WHAT IS A PERIPHERAL NERVE BLOCK?
A nerve block (regional anaesthesia) is the injection of numbing medication (local anaesthetic) near a nerve or group of nerves that supply the part of your body being operated on. It provides long-lasting pain relief, during and after surgery, that can last from 2 to 18 hours, depending on the injection site and which medicines are used, and can be repeated.
A nerve block can be used for surgery on the shoulder, elbow, forearm, wrist, hand, fingers, knee, leg, ankle, or foot, and also for some procedures on thorax and abdomen. It is usually done before the surgical procedure but can also be done after the surgery for post-operative pain relief.
Your anaesthetist will explain the particular nerve block that is selected for your surgery. In some operations, the nerve block will be combined with sedation and/or a general anaesthetic.
WHAT ARE THE DIFFERENT TYPES OF NERVE BLOCKS?
Peripheral nerve blocks are now a common component of analgesia for both upper extremity and lower extremity procedures:
- Femoral nerve block, for surgery on the knee and the front of the thigh
- Sciatic nerve block, for surgery on the knee, ankle, or foot
- Popliteal fossa nerve block, for surgery on the lower leg or foot
- Interscalene block, for surgery on the shoulder, arm, or elbow
- Brachial plexus nerve block, for surgery on the arm, elbow, or hand.
There are also nerve blocs used for chest and abdominal surgeries:
- Erector Spinae Plane block for for rib fractures, back and chest wall surgeries, breast surgeries, abdominal operations such as hepatectomy, laparotomy and more;
- Pectoral nerve blocks I and II for breast surgeries and other procedures involving the anterior chest wall;
- Transversus Abdominis Plane block for abdominal and pelvic procedures including C-section.
WHAT ARE THE BENEFITS OF A PERIPHERAL NERVE BLOCK?
A nerve block can be done in addition to a general anaesthesia for pain relief after the surgery or to avoid a general anaesthesia. In that case you will remain alert and aware of your surroundings, unless you are having sedation. If you are having sedation, you will be sleepy and relaxed. However, you may be aware of events around you. You never get to see the surgery itself because a large sterile drape is always placed between you and the surgeon. Your anaesthetist is always near you and you can speak to him or her whenever you want to.
Nerve blocks give better pain relief than other methods, allowing you to move about earlier and engage in physical therapy sometimes as soon as the first postoperative day.
You may not need as much strong pain-relieving medicine, such as morphine: this will help reduce the side-effects associated with these medicines, which include nausea, drowsiness and constipation, and you are likely to be more alert.
The above benefits may lead to a reduced stay in hospital for you.
WHAT ARE THE RISKS OF A NERVE BLOCK?
Every anaesthetic has a risk of side-effects and complications. Whilst these are usually temporary, some of them may cause long-term problems.
Common side-effects and complications include:
- Pain at the injection site
- Bruising (haematoma) at the injection site.
Uncommon side-effects and complications include:
- Failure of block (1 in 100): this may require a further injection of anaesthetic or a different method of anaesthesia to be used;
- Temporary nerve damage (1 in 100) recovering in a few days to months, damage may cause weakness and/or numbness of the body part that the nerve goes to;
- Overdose of local anaesthetic;
- Allergic reaction;
- Lung collapse (only with some blocks);
- Damage to surrounding structures such as blood vessels, nerves and muscles.
Rare risks and complications include:
- Permanent nerve damage, very rare (1 in 5000 to 1 in 30,000);
- Serious allergic reaction;
- Infection at the site of injection: may require antibiotics and further treatment.
DO I HAVE THE RIGHT TO REFUSE THE BLOCK?
Yes. We can only tell you about your options. We will advise you to have surgery with a nerve block if we think it provides the best anaesthetic conditions with the least side-effects.
Without a nerve block we will use IV opiates (morphine-like drugs) to control your pain during and after surgery. These drugs have side-effects and may or may not be as effective as a nerve block.
CAN ANYONE HAVE A PERIPHERAL NERVE BLOCK?
No. A nerve block is not possible for some people. You will need to talk to your anaesthetist if:
- You take blood thinning drugs, such as warfarin;
- You have a blood clotting problem;
- You are allergic to local anaesthetic;
- You have an infection in the area of the block;
- You have had problems with a nerve block in the past.
HOW IS THE BLOCK DONE?
We do the nerve blocks in the pre-operative area before your surgery. This lets you have the block done in a quiet place before you are moved to the operating room for surgery. Your operation will only go ahead when you and your anaesthetist are sure that the area is numb.
The nerve block is done predominantly under ultrasound guidance, which is the most modern technique. This technique allows us to see the needle direction and local anaesthetic injection in “real time”.
A cannula (drip) is placed in a vein in your arm for giving fluid, then a needle is put into your skin and medicine to numb the area is injected. The ultrasound machine is used to locate the nerves to be blocked; then a needle is used to place a thin plastic tube (catheter) near the nerves of interest; the needle is removed, leaving only the catheter in place.
The anaesthetist may sometimes also use a small hand-held machine called a nerve stimulator. This machine sends a low-level electrical pulse below your skin to help pinpoint the exact location of the nerve. The signal causes a painless muscle twitch and possibly a tingling sensation.
WHAT WILL I FEEL?
The local anaesthetic injection in the skin will hurt briefly. You will then have the feeling of pushing, but usually no more than discomfort as the needle and catheter is inserted. Occasionally, you may feel a sharp feeling, like an electric shock. If this happens, it will be obvious to your anaesthetist. He/she may ask you where you felt it. A sensation of warmth and numbness gradually develops. Overall, most people do not find these sensations to be unpleasant, just a bit strange. The area with the block will feel numb, tingly, or heavy as the nerve block takes effect. You may still feel some sensations in the area particularly at the beginning of the procedure but no pain.
While your nerve block is in effect, you won’t be able to feel much in the area that is blocked, so you need to be careful to protect yourself from injury. For your own safety:
- Take care not to injure or bump the area that has been numbed with the local anaesthetic as you will not be able to feel pain;
- Do not place hot or very cold things on the affected part as this could cause burns;
- If you have a “weak leg”, do not walk without a person to assist you.
It’s important to start taking the pain medication your anesthetist prescribed at the first sign of sensitivity coming back. This usually means the nerve block is starting to wear off.