The Clinical journal of pain
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Randomized Controlled Trial Clinical Trial
Postdelivery of alfentanil and ketamine has no effect on intradermal capsaicin-induced pain and hyperalgesia.
The predelivery of intravenous alfentanil (a mu opioid agonist) and ketamine (an -methyl d-aspartate antagonist) has recently been shown to decrease the secondary hyperalgesia induced by intradermal capsaicin. The focus of this study was to determine the effects of the postdelivery of intravenous alfentanil and ketamine on intradermal capsaicin-induced secondary hyperalgesia. ⋯ Consistent with animal studies on preemptive analgesia, this study demonstrates that alfentanil and ketamine have a differential effect when delivered before and after a painful stimulus. Because of the differential effect seen, future studies on the pharmacology of human experimental pain should evaluate both predrug and postdrug delivery.
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Chronic pain is a prevalent and costly problem. This review addresses the question of the clinical effectiveness and cost-effectiveness of the most common treatments for patients with chronic pain. ⋯ There are limitations to the success of all the available treatments. The author urges caution in interpreting the results, particularly in comparisons between treatments and across studies, because there are broad differences in the pain syndromes and inclusion criteria used, the drug dosages, comparability of treatments, the definition of "chronic" used, the outcome criteria selected to determine success, and societal differences. None of the currently available treatments eliminates pain for the majority of patients. Pain rehabilitation programs provide comparable reduction in pain to alternative pain treatment modalities, but with significantly better outcomes for medication use, health care utilization, functional activities, return to work, closure of disability claims, and with substantially fewer iatrogenic consequences and adverse events. Surgery, spinal cord stimulators, and IDDSs appear to have substantial benefits on some outcome criteria for carefully selected patients. These modalities are, however, expensive. Pain rehabilitation programs are significantly more cost effective than implantation of spinal cord stimulators, IDDSs, conservative care, and surgery, even for selected patients. Research is needed to identify which patients are most likely to benefit from the available treatments and to study combinations of the available treatments since none of them appear capable of eliminating pain or significantly improving functional outcomes for all treated.
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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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Spasticity is an abnormal increase in muscle contraction often caused by damage to central motor pathways that control voluntary movement. During clinical examination, spasticity manifests as an increase in stretch reflexes, producing tendon jerks and resistance appearing as muscle tone. There are many causes of spasticity, including demyelination from multiple sclerosis, congenital damage from diseases such as cerebral palsy, trauma to the brain or spinal cord, hemorrhage or infarction, and other pathologic conditions that interrupt neural pathways. ⋯ Botulinum toxin therapy may be particularly useful for patients with spasticity due to stroke, whose treatment can be tailored based on recovery of function over time. In addition, botulinum toxin therapy is safe for pediatric patients, including children with cerebral palsy, who may not be able to tolerate the cognitive side effects of oral medications. Results of studies evaluating botulinum toxin for the treatment of spasticity due to various causes are presented here.
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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.