John Thomas, Mathew Asha Elizabeth
Department of Neurology, Amala Institute of Medical Sciences, Amala Nagar, Thrissur, Kerala, India.
Department of Physical Medicine and Rehabilitation, Amala Institute of Medical Sciences, Amala Nagar, Thrissur, Kerala, India.
Ann Indian Acad Neurol. 2022 Jan-Feb;25(1):92-99. doi: 10.4103/aian.aian_305_21. Epub 2021 Dec 7.
Previous researchers have used a 30-min eutectic mixture of local anesthetic (EMLA) test, which assesses the sympathetically mediated vasomotor function, in diagnosing carpal tunnel syndrome (CTS). However, its specificity was low, limiting its clinical diagnostic utility. In this study, we assessed the efficiency of 90-min extended EMLA-induced stimulated skin-wrinkling (SSW) test in CTS diagnosis.
A cross-sectional study was designed among patients clinically diagnosed with CTS. Hands of healthy volunteers and the asymptomatic hands of selected patients served as control. The Boston symptom severity scale (SSS) and the neuropathic pain severity inventory (NPSI) were used to assess symptom severity, and nerve conduction study (NCS) was used to assess electrophysiological severity. EMLA-induced SSW was visually graded after 90 min of application and correlated with symptom and NCS severities.
Forty-two symptomatic hands and 30 asymptomatic hands were enrolled as cases and controls, respectively. The diagnostic efficiency of the extended EMLA test was found to be 83.4% for digit 2 and 87.3% for the lateral 4 digits (mean), whereas the diagnostic efficiency of standard NCS was 88.1%. Boston SSS and NPSI were better correlated with EMLA positivity than NCS positivity. A linear regression analysis showed negative correlation of wrinkling grade with NCS grade.
With its improved diagnostic efficiency, the 90-min extended EMLA test can feasibly be used as an alternative to NCS, especially in general practice settings. Its potential clinical utility should be explored in a large population of CTS patients showing varying clinical and electrophysiological severities.
既往研究人员使用局部麻醉剂共熔混合物（EMLA）进行30分钟测试，该测试用于评估交感神经介导的血管运动功能，以诊断腕管综合征（CTS）。然而，其特异性较低，限制了其临床诊断效用。在本研究中，我们评估了90分钟延长EMLA诱导的刺激性皮肤皱纹（SSW）测试在CTS诊断中的有效性。
对临床诊断为CTS的患者进行横断面研究。健康志愿者的手以及部分患者无症状的手作为对照。使用波士顿症状严重程度量表（SSS）和神经性疼痛严重程度量表（NPSI）评估症状严重程度，使用神经传导研究（NCS）评估电生理严重程度。应用EMLA 90分钟后，通过视觉对诱导的SSW进行分级，并与症状和NCS严重程度相关联。
分别纳入42只患侧手和30只无症状手作为病例组和对照组。发现延长EMLA测试对第2指的诊断效率为83.4%，对外侧4指（平均）的诊断效率为87.3%，而标准NCS的诊断效率为88.1%。与NCS阳性相比，波士顿SSS和NPSI与EMLA阳性的相关性更好。线性回归分析显示皱纹分级与NCS分级呈负相关。
90分钟延长EMLA测试具有更高的诊断效率，可切实用作NCS的替代方法，尤其是在全科医疗环境中。应在大量临床和电生理严重程度各异的CTS患者中探索其潜在的临床效用。
