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Preclinical studies on impulsive decision-making in chronic pain conditions are sparse and often contradictory. Outbred rat populations are heterogeneous regarding trait impulsivity manifestations and therefore we hypothesized that chronic pain-related alterations depend on individual traits. To test this hypothesis, we used male Wistar-Han rats in two independent experiments. Firstly, we tested the impact of spared nerve injury (SNI) in impulsive behavior evaluated by the variable delay-to-signal test (VDS). In the second experiment, SNI impact on impulsivity was again tested, but in groups previously categorized as high (HI) and low (LI) trait impulsivity in the VDS. Results showed that in an heterogenous population SNI-related impact on motor impulsivity and delay intolerance cannot be detected. However, when baseline impulsivity was considered, HI showed a significantly higher delay intolerance than the respective controls more prevalent in left-lesioned animals and appearing to result from a response correction on prematurity from VDS I to VDS II, which was present in Sham and right-lesioned animals. In conclusion, baseline differences should be more often considered when analyzing chronic pain impact. While this study pertained to impulsive behavior, other reports indicate that this can be generalized to other behavioral dimensions and that trait differences can influence not only the manifestation of comorbid behaviors but also pain itself in a complex and not totally understood manner.
Learn More >Medication iatrogeny is a major public health problem that increases as the population ages. Therapeutic escalation to control pain and associated disorders could increase polypharmacy and iatrogeny. This study aimed to characterize the medication iatrogenic risk of elderly outpatients with chronic pain.
Learn More >Central post-stroke pain (CPSP) is a type of neuropathic pain caused by dysfunction in the spinothalamocortical pathway. However, no animal studies have examined comorbid anxiety and depression symptoms. Whether the typical pharmacological treatments for CPSP, which include antidepressants, selective serotonin reuptake inhibitors (SSRIs), and anticonvulsants, can treat comorbid anxiety and depression symptoms in addition to pain remains unclear? The present study ablated the ventrobasal complex of the thalamus (VBC) to cause various CPSP symptoms. The effects of the tricyclic antidepressants amitriptyline and imipramine, the SSRI fluoxetine, and the anticonvulsant carbamazepine on pain, anxiety, and depression were examined.
Learn More >Psychologically informed physical therapy (PIPT) blends psychological strategies within a physical therapist's treatment approach for the prevention and management of chronic musculoskeletal pain. Several randomized trials have been conducted examining the efficacy of PIPT compared to standard physical therapy on important patient-reported outcomes of disability, physical function, and pain. In this review, we examine recent trials published since 2012 to describe current PIPT methods, discuss implications from findings, and offer future directions. Twenty-two studies, representing 18 trials, were identified. The studied PIPT interventions included (1) graded activity or graded exposure (n = 6), (2) cognitive-behavioral-based physical therapy (n = 9), (3) acceptance and commitment-based physical therapy (n = 1), and (4) internet-based psychological programs with physical therapy (n = 2). Consistent with prior reviews, graded activity is not superior to other forms of physical activity or exercise. In a few recent studies, cognitive-behavioral-based physical therapy had short-term efficacy when compared to a program of standardized exercise. There is a need to further examine approaches integrating alternative strategies including acceptance-based therapies (ie, acceptance and commitment therapy or mindfulness) or internet-based cognitive-behavioral programs within physical therapy. Although PIPT remains a promising care model, more convincing evidence is needed to support widespread adoption, especially in light of training demands and implementation challenges.
Learn More >Adverse childhood experiences (ACEs) are common occurrences that are related to poor health outcomes, including chronic pain, in youth and adults. Research suggests that children of parents exposed to ACEs are also at risk of poor outcomes. However, little is known about the risk that ACEs confer for chronic pain across generations. Parent ACEs may play an important role in pediatric chronic pain, given their association with key parent factors (eg, mental and physical health).
Learn More >To describe the pain characteristics of five index chronic overlapping pain conditions (COPCs) and to assess each COPC separately in order to determine whether the presence of comorbid COPCs is associated with bodily pain distribution, pain intensity, pain interference, and high-impact pain of the index COPC.
Learn More >The study aimed to identify and compare (1) what physical therapists perceive to be the main concerns, fears, and worries that patients with whiplash-associated disorders (WAD) and nontraumatic neck pain (NTNP) have as a result of their condition, and (2) the strategies used by physical therapists to address these fears and concerns.
Learn More >All treatments are given in a context, suggesting that conditioning cues may significantly influence therapeutic outcomes. We tested the hypothesis that context affects placebo analgesia in rodents. To produce neuropathic pain in rats, we performed chronic constriction injury of the infraorbital nerve. We then treated the rats daily, over a seven day period, with injections of either fentanyl or saline, with or without associated conditioning cues; a fourth group received no treatment. On the eighth day, we replaced fentanyl with saline to test for conditioned placebo analgesia. We tested the effects of treatment by measuring sensitivity to mechanical stimuli and grimace scale scores. We found no significant differences in either of these outcomes among the four experimental groups. These findings suggest that chronic, neuropathic pain in rats may not be susceptible to placebo analgesia.
Learn More >Avoidance is considered key in the development of chronic pain. However, little is known about how avoidance behaviour subsequently affects pain-related fear and pain. We investigated this using a robotic arm reaching avoidance task to investigate this. In a between-subjects design both Experimental Group (n=30) and Yoked Control Group (n=30) participants perform either of three movement trajectories (T1-T3) to reach a target location. During acquisition, only participants of the Experimental Group could partially or fully avoid a painful electrocutaneous stimulus by choosing the intermediate trajectory (T2; 50% reinforcement) or the longest trajectory (T3; 0% reinforcement) versus the shortest trajectory (T1: 100% reinforcement). After acquisition, contingencies changed (all trajectories 50% reinforced), and the acquired avoidance behaviour no longer effectively prevented pain from occurring. The Yoked Control Group received the same reinforcement schedule as the Experimental Group irrespective of their behaviour. When avoidance behaviour became ineffective for the Experimental Group, pain-related fear increased for the previously safe(r) trajectories (T2 and T3) and remained the same for T1, whereas pain threshold and tolerance declined. For the Yoked Group, pain-related fear increased for all trajectories. The Experimental Group persisted in emitting avoidance behaviour following the contingency change, albeit at a lower frequency than during acquisition. PERSPECTIVE: Results indicate participants become more afraid of and sensitive to pain, when previously acquired avoidance is no longer effective. Also, participants continue to show avoidance behaviour despite it being not adaptive anymore. These findings suggest that ineffective avoidance may play role in the maintenance and development of chronic pain.
Learn More >Acupuncture is a complementary and nonpharmacological intervention that can be effective for the management of chronic pain in addition to or instead of medication. Various animal models for neuropathic pain, inflammatory pain, cancer-related pain, and visceral pain already exist in acupuncture research. We used a newly validated human pain model and examined whether acupuncture can influence experimentally induced dental pain. For this study, we compared the impact of manual acupuncture (real acupuncture), manual stimulation of a needle inserted at non-acupuncture points (sham acupuncture) and no acupuncture on experimentally induced dental pain in thirty-five healthy men who were randomized to different sequences of all three interventions in a within-subject design. BORG CR10 pain ratings and autonomic responses (electrodermal activity and heart rate variability) were investigated. An initial mixed model with repeated measures included preintervention pain ratings and the trial sequence as covariates. The results showed that acupuncture was effective in reducing pain intensity when compared to no acupuncture (β =-0.708, p = 0.002), corresponding to a medium Cohen's d effect size of 0.56. The comparison to the sham acupuncture revealed no statistically significant difference. No differences in autonomic responses between real and sham acupuncture were found during the intervention procedures. Perspective: This study established a dental pain model for acupuncture research and provided evidence that experimentally induced dental pain can be influenced by either real acupuncture or manual stimulation of needles at non-acupuncture points. The data do not support that acupoint specificity is a significant factor in reducing experimental pain. Trial registration: The study was registered at clinicaltrials.gov (registration ID: NCT02589418).
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