Pain
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Randomized Controlled Trial Clinical Trial
Motor cortex electrical stimulation applied to patients with complex regional pain syndrome.
Motor cortex stimulation (MCS) is useful to treat patients with neuropathic pain syndromes, unresponsive to medical treatment. Complex regional pain syndrome (CRPS) is a segmentary disease treated successfully by spinal cord stimulation (SCS). However, CRPS often affects large body segments difficult to cover by SCS. ⋯ VAS and McGill pain scales diminished significantly (p<0.01) throughout the follow-up, accompanied by disappearance of the sensory (allodynea and hyperalgesia) and sympathetic signs. MCS is effective not only to treat pain, but also improve the sympathetic changes in CPRS. Mechanism of action is actually unclear, but seems to involve sensory input at the level of the spinal cord.
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Mu-opioid receptor (MOPr) agonists, such as morphine, produce greater antinociception in male compared to female rats. The ventolateral periaqueductal gray (vlPAG) appears to contribute to this sex-difference despite fewer vlPAG output neurons projecting to the rostral ventromedial medulla in male compared to female rats. This greater projection in female rats suggests that non-opioid activation of vlPAG output neurons should produce greater antinociception in female compared to male rats. ⋯ Antinociceptive potency was significantly greater in male compared to female rats following microinjection of morphine, DAMGO, and bicuculline, but not following microinjection of fentanyl or kainic acid. In no case did activation of the vlPAG produce greater antinocicepiton in female compared to male rats. These findings demonstrate that the vlPAG can produce comparable antinociception in female and male rats, but antinociception produced by inhibition of GABAergic neurons (whether by morphine or the GABA(A) receptor antagonist bicuculline) produces greater antinociception in males.
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Randomized Controlled Trial
Diffuse analgesic effects of unilateral repetitive transcranial magnetic stimulation (rTMS) in healthy volunteers.
We investigated the analgesic effects of unilateral repetitive transcranial magnetic stimulation (rTMS) of the motor cortex (M1) or dorsolateral prefrontal cortex (DLPFC) in two models of experimental pain in healthy volunteers. Two studies were carried out in parallel in two groups of 26 paid healthy volunteers. The effects of active or sham rTMS (frequency, 10Hz; intensity, 80% resting motor threshold) applied to the right M1 or DLPFC were compared in a double-blind randomized cross-over design. ⋯ By contrast, the second study showed that rTMS of M1 or DLPFC had no significant effect on the threshold or recruitment curve of the nociceptive flexion RIII reflex. Our findings demonstrate that unilateral rTMS of M1 or DLPFC induces diffuse and selective analgesic effects in healthy volunteers. The lack of effect on the RIII reflex suggests that such analgesic effects may not depend on the activation of descending inhibitory systems.
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Studies on the determinants of pain-related support are needed to enhance couples-based treatments for pain. The purpose of this study was to determine the extent to which pain catastrophizing and perceived entitlement to pain-related support (i.e., support entitlement) were associated with perceived and observed social support. Participants were 106 chronic pain couples recruited from the community. ⋯ Among those with a greater entitlement to support, catastrophizing was associated with greater punishing spouse responses and observed invalidation by the spouse. These results suggest that support entitlement plays an important role in couples' supportive interactions about pain. Continued research is needed to determine how a desire for pain-related attention and support and catastrophizing translate into behaviors that affect support provision and receipt.
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A wide variety of risk factors for the occurrence and prognostic factors for persistence of non-specific musculoskeletal pain (MSP) are mentioned in the literature. A systematic review of all these factors is not available. Thus a systematic review was conducted to evaluate MSP risk factors and prognostic factors, classified according to the dimensions of the International Classification of Functioning, Disability and Health. ⋯ For whiplash-associated disorders these factors were older age, being female, having angular deformity of the neck, and having an acute psychological response. Similarly, for persistence of low back pain, high evidence was found for having fear-avoidance beliefs and meagre social support at work. For low back pain, high evidence was found for meagre social support and poor job content at work as not being risk factors.