The journal of pain : official journal of the American Pain Society
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Review Meta Analysis
The Effect of Acute and Sustained Pain on Corticomotor Excitability: A Systematic Review and Meta-analysis of group- and individual-level data.
Pain alters motor function. This is supported by studies showing reduced corticomotor excitability in response to experimental pain lasting <90 minutes. Whether similar reductions in corticomotor excitability are present with pain of longer durations or whether alterations in corticomotor excitability are associated with pain severity is unknown. ⋯ In otherwise healthy individuals, suppression of corticomotor excitability may be a beneficial short-term strategy with long-term consequences. PERSPECTIVE: This systematic review synthesised the evidence for altered corticomotor excitability in response to experimentally induced pain. Reduced corticomotor excitability was associated with lower acute pain severity but higher sustained pain severity, suggesting suppression of corticomotor excitability may be a beneficial short-term adaptation with long-term consequences.
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Psychedelic substances have played important roles in diverse cultures, and ingesting various plant preparations to evoke altered states of consciousness has been described throughout recorded history. Accounts of the subjective effects of psychedelics typically focus on spiritual and mystical-type experiences, including feelings of unity, sacredness, and transcendence. Over the past 2 decades, there has been increasing interest in psychedelics as treatments for various medical disorders, including chronic pain. ⋯ Challenges in evaluating psychedelics as treatments for chronic pain include identifying neurobiologic and psychosocial mechanisms of action and determining which pain conditions to investigate. Truly informative proof-of-concept and confirmatory randomized clinical trials will require careful selection of control groups, efforts to minimize bias from unblinding, and attention to the roles of patient mental set and treatment setting. PERSPECTIVE: There is considerable promise for the use of psychedelic therapy for pain, but evidence-based recommendations for the design of future studies are needed to ensure that the results of this research are truly informative.
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Observational Study
Preoperative Predictors of Complex Regional Pain Syndrome Outcomes in the 6 Months Following Total Knee Arthroplasty.
This prospective observational study evaluated preoperative predictors of complex regional pain syndrome (CRPS) outcomes in the 6 months following total knee arthroplasty (TKA). Participants were n = 110 osteoarthritis patients (64.5% female) undergoing unilateral TKA with no prior CRPS history. Domains of negative affect (depression, anxiety, catastrophizing), pain (intensity, widespread pain, temporal summation of pain [TSP]), pain interference, sleep disturbance, and pro-inflammatory status (tumor necrosis factor-alpha [TNF-a]) were assessed preoperatively. ⋯ Preoperative negative affect is unlikely to directly influence long-term CRPS risk. PERSPECTIVE: This article identifies preoperative predictors of CRPS features at 6 months following total knee arthroplasty, including more widespread pain and higher pain intensity, temporal summation of pain, pain interference, and tumor necrosis factor-alpha levels. Findings suggest the importance of central sensitization and inflammatory mechanisms in CRPS risk following tissue trauma.
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Dexamethasone supplementation to local anesthetics prolongs its action, yet the underlying mechanism is unclear. Previous studies have reported that increased p-p38 mitogen-activated protein kinase (MAPK) in the dorsal root ganglia (DRG) is associated with pain-associated behavior and that nitric oxide (NO), which is known to be a pronociceptive substance, directly inhibits sciatic nerve conduction. Here, we investigated the temporal changes in the hyperalgesic effect and p-p38 MAPK and NO synthase (NOS) expression levels in the DRG when dexamethasone was added to ropivacaine used for a sciatic nerve block (SNB) in postoperative pain model mice. ⋯ These results suggest that dexamethasone supplementation to local anesthetics prolongs the analgesic effect by inhibiting nNOS activity. PERSPECTIVE: The current study revealed that dexamethasone supplementation to local anesthetics prolongs the analgesic effect by inhibiting the activity of neuronal NOS and that p-p38 MAPK may not be involved in this phenomenon. Our findings offer a new target for the discovery of long-acting local anesthetics.
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Wide-spread cultural beliefs influence personal experiences and clinical treatment of pain, yet are often unexamined and unchallenged in the pain literature. The common cultural belief that people generally over-report or exaggerate pain is familiar, reflected in discordant patient-provider pain assessments, and compounded in the context of disparities in pain treatment. However, no studies have directly measured the prevalence of this belief among the general population, nor challenged the validity of this assumption by assessing normative pain reporting in clinical settings. ⋯ Results reinforce the need for respecting patient pain reports, and suggest that distrust surrounding others' pain experiences is prevalent in society. PERSPECTIVE: Most people claim to report their pain as accurately as possible, while simultaneously perpetuating common cultural beliefs that others over-report their pain. This fundamental pain bias highlights a pervasive misconception that likely contributes to patient-provider mistrust and broader cultural pain stigma.