Offset analgesia (OA), a psychophysical test of endogenous pain inhibition, is diminished in many adult chronic pain disorders but OA has not been investigated in youth with chronic pain disorders. The present study assessed OA responses in 30 youth with chronic primary and secondary pain disorders and 32 healthy controls. The OA, control and constant thermal tests were evoked with an individualized noxious heat stimulus of approximately 50/100 mm on a visual analog scale followed by 1°C offset temperature. This study also examined the association of OA responses with two self-report measures of pain sensitivity, the Central Sensitization Inventory (CSI) and Pain Sensitivity Questionnaire (PSQ). Patients exhibited diminished capacity to activate OA with a reduction in ΔeVASc of 53 ± 29% vs. controls 74 ± 24% (P = 0.003) even after multivariate regression adjusting for age, sex and body mass index. Patients also showed decreased ability to habituate to a constant noxious heat stimulus compared to controls (P = 0.021). CSI scores showed excellent predictive accuracy in differentiating patients from controls (AUC= 0.95; 95% CI: 0.91, 0.99) and CSI score ≥ 30 was identified as an optimal cut-off value. PSQ scores did not differentiate patients from controls nor correlate with OA. In this study 60% of youth with chronic pain showed reduced capacity for endogenous pain inhibition.

References

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