Interscalene Block: A guide for Patients
This page provides important information about an interscalene block (ISB), also known as a specific type of brachial plexus block. This is a type of injection of local anesthestic commonly used to help reduce pain during and after shoulder surgery (for example a shoulder arthroscopy with reconstruction), or some types of arm surgery.
The ISB causes a profound reduction in sensation and muscle power to the shoulder and arm, and care must be taken by the patient to ensure that no injury (eg scalds from hot water) occurs to the arm or hand until the effects of the ISB have worn off.
The Process
This injection can be performed with you either awake, sedated or under anaesthetic. Your doctor will normally use an ultrasound machine (some doctors may use a nerve stimulator instead) to identify the collection of nerves that originate at the base of the neck and move out to the shoulder. The best spot for injection is usually several centimetres above your collar bone.
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Local anaesthetic may be injected into the skin around this area if you are awake. Your doctor will then pass a special needle to the area around the nerves under ultrasound guidance, and inject local anaesthetic near the nerves. You may feel a temporary pressure at the injection point while this occurs.
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Depending on the type, strength and amount of local anaesthetic injected, this block may last from several hours to more than 24 hours. Offset of the ISB often causes 'pins and needles' in the arm for a short time.
Risks
Almost all medical care and procedures carry some degree of risk of something not going according to plan, and it's important to be aware of this beforehand. Your anaesthetist is always best placed to provide information about the risks of anaesthesia specific to you and your upcoming surgery. The risks listed here are generic and not tailored to you and your circumstances. There are also multiple other less frequently encountered side effects/complications which are not listed here, to avoid providing an overwhelming list.
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1. Failure of the block. Normally this block works well, but on occasion has little or no effect
2. Nerve damage. Very rarely either temporary or permanent nerve damage to any of the nerves that serve the arm.
3. Infection resulting from this injection is incredibly rare
4. Bleeding resulting from this injection is rare
5. Collapsed lung (or bleeding around the lung) is very rare but can happen if the lung lining makes contact with the needle tip. The lining of the lung comes within a very short distance of the target nerves
6. Shortness of breath can occur as the local anaesthetic commonly also temporarily affects one of the nerves that serves the diaphram (called the phrenic nerve). This effect if normally only noticed by patients who have significant underlying breathing problems
7. Local Anaesthetic Systemic Toxicity (LAST) occurs when local anaesthetic makes its way into the blood circulation, and can cause complications with the heart and brain.