Having injected several hundred individual patients with Botox over the last several years, I thought it was an appropriate time to share my experience, as well as more information about the use of Botox in migraine. I will go through the scientific evidence about whether it works, what is actually done and what it feels like.
Let’s start with who is it used for.
Who is it for?
Chronic migraine is defined as 15 headache days per month, of which 8 are migraines
Botox is approved (under the PBS, so you can get the Botox provided under Medicare) for patients with chronic migraine only, so there needs to be a headache diary with those number of days marked off a month. You then receive two courses of Botox (we’ll go through what that involved below), and can continue if the headache frequency (how often there are headaches) is halved. Another criterion is that you have failed 3 specific headache preventative medications.
In other words, this is for patients with a high number of headaches and can only be continued if it shows a significant reduction in the number of headaches. This sounds uncommon, but chronic migraine affects 1-2% of the world’s adult population, so it really is under-rated.
Where do the injections go?
The Botox used for migraine is injected according to the PREEMPT protocol, which was a clinical trial to show the effectiveness of Botox in chronic migraine. There are 31 injections over the head and neck, which cover the common trigger points of migraine and a total of 155U of Botox is used. There is a sting with each, but usually this is manageable.
In general, there are few side effects: most patients feel local soreness for 1-2 days and then settle. There are very rare risks of drooping of the eyelid – I have seen this only once and for a few days only – and otherwise others rarely described. Clinical trials discuss neck pain in 4%, worsening migraine in 4% and a rash or itch at the site in less than 1%.
Botox lasts for 10-12 weeks and can be re-injected under Medicare every 12 weeks.
Does it work?
In my experience, yes, but like everything, not for everyone. However, the response rates are very good, at least if not better than other medications in headache prevention. In data collected from patients after the clinical trials were completed, of patients who received Botox for the first time, 65% were satisfied or very satisfied with the treatment (presented at the Congress of European Neurology, 2017, abstract 04108).
The clinical trials showed 40-50% of patients had a greater than 50% reduction in the number of headache days per month. The effects, when compared to other migraine medications, such as topiramate, valproate and amitriptyline were similar.
In the clinical trials of Botox, 40-50% of patients had a greater than 50% reduction in the number of headache days per month
How does it work?
This remains speculative, although what you will commonly read about it being related to relaxation of the muscles is likely incorrect, as Botox has been shown to work in patients when there was no muscle relaxation.
The most likely mechanism proposed so far is actually the toxin being taken up into nerve cells upstream of the injection and blocking the release of the brain chemical (neurotransmitter) that is seemingly most responsible for the inflammation of the covering of the brain (meninges) – CGRP. This is the site of action of new medications soon to be released onto the market, so watch this space…