Pain
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Randomized Controlled Trial
Failure of intrathecal ketorolac to reduce remifentanil-induced postinfusion hyperalgesia in humans.
In rodents, acute exposure to opioids results in transient antinociception followed by longer lasting hypersensitivity to tactile or thermal stimuli, a phenomenon termed opioid-induced hyperalgesia. This hypersensitivity can be blocked or reversed by intrathecally administered cyclooxygenase inhibitors, including ketorolac, suggesting a role for spinal prostaglandins. In surgical patients, the dose of intraoperative opioid, particularly the short-acting drug, remifentanil, is directly related to increased pain and opioid requirements for many hours postoperatively. ⋯ The primary outcome measure, area of capsaicin-induced hypersensitivity after stopping remifentanil, showed a similar increase in those receiving ketorolac as in those receiving saline. Cerebrospinal fluid prostaglandin E2 concentrations did not increase during postinfusion hyperalgesia compared with those during infusion, and they were not increased during infusion compared with those in historical controls. These data fail to support the hypothesis that acute opioid-induced hyperalgesia reflects spinal cyclooxygenase activation causing central sensitization.
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Randomized Controlled Trial
Transcranial direct current stimulation as a treatment for patients with fibromyalgia: a randomized controlled trial.
Previous studies suggest that transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) reduces chronic pain levels. In this randomized controlled trial, we investigated the effects of 5 consecutive 20-minute sessions of 2-mA anodal tDCS directed to the M1 in 48 patients (45 females) with fibromyalgia. Changes in pain, stress, daily functioning, psychiatric symptoms, and health-related quality of life were measured. ⋯ Fibromyalgia-related daily functioning improved in the active tDCS group compared with the sham group. The stimulation was well tolerated by the patients, and no significant difference in the adverse effects between the groups was observed. The results suggest that tDCS has the potential to induce statistically significant pain relief in patients with fibromyalgia, with no serious adverse effects, but small effect sizes indicate that the results are unlikely to reflect clinically important changes.
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Randomized Controlled Trial
Opposite effects of the same drug: reversal of topical analgesia by nocebo information.
Several studies have shown that psychological factors such as learning, expectation, and emotions can affect pharmacological treatment and shape both favorable and adverse effects of drugs. This study investigated whether nocebo information provided during administration of an analgesic cream could reverse topical analgesia to hyperalgesia. Furthermore, we tested whether nocebo effects were mediated by negative emotional activation. ⋯ The results revealed that pain was significantly lower in the group receiving Emla with positive information and highest in the groups receiving suggestions of hyperalgesia, regardless of whether Emla or the placebo was administered. Mediation analyses showed that stress and blood pressure mediated hyperalgesia after nocebo suggestions. These results suggest that nocebo information can reverse topical analgesia and that emotional factors can explain a significant proportion of variance in nocebo hyperalgesia.
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Patients with knee osteoarthritis demonstrate decreased pressure pain thresholds (PPTs), facilitated temporal summation (TS) of pain, and decreased conditioned pain modulation (CPM) compared with healthy controls. This study aimed to correlate preoperative PPTs, TS, and CPM with the development of chronic postoperative pain after total knee replacement (TKR) surgery. Knee pain intensity (visual analog scale [VAS]: 0-10), PPTs, TS, and CPM were collected before, 2 months, and 12 months after TKR. ⋯ Preoperative TS level correlated to 12-month postoperative VAS (R = 0.240, P = 0.037). Patients who developed moderate-to-severe pain had pronociceptive changes compared with patients who developed mild pain postsurgery. Preoperative TS level correlated with the postoperative pain intensity and may be a preoperative mechanistic predictor for the development of chronic postoperative pain in patients with osteoarthritis after TKR.