Outcomes of muscle brachialis transfer to restore finger flexion in brachial plexus palsy

Background: In adults with lower trunk brachial plexus injury, proximal nerve surgery for restoration of prehension demonstrates poor outcomes secondary to long distances required for nerve regeneration and time-dependent degradation of motor endplates. Options for reconstruction are limited to distal tendon or nerve transfers and free-functioning muscle transfers. In this article, the authors describe the long-term outcomes of brachialis muscle-to-flexor digitorum profundus transfer to restore prehension in patients with traumatic lower trunk brachial plexus injuries. Methods: Eighteen adult patients with lower trunk brachial plexus palsy underwent brachialis muscle-to-flexor digitorum profundus transfer with the goal of restoring rudimentary prehensile function at a single institution. The patients were followed throughout their recovery with functional outcomes and patient satisfaction ratings. Results: Brachialis muscle transfer resulted in restoring modified British Medical Research Council grade 3 or better function in 11 of 18 patients and grade 4 function in eight of 18 patients. Eleven of the 18 patients demonstrated a postoperative functional grasp for assistance with activities of daily living. Overall patient satisfaction following brachialis muscle transfer was 56 percent. Patient preoperative wrist extension (p < 0.018) and finger extension (p < 0.029) strength correlated with improved outcomes, whereas concomitant upper extremity fracture (p < 0.023) was associated with poorer outcomes. Conclusions: Brachialis muscle transfer is an option for reconstruction of prehensile function in patients with lower trunk brachial plexus palsy with preserved wrist extension. Brachialis muscle transfer is particularly useful in patients who are poor candidates for microsurgical free-functioning muscle transfer for grasp; however, its functional outcomes are not universally successful.