Pain
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Incidence rate estimates of neuropathic pain are scanty and mostly address single types whereas the scope of the disease is wide. We aimed to calculate the incidence rates of neuropathic pain conditions in the Dutch general population and to assess treatment strategies in primary care. The study population included persons registered for at least one year in the Integrated Primary Care Information (IPCI) database between 1996 and 2003. ⋯ Anticonvulsants and tricyclic antidepressants were only used by 4.8 and 4.7% of cases. Neuropathic pain is a rather frequent condition with an annual incidence of almost 1% of the general population and affecting women and middle-aged persons more often. The treatment mostly consisted of regular analgesics suggesting that pharmacological treatment of neuropathic pain is suboptimal.
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Peripheral nerve injury causes neuropathic pain including mechanical allodynia and thermal hyperalgesia due to central and peripheral sensitization. Spontaneous ectopic discharges derived from dorsal root ganglion (DRG) neurons and from the sites of injury are a key factor in the initiation of this sensitization. Numerous studies have focused primarily on DRG neurons; however, the injured axons themselves likely play an equally important role. ⋯ The function of these accumulated channels was verified by local application of ZD7288, a specific HCN blocker, which significantly suppressed the ectopic discharges from injured nerve fibers with no effect on impulse conduction. Moreover, mechanical allodynia, but not thermal hyperalgesia, was relieved significantly by ZD7288. These results suggest that axonal HCN channel accumulation plays an important role in ectopic discharges from injured spinal nerves and contributes to the development of mechanical allodynia in neuropathic pain rats.
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Trying to control pain is a common human goal. But little is know about what happens when one loses control over pain. This paper reports an experiment with 74 healthy volunteers, half of whom were given control over a pain stimulus and subsequently lost control, and half of whom never had control over the pain. ⋯ These findings are discussed within the context of a dual process model of coping with uncontrollable adverse events [Brandtstädter J, Renner G. Tenacious goal pursuit and flexible goal adjustment: explication and age-related analysis of assimilative and accommodative strategies of coping. Psychol Aging 1990;5:58-67] and possible mechanisms for perseverance with ineffective solutions.
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Attenuation of the lower limb nociceptive flexion reflex (NFR) during the cardiac cycle has been attributed to inhibition of sensorimotor function by arterial baroreceptor activation. It has been proposed that cardiopulmonary baroreceptors might have similar inhibitory effects. ⋯ Nociceptive responding and pain ratings did not differ between postures suggesting no cardiopulmonary effects. This phasic modulation of the upper limb withdrawal response provides further support for arterial baroreceptor-mediated inhibition of nociceptive transmission.