European journal of pain : EJP
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The mechanisms through which electro-acupuncture (EA) and tricyclic antidepressants produce analgesia seem to be complementary: EA inhibits the transmission of noxious messages by activating supraspinal serotonergic and noradrenergic neurons that project to the spinal cord, whereas tricyclic antidepressants affect pain transmission by inhibiting the reuptake of norepinephrine and serotonin at the spinal level. This study utilized the tail-flick test and a model of post-incision pain to compare the antihyperalgesic effects of EA at frequencies of 2 or 100 Hz in rats treated with intraperitoneal or intrathecal amitriptyline (a tricyclic antidepressant). A gradual increase in the tail-flick latency (TFL) occurred during a 20-min period of EA. ⋯ In contrast, it did not significantly change the intensity of the antihyperalgesic effect of 2-Hz EA. The EA-induced antihyperalgesic effects lasted longer after intraperitoneal or intrathecal amitriptyline than after saline, with this effect of amitriptyline being more evident after 100- than after 2-Hz EA. The synergetic effect of amitriptyline and EA against post-incision pain shown here may therefore represent an alternative for prolonging the efficacy of EA in the management of post-surgical clinical pain.
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Anxiety sensitivity has been included in the fear-avoidance model as a vulnerability factor to explain individual differences in fear of pain. Several studies have suggested that the relationship between anxiety sensitivity and some psychopathological disorders is mediated by experiential avoidance, an affect-related regulatory process that involves unwillingness to endure private experiences. The role of these constructs as vulnerability variables has not been investigated in chronic pain patients. ⋯ The alternative model, in which experiential avoidance mediates the relationship between anxiety sensitivity and pain fear-avoidance, gave a much worse fit. These results highlight the importance of both anxiety sensitivity and experiential avoidance as variables which could explain individual differences in pain fear-avoidance. Thus, in terms of prevention, it should be a priority to identify patients with increased anxiety sensitivity and experiential avoidance during the first stages of the development of chronic pain conditions.
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The present study examined the hyperresponsiveness of the central nervous system in patients with fibromyalgia syndrome (FMS) related to mechanical hyperalgesia. The goals were to differentiate between increased pain ratings and hyperalgesia related either to peripheral or to central sensitization and to correlate with cerebral activation pattern. Seventeen patients and 17 healthy controls were examined, placing an experimental incision in the right volar forearm and causing tonic pain. ⋯ In patients with FMS, the cerebral pattern corresponding to secondary hyperalgesia was altered. The activity in the dorsolateral prefrontal cortex was inversely correlated with secondary hyperalgesia in healthy controls (R = -0.34 p = 0.005); in patients, this correlation was disrupted (R = 0.19 p = 0.12). These findings point to an alteration of pain transmission at the central level in FMS (e.g., loss of inhibition) and might be related to changes in cerebral-midbrain-spinal mechanisms of pain inhibition.
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Randomized Controlled Trial Multicenter Study
Value of TENS for relief of chronic low back pain with or without radicular pain.
To evaluate the efficacy of transcutaneous electrical neurostimulation (TENS) in patients with chronic low back pain (LBP). ⋯ There was no functional benefit of TENS in the treatment of patients with chronic LBP.
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Randomized Controlled Trial
One-year evaluation of the effect of physical therapy for masticatory muscle pain: a randomized controlled trial.
Physical therapy is widely used to decrease pain and restore function in patients suffering from masticatory muscle pain. Controlled studies on its efficacy are scarce. This study evaluated the 1-year effect of a 6-week physical therapy programme in a single blind, randomized, controlled trial. ⋯ All pain rating variables decreased and all function variables increased significantly over time in both groups. No significant differences in improvement between the groups (time-treatment interaction) were found. These data suggest that the long-term decrease in pain and the improvement of function are not related to active physical therapy.