Botox® (onabotulinum toxin A) has been approved to treat frequent migraines since July 2010 by the Medicines and Healthcare products Regulatory Agency (MHRA). Botox® is not yet approved for infrequent migraines, tension headaches, or cluster headaches.
What is botulinum toxin?
Concentrated exposure to botulinum toxin can cause botulism, an illness first studied in the early 1800s, though the bacteria that produces the toxin, Clostridium botulinum, was not actually discovered until much later in the century. Seven different types of the toxin, classified A-G, have been discovered. A weak solution of botulinum toxin type A (Botox®) was first used clinically as therapy for squint and blepharospasm. Since that time it has been shown to be effective in treating muscle spasms, spasticity and hyperhidrosis. Other solutions consisting of botulinum toxin type A and type B are available, but they have not been used to treat headaches.
Botulinum toxin and headache
In the 90s, people who were being treated with botulinum toxin for other conditions started reporting a reduction in frequency and intensity of headaches. Clinical trials for headaches were conducted with unfavorable outcomes. In most cases, botulinum toxin was no more effective than a placebo for tension headaches, infrequent migraines and other types of headaches. Later examination of the results of the studies suggested that some patients with persistent migraines might see a reduction in frequency, duration or intensity of their headaches.
PREEMPT trials of (Botox®) for persistent migraine
1,384 chronic migraine sufferers participated in Phase 3 Research Evaluating Migraine Prophylaxis Therapy (PREEMPT) studies. Patients were randomised into Botox® or placebo. Prior to the study, participants experienced headaches 20 days a month on average, with 18 headache days being moderate to severe. Participants received injections of either Botox® or a placebo into specific sites on the head and neck once every 12 weeks over a course of 56 weeks. After only two of these treatments, the participants who received Botox® averaged 8 fewer headache days per month. By the end of the study, 70% participants who received Botox® reported less than half as many headache days as before. The side effects of Botox® were minimal with the most common being neck pain, muscle weakness and drooping eyelids. These side effects were temporary.
How does botulinum toxin provide relief from chronic migraine?
Scientists haven’t yet figured out the mechanism whereby Botox® alleviates migraine pain. In most conditions, Botox® works by relaxing muscles. In migraine, it’s thought that Botox® works by blocking certain neurotransmitters that trigger migraines.
Could Botox® work for me?
Only chronic migraine sufferers, those with at least 15 headache days per month, with at least half of headache days being migraines, are currently able to receive treatment with Botox®. Botox® isn’t the only treatment available for chronic migraines, so talk to your doctor about your options.
Who can administer Botox® for chronic migraine?
While Botox® is not restricted to special headache clinics, you should be certain that the person administering Botox® has been properly trained, both in diagnosing and managing chronic migraines, as well as the administration of Botox® according to the PREEMPT guidelines.
Expect to give a thorough history of your headaches, including frequency, intensity, duration, triggers, symptoms and any medications or remedies that have been taken.