Pain
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Randomized Controlled Trial
Tropisetron blocks analgesic action of acetaminophen: a human pain model study.
Because the mechanism underlying the analgesic action of acetaminophen remains unclear, we investigated the possible interaction of acetaminophen with central serotonergic pathways. The effects of acetaminophen, tropisetron, the combination of both drugs, and saline on pain perception and central sensitization in healthy volunteers were compared. Sixteen healthy volunteers were included in this randomized, double-blind, placebo-controlled crossover study. ⋯ In summary, while the combination of acetaminophen and tropisetron showed no analgesic action, each drug administered alone led to decreased pain ratings as compared to saline. In an electrically evoked human pain model, the combination of acetaminophen with tropisetron was free of any analgesic potential. However, when administered on its own, both acetaminophen and tropisetron were mildly analgesic.
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Distinct developmental trajectories for neck disability and posttraumatic stress disorder (PTSD) symptoms after whiplash injury have recently been identified. This study aimed to identify baseline predictors of membership to these trajectories and to explore their dual development. In a prospective study, 155 individuals with whiplash were assessed at <1 month, 3, 6, and 12 months postinjury. ⋯ These findings support the proposal of links between the development of chronic neck related disability and PTSD after whiplash injury. Developmental trajectories of disability and posttraumatic stress disorder (PTSD) after whiplash injury are mostly in synchrony, and similar factors predict their membership. This suggests links between the development of chronic neck pain-related disability and PTSD.
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Recent studies have shown that leptin (an adipocytokine) played an important role in nociceptive behavior induced by nerve injury, but the cellular mechanism of this action remains unclear. Using the whole-cell patch-clamp recording from rat's spinal cord slices, we showed that superfusion of leptin onto spinal cord slices dose-dependently enhanced N-methyl-d-aspartate (NMDA) receptor-mediated currents in spinal cord lamina II neurons. At the cellular level, the effect of leptin on spinal NMDA-induced currents was mediated through the leptin receptor and the JAK2/STAT3 (but not PI3K or MAPK) pathway, as the leptin effect was abolished in leptin receptor-deficient (db/db) mice and inhibited by a JAK/STAT inhibitor. ⋯ Our data demonstrate a relationship between leptin and NMDA receptor-mediated spinal neuronal excitation and its functional role in nociceptive behavior. Since leptin contributes to nociceptive behavior induced by nerve injury, the present findings suggest an important cellular link between the leptin's spinal effect and the NMDA receptor-mediated cellular mechanism of neuropathic pain. A functional link is demonstrated between leptin, an adipocytokine, and the cellular mechanisms of neuropathic pain via enhancement of function and expression of spinal N-methyl-d-aspartate receptors.
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Problems in diagnosing fibromyalgia syndrome (FM) among motor vehicle collision (MVC) patients with whiplash (WL) include the following: the predominance of tender points (TPs) in the neck/shoulder girdle region; the 3-month duration of widespread pain criterion; and, the stability of diagnosis. The present study examined the prevalence of FM in a cohort (N = 326) patients with persistent neck pain 3 months after WL injury who were enrolled in a treatment program. Physical examinations were performed at baseline and at the end of treatment. ⋯ In conclusion, present criteria used in determining FM may result in spuriously inflated rates of diagnosis among WL patients because of persistent localized tenderness after an MVC. Furthermore, the transient nature of FM "symptoms" among WL patients should be taken into account before making a final diagnosis. The present criteria used in determining fibromyalgia may result in spuriously inflated rates of diagnosis among whiplash patients because of persistent localized tenderness after motor vehicle collisions.
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It has been proposed that goal pursuit plays a role in the development of chronic pain disorders. On the basis of (affective) motivational theories, it was hypothesized that both long-term achievement goals and short-term hedonic goals would be related to increased levels of pain and disability, particularly in patients with high negative affect. Participants with musculoskeletal pain complaints (N=299) completed a battery of questionnaires including a novel goal pursuit questionnaire (GPQ) measuring the extent to which participants preferred hedonic goals (mood-management or pain-avoidance goals) over achievement goals in various situations. ⋯ These findings provide support for the validity of an affective-motivational approach to chronic pain, suggesting that the experience of pain and the interference of pain on daily life activities depends on goal pursuit and negative affect. Interventions aimed at improving disability in chronic pain should address both patient's goal pursuit and negative affect. An affective-motivational approach to chronic pain indicates that achievement and pain-avoidance goals are associated with pain severity and disability, particularly in patients with high negative affect.