Evidence of Subclinical Visual Pathway Dysfunction in Polio Survivors: A Visual Evoked Potential Study

Objective: The aim of this study was to assess visual evoked potential (VEP) abnormalities as indicators of subclinical visual pathway dysfunction in polio survivors (PSs) and to examine the relationship between visual cortical excitability and fatigue severity.

Thirty PSs with a history of childhood poliomyelitis and 30 healthy age- and sex-matched controls underwent pattern-reversal VEP (PRVEP) and flash VEP testing between July 2022 and November 2024 in this prospective case-control study. Participants with ophthalmologic, neurological, or systemic diseases affecting visual pathways were excluded. Fatigue Severity Scale (FSS) scores were assessed in all PSs.

Compared to controls, PSs demonstrated significantly reduced amplitudes of the positive wave appearing approximately 100 ms after the stimulus (P100) in PRVEP recordings (p < 0.05), while latencies and flash VEP amplitudes were comparable. VEP responses were unobtainable in two PSs. Seven of the PSs had post-polio syndrome. No significant differences in VEP findings were observed between PSs with and without post-polio syndrome. Fatigue was present in 87% of PSs (FSS >4), but no significant correlation was found between FSS scores and VEP parameters.

The reduction in PRVEP amplitudes in PSs, in the absence of ophthalmologic pathology, may reflect subclinical involvement of central visual structures such as the lateral geniculate nucleus or reticular formation. These findings appear to be independent of subjective fatigue severity.