Pain
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Randomized Controlled Trial Multicenter Study Comparative Study
Practice, practitioner, or placebo? A multifactorial, mixed-methods randomized controlled trial of acupuncture.
The nonspecific effects of acupuncture are well documented; we wished to quantify these factors in osteoarthritic (OA) pain, examining needling, the consultation, and the practitioner. In a prospective randomised, single-blind, placebo-controlled, multifactorial, mixed-methods trial, 221 patients with OA awaiting joint replacement surgery were recruited. Interventions were acupuncture, Streitberger placebo acupuncture, and mock electrical stimulation, each with empathic or nonempathic consultations. ⋯ Needle and nonneedle placebos are equivalent. An unknown characteristic of the treating practitioner predicts outcome, as does the patient's belief (independently). Beliefs about treatment veracity shape how patients self-report outcome, complicating and confounding study interpretation.
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Randomized Controlled Trial Multicenter Study
Group cognitive behavioural interventions for low back pain in primary care: extended follow-up of the Back Skills Training Trial (ISRCTN54717854).
Group cognitive behavioural intervention (CBI) is effective in reducing low back pain and disability over a 12-month period, in comparison to best practice advice in primary care. The aim was to study the effects of this CBI beyond 12 months. We undertook an extended follow-up of our original randomised, controlled trial of a group CBI and best practice advice in primary care, in comparison to best practice advice alone. ⋯ There was no between-group difference in Modified von Korff Scale pain outcomes. The results suggest that the effects of a group CBI are maintained up to an average of 34 months. Although pain improves in response to best practice advice, longer-term recovery of disability remains substantially less.
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Randomized Controlled Trial
Effect of intravenous tropisetron on modulation of pain and central hypersensitivity in chronic low back pain patients.
The activation of 5-hydroxytryptamine-3 (5-HT-3) receptors in spinal cord can enhance intrinsic spinal mechanisms of central hypersensitivity, possibly leading to exaggerated pain responses. Clinical studies suggest that 5-HT-3 receptor antagonists may have an analgesic effect. This randomized, double-blind, placebo-controlled crossover study tested the hypothesis that the 5-HT-3 receptor antagonist tropisetron attenuates pain and central hypersensitivity in patients with chronic low back pain. ⋯ However, there was no statistically significant difference between tropisetron and placebo in VAS scores. Compared to placebo, tropisetron produced a statistically significant increase in pain threshold after single electrical stimulation, but no difference in all other secondary outcomes was found. A single-dose intravenous administration of tropisetron in patients with chronic low back pain had no significant specific effect on intensity of pain and most parameters of central hypersensitivity.
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Randomized Controlled Trial
Experimental characterization of the effects of acute stresslike doses of hydrocortisone in human neurogenic hyperalgesia models.
Relative hypothalamic-pituitary-adrenal axis dysfunction has been described as a common feature of several dysfunctional pain syndromes, and its end hormone cortisol may thus constitute a protective factor against the development of chronic pain. We investigated the potential influence of experimentally induced stress-like hypercortisolism on the induction of neurogenic hyperalgesia using 2 human surrogate models: secondary hyperalgesia after intradermal capsaicin injection into the volar forearm, and perceptual windup in normal skin. In a double-blind, placebo-controlled, randomized, crossover study, a psychophysical study was performed in 10 healthy subjects (median age 23 years) examining the effects of 40 mg orally administered hydrocortisone. ⋯ Temporal summation (windup) to mechanical pain stimuli and electrically induced windup of second pain (tested in an independent cohort of 10 other subjects) were also unchanged. The selective effects of hydrocortisone on pinprick hyperalgesia but not pinprick pain suggest an antihyperalgesic rather than analgesic effect. The findings suggest that hypothalamic-pituitary-adrenal axis reactivity might be an important mechanism in resilience to dysfunctional pain syndromes.
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Randomized Controlled Trial Comparative Study
Lidocaine patch (5%) produces a selective, but incomplete block of Aδ and C fibers.
Topical lidocaine (5%) leads to sufficient pain relief in only 29%-80% of treated patients, presumably by small-fiber block. The reasons for nonresponse are unclear; it may be due to different underlying pain mechanisms or partly insufficient anesthetic effect. Using quantitative sensory testing (QST) following the protocol of the DFNS (German Research Network on Neuropathic Pain), this study aims to assess the type and extent of somatosensory changes after lidocaine application in healthy volunteers. ⋯ Interindividually, the extent of the small-fiber block varied widely (eg, thermal detection thresholds: in 54% of the subjects there were only minimal changes; in only 8% were there changes of >60% of the maximal achievable value). Topical lidocaine (5%) induces thermal hypoesthesia and pinprick hypoalgesia, suggesting an isolated but only partial block of Aδ and C fibers of unpredictable extent. Further studies must analyze the influencing factors and determine whether patients with poor analgesic effect, in particular, are those with insufficient small-fiber block.