Articles: neuralgia.
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We investigated behavioral symptoms of neuropathic pain, and associated changes in dorsal horn neurons, in a rat model involving loose ligation of lumbar dorsal roots. The L4-L6 dorsal roots were exposed unilaterally and loosely constricted central to the respective ganglia with one (1-ligation) or two (2-ligation) silk 7-O ligatures. In control groups the dorsal roots were exposed but not ligated (sham-operated), or sutures were placed lengthwise between the dorsal roots (suture control). ⋯ Enlarged cutaneous receptive fields of dorsal horn neurons may contribute to mechanical allodynia associated with dorsal root constriction. However, the slow (>5 week) development of receptive field enlargement does not match the rapid development of allodynia. The lack of effect of dorsal root constriction on thermal sensitivity of dorsal horn units ipsilaterally corresponds to the lack of marked thermal hyperalgesia observed behaviorally.
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Clinical Trial Controlled Clinical Trial
Topical EMLA pre-treatment fails to decrease the pain induced by 1% topical capsaicin.
Topical capsaicin has been reported to be beneficial for the treatment of neurogenic pain. However, due to the burning pain associated with topical capsaicin, many patients discontinue treatment before therapeutic benefits are obtained. This study assessed the efficacy of EMLA (eutectic mixture of 2.5% prilocaine and 2.5% lidocaine) to block pain induced by the topical application of 1% capsaicin. ⋯ The 6 h treatment with high dose topical capsaicin (1%) produced significant desensitization to heat stimuli that was not affected by EMLA treatment. EMLA fails to produce a long lasting attenuation of the pain induced by topical application of 1% capsaicin. These results argue against the use of EMLA to block pain to topical capsaicin during the treatment of neurogenic pain.
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Complex regional pain syndrome (CRPS) remains a poorly understood chronic pain disorder. Little data has been published assessing the epidemiology of CRPS (and reflex sympathetic dystrophy, RSD). This study assessed epidemiological variables in 134 CRPS patients evaluated at a tertiary chronic pain clinic in the US, including demographic, health care utilization and legal/workman's compensation measures. ⋯ The duration of CRPS symptoms and the involvement of the upper extremity was significantly associated with the presence of myofascial dysfunction. Thus, this study found that most CRPS patients are referred to a pain specialty clinic after several years of symptoms and many failed therapies. The data also suggest the lack of utility of a diagnostic bone scan and highlight the prominence of myofascial dysfunction in a majority of CRPS patients.
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Ugeskrift for laeger · Mar 1999
Case Reports[Diagnosis and treatment of postoperative nerve damage. Chronic neuropathic pain].
Neuropathic pain is caused by lesions in the peripheral and/or central nervous system. Patients with pain due to nerve damage after operations are often misinterpreted and met with suspicion of malingering. Neuropathic pain typically presents with a characteristic set of sensory disorders independent of the cause. ⋯ Instead, antidepressants and anticonvulsants may be tried. The pain condition is unknown to most physicians. This may result in mistreated patients having undergone several unnecessary and ineffective investigations and treatments.
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The unilateral sciatic nerve chronic constriction injury (CCI) model of Bennett and Xie [G. J. Bennett, Y.-K. ⋯ Fos counts ipsilateral to the injury in laminae 3-10 correlated with hyperalgesia scores in the CCI but not sham animals. Analysis at the 28-day time point showed that MK-801 differentially affected Fos expression: MK-801 significantly reduced the Fos count bilaterally in laminae 3-10 in the CCI but not in the sham group animals. These results indicate that Fos expression is initiated by different peripheral and central mechanisms following nerve injury or sham operation.