Articles: peripheral-nerve-injuries.
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Some of the chronic pains that follow disc rupture, myelography, and discectomy may be due to injury to peripheral nerves or nerve roots. The neural mechanisms underlying these pain syndromes are discussed and possible etiologies examined. The roles of peripheral and central changes in neuronal activity and connectivity are explored: plasticity in the nervous system may either be the cause of pain in the 5% of people who develop chronic pain after nerve injury or what prevents pain in the 95% who do not become painful after nerve injury. More research on the behavior of damaged nerves and their central connections is essential.
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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.