Restoration of elbow flexion by transfer of the phrenic nerve to musculocutaneous nerve after brachial plexus injuries

Abstract

Traumatic brachial plexus injuries are a devastating injury that results in partial or total denervation of the muscles of the upper extremity. Treatment options that include neurolysis, nerve grafting, or neurotization (nerve transfer) has become an important procedure in the restoration of function in patients with irreparable preganglionic lesions. Restoration of elbow flexion is the primary goal in treating patients with severe brachial plexus injuries. Nerve transfers are used when spinal roots are avulsed, and proximal stumps are not available. In the present study, we analyze the results obtained in 20 patients treated with phrenic-musculocutaneous nerve transfer to restore elbow flexion after brachial plexus injuries. A consecutive series of 25 adult patients (21 men and 4 women) with a brachial plexus traction/crush lesion were treated with phrenic-musculocutaneous nerve transfer, but only 20 patients (18 men and 2 women) were followed and evaluated for at least 2 years postoperatively. All patients had been referred from other institutions. At the initial evaluation, eight patients received a diagnosis of C5-6 brachial plexus nerve injury, and in the other 12 patients, a complete brachial plexus injury was identified. Reconstruction was undertaken if no clinical or electrical evidence of biceps muscle function was seen by 3 months post injury. Functional elbow flexion was obtained in the majority of cases by phrenic-musculocutaneous nerve transfer (14/20, 70%). At the final follow-up evaluation, elbow flexion strength was a Medical Research Council Grade 5 in two patients, Grade 4 in four patients, Grade 3 in eight patients, and Grade 2 or less in six patients. Transfer involving the phrenic nerve to restore elbow flexion seems to be an appropriate approach for the treatment of brachial plexus root avulsion. Traumatic brachial plexus injury is a devastating injury that result in partial or total denervation of the muscles of the upper extremity. Treatment options include neurolysis, nerve grafting, or neurotization (nerve transfer). Neurotization is the transfer of a functional but less important nerve to a denervated more important nerve. It has become an important procedure in the restoration of function in patients with irreparable preganglionic lesions. Restoration of elbow flexion is the primary goal in treating patients with severe brachial plexus injuries. Nerve transfers are used when spinal roots are avulsed, and proximal stumps are not available. Newer extraplexal sources include the ipsilateral phrenic nerve as reported by Gu et al. (Chin Med J 103:267-270, 1990) and contralateral C7 as reported by Gu et al. (J Hand Surg [Br] 17(B):518-521, 1992) and Songcharoen et al. (J Hand Surg [Am] 26(A):1058-1064, 2001). These nerve transfers have been introduced to expand on the limited donors. The phrenic nerve and its anatomic position directly within the surgical field makes it a tempting source for nerve transfer. Although not always, in cases of complete brachial plexus avulsion, the phrenic nerve is functioning as a result of its C3 and C4 major contributions. In the present study, we analyze the results obtained in 20 patients treated with phrenic-musculocutaneous nerve transfer to restore elbow flexion after brachial plexus injuries.

Figure 1

Operative photograph showing transfer of the phrenic nerve to the musculocutaneous nerve. a Exposure of C6 root avulsed (Penrose drain and white arrow) and the phrenic nerve on the surface of the scalenus anterior (black arrow). b The phrenic nerve (large black arrow) was distally transected and neurotized with the MC nerve via the sural nerves (large white arrow). Tension and pressure at the suture site must be avoided during the repair (two small black arrows).

Figure 2

Photograph of the patient in Case 1 after surgical treatment of C-5 and C-6 nerve root avulsion. Flexion of the elbow joint against gravity was possible after operation in most cases. Note the bulk of the previously paralyzed left biceps muscle.