Pain
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Comparative Study
Inflammation-induced decrease in voluntary wheel running in mice: a nonreflexive test for evaluating inflammatory pain and analgesia.
Inflammatory pain impacts adversely on the quality of life of patients, often resulting in motor disabilities. Therefore, we studied the effect of peripheral inflammation induced by intraplantar administration of complete Freund's adjuvant (CFA) in mice on a particular form of voluntary locomotion, wheel running, as an index of mobility impairment produced by pain. The distance traveled over 1 hour of free access to activity wheels decreased significantly in response to hind paw inflammation, peaking 24 hours after CFA administration. ⋯ The CFA-induced decrease in voluntary wheel running was dose-dependently reversed by subcutaneous administration of antiinflammatory and analgesic drugs, including naproxen (10-80 mg/kg), ibuprofen (2.5-20mg/kg), diclofenac (1.25-10mg/kg), celecoxib (2.5-20mg/kg), prednisolone (0.62-5mg/kg), and morphine (0.06-0.5mg/kg), all at much lower doses than reported in most rodent models. Furthermore, the doses that induced recovery in voluntary wheel running did not reduce CFA-induced mechanical allodynia, indicating a greater sensitivity of the former as a surrogate measure of inflammatory pain. We conclude that monitoring changes in voluntary wheel running in mice during peripheral inflammation is a simple, observer-independent objective measure of functional changes produced by inflammation, likely more aligned to the global level of pain than reflexive measures, and much more sensitive to analgesic drug effects.
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Randomized Controlled Trial Multicenter Study Comparative Study
Clinical variables associated with recovery in patients with chronic tension-type headache after treatment with manual therapy.
The aims of this study were to describe the course of chronic tension-type headache (CTTH) in participants receiving manual therapy (MT), and to develop a prognostic model for predicting recovery in participants receiving MT. Outcomes in 145 adults with CTTH who received MT as participants in a previously published randomised clinical trial (n=41) or in a prospective cohort study (n=104) were evaluated. Assessments were made at baseline and at 8 and 26 weeks of follow-up. ⋯ In participants classified as being likely to be recovered, the posterior probability for recovery at 8 weeks was 92%, whereas for those being classified at low probability of recovery this posterior probability was 61%. It is concluded that the course of CTTH is favourable in primary care patients receiving MT. The prognostic models provide additional information to improve prediction of outcome.
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Review
Pain, affective symptoms, and cognitive deficits in patients with cerebral dopamine dysfunction.
Converging preclinical, and human epidemiological, neuroimaging, and genetic evidence suggests a central role for dopamine neurotransmission in modulating pain perception and analgesia. Dysregulation in dopamine signaling may modulate the experience of pain both directly, by enhancing or diminishing the propagation of nociceptive signals, and indirectly, by influencing affective and cognitive processes, which affect the expectation, experience, and interpretation of nociceptive signals. ⋯ Although patients are typically affected most by the primary symptoms of their disorders, alterations in pain perception may further increase the burden of their illness, compromising their quality of life. The present review focuses on this relationship, and discusses clinical and potential therapeutic implications for both patients with dopamine-related disorders and those with chronic pain syndromes.
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Randomized Controlled Trial Comparative Study
Patients who display protective pain behaviors are viewed as less likable, less dependable, and less likely to return to work.
In the present study, participants (ie, observers) watched video sequences of patients with chronic back pain performing a physically demanding lifting task. Participants were asked to make judgments about patients' levels of pain and readiness to work. For each patient, observers were also asked to make judgments about personality traits relevant to work performance and employment. ⋯ Analyses also revealed that patients displaying protective pain behaviors were perceived as being significantly less likable, less dependable, and less ready to work than patients displaying other forms of pain behavior. Discussion addresses the processes by which pain behaviors might influence observers' judgments about patients' personality traits and readiness to work. Implications of the present findings for clinical practice and the management of patients presenting with pain conditions are also discussed.
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Comparative Study
A critical period in the supraspinal control of pain: opioid-dependent changes in brainstem rostroventral medulla function in preadolescence.
We have previously shown that the balance of electrically evoked descending brainstem control of spinal nociceptive reflexes undergoes a switch from excitation to inhibition in preadolescent rats. Here we show that the same developmental switch occurs when μ-opioid receptor agonists are microinjected into the rostroventral medulla (RVM). Microinjections of the μ-opioid receptor agonist [D-Ala(2), N-MePhe(4), Gly-ol]-enkephalin (DAMGO) into the RVM of lightly anaesthetised adult rats produced a dose-dependent decrease in mechanical nociceptive hindlimb reflex electromyographic activity. ⋯ Enhancing opioidergic activity with chronic morphine over P7 to P14 accelerated this development. These results show that descending facilitation of spinal nociception in young animals is mediated by μ-opioid receptor pathways in the RVM. Furthermore, the developmental transition from RVM descending facilitation to inhibition of pain is determined by activity in central opioid networks at a critical period of periadolescence.