Corneal confocal microscopy detects small-fiber neuropathy in patients with amyotrophic lateral sclerosis

Abstract

Objective: To investigate small fiber neuropathy in patients with amyotrophic lateral sclerosis (ALS) by corneal confocal microscopy. Methods: A total of 57 ALS patients were consecutively enrolled in Department of Neurology between June 2015 and February 2016, including 37 men and 20 women with mean age 24-80 (52±11) years. There were 30 controls including 21 men and 9 women with mean age 23-76 (55±13) years. All subjects underwent corneal confocal microscopy (CCM), contact heat evoked potential (CHEP) and skin sympathetic reflection (SSR) to quantify small nerve fiber pathology. Four parameters, such as nerve fiber length (NFL), nerve branch density (NBD), nerve fiber density (NFD) and nerve fiber tortuosity (NFT) were assessed by corneal confocal microscopy. All statistical calculations were conducted using SPSS version 12.0. Results: Compared with control group, corneal nerve fiber length (NFL),nerve fiber density (NFD) were significantly decreased [(12.2±4.4)mm/mm2 vs.(15.1±4.5) mm/mm2,P=0.028;(50.8±24.0)/mm2 vs. (68.3±16.4)/mm2,P=0.002],and nerve fiber tortuosity (NFT) were significantly increased [(2.6±1.0)level vs.(1.0±0.5)level, P<0.01)] in SFN group, while nerve branch density (NBD) were comparable (P=0.700).The course of disease is correlated with NFT (r=0.25,P=0.030). Conclusions: CCM is a new sensitive noninvasive clinical technique that detects early small fiber nerve damage in patients with ALS.