Quantifying Donor Deficits Following Nerve Transfer Surgery in Tetraplegia

Purpose: Nerve transfer (NT) surgery can improve function in people with cervical spinal cord injury (SCI). However, the impact of donor nerve deficits remains unclear. The purpose of this study was to quantify donor deficits experienced by individuals with cervical SCI following NT. Methods: This prospective single-arm, comparative study included people with SCI undergoing upper extremity NTs. Myometry was used to assess muscle strength at baseline and follow-up. The Spinal Cord Independence Measure was used to measure the ability to perform activities of daily living. Results: Ten individuals underwent 20 NTs to restore elbow extension (donor, posterior deltoid; n = 2), hand opening (donor, supinator; n = 7), and hand closing (donor, brachialis; n = 11). Shoulder abduction strength decreased (−5.6% at early and −4.5% late follow-up) in the elbow extension NT. Wrist extension strength decreased at early (−46.9% ± 30.3) and increased by late (76.4% ± 154.0) follow-up in the hand opening NT. No statistically significant change in elbow flexion strength was noted in the hand closing NT. Spinal Cord Independence Measure scores did not change significantly between baseline and early postoperative follow-up; they improved at late follow-up. Conclusions: Use of expendable donor nerves with redundant function to perform NT surgery has relatively little impact on strength or capacity to perform activities of daily living, even in the unique and highly vulnerable SCI population. Early, temporary loss in wrist extension strength can be seen after the supinator to posterior interosseous nerve transfer. This study offers quantitative data about possible diminution of donor function after NT, enabling hand surgeons to better counsel individuals contemplating upper extremity reconstruction. Type of study/Level of Evidence: Prognostic I.