Pain
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Complex regional pain syndrome (CRPS) and fibromyalgia are chronic pain conditions of unexplained origins. In addition to symptoms in the diagnostic criteria, patients can report changes to vision and other sensations or bodily functions. It is unclear whether these are greater than would be expected due to normal ageing, living with chronic pain generally, or common comorbidities of chronic pain such as depression or anxiety. ⋯ Complex regional pain syndrome related to changes in hair, skin, and nails; and infection and healing. The CRPS+fibromyalgia group presented with features of both disorders with minimal additional stressors or symptoms over and above these. Our findings suggest that CRPS and fibromyalgia share underlying pathophysiologies, although specific mechanisms might be different.
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Chronic musculoskeletal pain is a common problem globally. Current evidence suggests that maladapted central pain pathways are associated with pain chronicity, for example, in postoperative pain after knee replacement. Other factors such as low mood, anxiety, and tendency to catastrophize are also important contributors. ⋯ In chronic knee pain, significant patterns of relative hypoperfusion were evident in anterior default-mode and salience network hubs, while hyperperfusion was seen in posterior default mode, thalamus, and sensory regions. One component correlated positively with the pain sensitization score (r = 0.43, P = 0.006), suggesting that this CBF pattern reflects neural activity changes encoding pain sensitization. Here, we report a distinct chronic knee pain-related representation of CBF, pointing toward a brain signature underpinning central aspects of pain sensitization.
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Nonspecific chronic low back pain (CLBP) is a multifactorial disorder. Pain-related fear and altered movement preparation are considered to be key factors in the chronification process. Interactions between both have been hypothesized, but studies examining the influence of situational fear on movement preparation in low back pain (LBP) are wanting, as well as studies differentiating between recurrent LBP (RLBP) and CLBP. ⋯ Concerning APAs, no effects of fear were found, but group differences with generally delayed APAs in CLBP compared with controls and RLBP patients were evident. These results suggest that with fear, an attentional redirection towards more conscious central movement preparation strategies occurs. Furthermore, differences in movement preparation in patients with RLBP and CLBP exist, which could explain why patients with RLBP have more recovery capabilities than patients with CLBP.
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Classical conditioning and expectations are well-known underlying mechanisms of placebo hypoalgesia. Only little is known about their differential effect in adults, however, and even less in children. Previous studies in children evoked placebo hypoalgesia either with expectations alone or in combination with classical conditioning and revealed conflicting results. ⋯ It was also stronger in participants who noticed a strong pain reduction during learning trials. These results encourage the use of placebo effect in clinical practice, particularly for younger children. They underline the relevance of an initial pain reduction and encourage the inclusion of parents in treatment.
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Headache disorders are highly prevalent and debilitating, with limited treatment options. Previous studies indicate that many proinflammatory immune cells contribute to headache pathophysiology. Given the well-recognized role of regulatory T (Treg) cells in maintaining immune homeostasis, we hypothesized that enhancing Treg function may be effective to treat multiple headache disorders. ⋯ Furthermore, treating mice with ld-IL2 1 to 7 days after mild traumatic brain injury effectively prevented as well as reversed the development of behaviors related to acute and chronic post-traumatic headache. In a model of medication overuse headache, Ld-IL2 completely reversed the cutaneous hypersensitivity induced by repeated administration of sumatriptan. Collectively, this study identifies ld-IL2 as a promising prophylactic for multiple headache disorders with a mechanism distinct from the existing treatment options.