Supraclavicular Block Coverage of the Intercostobrachial Nerve
No, a supraclavicular nerve block does not reliably cover the intercostobrachial nerve, which requires separate blockade for complete anesthesia of the upper arm and axilla.
Anatomic Basis for Coverage Gap
The intercostobrachial nerve (ICBN) is not part of the brachial plexus—it arises from the T2 intercostal nerve and provides sensory innervation to the medial upper arm and axilla 1. Because supraclavicular blocks target the brachial plexus at the level of the trunks/divisions, they cannot anesthetize nerves that originate outside this plexus structure 2.
Clinical Implications
For Tourniquet Pain
- The incidence of tourniquet pain with supraclavicular block alone is actually low, even without ICBN blockade, and can be easily managed with small amounts of systemic analgesics when it occurs 3
- A randomized trial found no significant association between ICBN block placement and prevention of tourniquet pain in patients receiving supraclavicular blocks 3
- Tourniquet pain has both cutaneous and ischemic components, and blocking a purely sensory nerve like the ICBN may not address the ischemic component 3
For Surgical Anesthesia Below the Shoulder
- When performing upper extremity surgery below the shoulder with a supraclavicular approach, separate blockade of the ICBN and medial brachial cutaneous nerve is recommended to ensure complete anesthesia of the medial upper arm and axilla 2
- All three major brachial plexus approaches (supraclavicular, infraclavicular, and axillary) require supplemental ICBN blockade for complete coverage 2
Common Pitfalls
The ICBN has a variable anatomic location and source of innervation, resulting in an inherently higher failure rate for this block 3. However, the clinical significance of incomplete ICBN coverage depends on the surgical site and use of a tourniquet. For distal upper extremity procedures, the impact is often minimal and manageable with systemic analgesics 3.
Coverage Characteristics of Supraclavicular Block
The supraclavicular approach provides the most compact arrangement of the brachial plexus and has high success rates for blockade of all major terminal nerves including the ulnar and musculocutaneous nerves 4. It demonstrates superior total anesthesia-related time and higher success rates compared to axillary approaches for distal arm surgery 5.