| Objective:We observed the ultrasonic characteristics of carpal tunnel syndrome(CTS)by high-frequency ultrasound and shear wave elastography(SWE),and analyzed cross-sectional area(CSA),nerve flat rate(FR),elastic modulus(E)and the transverse ligament thickness at the pisiform bone level,aiming to respectively explore the value of high-frequency ultrasound and SWE in the diagnosis of CTS.Methods:The CTS group recruited 55 cases(101 wrists)of CTS patients from the First Affiliated Hospital of Guangxi Medical University from April to November in 2019.All patients were diagnosed with CTS according to clinical physical examination and electrophysiological examination.During the same period,56 cases(112 wrists)of volunteers without CTS symptoms from the ultrasound department of the First Affiliated Hospital of Guangxi Medical University were enrolled as the control group.Each subject was collected gender,age,height,weight,occupation information.The body mass index(BMI)was calculated based on their height and weight.All subjects underwent the following ultrasound examination:(1)We observed the characteristics of the median nerve imaging in the carpal tunnel,including its movement,echo,internal structure and blood flow signal by high-frequency ultrasound.In the transverse section we measured the median nerve CSA at the pisiform bone level,and transverse diameter and anteroposterior diameter of the median nerve were measured to calculate the median nerve FR.The transverse carpal ligament thickness was measured in the longitudinal section at the same level.(2)We observed the median nerve in the carpal tunnel and measured E of the median nerve in the longitudinal section at the pisiform bone level by SWE.The SPSS25.0 was used for statistical analysis.Results:1.There were 101 wrists in 55 cases of the CTS group and 112wrists in 56 cases of the control group.Most patients in the CTS group were engaged in farm work,cleaning or other heavy manual work for a long time.There was no significant difference in gender,age and height between the two groups(all P>0.05).There were statistically significant differences in weight and BMI between the two groups(all P<0.05).2.High-frequency ultrasound showed:(1)the two-dimensional ultrasound performance:In the CTS group,the median nerve presented diffuse or localized swelling,reduced echo or blurred texture,internal structure disorder,and the parallel lines echo and mesh structure blur or disappear.Nerve were flattened and CSA increased in the transverse section.Nerve swelling and uneven thickness,with"notch"or"inverted notch"in the longitudinal section.The transverse carpal ligament had thickened.In the control group,the median nerve showed parallel arrangement and incomplete continuous structure,the whole was uniformly low echo,and in the transverse section showed round or"sieve"or"honeycomb"structure.The longitudinal section presented a strip-like hypoechoic sign,with several parallel hypoechoic sign(nerve bundles),separated by parallel but incompletely continuous linear echoes(nerve bundle membrane),both sides of which were high echo epineurium.The echo of the nerve is lower than the surrounding tendon.The transverse carpal ligament showed a thin strip hyperechoic structure which attached to the median nerve.(2)The blood flow situation:In the CTS group,color doppler flow imaging(CDFI)of the median nerve most showed as rod,strips,multidots signal(69.3%).In the control group most showed no or spot signal(93.7%).Nerve blood flow signals were significantly increased in the CTS group.(3)The two-dimensional ultrasound parameters:in the CTS group,CSA,FR and the transverse carpal ligament thickness average were(0.15±0.04)cm~2,(3.07±0.81),(0.26±0.06)cm,respectively;in the control group they were(0.09±0.02)cm~2,(2.34±0.57),(0.23±0.04)cm,respectively.CSA,FR,the transverse carpal ligament thickness were greater than that of the control group(all P<0.001).3.SWE showed:In the CTS group the median nerve area of elastic image appeared in blue-yellow or red,and the control group was mostly appeared in blue or blue-green,which indicated that the nerve stiffness in the CTS group was higher.E average in the CTS group and the control group were(118.85±32.44)k Pa and(63.84±11.06)k Pa,respectively.E in the CTS group was significantly greater than that of the control group(P<0.001).4.Establishing the ROC curve to analyze the ultrasonic parameters of the CTS group.The area under curve of E,CSA,FR,the transverse carpal ligament thickness were 0.957,0.935,0.779,0.692,respectively;the optimal threshold value were 83.59k Pa,0.115cm~2,2.27,0.265cm,respectively;the sensitivity were 87.1%,80.2%,91.1%,46.5%,respectively;the specificity were 97.3%,93.7%,51.8%,83.9%,respectively.Comparing the area under the ROC curve of each ultrasonic parameter showed that the diagnostic efficacy of E and CSA was similar,and the diagnostic efficacy of E and CSA was better than that of FR and the transverse carpal ligament thickness.Conclusion:1.High-frequency ultrasound can clearly display the morphological changes of the median nerve,blood flow signals and changes of the transverse ligament carpal thickness,and the measured values of the median nerve cross-sectional area showed high diagnostic value.In this study,the optimal threshold value is 0.115cm~2for diagnosing CTS.2.SWE can display the stiffness information of the median nerve,and the elastic modulus showed high diagnostic value.In this study,the optimal threshold value is 83.59kpa for diagnosing CTS.3.The diagnostic efficacy of the elastic modulus and the cross-sectional area of the median nerve was similar,and the diagnostic efficacy of both was superior to that of the median nerve flattening rate and the transverse ligament carpal thickness.4.SWE as an emerging technology,is the effective complement to traditional ultrasound.Using SWE to provide the median nerve stiffness information and high-frequency ultrasound to reflect nerve structural changes which can provide new perspective for diagnosing CTS and have good clinical diagnostic value. |
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