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How can Botulinum toxin be used to treat migraine?

The use of Botulinum toxin in headaches came around serendipitously, via cosmetic injectors in the early 2000s injecting people in the usual cosmetic areas and patients were reporting that their headaches were miraculously improving after years of headache. So then a number of trials were undertaken of various headache syndromes, including migraine, and none of them proved better than placebo until 2010.

So there is a treatment protocol called PREEMPT Botox which came out in 2010 and it only shows evidence in chronic migraine. So I need to be very specific with people. If you have four or five migraines a month, or two or three a year, even if they are severe, I’m not convinced that I can help you with Botox. Also the Australian Government, where we work, does not supply Botox for people with episodic migraine or tension headache or other syndromes. It’s only licensed for use in chronic migraine.

Having said that, there is the greatest evidence for chronic migraine. With this protocol, and this has been confirmed in a follow-up Australian multi-centre study, the response rate, depending on how you measure it, is 70-75%. So you’ll get people who have failed a number of oral medications, are highly disabled and essentially three quarters of them in less than six months will have 50% less headaches. Which is one of the definitions of success. If you had 45% improvement, that is still in my eyes a success.

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At twelve months we are seeing a reduction in headache frequency in the order of 75%. So what does this mean in real terms? If you come in with a headache diary showing three weeks with headache and 14 days with migraine and ten days with disabling episodes, what we see at six months is 50% less, but at 12 months these people have reverted to episodic migraine, which is less frequent episodes, shorter duration, less severe pain when present and easier to treat. They may still have the occasional severe attack. I tell people we’re not going to cure you, but it is at present the most effective and evidence-based treatment we have for chronic migraine.

Botox treatment PREEMPT protocol clinic data

Who is eligible for Botox treatment for migraine?

While Botox is the most effective treatment for migraine, we can’t use it first up for patients that we see. The system I work in requires the patient to have tried at least three oral prophylactic migraine drugs and they may have been intolerant of them, as in the side effects, or have failed to benefit from them. So they must have had a headache for at least six months and we need to manage people who are overusing acute or analgesic medication.

I didn’t mention this before but a lot of patients with chronic migraine have something called medication overuse headache. So that’s when we take a helpful medication, an analgesic, an anti-inflammatory, a triptan, and we take it frequently. Anything more than two or three days a week with these medications have been shown to increase headache. By that I mean it will work initially, and then the headache will rebound and they’ll be taking more and more of these pills, and the headache that returns is exactly like their original headache, so it’ll feel just like their migraine coming on. So they’ll take another triptan and the cycle just continues, and they end up with a continuous headache.

So that is another one of the causes of chronic headache and migraine. Before we start someone on Botulinum toxin we need to educate them about medication overuse headache. There are different approaches to managing it, one of which is getting them to come off all their medications. That’s sometimes not possible.

One other option is to commence Botox. We know that 50% of patients will respond within the first treatment cycle which is nice, because then they will naturally decrease their acute medication intake. If people aren’t improving after two treatment cycles we really need to say to them, “Look, you need to look at seriously detoxing off all these medications and trying Botox again.”

And that conversation is really important to have up front, because another restriction we have on prescribing Botox in Australia for chronic migraine is that patients who don’t achieve a 50% reduction at six months are deemed “treatment failures” and can no longer access the treatment.

What are the side effects of Botulinum toxin?

Botox has been used since the 1990s for various medical conditions. We know its safety profile. When used correctly it is a very safe medication. There are certain conditions and patient groups that should not have Botulinum toxin. They are generally people who have neuromuscular disorders. We would know that, we would be taking a medical history and these people would not be suitable for Botox.

In those that do undergo Botox treatment with the specific PREEMPT protocol for migraine, the side effect profile is quite good. So what I say to patients is that some people, in the order of 3-5% will experience either heaviness over the forehead or the neck area for a few weeks after the first treatment. It tends to fade and it tends not to recur when we do the second and subsequent treatments. And I explain that on the basis that Botox, or firstly the mechanism of action of Botox in migraine is unknown, but is thought to work via central nervous system mechanisms. And I tell people, “Your brain is registering some weakness, of these muscles, even tiny amounts of weakness can be registered by the brain and it feels like there is heaviness.” So that’s the first thing I tell people.

People can be sensitive to the medication because their muscles are smaller and they can get drooping of the brow or eyelid. That’s managed with dose reduction and these symptoms are also temporary. Remember Botox only lasts three months, so that is a good thing and a bad thing. If there is a side effect such as a drooping of an eyelid, that will last 2-6 weeks and it always comes good. Then we can reduce the dose or adjust the recipe, the protocol, to minimise the chance of it happening again.

Rare allergic reactions have been reported. I’ve seen one in almost 15 years, but really, it’s a safe treatment. People come into the clinic and have the injections and they leave and go back about their daily business. Back to work or school or whatever they were doing.

Is Botulinum toxin safe in pregnancy?

The use of Botox in pregnancy has not been well studied, as you can imagine. I go along with the general principle of do not inject anyone who is actively trying to become pregnant. If I do have patients who are having regular treatment for migraine or other neurological conditions, I’ll say to them, “Look, we don’t know, it’s probably safe. There is no biological, plausible reason why this would be harmful to the foetus or teratogenic, but let’s just be sensible and not inject you in the first trimester when all the organs are forming.”


Video kindly featuring:

Dr Julian Rodrigues MBBS FRACP; Consultant Neurologist at Hollywood Medical Centre, and Editorial Advisory Board Member of the Virtual Neuro Centre.



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