Marmoy, Oliver R; Horvat-Gitsels, Lisanne A; Cortina-Borja, Mario; Thompson, Dorothy A; (2023) Pattern visual evoked potentials show an inferior-superior topographic shift through maturation in childhood. The Journal of Physiology 10.1113/JP283408. (In press).

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Text The Journal of Physiology - 2023 - Marmoy - Pattern visual evoked potentials show an inferior superior topographic shift.pdf - Published Version Download (1MB) | Preview

Abstract

BACKGROUND: The pattern-reversal visual evoked potential (prVEP) is an established routine clinical test. Its objectivity is particularly valuable for assessing visual pathway function in children. International standards specify at a minimum, that an active electrode is placed on the occiput at Oz, but the authors find an additional inferior electrode at the inion (Iz) provides larger and more sensitive prVEPs in young persons. This study assesses the significance and age-dependence of these observations. METHODS: PrVEPs were recorded from 1487 patients considered ophthalmologically normal aged <20 years old, to a range of check widths including ISCEV standard large (50') and small (12.5') check widths. P100 peak-time and amplitude from both electrode sites were analysed. A subset of 256 children were studied longitudinally fitting logistic regression models including a random effect on subjects. RESULTS: PrVEPs were largest over the Iz electrode for the majority of infants and children. This transitioned with age to become equal or smaller at Oz as a function of check width. For ISCEV standard large and small check widths, transition periods were ∼8 and ∼12 years of age, respectively. We estimated abnormal result classifications of 3.7% with use of an Oz electrode alone, which decreases to 0.0-0.5% when adding or using an Iz electrode. CONCLUSION: The inferior dominance of prVEP topography in children may be explained by age-related anatomical changes altering the cortical dipole, combined with physiological maturation of the neural generators of the prVEP. We recommend the Iz electrode is used routinely in recording of prVEPs in children. KEY POINTS: Pattern visual evoked potentials (PVEPs) are an established clinical test which provide objective assessment of visual pathway function. These are particularly valuable in providing objective information of vision in children. International standards specify the active recording electrode should be placed at the mid-occiput (Oz), but we find that prVEP amplitudes are larger for a lower placed electrode (Iz) in young persons. This was assessed in 1487 patients who had simultaneous PVEP recording at both electrode positions, and we found the majority of PVEPs in children were larger over the Iz electrode. The developmental differences in PVEP distribution transitioned to be equal between Iz and Oz with increasing age as a function of check width, at ∼8 and ∼12 years old for large and small check widths respectively. These differences will improve diagnostic accuracy of paediatric PVEPs. We hypothesise these changes reflect developmental anatomical and neurophysiological changes altering the PVEP dipole. Abstract figure legend Schematic of prVEP response measurement. Responses were recorded from mid-occipital (Oz) and inion (Iz) electrodes simultaneously, referred to a mid-frontal electrode (Fz) and ground centrally (Cz). Peak-time was taken from stimulus onset (0ms) to peak of the P100 component (red dashed line). Amplitude was taken from the N75 trough to P100 peak (red solid line). This article is protected by copyright. All rights reserved.

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