Pain
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Endometriosis is a painful disorder defined by extrauteral endometrial growths whose contribution to pain symptoms is poorly understood. Endometriosis is created in rats by autotransplanting on abdominal arteries pieces of either uterus (ENDO), which form cysts, or fat (shamENDO), which do not form cysts. ENDO, but not shamENDO induces vaginal hyperalgesia. ⋯ The increases in ENDO-induced hyperalgesia produced by the sham-cyst-removal surgery were smaller in proestrus than in other estrous stages. During the other stages (but not during proestrus), sympathetic innervation of the cysts increased. These results suggest that maintenance of ENDO-induced vaginal hyperalgesia requires continued presence of at least some ectopic endometrial tissue, and that surgical treatment that fails to remove ectopic endometrial tissue can exacerbate the hyperalgesia, possibly due in part to an increase in the cysts' sympathetic innervation.
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Randomized Controlled Trial Clinical Trial
Analgesic efficacy of tramadol, pregabalin and ibuprofen in menthol-evoked cold hyperalgesia.
We investigated the analgesic efficacy of single doses of ibuprofen, tramadol and pregabalin in menthol-evoked cold pain in a randomized, placebo-controlled four-way cross-over study in 20 healthy volunteers. Tramadol 100mg significantly reduced menthol-evoked cold hyperalgesia. Effects of ibuprofen 600mg and pregabalin 100mg were not significant. ⋯ Minor side effects also accompanied analgesic effects of pregabalin and ibuprofen in subjects responding to these drugs, mostly fatigue, dizziness and difficulties to concentrate for pregabalin and gastric upset for ibuprofen. Five out of 18 subjects had a 50% reduction of cold hyperalgesia with tramadol, three of these additionally responded to pregabalin, and two with all three drugs. The numbers needed to treat (NNT >or= 50% for tramadol 4.5, for pregabalin 9) largely agree with the reported efficacy of tramadol and of moderate dosages of pregabalin in patients with peripheral or central neuropathic pain suggesting that menthol-evoked cold pain hypersensitivity may represent a valid model for neuropathic pain, particularly cold allodynia.
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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.
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Individual differences in sensitivity to fentanyl, a widely used opioid analgesic, can hamper effective pain treatment. Still controversial is whether the single nucleotide polymorphisms (SNPs) of the human OPRM1 gene encoding the mu-opioid receptor influence the analgesic effects of opioids. We examined associations between fentanyl sensitivity and the two SNPs, A118G and IVS3+A8449G, in the human OPRM1 gene in 280 Japanese patients undergoing painful orofacial cosmetic surgery, including bone dissection. ⋯ Furthermore, the IVS3+A8449G SNP in intron 3, which represents a complete linkage disequilibrium block with more than 30 SNPs from intron 3 to the 3' untranslated region, was associated with 24-h postoperative fentanyl requirements. Subjects carrying the minor G allele of the IVS3+A8449G SNP required significantly less fentanyl for 24-h postoperative pain control (median: 1.5microg/kg) compared with subjects not carrying this allele (median: 2.5microg/kg, p=0.010). Although further validation is needed, the present findings shed light on the involvement of OPRM1 3' untranslated region polymorphisms in fentanyl sensitivity in addition to the A118G SNP and open new avenues for personalized pain treatment with fentanyl.
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Facial pain has a considerable impact on quality of life. Accurate incidence estimates in the general population are scant. The aim was therefore to estimate the incidence rate (IR) of trigeminal neuralgia (TGN), postherpetic neuralgia (PHN), cluster headache (CH), occipital neuralgia (ON), local neuralgia (LoN), atypical facial pain (AFP), glossopharyngeal neuralgia (GPN) and paroxysmal hemicrania (PH) in the Netherlands. ⋯ The IR increased with age for all diseases except CH and ON, peaking in the 4th and 7th decade, respectively. Postherpetic neuralgia, CH and LoN were more common in men than women. From this we can conclude that facial pain is relatively rare, although more common than estimated previously based on hospital data.