Pain
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The nociceptive flexion reflex (NFR) is a spinally mediated withdrawal response and is used as an electrophysiological marker of descending modulation of spinal nociception. Chemical and pharmacological modulation of nociceptive neurotransmission at the spinal level has been evidenced by direct effects of neurotransmitters and pharmacological agents on the NFR. Largely unexplored are, however, the effects of nonpharmacological noninvasive conservative interventions on the NFR. ⋯ Such interventions may help prevent and treat chronic pain characterized by enhanced spinal nociception. Furthermore, given the responsiveness of the NFR to conservative interventions, the NFR assessment seems to be an appropriate tool in empirical evaluations of treatment strategies. PROSPERO registration number: CRD42020164495.
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This study aimed to identify patterns of opioid dispensing in Australian workers with low back pain (LBP) and determine the association of dispensing patterns with wage replacement duration. Australian workers' compensation claimants with LBP and at least 1 day of wage replacement were included. We used group-based trajectory modelling to identify opioid dispensing patterns over a two-and-a-half-year period from reported LBP onset and quantile regression to compare wage replacement duration between each dispensing pattern group. ⋯ In addition, moderate-volume and high-volume long-term dispensing groups had significantly longer wage replacement duration compared with the short-term dispensing group (median [weeks]: 126.9, 126.0, and 30.7, respectively). Without controlling for pain severity, these results offer limited evidence that opioids lead to longer wage replacement duration. Further research controlling for pain severity, psychosocial factors, and recovery expectations is required to confirm whether the relationship between opioid dispensing pattern and wage replacement duration is causal in nature.
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We developed an automated squint assay using both black C57BL/6J and white CD1 mice to measure the interpalpebral fissure area between the upper and lower eyelids as an objective quantification of pain. The automated software detected a squint response to the commonly used nociceptive stimulus formalin in C57BL/6J mice. ⋯ Finally, we found that the calcitonin gene-related peptide amylin induced squinting behavior in female mice, but not males. These data demonstrate that an automated squint assay can be used as an objective, real-time, continuous-scale measure of pain that provides higher precision and real-time analysis compared with manual grimace assessments.
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Low back pain is the most common pain condition and cause for disability in older adults. Older adults suffering from low back pain are more disabled than their healthy peers, are more predisposed to frailty, and tend to be undertreated. The cause of increased prevalence and severity of this chronic pain condition in older adults is unknown. ⋯ When separated by age groups, brain patterns predictive of older patients with CLBP showed extensive involvement of limbic brain areas including the ventromedial prefrontal cortex, the nucleus accumbens, and hippocampus, whereas only anterior insula paracingulate and fusiform gyrus predicted CLBP in the younger patients. In addition, we validated the relationships between back pain intensity ratings and CLBP brain activity patterns in an independent data set not included in our initial patterns' identification. Our results are the first to directly address how aging affects the neural signature of CLBP and point to an increased role of limbic brain areas in older patients with CLBP.