Pain
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Rare patients are left with chronic pain, vasodysregulation, and other symptoms that define complex regional pain syndrome (CRPS), after limb traumas. The predisposing factors are unknown. Genetic factors undoubtedly contribute, but have not yet been identified. ⋯ All had sustained joint injury; in three this had been surgically treated. The association of these two diagnoses leads us to hypothesize that EDS might contribute to the development of CRPS in one or more of the following ways: via stretch injury to nerves traversing hypermobile joints, increased fragility of nerve connective tissue, or nerve trauma from more frequent surgery. We review the clinical presentation of the different Ehlers Danlos syndromes and provide clinical criteria that can be used to screen CRPS patients for EDS for clinical or research purposes.
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Osteoarthritis (OA) is a debilitating disease in which primarily weight-bearing joints undergo progressive degeneration. Despite the widespread prevalence of OA in the adult population, very little is known about the factors responsible for the generation and maintenance of OA pain. Vasoactive intestinal peptide (VIP) was identified in the synovial fluid of arthritis patients nearly 20 years ago and the aim of this study was to examine whether VIP could be involved in the generation of OA pain. ⋯ Treatment of OA knees with a single injection of VIP6-28 diminished hindlimb incapacitance while increasing paw withdrawal threshold. This study showed for the first time that peripheral application of VIP causes increased knee joint allodynia and secondary hyperalgesia. Furthermore, antagonists that inhibit VIP activity may prove beneficial in the alleviation of OA pain.
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Comparative Study
Psychological "resilience" and its correlates in chronic pain: findings from a national community sample.
The display of effective functioning despite exposure to stressful circumstances and/or internal distress is often termed 'resilience'. The study of resilience is believed to provide information about the nature of illness adaptation that is distinct from that obtained via the analysis of clinically impaired groups. In recent years, the concept of resilience has seen only limited exploration in the chronic pain literature. ⋯ An age- and gender-matched non-resilient subsample was then selected who scored high (at least one standard deviation above the mean) on Severity, Interference, and Emotional Burden. The results of a series of comparisons between the resilient and non-resilient groups revealed significant differences favoring resilient individuals in coping style, pain attitudes and beliefs, catastrophizing tendencies, positive and negative social responses to pain, and health care and medication utilization patterns. The findings provide a preliminary foundation for further research aimed at understanding the nature and causal underpinnings of resilience in persons with chronic pain.
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Past research has shown that pain catastrophizing contributes to heightened pain experience. The hypothesis advanced in this study was that individuals who score high on measures of pain catastrophizing would also perceive more intense pain in others. The study also examined the role of pain behaviour as a determinant of the relation between catastrophizing and estimates of others' pain. ⋯ Catastrophizing was associated with more accurate pain inferences on only one of three indices of inferential accuracy. The pattern of findings suggests that increasing reliance on pain behaviour as a means of inferring others' pain will not necessarily yield more accurate estimates. Discussion addresses the processes that might underlie the propensity to attend more to others' pain behaviour, and the clinical and interpersonal consequences of perceiving more pain in others.
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The aim of this study was to investigate involvement of central mechanisms in complex regional pain syndrome (CRPS). In particular, we wished to determine whether hyperalgesia extends ipsilaterally from the affected limb to the forehead. The heat-pain threshold, pressure-pain threshold, and ratings of cold and sharpness were investigated on each side of the forehead and in the affected and unaffected limbs of 38 patients with features of CRPS. ⋯ Although the heat-pain threshold and ratings of sharpness and cold did not differ between the two sides of the forehead in the group as a whole, the sharpness of pinprick sensations in the affected limb was mirrored by similar sensations in the ipsilateral forehead. Conversely, diminished sensitivity to light touch in the affected limb was associated with diminished sensitivity to sharpness, cold and heat-pain in the ipsilateral forehead. These findings suggest that central nociceptive processing is disrupted in CRPS, possibly due to disturbances in the thalamus or higher cortical centres.