Objective
To compare the diagnostic value between Phalen's test and reverse Phalen's test using a morphological change of the median nerve and the carpal tunnel seen by high-resolution ultrasonography and to research on an ultrasonography as an available tool for the screening and follow up aid-test of the carpal tunnel syndrome (CTS).
Method: A cross-sectional area and a flattening ratio of the median nerve, and a cross-sectional area of the carpal tunnel were measured in neutral, maximally flexed (Phalen's test), and maximally extended (reverse Phalen's test) positions in 59 wrists of 30 normal subjects.
Results: The cross-sectional area of median nerve was significantly decreased in maximal flexion (p＜0.01), and in maximal extension (p＜0.01). The mean flattening ratio of median nerve was revealed significant change in maximal flexion (p＜0.01), and in maximal extension (p＜0.01). The mean cross-sectional area of the carpal tunnel was significantly decreased in maximal flexion (p＜0.01), and in maximal extension (p＜0.01), with comparing to neutral position, respectively.
Conclusion: Phalen's test reveals higher degree of irritation to median nerve. The high-resolution ultrasonography is suggested as an available tool for the screening and follow up aid-test for the CTS. (J Korean Acad Rehab Med 2003; 27: 228-231)
