Pain
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Persistent postoperative pain is a well-established clinical problem with potential severe personal and socioeconomic implications. The prevalence of persistent pain varies across surgery types. Severe persistent pain and related impairment occur in 5% to 10% of patients after groin hernia repair. ⋯ For GCH1, the A allele of SNP rs3783641, T allele of rs8007267, and AT haplotype showed a protective effect trend (although nonsignificant; P = 0.08, 0.06, and 0.08, respectively). A prediction model of substantial PPP-related activity impairment, combining COMT and GCH1 SNPs with clinical, psychophysical, and psychological risk factors, had a "good" (0.8 < area under curve < 0.9) discriminatory power. These data suggest that functional variations in COMT and GCH1 combined with clinical factors are predictive of PPP-related impairment after groin herniotomy.
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Central dopamine and norepinephrine regulate behavioral and physiological responses during rewarding and aversive stimuli. Here, we investigated and compared norepinephrine and dopamine transmission in 2 limbic structures, the ventral bed nucleus of the stria terminalis and the nucleus accumbens shell of anesthetized rats, respectively, in response to acute tail pinch, a noxious stimulus. Norepinephrine release in the ventral bed nucleus of the stria terminalis responded monophasically, increasing at the time of the tail pinch and remaining elevated for a period after its cessation. ⋯ At the termination of the stimuli, however, extracellular dopamine either recovered back to or spiked above the initial baseline concentration. These signaling patterns were more clearly observed after administration of selective catecholamine autoreceptor and transporter inhibitors. The results suggest that the opposing responses of these catecholamines can provide integration of noxious inputs to influence behavioral outputs appropriate for survival such as escape or fighting.
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Review Meta Analysis
Early changes in somatosensory function in spinal pain: a systematic review and meta-analysis.
Alterations in sensory processing have been demonstrated in chronic low back and neck pain. However, it has not been yet systematically summarized how early these changes occur in spinal pain. This systematic review examines the available literature measuring somatosensory function in acute (<6 weeks) and subacute (6-12 weeks) spinal pain. ⋯ Sources of bias included lack of assessor blinding, unclear sampling methods, and lack of control for confounders. We found that: (1) there is consistent evidence for thermal and widespread mechanical pain hypersensitivity in the acute stage of whiplash, (2) there is no evidence for pain hypersensitivity in the acute and subacute stage of idiopathic neck pain, although the body of evidence is small, and (3) hyperalgesia and spinal cord hyperexcitability have been detected in early stages of nonspecific low back pain, although evidence about widespread effects are conflicting. Future longitudinal research using multiple sensory modalities and standardized testing may reveal the involvement of somatosensory changes in the development and maintenance of chronic pain.
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Randomized Controlled Trial
Effects of testosterone replacement in men with opioid-induced androgen deficiency: a randomized controlled trial.
Symptomatic androgen deficiency is common in patients taking opioid analgesics, as these drugs potently suppress the hypothalamic-pituitary-gonadal axis. However, the efficacy of testosterone replacement in this setting remains unclear. The objective of this trial was to evaluate the efficacy of testosterone replacement on pain perception and other androgen-dependent outcomes in men with opioid-induced androgen deficiency. ⋯ Testosterone administration was also associated with an improvement in body composition. There were no between-group differences in changes in self-reported pain. In conclusion, in men with opioid-induced androgen deficiency, testosterone administration improved pain sensitivity, sexual desire, body composition, and aspects of quality of life.