American Society for Peripheral Nerve

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Salvaging a Missed Opportunity: The Inverted Free Functional Gracilis Muscle Transfer for Restoration of Elbow Flexion Following an Upper Trunk Injury
Sean M. Wade, MD; Leon J. Nesti, MD; Robert T. Howard, MD; Matthew E. Miller, MD; Jonathan K. Smith, MD; Jason M. Souza, MD
Walter Reed National Military Medical Center, Bethesda, MD

Background: Following injury to the upper trunk of the brachial plexus, elbow flexion can be restored with fascicular nerve transfers from the ulnar and/or median nerves. However, delayed presentation or a failed fascicular nerve transfer may result in native elbow flexors that are no longer suitable for reinnervation. In this setting, restoration of elbow flexion can be achieved with a free functional gracilis transfer. As typically described, the gracilis' origin is anchored to the clavicle and its tendinous insertion woven into the biceps aponeurosis. This conventional flap orientation places the recipient obturator nerve near the clavicle, where it is commonly coapted to the spinal accessory nerve. However, given the superiority of intra-plexal donor nerves over extra-plexal sources for functional muscle transfer, an upper trunk injury allows for use of lower trunk fascicles to power the transferred gracilis. This case describes the first report of inverting the gracilis to orient the obturator nerve closer to the donor median or ulnar nerve fascicles in the distal upper arm. The goal of this modified orientation is to decrease the time to reinnervation, while facilitating use of a superior donor nerve source and preserving the spinal accessory nerve for restoration of shoulder function.

Methods: A 32 year-old man with a traumatic C5-C6 brachial plexus injury presented to our clinic with a persistent upper trunk palsy 2 years after undergoing an upper trunk nerve grafting procedure at an outside institution. In an attempt to restore elbow flexion, the patient underwent an inverted gracilis transfer, whereby the origin of the muscle was anchored to the biceps aponeurosis and the tendon sutured to the clavicle. The median nerve fascicle to the flexor carpi radialis was coapted to the obturator nerve approximately 5cm from the motor entry point. Vascular anastomosis was performed end-to-side to the brachial artery.

Results: Electrophysiologic evidence of reinnervation was detectable within 4 months of the procedure. M4 elbow flexion was obtained approximately 9 months following surgery. The patient retained M5 wrist flexion.

Conclusion: The presented case provides proof of concept that inverting the orientation of a conventional free functional gracilis transfer can facilitate use of an intra-plexal donor nerve in the setting of a failed nerve transfer or delayed presentation of an upper trunk brachial plexus injury. Orienting the recipient obturator nerve closer to its donor appears to decrease the time to reinnervation and should optimize functional restoration of elbow function for these patients.

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