Axillary to Triceps Nerve Transfer for Restoration of Elbow Extension in Tetraplegia: A Cautionary Tale
Jana Dengler, MD1,2, Ida K. Fox, MD3, Scott H Kozin, MD4 and Dan A Zlotolow, MD4, (1)Washington University School of Medicine, St Louis, MO, (2)Sunnybrook Health Sciences Centre, Toronto, ON, Canada, (3)Department of Surgery, Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, St. Louis, MO, (4)Shriners Hospital for Children Philadelphia, Philadelphia, PA
Introduction
Spinal cord injury (SCI) at the C7 level results in loss of triceps function, which hinders patient's ability to transfer and position their hand in space. Traditional tendon transfer techniques to restore elbow extension provide functional improvement but require splinting and post-operative non-weight bearing, which can be challenging. Nerve transfer surgery obviates immobilization and others have reported promising clinical results. The authors provide a critical summary of their clinical experience with branches of the axillary to triceps nerve transfers in SCI, with the goal of elucidating what factors contribute to the success of this procedure.
Methods
A retrospective multi-centre cohort study of people with SCI who underwent axillary to triceps nerve transfer over a 5 year period (2013-2018) was performed. Pre-operative, intra-operative and post-operative clinical and electrodiagnostic (EDX) variables were recorded. The primary outcomes were triceps Medical Research Council (MRC) grade strength at final follow-up and time to innervation. Clinical features of successful and unsuccessful nerve transfers were assessed.
Results
Ten limbs in 6 individuals with SCI were included in this study (70% male, mean age 21 ± 11 years). Motor level at time of injury was C5 (20%) or C6 (80%), and 90% had ASIA A (motor complete) patterns of injury. Nerve transfer surgery was performed 9 ± 3 months after injury, with final post-operative follow up of 25 ± 7 months. In 2 of 10 limbs, MRC grade > 3 of elbow extension was achieved. Time to reinnervation was 23 ± 3 months. Factors that correlated with successful outcomes included an excellent quality donor (as determined by pre-operative exam and electrodiagnostic testing and intra-operative stimulation and frozen section), and the absence of scarring in the recipient nerve (as determined by intra-operative frozen section).
Conclusion
In the authors' experience, the axillary to triceps nerve transfer to restore elbow extension in people with SCI needs to be approached cautiously. Careful pre and intraoperative exam of donor and recipient quality (including intraoperative frozen section testing) may optimize outcomes. Further work is needed to delineate other reasons for failure including investigation into the overlap in innervation between donor and recipients, timing of surgery and surgical technique.
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