Articles: neuralgia.
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A hypothesis is presented concerning the neuronal mechanisms which subserve the sympathetically maintained pains such as causalgia and reflex sympathetic dystrophy. The hypothesis rests on two assumptions: that a high rate of firing in spinal wide-dynamic-range (WDR) or multireceptive neurons results in painful sensations; and that nociceptor responses associated with trauma can produce long-term sensitization of WDR neurons. The hypothesis states that chronic sympathetically maintained pains are mediated by activity in low-threshold, myelinated mechanoreceptors, that this afferent activity results from sympathetic efferent actions upon the receptors or upon afferent fibers ending in a neuroma and that these afferent fibers evoke sufficient activity in sensitized spinal WDR neurons to produce a painful sensation. ⋯ This hypothesis does not require nerve injury or dystrophic tissue. It explains both the continuous pain and the allodynia that are common to these syndromes and their abolition by sympathetic block. Specific changes are proposed in the diagnosis and treatment of post-traumatic pains.
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Inguinal neuralgia, an uncommon condition, can readily be diagnosed if the anatomy of the sensory nerves of the lumbar plexus is understood. The authors review 50 patients with this condition, pointing out the importance of injury to these nerves, not only on the anterior abdominal wall but also in the retroperitoneal space on the posterior abdominal wall. Successful treatment is achieved by surgical section of the nerves. First the inguinal region is explored; if this does not result in cure the authors recommend retroperitoneal section of the nerve.
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The treatment of 77 consecutive cases of post-herpetic neuralgia is reviewed. Stellate blockade proved helpful in 75% of patients with pain of less than 1 year's duration; 40% became virtually pain free. ⋯ Stellate blockade carried out within 1 year of the onset of symptoms would appear to be one of the treatments of choice for post-herpetic neuralgia. It would be of interest to see the results of a controlled randomised trial.
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In each of four patients with suspected thoracic outlet syndromes, the transaxillary approach to resection of the first thoracic and cervical ribs resulted in severe and permanent damage to the brachial plexus. The most severe sequela was causalgia. ⋯ Two patients suffered severe psychological depressions, with one committing suicide. Current enthusiasm with transaxillary rib resections in cases of thoracic outlet syndrome should be tempered by the possibility of severe and permanent injury to the brachial plexus and intractable causalgia.