팔목터널 증후군에서 정중-척골신경 비교 검사법의 임상적 유용성

Abstract

Objectives : In addition to the conventional nerve conduction study (Conventional NCS), several new techniques have been developed to improve the diagnostic sensitivity for the carpal tunnel syndrome (CTS). This study is performed to ascertain whether these new techniques are better than the previously reported conventional studies. Methods : In 40 patients of clinically suspected CTS, we performed on both hands the conventional NCS and three median to ulnar comparative tests which consists of: (1) the difference between median and ulnar motor latencies recorded from the second lumbrical and interossei muscles(2L-INT); (2) the difference between median and ulnar sensory nerve conduction velocities(NCV)from digit 4 stimulation(D4M-D4U); (3) the difference between median and ulnar mixed nerve conduction velocities(NCV) from palmar stimulation(PM-PU). also, we calculated the following diagnostic criteria: (1) the difference of median ro ulnar terminal latencies; (2) the difference of median to ulnar sensory NCV over F-W segment; and (3) the median to ulnar SNAP ratio, the results of conventional NCS. Results : 1) Among the 40 patients, 30 patients(75%) were clinically bilateral CTS, and the other 10 patients(25%) were unilateral CTS. 2) In symptomatic hands of CTS patients, the electrophysiological abnormalities were found in 75.5-88.6% on the standard criteria, 77.1-92.9% on the median to ulnar comparative test, and 65.7-94.2% on the calculated criteria. In asymptomatic hands 30-80% revealed abnormalities. 3) The most sensitive diagnostic test of CTS was the (M-U)FW followed by the PM-PU, Median FW, 2L-INT, Median TL in descending order of sensitivity. 4) The diagnostic sensitivity between conventional NCS and median-ulnar comparative test were not significantly different. Conclusion : We concluded that detailed interpretation of conventional NCS was more desirable than using three median to ulnar comparative tests in the diagnosis of clinically suspected CTS.