Evoked potential-based sensory monitoring in chronic itch: toward objective assessment of neural hyperexcitability

Chronic itch is a neuro–immune disorder in which inflammatory cytokines and neurotrophic factors drive sensory hyperexcitability across peripheral and central pathways. Persistent inflammation sensitizes C- and A<i>δ</i>-fibers, alters conduction properties, and disrupts inhibitory circuits within the spinal cord and cortex, ultimately producing central sensitization. Despite these well-characterized neurophysiologic alterations, clinical assessment continues to rely on subjective scales such as the visual analogue scale and numerical rating scale, highlighting the lack of objective biomarkers. Evoked potentials (EPs), which reflect cortical responses within hundreds of milliseconds after sensory stimulation, provide quantitative measures of latency and amplitude that correspond to conduction velocity and cortical synchrony. In chronic inflammatory itch, prolonged N₂–P₂ latency and reduced amplitude have been consistently reported, indicating impaired sensory conduction and heightened central excitability. This review synthesizes current insights into inflammation-induced neural sensitization, explains EP principles and fiber-specific activation patterns, and evaluates the potential of integrating electroencephalography and EPs for clinical assessment. Overall, accumulating evidence supports EPs as a noninvasive biomarker for visualizing sensory hyperexcitability in chronic itch and underscores their promise in establishing evoked potential–based sensory monitoring as an objective framework for evaluating sensory neural function.