Variations in the Origin and Communication of the Intercostobrachial Nerve: Surgical Implications

The intercostobrachial nerve (ICBN) supplies the upper part of the postero-medial region of the arm, lateral thoracic wall, and axilla. It is susceptible to being damaged during various axillary surgeries like axillary lymph node dissection, sentinel lymph node biopsy, and mastectomy because of its diverse origin and branching configuration. Safeguarding the ICBN during axillary surgical procedures can minimise postoperative discomfort and paraesthesia. During standard dissection of the right side axilla and pectoral region of a female cadaver, the ICBN was detected, and its path was followed. The normally originating ICBN was observed to split into two branches after emerging from the second intercostal space (ICS). The lateral cutaneous branch of the third intercostal nerve emerged from the third ICS as a variant ICBN and joined with the lower branch of the ICBN. Subsequently, both the ICBNs supplied the upper one-third of the posteromedial region of the right arm. The ICBNs were not observed to be linked with the medial cutaneous nerve of the arm (MCNA). Furthermore, the medial cord of the right brachial plexus provided a combined trunk, which split at the middle of the arm as the MCNA and median cutaneous nerve of the forearm. The variant site of origin of the ICBN from the third ICS and its communication with the normally originating ICBN, as seen in the present case, may enhance the likelihood of its injury during several operative procedures such as mastectomy, breast reconstruction, and axillary lymph node dissection. Thorough awareness of such cases of diverse origin and communication of the ICBNs, combined with careful surgical approaches, can potentially help in the reduction of post-surgical pain and paraesthesia.