Investigating the Relationship Between Visual Evoked Potentials, Neurological and Neuropsychological Status in Primary Progressive Multiple Sclerosis

Background/Objectives: Visual evoked potential (VEP) P100 maximum latency is known to predict fatigue and cognition in multiple sclerosis (MS). However, the relationship between VEP and neurological (impairment)/neuropsychological status is not well understood in MS. Therefore, the aim of the present prospective cross-sectional study was to investigate associations among VEP, neurological impairment, and neuropsychological status in MS. Methods: The study included 25 subjects with primary progressive MS (PPMS), with a median EDSS score of 4.5, and 30 control subjects. Neurological status of PPMS subjects was evaluated with the Expanded Disability Status Scale (EDSS), while neuropsychological assessment included the Symbol Digit Modalities Test (SDMT), Nine-Hole Peg Test (9HPT), Fatigue Severity Scale (FSS), Depression, Anxiety and Stress Scale (DASS-21), and Multiple Sclerosis Impact Scale (MSIS-29). Statistical analysis included group comparisons, Spearman correlations, multivariable linear regression analyses, bidirectional stepwise selection, and a parsimonious multivariable model. Results: PPMS subjects had significantly prolonged P100 maximum latencies (p < 0.01) compared to control subjects, as well as significantly poorer performance on the 9HPT (p < 0.01) and higher fatigue scores (FSS; p < 0.01). In multivariable analyses within the PPMS group, disease duration was independently associated with the EDSS (p = 0.009), whereas neuropsychological measures were intercorrelated (ρ > 0.45) and associated with the EDSS at intermediate stages of model selection. P100 maximum latency showed a positive but non-significant association after adjustment for sex and disease duration in the parsimonious model, which explained approximately 49% of the variance in the EDSS. Conclusions: The findings provide insight into the complex interplay among neurophysiological (VEP), neuropsychological and neurological status in MS.