"Undercutting of the corresponding rib": a novel technique of increasing the length of donor in intercostal to musculocutaneous nerve transfer in brachial plexus injury

Intercostal nerves (ICN) are often utilized as donors for various neurotization procedures in brachial plexus injuries. ICN to musculocutaneous nerve (MCN) transfer is usually a standard in pan brachial plexus injuries, in order to restore flexion at the elbow. A tensionless co-aptation of the donor-recipient nerves often necessitates either a distal dissection of the ICNs where the number of fascicles is rather low or a proximal dissection, often at the cost of dissection of the serratus anterior digitation with a risk of later fibrosis and adhesion. We report two cases of pan brachial plexus injuries where ICN-MCN transfer was performed to restore elbow function. These patients underwent clinical and electrodiagnostic evaluation before surgery. We used the standard technique of harvesting ICNs 3-5, with our technical modification of "undercutting of rib" for increasing the donor length. The procedure was applied in two patients with pan brachial plexus injury (mean age = 23). Mean duration since the injury to surgery was ten months. Both patients underwent tensionless anastomosis with a combination of suture and fibrin glue co-aptation. While one patient had some improvement in elbow flexion, another one was under active rehabilitation protocol during follow-up. We found that undercutting of the ribs near serratus digitations can allow mobilization of the ICN from its groove, which in turn lengthens the donor nerve length without violating the serratus anterior digitations and without too anterior dissection of the nerve. It can be a viable option when a tensionless co-aptation at the axilla is otherwise not feasible intraoperatively.