This is a good question and it doesn't have a simple answer. The reason is there are often multiple causes contributing the the problem.
Think of it like a bushfire - we have essential factors required to start a fire, but many different factors that will vary from fire to fire to cause it to be an 'out of control fire'.
The three essential elements to create the fire are, fuel, heat and oxygen. Most commonly the hear element also comes in the form of an ignition or 'trigger'.
But these are present every summer, and indeed fires start every year but we rarely see them grow out of control. We now add strong winds and sloping topography, then isolation from resources to put it out to spread the fire rapidly.
Indeed going deeper again we see building codes, communications systems and public infrastructure maintenance all playing a part in major fire events.
We can think of the causes of migraine in the same way. There may well be an obvious precipitating event or trigger (i.e. spark) - such as stress, ingestants, light, etc. and just like different major fires, different people will have different factors that contribute - be they genetic disorders related to gut or calcium channel activity, reactions to certain chemicals in food or drink, or indeed light or sound.
All these vastly different combinations...........they all lead to pain in the head.
Regardless of the trigger we know from a broad section of research that all headache sufferers have an increase in the resting activity levels of the trigeminal nucleus - the part of the brainstem housing all the nerves for the head and the face (trigeminal) and neck (upper cervical spine).
It makes perfect sense then that treatments targetting proteins in inflammatory substances in the blood (CGRP), or reducing stress, or reducing tension of scalp muscles (botox) will only be effective for a few (the lucky ones who have one major cause - i.e. a gas plant fire) as opposed to those with multiple causes.
You would expect the research to show modest changes with these types of treatments.
Thats exactly what we see.
Research into a drug that blocks CGRP, a protein that causes significant vasodilation, and botox show similar modest effects.
For CGRP, in a group suffering 18 migraine days per month the treatment group had an improvement of 6.6 days per month. (Hold your applause)
Placebo group improved by 4.2 days per month.
The botox studies showed in suffers with around 19 headache days per months treatment reducing headaches by 1.8 days per month more than placebo (7.6 days vs 5.8).
Interestingly, the usual bar of 50% reduction in frequency to be deemed effective was lowered to 30% for the botox trial........just snuck in........but then the placebo hits the mark too.
In both the case of botox and CGRP the treatments are not without potentially harmful side effects.
Maybe worth the risk if the results were outstanding, but I think I'd go with the placebo which also proved to be effective, less expensive and no side effects.
The reason for limited effect here is clear when you consider the multiple causes - these are only targeting a very narrow band.
The most effective drugs to date - the triptans, target the sensitivity of the trigeminal nucleus. By helping the body absorb serotonin, the activity in the brainstem reduces and can abort episodes.
The technique we use, the Watson Headache Approach, has been shown to do the same thing, without needing to take tablets.
In other words, if we minimise the fuel loads to begin with, it doesn't matter how hot it is, how dry it is, or how strong the wind is...............we can minimise the size of the fire, or indeed it just doesn't take hold in the first place.
We can safely, and naturally decrease the activity of the brainstem - regardless of triggers, and regardless of the multiple causes.
We target the structure that all these factors affect, and lead directly to migraine.
Roger O'Toole is the Director and Senior Clinician of the Melbourne Headache Clinic and has over 10 years experience as a physiotherapist.