Pain
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Meta Analysis
Treatment of fibromyalgia syndrome with gabapentin and pregabalin--a meta-analysis of randomized controlled trials.
The efficacy of gabapentin (GPT) and pregabalin (PGB) in the treatment of fibromyalgia syndrome (FMS) was assessed. We screened MEDLINE, PsycINFO, SCOPUS, www.clinicaltrials.org, the Cochrane Library (through October 2008), and the reference sections of original studies on GPT/PGB in FMS. Randomized controlled trials (RCTs) on the treatment of FMS with GPT and PGB were analyzed. ⋯ There was strong evidence for a reduction of pain (SMD -0.28, 95% CI -0.36, -0.20; p<0.001), improved sleep (SMD -0.39, 95% CI -0.48, -0.39; p<0.001), and improved health-related quality of life (HRQOL) (SMD -0.30, 95% CI -0.46, -0.15; p<0.001), but not for depressed mood (SMD -0.12, 95% CI -0.30, 0.06; p=0.18). There was strong evidence for a non-substantial reduction of fatigue (SMD -0.16, 95% CI -0.23, -0.09, p<0.001) and of anxiety (SMD -0.18, 95% CI -0.27, -0.10; p<0.001). The external validity of the studies was limited because patients with severe somatic and mental disorders were excluded.
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Complex Regional Pain Syndrome type 1 (CRPS1) is a complication after trauma or surgery. Its pathophysiology is still a matter of debate, and psychological factors have been suggested to play a role, although their influence is unclear. The aim of this study was to investigate the evidence for the influence of psychological factors on the onset and maintenance of CRPS1 in adults. ⋯ Although many patients with CRPS1 are stigmatized as being psychologically different, this literature review identified no relationship between CRPS1 and several psychological factors. Only life events seemed to be associated with CRPS1: patients who experienced more life events appeared to have a greater chance of developing CRPS1. More studies with greater methodological quality and more participants should be performed on the association between psychological factors and the development and course of CRPS1.
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Randomized Controlled Trial
Enhanced central pain processing of fibromyalgia patients is maintained by muscle afferent input: a randomized, double-blind, placebo-controlled study.
Fibromyalgia (FM) syndrome is characterized by pain and widespread hyperalgesia to mechanical, thermal, and electrical stimuli. Despite convincing evidence for central sensitization of nociceptive pain pathways, the role of peripheral tissue impulse input in the initiation and maintenance of FM is unclear. Therefore this randomized, double-blind, placebo-controlled trial of 22 female normal controls (NCs) and 28 female FM subjects tested the effects of trapezius muscle (TrapM) tender point injections with 1% lidocaine on local pain thresholds as well as on remote heat hyperalgesia at the forearm. Prior to muscle injections shoulder pain was standardized by tonic mechanical muscle stimulation, resulting in local pain ratings of 4.0+/-0.5 VAS units. Tonic muscle stimulation was interrupted for the TrapM injections but was continued afterwards at the same level. NC as well as FM subjects experienced significant increases of TrapM pressure pain thresholds from lidocaine injections but not from placebo injections (p<0.001). Additionally, heat hyperalgesia of FM participants was significantly reduced at areas remote from the injection site (forearm) by lidocaine but not by placebo (p=0.02). Neither lidocaine nor saline injections significantly affected clinical FM pain ratings, a result most likely due to the very low dose of lidocaine (50mg) used in this trial. ⋯ Lidocaine injections increased local pain thresholds and decreased remote secondary heat hyperalgesia in FM patients, emphasizing the important role of peripheral impulse input in maintaining central sensitization in this chronic pain syndrome; similar to other persistent pain conditions such as irritable bowel syndrome and complex regional pain syndrome.
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Somatisation is often invoked to explain pain and suffering in patients. Lipowski [34] defined somatisation as "a tendency to experience and communicate somatic distress and symptoms unaccounted for by pathological findings, to attribute them to physical illness, and to seek medical help for them" (p. 1359). His concept is widely accepted. ⋯ Most studies focus upon the extent and diversity of somatic complaints. We recommend that researchers who use self-report instruments do not use the term "somatisation" (even if the instrument is labeled as a "somatisation" scale), but use the term "multiple physical symptoms" instead. The current operational use may unduly lead to a "psychologisation" of physical complaints.
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Randomized Controlled Trial
Activation of the prostaglandin system in response to sleep loss in healthy humans: potential mediator of increased spontaneous pain.
Insufficient duration of sleep is a highly prevalent behavioral pattern in society that has been shown to cause an increase in spontaneous pain and sensitivity to noxious stimuli. Prostaglandins (PGs), in particular PGE2, are key mediators of inflammation and pain, and we investigated whether PGE2 is a potential mediator in sleep-loss-induced changes in nociceptive processing. Twenty-four participants (7 females, age 35.1+/-7.1 years) stayed for 7 days in the Clinical Research Center. ⋯ Urinary PGE2 metabolite significantly increased by about 30% in TSD over sleep condition. TSD-induced increase in spontaneous pain, in particular headache and muscle pain, was significantly correlated with increase in PGE2 metabolite. Activation of the PGE2 system appears to be a potential mediator of increased spontaneous pain in response to insufficient sleep.