Brachial plexus injuries (BPIs) are often devastating and may include avulsion, stretching, or rupture of cervical nerve roots, resulting in significant disability8). Critical motor function in the limb may be lost, sensation in the hands may be impaired, and disabling pain may ensue. BPIs can affect individuals of any age and of either sex. Traumatic lesions usually arise from motor vehicle accidents and falls, and stretch injuries may also follow lesser damage such as stab injuries. Moreover, tumor irradiation is another cause of BPIs. Overall, the incidence of BPIs has rapidly increased due to technological advancements in transportation, resulting in a greater number of motor vehicle accidents.

Microsurgical treatment of BPIs has significantly advanced and can be used for the reinnervation of target muscles, resulting in new modalities to improve the clinical outcome of brachial plexus lesions. Treatment strategies are focused toward restoring shoulder stabilization, shoulder abduction, and elbow flexion. Many systematic reviews have been published in support of a preferred surgical treatment; however, the surgical management of BPIs remains a challenge. Four surgical procedures have been reported to improve functional outcome and are commonly used to repair BPIs: neurolysis, nerve repair, nerve grafting, and nerve transfer. Traditionally, brachial plexus surgery begins with nerve exploration to determine the pathoanatomy of the lesion, plan the strategy of nerve reconstruction, determine whether there is rupture or avulsion of each nerve root, and identify available donors and recipients. Despite improvements in surgical techniques, surgical outcome and functional restoration of the affected arm is still very limited10).

The strategies commonly used to reconstruct the brachial plexus mainly include peripheral nerve grafting and/or neurotization12). Neurotization of the brachial plexus is usually accomplished using the intercostal, accessory or in some cases, the phrenic nerve to reinnervate the musculocutaneous nerve for elbow flexion or the suprascapular nerve for shoulder abduction1,4,12).

In this study, we compared recovery of elbow function by reinnervating the musculocutaneous nerve after intercostal nerve transfer (ICNT) with or without spinal accessory nerve transfer (SANT) by sural nerve graft interposition in patients with traumatic BPIs. Functional outcome was analyzed to provide useful guidance for the management of BPIs.

Most BPIs result from closed traction injuries that affect the supraclavicular plexus and the C5, C6, and C7 nerve roots, resulting in lack of shoulder and elbow functions. C5 and C6 root involvement results in significant problems with shoulder abduction, external rotation, elbow flexion, and forearm supination, while C7 root involvement may lead to additional deficits involving finger, wrist, and elbow extension.

There are two types of characteristic lesions seen in BPIs: avulsion and rupture. Avulsion refers to a nerve torn from its attachment, while rupture refers to a nerve injury involving a traction force on an incompletely divided nerve, causing irregular proximal and distal ends. In the majority of patients, nerve roots are still in continuity and can therefore be used for reconstruction of the brachial plexus nerves12). Selection of optimal reconstructive surgery for traumatic BPIs differs among surgeons.

Nerve transfer is a surgical option that intentionally divides a physiologically active nerve and transfers it to a distal, more important but irreparable, paralytic nerve. Nerve transfer can be achieved with several donor nerves, but use of the intercostal nerves remains a popular choice for many surgeons. The motor portion of the intercostal nerve contains 500 to 700 myelinated motor fibers3). Because they are small and contain few motor fibers, three intercostal nerves are usually transferred to restore elbow flexion. The spinal accessory nerve has approximately 1,500 myelinated axons and is often used as a transfer nerve to innervate the suprascapular nerve, or less commonly, the musculocutaneous nerve, for shoulder abduction.

Previous studies have noted that shoulder abduction is best restored by transfer of an accessory nerve to the suprascapular nerve, whereas elbow flexion is best restored using intercostal nerves without grafts7). However, with consideration of the patient’s quality of life, elbow flexion is the priority for brachial plexus reconstruction because it allows for placement of the hand in space. Thus, studies focus on reconstructing the musculocutaneous nerve, proving better outcomes for ICNT with sural nerve grafts on accessory nerves. However, SANT provides better motor recovery, while ICNT provides better pain relief14).

The time interval between trauma and surgery is one of the most important factors in determining surgical outcome2,11,13). Indeed, a substantial number of studies advocate early surgical exploration of the brachial plexus6,10). Furthermore, late-phase nerve reconstructions demonstrated poor outcomes due to nerve degeneration9). Some physicians believe that there is rarely a need for surgery, assuming that most injured nerves that do not regenerate with functional recovery are not amenable to surgical repair. Unfortunately, some patients present for surgery long after the injury occurred, when they are no longer good candidates for a fair outcome.

The population affected by BPIs is heterogeneous, and surgeons must consider various factors when developing an appropriate management plan for each patient. Our study provides a decision framework for considering treatment strategies to manage patients effectively.

In our study, we compared different parameters that play an important role in successful musculocutaneous nerve reconstruction for traumatic BPIs. Specifically, combined procedures (ICNT with SANT) produced better results than ICNT alone, and surgery should be performed within 6 months of injury.