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

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 and brevis in producing active wrist extension, one muscle can be utilized as a donor for a tendon transfer without sacrificing wrist extension. Needle electromyography does not routinely evaluate the extensor carpi radialis longus and extensor carpi radialis brevis, and the functional status of each muscle is difficult to discern based on clinical exam alone. Here is presented a case of a 20-yr-old man with C6 complete tetraplegia and preserved active wrist extension who underwent a novel ultrasound-guided electromyography technique to accurately and reproducibly assess the extensor carpi radialis brevis and extensor carpi radialis longus muscles. This technique was employed to aid his surgeon in determining candidacy for tendon transfer procedures utilizing the wrist extensors as donors. Ultrasound-guided electromyography showed intact volitional activation in both the extensor carpi radialis longus and extensor carpi radialis brevis. Subsequent extensor carpi radialis longus to flexor digitorum profundus tendon transfer was pursued, and he had preserved postoperative antigravity wrist extension strength through extensor carpi radialis brevis alone. Accurate assessment of the extensor carpi radialis longus and extensor carpi radialis brevis allows for more complete preoperative planning and provides critical information on whether active pinch and grasp reconstruction as possible.