BRACHIAL PLEXUS NERVE BLOCK
Introduction:
- Second most commonly practiced block after central neuraxial block (spinal & epidural anesthesia).
- Used for upper limb surgeries.
Techniques:
- Interscalene brachial plexus block.
- Supraclavicular (subclavian) brachial plexus block.
- Infraclavicular brachial plexus block.
- Axillary brachial plexus block.
1)Interscalene block:
- Blockade occurs at level of upper & middle trunks (between anterior and middle scalene).
- Spares ulnar nerve (distal root of plexus) – Hence inadequate shoulder anesthesia.
- Uncommonly used due to proximity to vital structures.
Indications:
- Shoulder, upper arm & forearm surgery.
- Post-operative analgesia for total shoulder arthroplasty
Complications:
- Severe hypotension & bradycardia (i.e., the Bezold-Jarisch reflex).
- Inadvertent epidural or spinal block.
- Nerve damage or neuritis
- Intravascular injection with seizure activity.
- Horner’s syndrome – Due to stellate ganglion block —> Causes dyspnea & hoarseness of voice.
- Hematoma & infection.
2. Supraclavicular block:
- Most commonly used block.
- Blockade occurs at the distal trunk–proximal division level.
- Needle insertion lateral to subclavian vessels.
Indications:
- Operations on elbow, forearm & hand.
Complications
- Pneumothorax – Most common.
- Phrenic nerve block (40% to 60%)
- Horner’s syndrome.
- Inadvertent intravascular injection
- Hematoma.
3. Infraclavicular block:
Indications:
- Hand, wrist, elbow & distal arm surgery
- Blockade occurs at level of cords of musculocutaneous & axillary nerves.
- Injection site: In close proximity to cords of brachial plexus.
- Spares axillary nerve.
4. Axillary block:
- Injection site: In close proximity to terminal branches of brachial plexus.
- Most intense block occur in (C7-T1) ulnar dermatomes & least in C5-C6 dermatomes (contrasting to interscalene approach).
- Spares mucocutaneous & intercostobrachial nerves.
- Hence, arm surgery cannot be performed.
Indications:
- Include surgery on the forearm & hand.
Adverse effects:
- Persistent paresthesia of forearm is due to injury to peripheral nerve.
- Intravascular injection.
- Hematoma and infection – Rare complications.
Exam Important
- Interscalene approach to brachial plexus block does not provide optimal surgical anesthesia in the area of distribution of ulnar nerve.
- Pneumothorax is a common complication of brachial plexus nerve block.
- Persistent paresthesia of forearm is due to injury to the peripheral nerve seen as complication of axillary nerve block.
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