Carpal tunnel syndrome assessment with ultrasonography: value of inlet-to-outlet median nerve area ratio in patients versus healthy volunteers.

Tengfei Fu,Yiming Xu,Gang Wang,Fang Liu,Xianxuan Feng,Manlin Cao,Dongmei Ye,Yuehong Bai,Jiaan Zhu,Cordula M Stover

doi:10.1371/journal.pone.0116777

Tengfei Fu, Yiming Xu + Show 8 more

Open Access

https://doi.org/10.1371/journal.pone.0116777

Copy DOI

Abstract

ObjectiveTo evaluate the diagnostic value of the Inlet-to-outlet median nerve area ratio (IOR) in patients with clinically and electrophysiologically confirmed carpal tunnel syndrome (CTS).MethodsForty-six wrists in 46 consecutive patients with clinical and electrodiagnostic evidence of CTS and forty-four wrists in 44 healthy volunteers were examined with ultrasonography. The cross-sectional area (CSA) of the median nerve was measured at the carpal tunnel inlet (the level of scaphoid-pisiform) and outlet (the level of the hook of the hamate), and the IOR was calculated for each wrist. Ultrasonography and electrodiagnostic tests were performed under blinded conditions. Electrodiagnostic testing combined with clinical symptoms were considered to be the gold standard test. Receiver operating characteristic (ROC) curves were used to evaluate the diagnostic value between the inlet CSA and IOR.ResultsThe study population included 16 men and 30 women (mean age, 45.3 years; range, 18–83 years). The control population included 18 men and 26 women (mean age, 50.4 years; range, 18–79 years). The mean inlet CSA was 8.7 mm2 in healthy controls and 14.6mm2 in CTS group (P<0.001). The mean IOR in healthy volunteers (1.0) was smaller than that in patients (1.6, P<0.001). Receiver operating characteristic analysis revealed a diagnostic advantage to using the IOR rather than the inlet CSA (P<0.01). An IOR cutoff value of ≥ 1.3 would yield 93% specificity and 91% sensitivity in the diagnosis of CTS.ConclusionThe IOR of median nerve area promises to be an effective means in the diagnosis of CTS. A large-scale, randomized controlled trial is required to determine how and when this parameter will be used.

Highlights

Carpal tunnel syndrome (CTS) is a combination of signs and symptoms due to compression and trapping of the median nerve at the wrist
Receiver operating characteristic analysis revealed a diagnostic advantage to using the Inlet-to-outlet median nerve area ratio (IOR) rather than the inlet cross-sectional area (CSA) (P
The IOR of median nerve area promises to be an effective means in the diagnosis of CTS

Summary

Introduction

Carpal tunnel syndrome (CTS) is a combination of signs and symptoms due to compression and trapping of the median nerve at the wrist. It is the most commonly reported peripheral nerve entrapment syndrome. CTS is typically diagnosed by history and physical examination and electrodiagnostic study results [3,4]. The measurement of cross-sectional area (CSA) of the median nerve at the wrist is the most widely used ultrasonography method in CTS diagnosis. The sensitivity and specificity range from 70 to 88% and 57 to 97%, respectively [12] Much of this variability can be attributed to different study conditions and measurement techniques, along with factors such as age, weight and gender. A ratio would be less affected by differences in measurement technique [14]

Methods

Results

Conclusion