A Clinical Study Of Ultrasonogaphic Median Nerve Cross-sectionareas Measurementin The Diagnosis Of Carpal Tunnel Syndrome

Objective:This study aims to determin the value of ultrasonography in the diagnostic of Carpal tunnel syndrome(CTS) by conducting both ultrasonography and Nerve conduction study to CTS patients. This study used ultrasonography to measure the median nerve's cross-section areas (CSAs) and to correlate with the nerve conduction study (NCS) severity and duration of carpal tunnel syndrome(CTS).Method:There are totally 70 hands of 49 people enrolled in this study, in which thirty six (36)"CTS-hands" from 26 CTS patients, who came to the neurology clinic complaining of upper arm sensory abnormality like numbness or pain and were then diagnosed with Carpal tunnel syndrome(CTS) through nerve conduction study.34 asymptomatic hands, "A-hands", came from 23 control individuals who were healthy volunteers currently doing physical examination in the same hospital with no sensory abnormality. The median nerve CSAs were measured at the 8-point,where represent levels at 4,3,2, and 1 cm distal to the wrist crease in the inlet of the carpal tunnel, the level of the wrist crease and levels at 1,2, and 3cm proximal to the wrist crease in the outlet of the carpal tunnel. To evaluate differences in CSA value at the 8-point tested between asymptomatic and CTS hands group, the Mann-Whitney U test or t test was used for comparison. The diagnostic criteria was based on the clinic symptoms and nerve conduction study results.The area under the ROC (Receiver Operating Characteristic) curves was calculated to determine the CSA cut-off-values, sensitivity, specificity of CSA diagnostic value. CTS patients were classified into three groups of mild, moderate, and severe group by NCS severity. And for comparative analysis, the duration of CTS was classified into three groups of less than three month, three month to twelve months, and over twelve months. The T test or Mann-Whitney U test was used for comparison among groups to evaluate differences in the CSA value. Significance was set at p<0.05 in the Mann-Whitney U tests or T test.Results:1. The comparative results revealed no significance(P>0.05) in age, sex, and height between A-hands and CTS-hands and significant difference in weight(P<0.05).2.The comparative results of CSAs at the 8-point of A-hands and CTS-hands revealed significantly difference(P<0.05). After comparison of the CSAs under the ROC, the largest area was 0.874 at the site of 4cm distal to the wrist crease in the inlet of the carpal tunnel,where the cut-off-values of the significant sites were 0.095cm2. The sensitivity is 88.9%, specificity is 76.5%.3. The measured CSAs in the A-hands group and the mild to extreme NCS severity groups were compared. The mild groups showed significant(P<0.05) difference at 4,3, 2, and 1 cm distal to the wrist crease in the inlet of the carpal tunnel. The moderate to severe groups showed significant(P<0.05)difference at the 8-point in comparison with A-hands group.4.The CSAs of A-hands were compared to those of CTS-hands with different CTS symptom duration. The comparative resultsshowed that CSAs of the"CTShands" with symptom duration 3-12monthsand>12 months were significantly(P<0.05) different from the CSAs of "A-hands".The difference between theCSAs of the"A-hands"and the"CTS-hands"with symptom duration<3 months was not significant(P>0.05).5.One median nerve was found to be variation in CTS-hands group duringexamination, and one median artery was found in the upper arm from A-hands group.Conclusion:1.High-resolution ultrasonography, the results of which have positive correlation with NCS results, is an effective way to help diagnose carpal tunnel syndrome by measuring the cross-section area of the median nerve.2.The cut-off-values at the site of 4cm distal to the wrist crease in the inlet of the carpal tunnel were>0.095cm2, which is of high diagnosis value.3. The CSAs of median nerve are correlative to the severity and duration of CTS.4.The factor of weight may have a correlation with CTS.5.High-resolution ultrasonography could show the exact position of median nerve and its adjacent vessel and variation, which could offer surgeons with local anatomical information.