A focused review on the use of botulinum toxins for neuropathic pain.

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. Common examples of neuropathic pain include postherpetic neuralgia, diabetic neuropathy, complex regional pain syndrome, and pain associated with spinal cord injuries. Nociceptive pain may have similar clinical characteristics to neuropathic pain. It is also possible for acute nociceptive pain to become neuropathic in nature, as with myofascial pain syndrome. 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.