Post-Operative Morphometric Analysis of Carpal Tunnel Syndrome using High Resolution Ultrasonography

ABSTRACT

We evaluated the morphologic changes that follow division of transverse carpal ligament in patients with carpal tunnel syndrome using high resolution sonography. Twenty hands of 10 patients underwent high- resolution ultrasonographic studies before the operation and 8 months after the operation. They were all diagnosed as bilateral idiopathic CTS. We evaluated the configuration of the median nerve and carpal tunnel at different three levels of the wrist; the distal radiocarpal joint level, the pisiform level, and the hook of hamate level. The median nerve remarkably gained its thickness at distal two levels after the operation. The morphology of carpal tunnel has also changed at distal levels. Increase in the anteroposterior diameter at distal two levels was obvious, but the cross sectional area of the carpal tunnel was increased significantly only at the hook of hamate level. The transverse diameters of the carpal tunnel were not significantly changed. As above, we found that the median nerve gained its volume significantly at distal part of carpal tunnel postoperatively, and the volumetric increase of carpal tunnel would have resulted from an anterior displacement of newly formed transverse carpal ligament and not from a widening of the bony carpal arch.