Up to 53% of migraineurs report weather changes as a consistent trigger making it one of the most commonly reported triggers for migraine behind stress, hormones and skipped meals. [1]
 
A subject of interest as far back as 1974, researchers have spent decades trying to examine the question: Does weather actually trigger migraine attacks, and if so, what are the factors related to weather change that is causing attacks in people?
Theories over the years have included temperature and barometric pressure changes, high and low humidity, high winds, stormy weather, and changes in light conditions (very bright or dull light as well as changes in daylight hours). 
The science however has provided contrasting and often confusing results making it difficult to understand what is happening.
 
In 1979 [2] researchers in London asked 310 migraineurs about the day and time of their attacks (subject to recall bias) and found no correlation with changes in wind, barometric pressure, humidity and temperature. 
 
Jump ahead to 2011 and Karin Zebenholzer and colleagues [3] undertook a 90-day prospective diary study in Vienna. Whilst they found trends when analyzing change in temperature, wind speed, sunshine duration in isolation, analysis of multiple variables to account for attacks yielded no positive findings.
Their conclusion was ‘the influence of weather factors on migraine and headache is small and questionable.

​In 2013 [4] researchers studied the effect of lightening strikes on 90 migraineurs who kept diaries for 3-6 months. When they analysed the data they also accounted for rainfall, and barometric pressure.
 
When there was a lightening strike within 25 miles (40kms) there was a 25-30% increased risk of both new-onset headache or new-onset migraine. They are following up with further research to try and determine what it is that lightening strikes do that can cause a slight increase in migraine incidence.

The odds of having a new headache or migraine start increased on days with lightening that had a more negative charge leading researchers to suggest that something to do with the electromagnetic interaction is causing some irritation of the nervous system and triggering an episode. 
 
Lead researcher Dr Vince Martin [5], explained that other environmental factors change in thunderstorms, in particular related to fungi and mold. Rain increases mold counts, and if lightening strikes the ground it aerosolizes the fungi. In other words we breathe in a lot of fungi and molds in the air during thunderstorms, contributing to our now famous ‘Thunderstorm Asthma’ events.
When this is coupled with the fact that migraineurs tend to have a higher incidence of non-allergic rhinitis (nasal and sinus irritation) it provides another possible mechanism for triggering an attack, but it is still interacting with a sensitized system as Dr Martin explains:
 
“I think that what we don’t realize is all these different things in our lives can influence that (migraine) threshold. So how much sleep you got the night before, how much stress you are under, whether you fasted for a prolonged period of time. All these things have a neurologic effect on migraine patients and can seek to lower that threshold and make people more vulnerable to migraine.”
 
The threshold to which he refers of course is the ‘explosiveness’ or the trigeminal nucleus. Read on for ideas on how to fix this sensitivity.

Barometric pressure is what we see weather forecasters referring to with weather patters. Low pressure allows clouds to form and typically rain and storms. High pressure is typically associated with clear blue skies and warmer weather.
 
The challenge is that pressure changes ahead of the weather that comes with it, so you won’t often ‘see’ the weather that might trigger you. This might result in many migraineurs claiming to be able to ‘predict the weather’ as they might be sensitive to falling barometric pressure. 
 
Dr Martin [5] explains that ‘some (migraineurs are) triggered by falling or rising barometric pressure. Interestingly if falling pressure does it then rising pressure is usually ‘protective’ and vice versa.’
 
Researchers in Japan [6] studies the effects of changing Barometric pressure in 34 migraineurs compared to a control group of tension-type headache sufferers. On face value there appears to be a link between small decreases in barometric pressure (6-10hPa) and increased incidence of migraine compared to tension-type headache controls. Unfortunately the diary-recording period only went for 18 days. The problem is that we don’t know if the migraine group had a higher incidence of attacks and whether either incidence was different to the previous 18-days prior to recording.
 
Cioffi and colleagues [7] investigated the effects of changing weather in patients with temporomandibular disorders (TMD) and migraine. Their results indicate that decrease in atmospheric pressure increased the intensity of TMD pain, however increase in pressure and temperature increased the intensity of migraine symptoms. Again the study is very limited, in part by a ‘lost' or 'not captured'  data rate of 25% and no indication of the baseline activity in both groups – in other words we don’t know whether the pain fluctuations can be attributed to the weather or if these are normal fluctuations.
 
More disturbingly, the authors claim as a starting point in their introduction that:
‘The pain course of subjects suffering from migraine is influenced by weather conditions’
citing two publications to support the statement. On reviewing these two publications the conclusions the authors draw themselves are quite the opposite:
‘The influence of weather factors on migraine and headache is small and questionable” [3]
and
“In a sub-group of migraineurs, a significant weather sensitivity could not be observed”. [8]

So this all seems a bit confusing, and we want a simple answer – do changes in weather cause migraines or not?
 
The answer is a simple as does chocolate, or wine, or perfume cause a migraine. The answer is obviously yes………..and no.
 
That is to say migraineurs as a group are heterogeneous. Some things that may trigger one migraineurs may not trigger another, so pooling together large groups to study effects of anything, be it a trigger (or a treatment for that matter) can dilute the effect that it might have on sub-groups. The difficulty is in discerning the sub-group in a way that allows better predictions of the effects of
The results of Hoffmann’s 12-month study [8], though inconclusive, did show trends leading to the conclusion that “only a sub-group of migraineurs is sensitive to specific weather conditions, explaining why previous studies, which commonly rely on pooled analysis, show inconclusive results”. 
 
One might expect a better result in migraineurs who report weather changes as a trigger, however Zebenholzer and colleagues looked at perceived weather changes compared to weather data and found a poor correlation. [3]
Not unsurprisingly, the ability of a migraine brain to accurately detect weather may be impaired (similar to its response to noise, light, smells in some cases), leading to inaccurate forecasting, and the feeling that ‘the weather is changing and here comes my migraine’ whereas in fact the sense that the weather is changing may be a part of the migraine itself. 
 
Another problem is that changes in weather do not influence migraineurs in isolation. What were the other factors occurring at the time of the study with regards to amount of sleep – over-sleeping, under-sleeping, dietary influences, hydration levels, stress levels etc 
As with many other triggers, often in isolation or at low doses they may be ok, but when a strong dose or in conjunction with others triggers may cause problems.
 
At the end of the day the research has failed to show what we know and see in the clinic, and that is, without question, migraine can be triggered by changes in the weather – but as with many other things migraine, the exact mechanism’s have eluded researchers and remains an area of ongoing focus for some.

What does chocolate, perfume, bright light, red wine, stress, hormones changes and weather changes have in common? Nothing apart from the fact that they can all (amongst a host of other things) be considered triggers for some peoples migraine.
 
Focusing on triggers can be helpful if you only have a small number. If on the other hand you have multiple triggers, then this line of migraine management often proves futile and frustrating as the next doctor pulls out yet another migraine diary for you (scream!).
 
The thing that ties these and every other migraine trigger together is that they all interact with a sensitized trigeminal nucleus to cause the symptoms we associate with primary headache conditions.
 
So aside from moving to somewhere with stable weather patterns that has just the right mix of heat, humidity, wind and small changes in pressure to prevent your weather related migraines, what else can you do.
 
I would urge you to ignore the triggers and focus on the sensitized brainstem.
 
The nerves from the top of the neck feed directly into this area making it the number one suspect in the frontline of fighting the underlying problems in migraine.
 
In recent years the migraine community has shifted away from the vascular theories to focus on a sensitized brainstem model. This brings the neck back into focus, and even Dr Andrew Charles has moved from:
‘this (neck pain) is just a symptom of their migraine’ in 2012 [9] to a 'greater appreciation of the potential role of the cervical nerves' acknowledging the 'frequent occurrence of neck pain could indicate a role for the upper cervical nerves in the transmission of migraine pain' in 2018 [10].
 
Come and get the underlying problem assessed and treated with the only technique developed specifically to lower trigeminal nucleus sensitivity. 
 
For those wanting more tips on how to minimise weather related migraine:

• Stay indoors with windows shut. This may minimise the impact of aerosolized molds and fungi.
• Monitor Weather forecasts for migraineursI’m not sure how they account for individual variation is triggers, but it may be of some help.
• If you know the upcoming changes that are forecast may be a trigger try to minimise your other triggers at that time – in other words be more watchful about skipping meals, careful with sleep patterns, drink plenty of fluids etc

[1] Pavlovic J. M. et al (2014) Trigger Factors and Premonitory Features of Migraine Attacks: Summary of Studies.Headache, Nov/Dec, 1670-1679.
 
[2] Wilkinson M and Woodrow J. (1979)Migraine and Weather. Headache. 19: 375–378.
 
[3] Zebenholzer K, Rudel E, Frantal S, Brannath W, Schmidt K,
Wober-Bingol C et al. (2011) Migraine and weather: a prospective diary-based analysis.Cephalalgia. 31:391-400
 
[4] Martin, G.V. et al (2013) Lightening Lightening and its association with the frequency of headache in migraineurs: an observational cohort study.Cephalalgia, 33 (6), 375-383
 
[5] Martin, G.V. (2018) Surviving weather-related Migraine.  Migraine World Summit. (2018)
 
[6] Okuma, H et al (2015) Examination of fluctuations in atmospheric pressure related to migraine.  SpringerPlus Open Journal.
 
[7] Cioffi, I et al (2017) Effect of weather on temporal pain patterns in patients with temporomandibular disorders and migraine.Journal of Oral Rehabilitation. 44; 333-339.
 
[8] Hoffmann, J et al (2015) The influence of weather on migraine – are migraine attacks predictable?Annals of Clinical and Translational Neurology, 2 (1); 22-28
 
[9] Charles, A (2012) Migraine ResearchMigraine Research.ABC Health Report.
 
[10] Charles, A (2018) The pathophysiology of migraine; implications for clinical management.
Lancet Neurology. 17; 174-182.

Dr Eller is a Neurologist at Neurology Network Melbourne, and gave a presentation at The Alfred Hospital on Tuesday 11th September. 
His talk focussed on a number of emerging treatment options for migraine. There were some interesting results first two based on electrical stimulation and the other was the new CGRP monoclonal antibody (mAb).

The first part of Dr Eller's talk was to discuss an often overlooked visual symptoms experienced my many migraineurs - visual snow. Visual snow is an effect where normally consistent colours look pixellated, or blotchy, or grainy in stead of clear and smooth. Sometimes the snow is coloured sometimes black or white, affecting parts of or the whole visual field. 
Other interesting visual phenomena are palinopsia (trailing or ghosting as objects move through the visual field), black floaters (white blood cells passing through capillaries across the retina) and nyctalopia (impared night vision). A number of these phenomena are 'normal' such as floaters (I can see them right now!) however they are enhanced in migraineurs. 

Dr Eller then went onto the part of the talk that he thought would be the most dry, but I found the most interesting. He went on to describe what a migraine is. I found this interesting because of his thoughts on the official classification rather than hearing something that I know by heart. Take from the ICHD-3 (International Classification of Headache Disorders version 3), Dr Eller described the familiar traits of a migraine attack according to the classification: Moderate to severe pain lasting 4-72 hours, containing two of - pulsatile pain, one sided, aggravated by routine activity and moderate to severe intensity. It must also have one of the following: nausea and/or vomiting, photpphobia or phonophobia.

Having laid this out he then described it as 'a bit silly' which might strike many as odd, but a sentiment I could not agree with more. The reason of course is that peoples symptoms change from one episode to the next, and despite clearly having migraine, the pain might be moderate, bilateral and aching instead of throbbing, yet if you get nausea with it its not a tension-type headache but not a migraine either - so what is it? The fact is they are all slightly different expressions of the same problem, a sensitised brainstem.
​The classification system is not reflective of hundreds of different pathological problems, but slightly different variations of the same problem. Imagine if we said two ankle sprains were totally different depending on were the bruising comes out?
Dr Eller pointed out that migraine is a 'primary headache disorder'. The way he defined primary was 'you scan the brain, its fine, do blood tests, they're fine.........its just a part of you'. It's another description which defies science now, assuming there is no 'faulty bit' we can test. In fact there are a number of faulty bits. Common to all so called 'primary headache disorders' is a sensitised trigeminal nucleus - the part of the brainstem receiving input from the head and face nerve (trigeminal nerve). We know this is overactive all the time (with or without symptoms) in migraine, tension-type headache and cluster headache. The nerves from the top of the neck feed directly into this area - making them candidate number 1 for a cause of this overactivity.

Dr Eller went on to describe migraine as a 'pathological brain state in which headache is only one possible feature along with visual, sensory, language, motor, cognitive symptoms, nausea, yawning, fatigue, dizziness, cutaneous allodynia, photophobia, phonophobia, osmophobia.
Dr Eller didn't mention the trigeminal nucleus, which is constantly irritated, but did talk about the hypothalamus, which is otherwise normal, but starts to become overactive at the start of the premonitory phase, incorrectly concluding that maybe its the generator. The hypothalamus is important in our bodies homeostasis - sleep wake cycle, body temperature regulation, 
If it was the generator it would precede the premonitory phase - not coincicde with it. Only the trigeminal nucleus along with the upper cervical nerves is constantly overexcited.
​

Dr Eller referred to two new forms of electrical stimulation that have been approved for use in migraine.

The first is called the eNeura, pictured here on the left. It differs from the cephaly which many people may be aware of in that instead of sending electrical impulses across the surface of the head, this generates electrical impulses inside the brain, in an attempt to disrupt the evolving electrical storm that leads to a migraine attack.  The device is like a plastic pillow that you hold to the back of your head (pictured) and has shown similar success rates to CGRP mAbs (see below). That is 46% of the treatment group achieved a 50% or greater reduction in symptom frequency. Cost is in the vicinity of $1000 over 3 months.

The 'gammaCore' is a vagal nerve stimulator, which is the nerve that goes down to the stomach and internal organs. Children with seizures sometimes have a vagal nerve stimulator implanted and in some of those that also had headaches they found in some cases their headaches got better as well. That led to the development of a hand held device that is pressed against the neck (pictured) that delivers an impulse to the vagal nerve as it descends in the neck. The results were similar to the above, but interestingly this also had a significant effect in cluster headache, which is often recalcitrant to treatment. 

I spoke to the supplier of these products at he recent AHS scientific meeting in San Fransisco. I managed to hide my shock at the pricetag and the way they have montetised the product. There are two vairites - one can give you 30 charges a day for 3 months, the other gives you 30 days worth of charges.
Either way you then have to order another. $1000 every 3 months approximately. What annoyed me was that if I ordered one (which I can't anyway) they would send a demo to me that I can simply recharge. In other words, it expires each month and you order a new one not for any limitation in the device, but just so you have to buy another one - instead of offering a rechargabale option as well. This speaks greatly to the midset of those developing medical products (devices and drugs) in this space. Why offer you a cure if we can offer you something that makes you a customer for life?

Speaking of customer for life, Erenumab the new CGRP mAb was the last topic of the talk. This was approved in the USA in May and approved in Australia in July. The cost is going to be $750-850 per month. I have written extensively on this in previous Blogs, but pleasingly, Dr Eller presented it warts and all. Initially saying 'There's some impressive and not so impressive figures related to this Erenumab. The impressive relates to the side effects profile. Almost identical to placebo. One question on the night Dr Eller wasn't able to answer - what were the SAE's for the medications (SAE = serious adverse event). There were 8 in the treatment group and 7 in the placebo group. This can seem alarming until you understand that any adverse event you have during the trial duration is counted. In other words if you had a car accident, or brooke your ankle playing football during the trial, you are counted as an SAE. The researchers then have to investigate each SAE afterwards and see if there is any probability that the SAE is attributable to the treatment. In the case of Erenumab the SAE's attributed to the medication was 0.

The 'not so good' figures relating to Erenumab is the cost and effectiveness. It is marginally more effective than topiramate and botox. The cost at $750-$850 per month for something you will need for life it significant.
Just last week the Pharmaceutical Benefits Advisory Committee (PBAC) provided a statement in their review of Erenumab:
The evidence used for the basis of the clinical claim that erenumab was more effective than botulinum toxin had significant limitations, resulting in a clinical effectiveness and cost-effectiveness estimates that were highly unreliable for decision making. In addition, the PBAC considered that the cost to Government was underestimated by the submission, both because the number of patients with chronic migraine was underestimated by the submission and because of the significant risk of leakage outside the proposed limited PBS listing (for example, patients with episodic migraine)

It is highly likely that it will be approved but the PBAC will await preliminary data to see if a narrower target treatment group emerges. 
Interestingly Norvatis, who manufacture Erenumab will provide 3 doses at no charge to see if it works for you. Dr Eller was of the belief that you would know in that time if it would be effective. After that initial period you would then revert to full price should you wish to continue. 
Erenumab will only be available by Neurologist prescription (not GP), but the amazing thing here is that every Neurologist, not just the headache specialists but all of them, as a part of a familiarisation protocol, can sign up 10 clients to use the drug for free........forever!
Dr Eller didn't elaborate and seemed a little bashful when asked about it, but you may be able to access it free for life!