taken the form of paralysis, weakness and oversensitivity and chronic pain. Unfortunately, these are also complications of some surgery and it may not be possible to distinguish harm caused by surgery and that caused by nerve blocks. 

Post-operative pain relief can take other forms such as NSAIDS and morphine, nerve blocks are usually only recommendations but can provide the best pain relief possible. They are a choice and by no means mandatory. Once the patient has been informed of the risks and benefits then they can make this choice.

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