Phenotyping peripheral neuropathic pain in male and female adolescents: pain descriptors, somatosensory profiles, conditioned pain modulation and child-parent reported disability.

Verriotis, Madeleine; Peters, Judy; Sorger, Clarissa; Walker, Suellen M

ABSTRACT Neuropathic pain (NeuP) can be difficult to diagnose and manage in children. Data regarding prevalence and sex-dependent differences is limited, and more detailed phenotyping is needed.This observational cohort study recruited adolescents (10-17years) with NeuP or complex regional pain syndrome (CRPS). Following pain and NeuP screening questionnaires, quantitative sensory testing (QST) was performed. Individual z-score plots were calculated with body-region control measures and matched to mechanism-related sensory profiles (sensory loss, thermal hyperalgesia, mechanical hyperalgesia). Conditioned pain modulation (CPM) was assessed with pressure pain threshold (PPT) and a contralateral cold conditioning stimulus, and meaningful CPM defined as twice the standard error of measurement. Patients and parents completed validated questionnaires for child quality of life (QoL), pain catastrophizing, and self-reported anxiety/depression.Males (n=23) and females (n=43) with NeuP (n=52) or CRPS (n=14) reported moderate-severe pain with neuropathic sensory descriptors. Mixed patterns of sensory gain/loss at pain sites were not sex-dependent. Thermal hyperalgesia was common in both NeuP and CRPS, whereas sensory loss occurred only with NeuP and in a smaller proportion than adult cohorts. CPM was inhibitory in 54%, facilitatory in 14%, and non-responders had variable cold conditioning sensitivity. Males and females reported marked impairment of QoL, increased emotional distress and pain catastrophising. Child-parent QoL scores correlated, but catastrophizing scores were discordant in parents or adolescents with higher anxiety/depression.NeuP in adolescents is associated with significant pain, physical and psychosocial impairment. Quantifying alterations in somatosensory profiles, descending modulation and child-parent psychological function will inform individualized therapy and stratification for future clinical trials.