Pain
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Clinical Trial
Influence of previous pain experience on the episode incidence of low back pain: results from the South Manchester Back Pain Study.
A pathological cause cannot be identified for most new episodes of low back pain (LBP) presenting to the general practitioner. One important potential influence on susceptibility is previous pain experience. To accurately investigate the contribution of this phenomenon to the onset of new episodes of LBP a prospective population study is required. ⋯ In those currently free of LBP a previous history of the symptom substantially increases the risk of a further episode, with pain in other sites an equally strong independent predictor of subsequent LBP.
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Breast surgery is a common procedure performed in women. Many women who undergo breast surgery suffer from ill-defined pain syndromes. Although there exists a few reports on the incidence of post mastectomy pain, there are no published reports on chronic pain after breast reconstruction. ⋯ The incidence of breast pain is highest in the mastectomy + reconstruction and augmentation groups which is assumed to be secondary to breast implants. Every effort should be made to achieve the best cosmetic result in breast reconstruction which in many cases justifies the use of breast implants. However, these women should be counseled on the possibility of developing chronic pain.
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Recent studies have reported a high prevalence of symptoms of post-traumatic stress disorder (PTSD) among individuals with chronic pain. Studies suggest that persons with pain and PTSD also display higher levels of affective disturbance. In the present study we examined self-reports of pain, affective disturbance, and disability among pain patients with and without symptoms of PTSD. ⋯ These findings suggest that PTSD symptoms in chronic pain patients are associated with increased pain and affective distress. Accident related pain, even without the presence of PTSD symptoms, appears to be associated with greater disability. The results indicate that the identification and treatment of PTSD symptoms in refractory pain patients may be a critical albeit subtle factor in the effective management of suffering and disability in this population.
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Behavioral and electrophysiological methods were used to investigate the hyperalgesia and allodynia, and functional changes in lumbar spinal dorsal horn neurons, in a model of neuropathic pain (Selzer et al. 1990) involving ligation of one-third to one-half of one sciatic nerve in rats. One and 5 weeks following ligation, there was a significant reduction in hind limb withdrawal latency to noxious radiant heat on the operated side and, to a lesser degree, on the unoperated side. By 16 weeks, heat withdrawal latencies were reduced about equally (approximately 40%) on both sides. ⋯ Mechanical receptive field areas were not significantly different between ipsi- and contralateral sides in the sham and 5-week post-ligation groups, or between sham and 5-week post-ligation groups. However, receptive field areas were significantly larger in the 16-week post-ligation group (both ipsi- and contralateral to ligation) compared to sham and 5-week post-ligation groups. The results suggest that allodynia may be associated with a chronic enhancement of neuronal mechanosensitivity, but that the thermal hyperalgesia is not associated with enhanced neuronal responsiveness or force of withdrawal.
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Treatment of adult rats with a single dose of nerve growth factor (NGF, 1 mg/kg, i.p.) results in a prolonged hypersensitivity to noxious thermal stimulation which becomes noticeable within 30 min of administration and lasts for several days. A significant mechanical hyperalgesia develops within 7 h following injection of NGF and persists for up to 7 days. In the present set of experiments we describe certain quantitative features of this hyperalgesia. ⋯ Injection of the neurokinin NK1 receptor antagonist CP-96345 or its inactive enantiomer CP-96344 one day after NGF both induced a transient block of NGF-induced thermal hyperalgesia indicating a non-specific effect rather than an action at NK1 receptors. This was confirmed by finding no reversal of NGF-induced hyperalgesia by RP67580, another NK1 receptor blocker. These results suggest upregulation and activation of BK1 but not NK1 receptors as an additional, probably peripheral, mechanism for the late phase of NGF-induced thermal hyperalgesia.