Dimensional changes of the carpal tunnel and the median nerve during manual mobilization of the carpal bones.

ABSTRACT

INTRODUCTION: The carpal tunnel is a clinically important fibro-osseous conduit for the median nerve and associated tendons. It is mechanically dynamic, such that the dimensions of the tunnel and median nerve change with position, movement and application of externally applied force with mechanical devices. Therapeutic manual techniques that appear to move and change tunnel shape are part of clinical practice. The aim of this study was therefore to measure changes in dimensions of the carpal tunnel and median nerve with manual mobilization of the carpal bones. MATERIAL AND METHODS: An analytical descriptive study with 18 volunteer subjects and a total of 33 records was designed. Ultrasound measurements of the cross-sectional area (CSA), anteroposterior diameter (APD), transverse diameter (TD), perimeter, flattening ratio and circularity of the carpal tunnel and of the median nerve, were measured, both in the anatomical position of the wrist and during mobilization techniques of the carpal bones. RESULTS: During the mobilization technique, the tunnel (p = 0.003) CSA significantly increased. APD also increased significantly for the tunnel (<0.001) while TD decreased. The median nerve showed similar and significant (p < 0.001) changes than the tunnel. However, because several of the obtained differences where smaller than the SDD obtained in a previous study, these differences were considered as irrelevant. CONCLUSIONS: Manual mobilization of the carpal bones produced significant changes in the dimensions of the carpal tunnel.