Grey-scale sonography and sonoelastography for diagnosing carpal tunnel syndrome

Figure 1 Demonstration of probe location at the forearm. The cross sectional area of the median nerve was measured (A) level with the pisiform bone (B) level with the proximal third of the pronator quadratus and (C) level with a point 12 cm proximal to the pisiform bone.

Figure 2 Transverse images in a 79-year-old female with carpal tunnel syndrome. A: A conventional grey scale sonographic image shows the cross-sectional area of the median nerve (CSA) corresponding to the circle in the normal side with an area of 8 mm² at the level of the pisiform bone; B: CSA in the carpal tunnel syndrome (CTS) side shows 21 mm² at pisiform bone level; C: CSA in the CTS side shows 7 mm² at the proximal third of the pronator quadratus level; D: CSA in the CTS side shows 6 mm² at a point 12 cm proximal to the pisiform bone. In this case, the calculated “delta CSA” and “CSA ratio” were 14 mm² and 3.5, respectively. *: Ulnar artery. FCR: Flexor carpi radialis; P: Pisiform bone; S: Scaphoid bone; PQ: Pronator quadratus muscle; R: Radius; U: Ulnar.