Ultrasound-guided needle electromyography of the extensor carpi radialis longus and brevis muscles for preoperative tendon transfer planning in cervical spinal cord injuries: technique description and case report.

Abstract

Abstract: Reconstructive surgery, including tendon transfers, can potentially offer marked improvement in function in those with cervical spinal cord injuries. Given the anatomic redundancy of both the extensor carpi radialis longus (ECRL) and brevis (ECRB) in producing active wrist extension, one muscle can be utilized as a donor for a tendon transfer without sacrificing wrist extension. Needle electromyography (EMG) does not routinely evaluate the ECRL and ECRB, and the functional status of each muscle is difficult to discern based on clinical exam alone. Here is presented a case of a 20-year-old male with C6 complete tetraplegia and preserved active wrist extension who underwent a novel ultrasound (US) -guided EMG technique to accurately and reproducibly assess the ECRB and ECRL muscles. This technique was employed to aid his surgeon in determining candidacy for tendon transfer procedures utilizing the wrist extensors as donors. US-guided EMG showed intact volitional activation in both the ECRL and ECRB. Subsequent ECRL to flexor digitorum profundus tendon transfer was pursued, and he had preserved postoperative anti-gravity wrist extension strength through ECRB alone. Accurate assessment of the ECRL and ECRB allows for more complete preoperative planning and provides critical information on whether active pinch and grasp reconstruction as possible.