角膜共焦显微镜对于糖耐量异常患者周围神经病变的早期诊断

Early diagnosis of peripheral neuropathy by corneal confocal microscopy in patients with impaired glucose tolerance

目的通过角膜共焦显微镜（CCM）观察糖耐量异常（IGT）患者角膜神经的形态改变，量化分析和周围神经病变的相关性。方法入选70例IGT患者，其中30例有周围神经病变，其余40例不伴有周围神经病变，另外选人年龄性别匹配的50名健康对照者，通过CCM观察所有入选者角膜上皮下神经的形态，量化分析各组间的不同。结果IGT不伴周围神经病变者角膜神经纤维密度与健康对照组相比差异无统计学意义，但角膜上皮下神经纤维长度[（17．1±4．9）mm／mm^2与（14．0±3．8）mm／mm^2]，神经曲折度[（2．07±0．76）级与（0．88±0．55）级]明显增加（t=13．484、12．957，均P〈0．05），神经分支密度[（53．1±18．8）mm／mm^2与（36．2±11．5）mm／mm^2]亦明显增加（t=9．369，P〈0．01）。而IGT合并周围神经病变组相比于健康对照组、IGT不伴周围神经病组，神经纤维长度、角膜神经纤维密度、神经分支密度均明显减少，神经曲折度进一步增加，差异均有统计学意义。结论糖代谢异常患者在未诊断糖尿病前，就已经出现角膜神经形态改变；IGT患者在未出现周围神经病变前，就已经出现角膜神经形态改变，提示使用CCM进行角膜上皮下神经的形态结构观察对周围神经病变的早期诊断有一定的价值。

Objective To investigate the relationship between alterations in the corneal innervation observed by laser confocal microscopy and peripheral neuropathy severity in the patients with impaired glucose tolerance （IGT）. Methods A total of 70 patients with IGT were consecutively enrolled into the study. Among them, 30 patients were diagnosed as peripheral neuropathy （ IGT-PN）, 40 patients without peripheral neuropathy （IGT-NPN）. Fifty age-matched healthy subjects were also studied. Corneal subbasal nerves were investigated by laser confocal microscopy. Results Corneal nerve fiber length （ 17. 1 ±4. 9） vs （14.0±3.8） mm/mm^2; t = 13.484,P〈0.05）, nerve branch density （（53.1±＋18.8） vs （36.2 ±11.5） mm/mm^2 ; t = 9. 369, P 〈 0. 01 ） and nerve fibre tortuosity （ （ 2. 07 ± 0. 76 ） vs （ 0. 88± 0. 55 ） levels, t = 12. 957 ,P 〈 0. 05 ）were significantly increased in IGT-NPN group when compared with control group, but nerve fibre density had no difference. Nerve fiber length, nerve braneh density and nerve fibre density were signifieantly decreased in IGT-PN group compared with eontrol group and IGT-NPN group , while NFT was significantly increased in IGT-PN group. Conclusions Patients with impaired glucose metabolism show alterations in corneal innervations before diagnosed with diabetes mellitus or peripheral neuropathy. It indieates that corneal confocal microscopy ean be used for early diagnosis of diabetie peripheral neuropathy.