Pain
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Review
Pressure-induced referred pain areas are more expansive in individuals with a recovered fracture.
Musculoskeletal trauma and pain can sensitize central pain mechanisms, but whether these normalize on recovery is unknown. This study compared the extent of pain referral in individuals recovered from a musculoskeletal trauma and healthy controls. Twenty pain-free participants recovered from a shoulder fracture and 20 age-/sex-matched controls participated in 2 experimental sessions (day-0 and day-1) separated by 24 hours. ⋯ An expansion of pressure-induced pain referral was found in both groups following the DOMS protocol on day-1 (P = 0.05) with a relatively larger expansion (P = 0.05) and higher frequency of pain in the shoulder (P = 0.04) in the recovered pain group. After complete recovery and absence of pain symptoms after a fracture, central pain mechanisms seem to normalize in the region of the trauma after recovery but when sensitized a heightened response can emerge. Such mechanisms could be important for recurrence of pain conditions.
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We describe qualitative and quantitative development and preliminary validation of the Patient Assessment for Low Back Pain-Impacts (PAL-I), a patient-reported outcome measure for use in chronic low back pain (cLBP) clinical trials. Concept elicitation and cognitive interviews (qualitative methods) were used to identify and refine symptom concepts. Classical test theory and Rasch measurement theory (quantitative methods) were used to evaluate item-level and scale-level performance of the PAL-I using an iterative approach between qualitative and quantitative methods. ⋯ Individual item scores and total score discriminated between numeric rating scale tertile groups and painDETECT categories. Interpretation of paper and electronic administration modes was equivalent. The PAL-I demonstrated content validity and is potentially useful to assess treatment benefit in clinical trials of cLBP therapies.
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Descending regulation of spinal cord responses to nociceptive signaling has a strong influence on pain perception. Previous studies using functional magnetic resonance imaging (fMRI) have indicated that in addition to reactive responses to nociceptive signals, there is a continuous component to regulation, and that it may vary with differences in pain sensitivity. We hypothesize that this continuous regulation component occurs routinely in fMRI studies before noxious stimulation, as well as during, and after stimulation. ⋯ The results support the conclusion that homeostatic autonomic control influences the net descending pain regulation, and therefore influences pain sensitivity. The results describe the overall properties of pain processing (specifically pain elicited by heat) in the healthy human brainstem and spinal cord, and mechanisms for variation across individuals. This understanding is expected to be important for studies of how pain processing is altered in chronic pain conditions.