Articles: pain.
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Peripheral damage is immediately assessed by the central nervous system by way of a gate control system so that the sensory outcome depends not only on the fact of the injury and the injury signals but also on other convergent impulses from the periphery and on descending controls from brain to spinal cord. However peripheral injury, particularly when nerves are affected, sets off a chain of slow reactions which start in the area of damage but spread centrally. ⋯ The arrival of injury produced impulses in the spinal cord triggers changes with a latency of many minutes which persist for hours even if no further impulses arrive. These increases of excitability and expansion of receptive fields which are triggered by C fibres may be the basis of the secondary hyperalgesias and reflex changes associated with injury.
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25 consecutive episodes of acute chest syndrome in 13 adult patients with sickle-cell disease were studied retrospectively. Chest symptoms were present on admission in 23 of 25 episodes. Abnormal chest signs and an abnormal chest X-ray were present on admission in only 11 and 9 episodes, respectively, but developed later in the remainder. ⋯ In 12 episodes (6 bilateral, 6 unilateral) exchange transfusion was required and produced striking improvement in 11. Despite intensive microbiological investigation, infection was found in only 2 episodes--1 mycoplasma and 1 evidence of Escherichia coli. Pulmonary intravascular sickling may account for much of the clinical picture.