Articles: chronic.
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The rostral ventromedial medulla (RVM) is a crucial structure in the descending pain modulatory system, playing a key role as a relay for both the facilitation and inhibition of pain. The chronic social defeat stress (CSDS) model has been widely used to study stress-induced behavioral impairments associated with depression in rodents. Several studies suggest that CSDS also causes changes related to chronic pain. ⋯ In addition, RVM inhibition in animals exposed to a subthreshold social defeat stress protocol induces a susceptible phenotype, facilitating all stress outcomes. Finally, chronic RVM inhibition-without any social stress stimulus-induces chronic pain but not depressive-like behaviors. Our findings provide insights into the comorbidity between chronic pain and depression by indicating the involvement of the RVM in establishing social stress-induced behavioral responses associated with both chronic pain and depression.
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Neuropathic pain is a type of chronic pain that entails severe prolonged sensory dysfunctions caused by a lesion of the somatosensory system. Many of those suffering from the condition do not experience significant improvement with existing medications, resulting in various side effects. In this study, Sprague-Dawley male rats were used, and long-term deep brain stimulation of the ventrolateral periaqueductal gray was conducted in a rat model of spared nerve injury. ⋯ At the spinal level, glial cells were still activated but only the 5-HT1a receptor in the spinal cord was activated, implying its inhibitory role in mechanical allodynia. This study found that peripheral neuropathy caused dysfunction in the descending serotonergic system, and prolonged stimulation of ventrolateral periaqueductal gray can modulate the pathway in an efficient manner. This work would provide new opportunities for the development of targeted and effective treatments for this debilitating disease, possibly giving us lower chances of side effects from repeated high-frequency stimulation or long-term use of medication.
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Chronic postoperative pain after total knee replacement (TKR) is a major clinical problem. It is still unclear if specific inflammatory mediators are associated with long-term postoperative pain complications. The current exploratory study aimed to (1) evaluate a multiplex of inflammatory mediators 5 years after TKR surgery in patients with different degrees of postoperative pain intensities and (2) study any association of the markers with clinical pain intensity, cognitive and functional outcomes. ⋯ This exploratory study evaluated a subset of inflammatory markers and the association to clinical pain intensity, knee function and pain catastrophizing in patients 5 years after total knee replacement surgery. Our results provide insights into the understanding of the underlying mechanisms that may drive the long experience of pain after TKR surgery.
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The Pain Responses Scale and its Short Form (PRS-SF) were recently developed to assess the affective, behavioral, and cognitive responses to pain based on the behavioral inhibition system (BIS) and behavioral activation system (BAS) model of chronic pain. The purpose of this study was to provide additional tests of the psychometric properties of the PRS-SF in a new sample of individuals with chronic pain. ⋯ The results provide additional support for the validity of the 4 PRS-SF Scale scores, and the reliability of 3 of the scales. If these findings are replicated in future research, investigators may wish to administer more items from the original Relaxation Scale when assessing this domain to ensure adequate reliability for this scale. The other items from the PRS-SF assessing despondent, escape, and approach responses appear to provide at least adequate reliability. When used in this way, the PRS-SF may be used to measure BIS and BAS responses to pain to: (1) provide further tests of the BIS-BAS model of chronic pain and/or (2) understand the potential mediating effects of BIS and BAS responses on the effects of psychological pain treatments to help determine which specific responses are most responsible for the benefits of treatment, and, therefore, which responses should be specifically targeted to enhance treatment response.
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Individuals must change the way they perform activities in response to chronic pain. In the literature, three activity patterns are commonly described: avoidance, pacing, and persistence. Many studies have explored these activity patterns. However, little research has delved into the factors that lead people to adopt a particular activity behaviour. This study aimed to explore the relationship that people with chronic musculoskeletal pain have with activity and highlight the factors underlying their practices. ⋯ Patients choose an activity pattern (avoidance, pacing, persistence) according to the challenges they face in their daily lives. Context, representations of self and activity, as well as goals sought influence these choices. Some patients report having learned to adapt their activity management strategies. Therefore, therapeutic approaches in the rehabilitation context could focus on these adaptive capacities to offer patients optimal pain and activity management and develop their ability to use different strategies according to the circumstance.