Clinical orthopaedics and related research
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Clin. Orthop. Relat. Res. · Jun 1998
Comparative StudyPossible mechanism of painful radiculopathy in lumbar disc herniation.
The pathophysiologic mechanisms of painful radiculopathy caused by a herniated intervertebral disc remain unknown. This study sought to determine whether the autologous intervertebral disc produces pain related behavior and whether phospholipase A2 and nitric oxide are involved in the pathophysiologic mechanism producing the behavior. A rat model, in which autologous intervertebral discs were implanted on the nerve root in the lumbar spine, was used to measure hyperalgesia, which is a pain related behavior in the rat. ⋯ Thermal hyperalgesia produced by application of the anulus fibrosus was abated and abolished by epidural injections of saline and one of the inhibitors for nitric oxide synthase, respectively. The authors suggest that chemical mediators such as phospholipase A2 and nitric oxide, induced by extruded or sequestrated intervertebral discs, are involved in the pathophysiologic mechanisms of painful radiculopathy in lumbar disc herniations. This study may be useful in attempting to develop new medical approaches for treatments of lumbar disc herniation.
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The industrial upper limb pain epidemic colloquially known as repetition strain injury rapidly increased in the early 1980s to peak in 1985. Its less precipitous decline coincided with an awareness that repetition strain injury was a nonphysical sociopolitical phenomenon and a corresponding loss of the pecuniary benefits enjoyed by the powerful vested interest groups. Although its protagonists incorrectly claimed that this was a new disease, the rise and fall of repetition strain injury followed its historical predecessors including telegraphists' wrist and writer's cramp. ⋯ These patients were differentiated from those with genuine work related injuries whose symptoms are reproducible, with physical signs easily defined, disease identifiable, and response to physical treatment predictable. Most patients with repetition strain injury genuinely suffered the symptoms of which they complained and made little secondary gain relative to the protagonists of repetition strain injury who had a vested interest. The similarities between Australian repetition strain injury in the 1980s and American cumulative trauma disorder in the 1990s is compelling.