Pain
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Concussion, asphyxia, and systemically administered general anesthetics all induce reversible depression of the organism's response to noxious stimuli as one of the elements of loss of consciousness. This is so even for barbiturate anesthetics, which have only modest analgesic efficacy at subanesthetic doses. Little is known about the neural circuits involved in this form of antinociception, although for anesthetic agents, at least, it is usually presumed that the drugs act in widely distributed regions of the nervous system. ⋯ The behavioral suppression is accompanied by slow-wave EEG and, presumably, loss of consciousness. This zone, which we refer to as the mesopontine tegmental anesthesia locus (MPTA), apparently contains a barbiturate-sensitive 'switch' for both cortical and spinal activity. The very existence of the MPTA locus has implications for an understanding of the neural circuits that control motor functions and pain sensation, and for the cerebral representation of consciousness.
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The results of a considerable number of recent prospective studies have demonstrated that greater acute pain severity in herpes zoster patients is associated with a significantly greater risk of developing postherpetic neuralgia (PHN). Only a few studies have examined the relationships between acute pain severity and demographic characteristics and clinical features of patients with herpes zoster, however, and the results of these studies have been inconsistent. ⋯ These results demonstrate that three of the established risk factors for PHN - older age, greater rash severity, and the presence of a prodrome - are also associated with more severe acute pain assessed soon after rash onset in patients with herpes zoster. The results of this study are consistent with the recommendation that herpes zoster patients who are older, who have had a prodrome, or who have severe rash or severe acute pain should be targeted for interventions designed to prevent PHN.
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Randomized Controlled Trial Clinical Trial
The role of fear-avoidance beliefs in acute low back pain: relationships with current and future disability and work status.
Fear-avoidance beliefs have been identified as an important psychosocial variable in patients with chronic disability doe to low back pain. The importance of fear-avoidance beliefs for individuals with acute low back pain has not been explored. Seventy-eight subjects with work-related low back pain of less than 3 weeks'duration were studied. ⋯ Fear-avoidance beliefs about work were significant predictors of 4-week disability and work status even after controlling for initial levels of pain intensity, physical impairment, and disability, and the type of therapy received. Fear-avoidance beliefs are present in patients with acute low back pain, and may be an important factor in explaining the transition from acute to chronic conditions. Screening for fear-avoidance beliefs may be useful for identifying patients at risk of prolonged disability and work absence.
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In this study we compare the intrinsic characteristics and localization of nociceptive CO(2) laser evoked potential (LEP) and non-nociceptive electrical EP (SEP) sources recorded by deep electrodes (one to two electrodes per patient, 10-15 contacts per electrode) directly implanted in the supra-sylvian cortex of 15 epileptic patients. Early CO(2) laser (N140-P170) and electrical (N60-P90) evoked potentials were recorded by all of the electrodes implanted in the supra-sylvian cortex contralateral to stimulation. SEPs and LEPs had similar waveforms and inter-peak latencies. ⋯ The spatial distribution of these contralateral responses fits with that of the modeled sources of scalp CO(2) LEPs, magneto-encephalographic studies, and PET data from pain and vibrotactile activation studies. These results permit us to define the SII cortex as a cortical integration area of non-nociceptive and nociceptive inputs. This is supported by: (i) anatomical data reporting that the SII area receives inputs from both posterior columns and spino-thalamic pathways conveying the non-noxious and noxious information, respectively, and (ii) single cell recordings in monkeys, demonstrating that the SII area contains both nociceptive-specific neurons and wide-dynamic-range neurons receiving convergent input from nociceptive and non-nociceptive somatosensory afferents.
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Inadequate relief from cancer pain is an international health problem. The aim of this study was to document the prevalence and patterns of cancer pain management in the Republic of South Africa. The first phase of this study consisted of screening 263 patients to document the prevalence of cancer pain in varying settings. ⋯ Of this group, 58.1% were experiencing severe 'worst pain'. Unrelieved cancer pain is a significant problem. Government and non-government leaders, educators, and practitioners must collaborate to address the barriers to effective pain management and to implement improvements in education, health policy, and health care delivery.