We often use the terms headache and migraines interchangeably but it can be useful to define what is really meant. A headache is a symptom rather than a disease and essentially refers to pain experienced in the head, face or upper neck. There can be many different causes of headache, and migraine is a neurological disorder that can be a common cause, but certainly is not the only cause of headache.
We use the term “Headache disorders” to describe a group of disorders which have headaches as their major feature. There are primary headache disorders and secondary headache disorders. Primary headache disorders are conditions such as migraine, cluster headache, and tension type headache. Secondary headache disorders are conditions that occur as a result of another problem – such as headaches associated with raised pressure in the brain, headaches due to meningitis, headaches due to neck pathology (cervicogenic headache), trigeminal neuralgia and many others.
Anything that causes inflammation or irritation to nerves in the lining of the brain (the meninges) as well as causing inflammation or irritation of nerves of the tissues of the head and neck can cause headache. Often the time course and the associated symptoms will make it clear what the cause is.
What is the cause of my headache?
If you have grown up with family members having migraine, you will probably recognise it easily. If you have intermittent headaches, associated with nausea, perhaps vomiting, feel as though you are sensitive to light and sound, and want to lie down in a dark room – it’s probably a migraine. Migraines last from four hours up to 72 hours typically, and then between the episodes you should feel normal. Headaches that are shorter than four hours in duration are less likely to be migraine. If it is a headache lasting longer than a few days, and if you don’t typically get headaches, you should see a doctor to get checked out.
Because there is no test to diagnose migraine, sometimes tests are done to rule out secondary causes of migraine, which are often more serious and need different treatment to migraine.
This is not to say that migraine is not serious, as we know it is one of the major causes of disability worldwide, having a serious impact on well-being and quality of life, and particularly affecting younger people. However, despite how severe the pain of a migraine can be, a migraine attack is not in itself dangerous.
Migraine is a leading cause of disability worldwide, second only to chronic back pain. One in ten people have migraine, and this affects women three times more than men.
Migraines are not just headaches – although the headache can often be the most disabling feature and the reason that people end up seeking help. There are usually several other symptoms that are experienced – this can vary from person to person. Some people experience neurological symptoms 15-40 minutes prior to the onset of the headache – this is called “aura”. This relates to a wave of abnormal electrical activity that slowly passes over the brain from the occipital lobe (back of the brain) to the front – this is called “cortical spreading depression”. This is one of the critical events that occurs in the brain – this abnormal electrical activity then causes chemicals to be released by neurons (nerve cells) which trigger inflammation. The inflammation then changes the reactivity of blood vessels in the brain, and a cascade of inflammation ultimately triggers the peripheral nerves supplying the head, face and neck. Together this is called the trigeminovascular system.
The symptoms of aura can vary from person to person. Some people will never experience aura, some people will experience it occasionally, some will always have aura and some can have aura but not headache! The most common type of aura is a visual aura – this can be blurred vision, like looking through dirty glass, or squiggly lines that shimmer and expand. It can be common to not remember words, to not be able to read, to experience tingling down one side of the face and body – this is all part of aura. Some people experience vertigo and ringing in the ears as part of their migraine type – this is called vestibular migraine, and sometimes there is not much headache experienced. The type of symptoms that are experienced, probably relates to where in the brain is being stimulated. Nausea and vomiting commonly occur in migraine because the nerve controlling the stomach causes it to stop contracting – therefore it doesn’t empty, it fills with stomach secretions and there is an urge to vomit in many cases. Not everyone experiences this however and over time it often becomes less common. Sensitivity to light, sound and smell is common but it is not unique to migraine.
Migraine is a complex neurological disorder that has a strong genetic basis, and is characterised by differences in the reactivity of nerves in the brain compared to people who never experience migraine. People who experience migraine have brains that we call “hyperexcitable” – this means that the nerves in the brain can be triggered by fairly minor events and that there lacks a shutting off mechanism that normally occurs for repeated stimuli. For instance, if you shine a light in the eye repeatedly, the migraine brain senses this as intensely all the times the light is shone, whereas in a “normal” brain, the signal is dampened after the first time the light is shone. Over time, the brain gets overloaded by various stimuli – sports day at school where it’s hot, with bright lights, you forget to drink enough water, and are running around – by the end of the day: migraine. You then hit puberty and there is a hormonal surge, you start staying up late to study, and wake up early for sports training in the morning, you start to drink caffeine, etc, etc and your migraines start to come more and more often. Each time you have a migraine, an inflammatory process is triggered and each time makes you more likely to have the next migraine.
It would be intriguing to know whether we can stop migraines by aggressively managing the first ones which typically occur in childhood or adolescence. Sadly, we don’t take it as seriously as we probably should.
It should be made clear that migraine triggers such as alcohol, foods, stress, and sleep deprivation for example are not the cause of migraines. Migraines are a genetically determined neurological condition. However, because the migraine brain is so sensitive, these factors can trigger a migraine episode, where they wouldn’t in a “normal” brain.
It can therefore be helpful to understand these triggers, in order to avoid them if possible. In many cases though, migraine can occur without any clear trigger. This especially occurs when migraines are very frequent, as the inflammation in the brain is high, the brain is sensitised and the threshold for a migraine to be triggered is incredibly low. This is what happens in “chronic migraine” and is a very disabling condition. It can be hard to reverse the changes that occur in the brain once migraine has become chronic, and so early intervention before this stage is critically important.
Chronification in migraine
We can classify migraine as “episodic” when there are eight or less migraine days per month, and generally we would expect that there are crystal clear days where there is no headache experienced at all. If there are eight headache days per month though, this is still a risky amount of headaches, as the brain is not fully recovering between each attack. There are brain changes 24-48 hours before the headache, and for another 24-48 hours after a headache, so if you think about it, there is a lot of abnormality occurring pretty much all the time at that frequency. That is why we don’t like to see more than four migraines per month and worry about it becoming chronic.
Migraines are very inconvenient in modern life. Very few of us can afford to take to bed and not attend to children, go to work, or feed pets for example, potentially for days on end. Therefore, there is pressure to take medication to stop the migraine so that we can function. This is not a bad thing, and if the migraines are infrequent, it is probably best to try to treat the migraine attack as early as possible, at the aura stage or even prior. However, when you start to have frequent migraines, such as weekly or twice a week, you can run into trouble where the medications you are taking to relieve the migraine can in fact start to cause more migraines. This is a rebound effect and it seems to be something very specific to migraine – we don’t see it happen in back pain for instance.
The medications that are most likely to cause rebound headache are opiates – such as codeine, tramadol, endone – so combinations such as panadeine and Nurofen plus would come into this category. You should only take these twice per month ideally. Triptans also can easily cause rebound headaches, it is easier to deal with them as there is generally no withdrawal syndrome coming off triptans, and they become effective again after a short time of not using them. Triptans are common causes of rebound or medication overuse headache because they are often so effective. It is easy to use them more than twice per week if there is a lot going on in life. Even ibuprofen and paracetamol can cause medication overuse headache, although you generally need to take more of it to cause a problem. If you are taking it for other reasons such as back pain, it will still contribute to your risk of medication overuse. Just another thing to thank your sensitive brain for.
This is why preventative medications are needed, so that there is a reduction in the “hyperexcitability” of the brain in the first place, and therefore fewer migraine episodes occur. It means that pain relief can still be given but is safer as it is not being used all the time.
There are also other ways to reduce the hyperexcitability of the brain that we are increasingly trying to understand. Other than looking at trigger avoidance, it has been known for decades that migraines can be controlled through a technique called biofeedback. It’s now not as commonly used because it is time-consuming and requires specially trained practitioners to teach you how to do it, but it can be well worth considering. There are multiple complementary techniques that probably also work similarly – essentially using techniques to regulate breathing and heart rate.
Reliance on a medication-dominant approach to treating migraine is frequently unsuccessful, especially once chronic migraine has occurred. Yet there are so many factors at play, that it is difficult to explore these in a medical appointment. Having a team of people involved in your care can be helpful in exploring the various factors that can be affecting the migraines. Just as important though is spending some time to think about your life and what is happening at the moment, and devoting some time to capturing data to look for insights and patterns.
There are a lot of strategies that can be used that don’t involve medications. It can be worth trying out various non-pharmacological treatments once you have worked out what may be the more clear-cut triggers or factors in your migraines. For instance, if there is a lot of emotional stress, then meditation, mindfulness, psychology assessment, or cutting down hours at work could be potential approaches. If you feel that migraine occurs at the end of the day when there is a lot of muscular tension in the neck and shoulders, perhaps massage, physiotherapy, or acupuncture are worth trying – or being aware of taking more breaks during the day if you are using a computer.
The last point
People with migraine often also experience “minor” headaches as well which are different to the severe episodes. Often we call them tension headaches, but they are probably low-grade migraine as well and can reflect chronification of the migraine disorder. If they are not disabling and interfering with function, they do not need to be treated with pain relief, however in most people with migraine they are probably not a second headache type.