the Best Approach for Blocking Intercostobrachial and Medial Brachial Cutaneous Nerves in the Upper Arm Surgery

Plain-language summary

Brachial plexus block (BPB) alone, whether performed at the axilla or more proximally, does not provide sufficient anesthesia for the skin of the medial upper arm and elbow, because thoracic roots contribute to the innervation of these areas. For surgery of the upper arm, the brachial plexus block needs to be completed by the Medial Brachial Cutaneous nerve (MBCN) and the Intercostobrachial nerve (ICBN) nerve blocks. The ICBN is not part of the brachial plexus; it usually originates from the lateral branch of the second intercostals nerve (T2). The MBCN and the ICBN are often interconnected. In the axilla, they are separated from the brachial plexus by the brachial fascia. Therefore, when an axillary brachial plexus block (ABPB) is performed, the local anesthetic solution may be prevented from spreading toward the MBCN and ICBN. These nerves are classically anesthetized by raising a subcutaneous wheel of local anesthetic spanning the entire width of the medial aspect of the arm at the level of the axilla, usually from anteriorly to posteriorly. The failure rate of this blind infiltration procedure has never been quantified in the literature. Traditional teaching suggests that the ICBN should be blocked to prevent tourniquet pain. Lanz et al (1) showed that BPB, whether performed to the axilla or more proximally, rarely extend to the ICBN (10% of cases). However, recent literature shows differences in opinion on the role of an ICBN/MBCN blocks in preventing tourniquet pain. Ultrasound guided ABPB is sufficient to provide anaesthesia for tourniquet even during prolonged ischemia. However, to ensure prevention of tourniquet discomfort a multiple injection technique that include musculocutaneous blockade should be preferred (2). The overall incidence of tourniquet pain in the setting of an effectively dense supraclavicular brachial plexus block for surgical anesthesia was low, even without the addition of an ICBN block. This tourniquet pain can be easily managed with small increases in systemic analgesics (3). However, in Magazzeni Ph et al (4) study, ultrasound-Guided Block of ICBN and MBCN was associated to a better sensory block and a less painful tourniquet compared to conventional block. The optimal access for an ultrasound guided block of the MBCN and the ICBN nerves is not yet known.

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