The Clinical journal of pain
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Botulinum toxin has been shown to effectively treat several types of pain associated with neurologic disorders. It has recently been evaluated for the treatment of various types of headaches. In studies of migraine headache, chronic daily headache (more than 15 days of headache per month), tension-type headache, and post-whiplash headache, patients have reported decreased pain after treatment with botulinum toxin type A. ⋯ It may also provide peripheral and central neurogenic effects and reduce inflammation. Large, rigorously controlled trials of botulinum toxin are needed to better characterize its effects on various types of headaches and its role as a therapeutic agent. Current data suggest that botulinum toxin is safe and does not produce systemic effects associated with other types of headache treatments.
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Botulinum toxin is approved for the treatment of muscle overactivity associated with several disorders, such as dystonias. However, control of muscle spasm often results in pain relief as well. Effective relief of pain associated with myofascial pain syndrome provides a model for the use of botulinum toxin to relieve pain associated with other types of soft-tissue syndromes, such as fibromyalgia. ⋯ Several studies have demonstrated the efficacy of botulinum toxin types A and B in treating several neuropathic pain disorders. Proper patient selection, injection technique, and dosing are critical to obtaining the best outcomes in managing pain with botulinum toxin. Additional study is needed to better characterize its use for the treatment of pain.
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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.
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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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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.