Pain
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Randomized Controlled Trial
Management of acute whiplash: A randomized controlled trial of multidisciplinary stratified treatments.
Acute whiplash is a heterogeneous disorder that becomes persistent in 40% to 60% of cases. Estimates of recovery have not changed in recent decades. This randomized, single-blind, controlled trial tested whether multidisciplinary individualized treatments for patients with acute whiplash (<4 weeks postinjury) could reduce the incidence of chronicity at 6 mo by 50% compared to usual care. ⋯ Analysis revealed no significant differences in frequency of recovery (NDI ≤ 8%) between pragmatic and usual care groups at 6 months (OR 95%, CI=0.55, 0.23-1.29), P=0.163) or 12 mo (OR 95%, CI=0.65, 0.28-1.47, P=0.297). There was no improvement in current nonrecovery rates at 6 mo (63.6%, pragmatic care; 48.8%, usual care), indicating no advantage of the early multiprofessional intervention. Baseline levels of pain and disability had a significant bearing on recovery both at 6 and 12 mo in both groups, suggesting that future research focus on finding early effective pain management, particularly for the subgroup of patients with initial high levels of pain and disability, towards improving recovery rates.
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Randomized Controlled Trial Multicenter Study
Endogenous opioid function mediates the association between laboratory-evoked pain sensitivity and morphine analgesic responses.
Predictors of responsiveness to opioid analgesic medications are not well understood. This study tested whether individual differences in endogenous opioid (EO) function are associated with analgesic responsiveness to morphine. In randomized, counterbalanced order over 3 sessions, 45 chronic low back pain participants and 31 healthy controls received an opioid antagonist (8 mg naloxone), morphine (0.08 mg/kg), or placebo. ⋯ These latter associations were significantly mediated by EO function for 4 of these 5 pain outcomes (all P values<0.05). In the laboratory-evoked pain context, opioid analgesic medications may supplement inadequate EO analgesia, with little incremental benefit in those with preexisting high EO function. Implications for personalized medicine are discussed.
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Randomized Controlled Trial
Specifying the nonspecific components of acupuncture analgesia.
It is well known that acupuncture has pain-relieving effects, but the contribution of specific and especially nonspecific factors to acupuncture analgesia is less clear. One hundred one patients who developed pain of ≥ 3 on a visual analog scale (VAS, 0 to 10) after third molar surgery were randomized to receive active acupuncture, placebo acupuncture, or no treatment for 30 min with acupuncture needles with potential for double-blinding. Patients' perception of the treatment (active or placebo) and expected pain levels (VAS) were assessed before and halfway through the treatment. ⋯ Expected pain levels accounted for significant and progressively larger amounts of the variance in pain ratings after both active and placebo acupuncture (up to 69.8%). This is the first study to show that under optimized blinding conditions, nonspecific factors such as patients' perception of and expectations toward treatment are central to the efficacy of acupuncture analgesia and that these factors may contribute to self-reinforcing effects in acupuncture treatment. To obtain an effect of acupuncture in clinical practice, it may therefore be important to incorporate and optimize these factors.
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Randomized Controlled Trial
Association between clinical signs assessed by manual segmental examination and findings of the lumbar facet joints on magnetic resonance scans in subjects with and without current low back pain: A prospective, single-blind study.
The relevance of magnetic resonance imaging (MRI) findings such as facet joint (FJ) effusion and edema in low back pain (LBP) is still unknown. Therefore, we prospectively evaluated the presence of these MRI findings in the lumbar spine (Th12-S1) and their association with pain evoked by manual segmental FJ provocation tests (spinal percussion, springing, and segmental rotation tests) in 75 subjects with current LBP (≥30 days in the past 3 months) compared with 75 sex- and age-matched control subjects. FJs were considered painful, if ≥ 1 provocation test triggered LBP. ⋯ True-positive findings occurred in 16% of LBP FJs and in 2% of control FJs (P<0.01); 46 LBP subjects (61%) and 9 control subjects (12%, P<0.01) had true-positive findings. Pain on provocation and FJ effusion and/or edema were significantly correlated only in patients with LBP. In conclusion, only true-positive findings (ie, concurrent effusion and/or edema and positive provocation test results in the same FJ) discriminate well enough between control subjects and subjects with current LBP, whereas neither effusion and/or edema nor FJ provocations tests alone are suitable to detect suspected FJ arthropathy.
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Randomized Controlled Trial
Nocebo hyperalgesia induced by social observational learning.
Nocebo effects can be acquired by verbal suggestion, but it is unknown whether they can be induced through observational learning and whether they are influenced by factors known to influence pain perception, such as pain anxiety or pain catastrophizing. Eighty-five female students (aged 22.5 ± 4.4 years) were randomly assigned to one of three conditions. Participants in the control condition (CC) received information that an ointment had no effect on pain perception. ⋯ The nocebo response correlated with pain catastrophizing but not with pain anxiety or somatosensory amplification. A nocebo response to pressure pain was induced by observational learning but not by verbal suggestion. This finding highlights the importance of investigating the influence of observational learning on nocebo hyperalgesia.