O-MN004. The selective and inverse u-shape curve alteration of retinal nerve fiber layer in ALS: A potential mirror of the disease

Abstract

Introduction. The alteration of the visual pathway involving retina has been reported in amyotrophic lateral sclerosis (ALS), but lack of consistency and subgroup analysis. We aim to assess the retinal nerve fiber layer (RNFL) alteration in different stages of ALS patients and its association with ALS progression parameters. Methods. Study population consisted of 70 clinically diagnosed ALS patients and 48 matched controls. All of them underwent glaucoma screening tests and Optical Coherence Tomography (OCT) imaging. Four quadrants of peripapillary RNFL (pRNFL) were observed and automated measured. Early stage distal motor neuron axon dysfunction in ALS was detected by compound muscle amplitude potential (CMAP) of distal limbs within 12 months. The ALS disease parameters including ALSFRSR score and disease progression index (DPI, (48-FRSR score)/months from symptom onset). Results. Generally compared with controls, the nasal (p = 0.00) and temporal (p = 0.03) quadrants of pRNFL were significantly thicker in ALS patients when controlling for age and DPI. The pRNFL was significantly thickened as disease progressed (r = 0.37, p = 0.04) within 12 months, while declined with time (r = -0.47, p = 0.02) after one year. ALS patients were sub- divided into thicken-RNFL (T-RNFL, >control mean + SD) and impaired-RNFL (I-RNFL) Conclusion. The alteration of retinal nerve was not consistent in ALS patients with diverse phenotypes and progression rates. In our study, the pRNFL thickened during the first year and then gradually declined. This inverse U-shape curve transformation might be due to the initially priming and then inflammatory reaction of microglia intermingled between retinal nerve axons, and was in accordance with early stage motor neuron inflammation and axonopathy.