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Since the 1980s, botulinum toxins (BTXs) have been used for many putative conditions that cause pain. The U.S. Food and Drug Administration (FDA) has approved BTX type A as a prophylactic treatment for headaches due to chronic migraines and approved both BTX type A and B for other medical conditions associated with pain and discomfort. Although BTX is currently not approved for any other headache disorders, it continues to be used successfully by a range of specialists to address pain control.
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Although there are many case reports and open-label studies on the effectiveness of BTX in treating painful conditions, a dearth of double-blind, placebo-controlled, randomized clinical trials exist that directly addresses its use for pain management. Some double-blind, placebo-controlled, randomized clinical studies show that botulinum toxin type A (BTX-A) injections are effective in treating various headache disorders (Table 34-1). However, so far, an open study has shown BTX is ineffective for patients with episodic cluster headaches.13
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All of the data presented in this chapter, and most of the published experience in headache management, is from BTX-A studies, but botulinum toxin type B (BTX-B) also may be effective, given the similarity of the two serotypes.
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Headache is one of the most common types of pain disorder, responsible for more than 10 million physician visits annually in the United States. Although the terminology of various types of headaches may be confusing, we limit our discussion here to mostly primary headaches, for which BTX data are available. More research continues, with the largest chronic migraine study to date done in 2010, leading to FDA approval of BTX. Other large, double-blind, randomized, placebo-controlled trials are coming forward for other types of headaches.
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