The Clinical journal of pain
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Comparative Study
Chronic pain and nonpainful sensations after spinal cord injury: is there a relation?
First, to define the clinical characteristics of nonpainful sensations (NP) that commonly appear after spinal cord injury (SCI); and second, to compare the clinical characteristics of NP and chronic pain (CP) after SCI. ⋯ While many aspects of the clinical picture of CP and NP are similar after SCI, the CP and spontaneous NP are not necessarily located in the same areas. Although the observed similarities between CP and NP may be based on pathophysiologic mechanisms, the significant relations between the interference patterns suggest that psychosocial mechanisms related to coping are also involved.
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An overview is presented of neuropathic pain syndromes, their characteristic symptoms and signs, and recent approaches to identifying their pathophysiologic mechanisms. ⋯ Precise estimates of the prevalence of neuropathic pain are not available, but chronic neuropathic pain may be much more common than has generally been appreciated and its prevalence can be expected to increase in the future. There is considerable agreement that both peripheral and central processes contribute to many chronic neuropathic pain syndromes, and that these different mechanisms may explain the qualitatively different symptoms and signs that patients experience. The limitations of existing treatments for neuropathic pain and the inability to provide relief for many patients has stimulated ongoing studies that examine different approaches to preventing neuropathic pain.
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Understanding the pathophysiology of a pain syndrome is helpful in selecting appropriate treatment strategies. Nociceptive pain is related to damage to tissues due to thermal, chemical, mechanical, or other types of irritants. Neuropathic pain results from injury to the peripheral or central nervous system. ⋯ A clear benefit of botulinum toxin therapy for treatment of neuropathic pain disorders is that it often relieves pain symptoms. Although the precise mechanism of pain relief is not completely understood, the injection of botulinum toxin may reduce various substances that sensitize nociceptors. As a result, botulinum toxin types A and B are now being actively studied in nociceptive and neuropathic pain disorders to better define their roles as analgesics.
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This article reviews the prevalence, risk factors, natural history, and impact on quality of life of painful diabetic neuropathy (PDN) and postherpetic neuralgia (PHN). ⋯ Both conditions are common complications of their underlying disorders and can profoundly diminish the quality of life of affected persons.
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The immune system is unable to determine whether material it encounters is deleterious, benign, or even beneficial to the organism. This presents a significant challenge when protein-based biological therapies, such as botulinum toxin, are administered to patients. Many factors combine to influence the likelihood and the magnitude of an immune response if a response is elicited. ⋯ The majority of anti-toxin antibodies do not affect its function. Finally, although crossreactivity has been reported among the seven botulinum toxin serotypes, non-neutralizing antibodies are present that recognize regions of similarity among the serotypes. No cross-neutralizing antibodies have been described in patients administered any of the toxin serotypes.