角膜共焦显微镜对2型糖尿病周围神经病变的诊断价值

Diagnostic value of corneal confocal microscopy in diabetic peripheral neuropathy of type 2 diabetes mellitus

目的探讨角膜共焦显微镜对2型糖尿病周围神经病变（DPN）的诊断价值及最佳诊断切点。方法2015年9月至2016年2月纳入2型糖尿病住院患者95例，男56例，女39例，平均年龄（57±14）岁。根据神经传导速度（NCV）是否异常分为DPN组（n=74）与非DPN组（n=21），受试者进行角膜共焦显微镜检查，记录角膜神经参数【神经纤维密度（CNFD）、神经分支密度（CNBD）、角膜神经纤维长度（CNFL）]。分析各参数与NCV的相关性，应用受试者工作特征曲线（ROC）评价角膜神经参数对DPN的诊断价值，并寻找最佳诊断切点。结果DPN组的各项角膜神经参数低于非DPN组。CNFD、CNBD、CNFL与正中神经、胫神经、腓神经运动神经传导速度呈正相关（相关系数r=O．348～0．453，均P〈0．01），与所有感觉神经传导速度呈正相关（r=0．203—0．478，均P〈0．05）。CNFD、CNBD、CNFL的ROC曲线下面积（AUC）为0．7～0．9，一致性检验CNFL的Kappa值最高，以CNFL≤20．6mm／mm。为DPN诊断切点时具有较高的灵敏度和特异度（82．4％，85．7％）。结论角膜共焦显微镜用于2型糖尿病DPN的诊断具有一定的诊断价值，以CNFL≤20．6mm／mm。为切点诊断DPN的灵敏度与特异度较高。

Objective To investigate the diagnostic value of corneal confocal microscopy in diabetic peripheral neuropathy （DPN） and the best diagnostic cut-off point in type 2 diabetes. Methods From September 2015 to February 2016, a total of 95 inpatients with type 2 diabetes were enrolled, including 56 males and 39 females, mean age（57±14）yrs. All the subjects were divided into DPN group and non-DPN group according to nerve conduction velocity（NCV）, and received in vivo corneal confocal microscope examination（IVCCM）. The corneal nerve fiber density （CNFD）, corneal nerve branch density （CNBD）, corneal nerve fiber length（CNFL） were recorded. The correlations between corneal nerve parameters and NCVs were analyzed. Receiver operating eharacteristic（ROC） curve was used for assessment of the values of corneal nerve parameters in diagnosis of DPN and finding best diagnostic cut-off point. Results The values of corneal nerve parameters in DPN group were significantly decreased than those in non-DPN group. The values of CNFD, CNBD, CNFL were positively correlated with motor nerve conduction velocity of median nerve, tibia1 nerve and peroneal nerve （r= 0.348-0.453, all P〈0.01）, and also positively correlated with sensory nerve conduction velocity of all the sensory nerve（r=0.203-0.478, all P〈0.05）. The areas under curve（AUC） in ROC curve of CNFD, CNBD and CNFL were among 0.7-0.9. In consistency test, Kappa value of CNFL was the highest. Taking CNFL≤20.6 mm/mm2 as the diagnostic cut-off point for DPN got the better sensitivity（82.4%） and specificity （85.7%）. Conclusion IVCCM has a certain diagnostic value in diagnosis of DPN of type 2diobetes. CNFL≤20.6 mm/mm2 as the diagnostic cut-off point for DPN may have better sensitivity and specificity.