Hypermobility and chronic pain in adolescents: diverging functional and neural profiles without sensory differences.

Chronic pain (CP) affects approximately 20% of children, significantly impacting their physical, emotional, and social well-being. Hypermobility disorders (HDs) are prevalent in pediatric populations, including those with CP, and often contribute to impairments in psychological and physical functioning. This study examined differences in sensory, functional, and neural circuitry among CP in youth with and without comorbid HD (CP + HD). Contrary to our a priori hypothesis and previous literature suggesting that youth with CP + HD would exhibit greater suprathreshold pain sensitivity and lower pain thresholds, our findings revealed no significant differences in quantitative sensory testing measures between the 2 groups. This suggests that heightened pain sensitivity observed in CP + HD cannot be solely attributable to their hypermobility. However, the CP + HD cohort reported greater pain spread, increased fatigue, and poorer sleep quality, indicating that while they may not be more vulnerable to pain sensitization, they experience greater overall impairment in health and functioning. Furthermore, site-stratified analyses of multisensory task-evoked fMRI data revealed group differences in cerebellar activation and baseline cerebellar-supplementary motor cortex connectivity in youth with CP + HD, indicating altered neural strategies for sensory-motor integration. Notably, these significant fMRI findings were observed at 1 of the 2 study sites. Our results underscore the need for a nuanced understanding of the interplay between hypermobility, CP, and functional impairment to inform targeted interventions that address the multifaceted challenges faced by these patients.