Characteristics and dynamics of pathological changes in visual evoked potentials in multiple sclerosis

Abstract

Clarification of the characteristics and dynamics of changes in the main indicators of visual evoked potentials (VEP) for a reverse chess pattern in patients with multiple sclerosis (MS) at various stages of the disease and severity of disability. The study of VEP was carried out on 477 subjects, 120 of which were healthy volunteers and 357 patients with MS, including those with clinically isolated syndrome (CIS; 22.7%), remitting course (RT; 55.7%), primary progressive course (PPT; 8.4%), secondary progressive course (VPT; 13.2%). Disability was assessed using the Expanded Disability Status Scale (EDSS). A high sensitivity of VEP in the detection of demyelinating damage to the visual pathways, including subclinical, was noted already at the initial stages of MS, which increases with the progression of the disease from 77.8 to 97.8%. There was a significant increase in latency (r=0.42, p<0.05) and a decrease in amplitude (r= -0.26, p<0.05) of the P100 peak as the EDSS score increased. In patients with MS, 5 patterns of VEP were identified depending on the level and severity of damage to the visual pathways, where pattern 1 is normative VEP, pattern 5 is the absence of VEP recording in case of a pronounced axonal-demyelinating lesion of the visual pathways (prechiasmal/postchiasmal levels). Patterns 1 and 2 are most typical for CIS (22.2 and 53.1%) or RT (20.1 and 26.6%). Patterns 3 and 4 are typical for APT (70 and 20%) and VPT (48.9 and 21.3%), pattern 5 - for VPT (19.1%). Patterns 3-5 predominated in patients with higher EDSS (r=0.54, p<0.05). The classification of VEP changes into patterns makes it possible to identify the dissemination of a focal lesion in the projections of the visual pathways, which increases the diagnostic efficiency of the study and makes it possible to assess the severity of MS.