Numbness Distribution Following Supraclavicular Peripheral Nerve Block
A supraclavicular peripheral nerve block produces numbness in the entire upper extremity below the shoulder, including the hand, forearm, and elbow, while typically sparing the shoulder and upper arm medial aspect.
Anatomical Basis for Numbness Distribution
The supraclavicular block targets the brachial plexus at the level where it is most compactly arranged, providing comprehensive anesthesia to the upper extremity with specific patterns:
- Complete coverage: Hand, wrist, forearm, and elbow
- Partial coverage: Lateral aspect of upper arm
- Typically spared: Medial upper arm (intercostobrachial nerve territory) and shoulder joint
Nerve Distribution Affected
- Median nerve: Palm, thumb, index, middle, and part of ring finger
- Ulnar nerve: Medial palm, little finger, and part of ring finger
- Radial nerve: Posterior forearm and dorsum of hand
- Musculocutaneous nerve: Lateral forearm
Advantages Over Other Approaches
The supraclavicular approach provides more comprehensive distal upper extremity coverage compared to other blocks 1:
- Higher success rate for ulnar nerve blockade compared to interscalene approach
- Better musculocutaneous nerve coverage than axillary approach
- More reliable distal coverage than interscalene block (which primarily targets the shoulder)
Clinical Considerations
Respiratory Function
When selecting a brachial plexus block, respiratory function should be considered. According to current guidelines, axillary or infraclavicular blocks may be preferred over supraclavicular blocks in patients with compromised respiratory function 2.
Motor Function
Supraclavicular blocks cause complete motor blockade of the hand and forearm. Studies show 100% loss of grip strength with supraclavicular blocks compared to only 21.4% loss with more distal nerve blocks 3.
Block Duration
Single-shot supraclavicular blocks typically provide 6-8 hours of analgesia 4. For longer procedures or post-operative pain management, continuous catheter techniques may be considered.
Potential Complications
- Phrenic nerve palsy: Less common than with interscalene blocks but still possible
- Suprascapular nerve palsy: Rare but documented complication that can cause shoulder weakness 5
- Pneumothorax: Historical concern, but significantly reduced with ultrasound guidance 1
Comparison to Other Approaches
- Interscalene block: Better for shoulder procedures but less reliable for hand/forearm
- Infraclavicular block: May provide superior continuous analgesia compared to supraclavicular approach for distal procedures 6
- Distal peripheral nerve blocks: Better preserve motor function but require multiple injections 3
Practical Application
For optimal block success, practitioners should:
- Use ultrasound guidance to reduce complications and improve success rates
- Target the brachial plexus where it is most compactly arranged in the supraclavicular fossa
- Ensure adequate motor response in the fingers (flexion or extension) before injection 7
The supraclavicular block remains an excellent choice for procedures below the shoulder, providing dense and reliable anesthesia while being technically straightforward to perform with modern ultrasound guidance.