Diagnostic Musculoskeletal Ultrasound in the Evaluation of the Carpal Tunnel and Median Nerve

Abstract

The carpal tunnel is a fibro-osseous canal at the wrist that is formed by the retinaculum and bony structures. The superficial border is composed of the flexor retinaculum, the floor of the tunnel is formed by the carpal bones, the medial (ulnar) border by the hamate, and the lateral (radial) border by the trapezium. Contents that originate in the forearm and run distally through the carpal tunnel include the finger and thumb flexors and the median nerve. Carpal tunnel syndrome, when the median nerve becomes compressed or entrapped, occurs due to various issues that will be discussed in this paper. Diagnostic musculoskeletal ultrasound (MSKUS) offers a portable, real-time, and cost-effective alternative that is gaining traction in rehabilitation and sports medicine settings. MSKUS has emerged as a valuable, non-invasive imaging modality for evaluating the size of the carpal tunnel and median nerve at the level of the wrist. MSKUS is excellent at detecting changes in carpal tunnel size, median nerve composition, thickness, and continuity. This manuscript will review the utility of MSKUS in evaluating carpal tunnel syndrome, including anatomy, common injury mechanisms, sonographic techniques, and clinical implications for those in the rehabilitation profession. Due to the confined area within the carpal tunnel and the number of structures that traverse through it, it is a very common site of pathology and symptoms. With a proper medical history and clinical examination, diagnosis is straightforward for this pathology. By integrating MSKUS into clinical practice, providers can improve the accuracy of diagnosis, enhance diagnostic confidence, monitor healing progression, and guide rehabilitation strategies to optimal patient outcomes for those with carpal tunnel overuse or injury.