Delayed Salvage of a Denervated Gracilis-FFMT with a Vascularized Nerve Flap in Severe Brachial Plexus Injury

Chang Gung Memorial Hospital, Linkou Branch, Taoyuan, Taiwan

A 20-year-old male presented with a right C4-C8 root avulsion injury in 2022, with paralysis of the right shoulder, elbow, and wrist. He exhibited some finger flexion in the index and thumb but had no movement in the 3rd-5th fingers and no finger extension. An MRI revealed complete dorsal and ventral rootlet avulsion of the C4-C8 roots, with partial avulsion of the T1 root. He underwent a gracilis free functioning muscle transplantation (FFMT) innervated by the spinal accessory nerve (XI) to restore elbow flexion and finger extension (Doi’s first stage). No additional nerve transfer was performed for shoulder due to the limited availability of donor nerves. The operation went smoothly, the monitoring skin paddle was well vascularized post-operatively, and the patient was discharged smoothly. He was followed by neck splinting for 3 weeks and elbow splinting for 6 weeks. Six months post-FFMT and nine months since the injury, the patient could not elicit any response of the gracilis muscle when trying to induce trapezius muscle movement. The gracilis was atrophied, and had no palpable contraction, with electromyography showing no response. Due to very limited options for a backup plan, a delayed exploration was performed. Intraoperative findings revealed no neuroma at the coaptation site but heavy scarring around the donor nerve (XI). Minimal response was elicited from the obturator nerve by electrical stimulation. We decided to harvest the vascularized ulnar nerve graft as a free flap (VUNF): 1) connect the proximal stump to the contralateral C7, 2) directly neurotize the gracilis FFMT with one distal stump, and 3) innervate the denervated musculocutaneous nerve with the other distal stump. Three years later, the patient showed MRC M3 elbow flexion, induced by trapezius movement and the contralateral C7. Additional tenodesis was performed to augment flexion of the 5th finger.