Sunday, 8 May 2016

So how can your neck give you a headache?

Chiropractors treat a lot of headaches, it’s a daily presentation and most patients are chronic sufferers who have tried remedy after remedy and have formulated a cocktail of pills, potions and routines to keep themselves functional. 

It is sometimes hard to explain to someone who doesn’t suffer from headaches or migraines what it’s like but try to imagine having a really bad hangover … only without any of the preceding pleasure and with the knowledge that it isn’t going to feel any better after coffee and aspirin, or indeed any time soon.

But what causes headaches? And how can chiropractors treat them?

The first thing to realise is that a headache isn’t an illness, it’s a symptom –and it’s a symptom that can have dozens of different causes.  As a clinician, one of the first jobs in establishing a diagnosis is to rule out any sinister causes: tumours, vascular problems and diseases such as temporal arteritis are rare but you can’t afford to miss them.
 Fortunately, most head pain is benign (even if it doesn’t feel like it!) and, if it is, there is a surprisingly short list of the things that can be c
ausing the pain because most of what’s inside your skull isn't pain sensitive. In order to feel pain, you need special nerves called ‘nociceptors’ – and the grey and white matter that   make up your brain actually don’t have any pain receptors, which is why brain surgeons just use local anaesthetic (to numb the scalp), they can cut and scrape away at your actual brain without you feeling it.

So if the brain isn’t the pain, what is? Well, there is one structure inside your skull that isn’t just good at causing pain, it’s the most pain sensitive bit of your body – the lining of the brain, called the dura (actually, it’s really three structures but that’s just making thinks more complicated than they need to be).  This is what becomes inflamed in meningitis – and to a lesser extent in flu – and, if you’ve ever had one of those headaches, you’ll appreciate exactly what misery it can cause.

The same sheet of material that wraps around the inside of your skull also wraps around the spinal cord as it descends through the vertebrae in your back – and it has a particularly strong attachment to the inside of the top three vertebrae; these attachments are know as the durovertebral ligaments.  If the vertebrae are twisted out of position or otherwise dysfunctional, it can not only cause pain in the back of the head but can also seemingly pull on the dural attachments at the front of the skull, particularly across the forehead and behind the eyes.

When we’re stressed, our body language changes and our head position is much further forwards.  This can easily double or even treble the strain on your cervical spine – which is why this type of headache tends to be dubbed a ‘stress’ headache.

This, unfortunately, is not the only head pain that stress can cause. Trigger points from the sub-occipital muscles – a small group of muscles that run between the top two vertebrae and the base of the skull – can also develop painful knots called ‘myofascial trigger points’.  Not only can these case pain in the back of the head, they also have a classic referral pattern giving the tight band around the entire skull – a ‘tension headache’ … and there are half a dozen other muscles that can also produce head pain, all with their own referral patterns.

There is also quite strong evidence that a third type of headache – this time a migraine, affecting just one side of the head – can be caused by upper cervical spine joint dysfunction. The mechanism behind this is the subject of some controversy, whether it is referral from an injured facet joint in one of the top three vertebrae or a ‘trapped nerve’ (actually interference with the nucleus of the nerve to the forehead and face); however, it seems clear that the neck is the direct source of the problem, which is why these headaches are known as ‘cervicogenic migraines’.

There is also condition in which a nerve genuinely does get trapped: greater occipital neuralgia. This nerve has to pass between the top two vertebrae and supplies the back of the skull, which is where it causes the headache (on one side only) when it gets trapped.  Although it’s almost entirely unresearched, I’ve never seen a ‘trapped’ great occipital nerve that couldn’t be ‘untrapped’.

So by now, you’ve probably gathered that the top of the spine can cause a lot of … well … headaches – and that stress can be a big trigger.  It is not, however, just head position and muscle tension that can cause dysfunction in this area – your teeth can also do so! If you’re a clencher or a grinder (and you may be doing it at night without even realising it), and your occlusion is unbalanced, then the asymmetrical muscle tension can also cause rotational forces through the neck and shoulders … and guess what that causes?  That’s right, the joint and muscle problems that we’ve just been talking about (or dehydration!).

It took me several years to work out why it was that not all of my headache patients got better, even when I was sure I had got the diagnosis right, and several years more to start working with an orthodontist and a psychotherapist to make sure that those patients who had poor occlusions and/or were overly stressed could get the joint management (pardon the pun) that they needed.

There is one other form of headache that this collaboration has seemingly helped treat, although once again the hard clinical ‘proof’ is lacking because nobody has done the research – cluster migraines, also known as ‘suicide headaches’ because the pain and frequency of attacks can drive a person to that level of despair.

I had a vested interest in discovering as much as I could about these headaches as my father-in-law had been a sufferer in the past and started getting attacks again not long after I married his daughter.  I read an interesting theory that the headaches were caused by temporalis muscle spasm and the reason the pain was so bad was that the tendons of the muscles insert no just into the temporal bone but into the sutures around the bone where, in some people, they go deep enough to meet the dura mater, which also runs up into the sutures from the inside … when the first starts putting pressure on the second, it’s as if you were squeezing the body’s most sensitive tissue in a vice.

The solution was to deal with the cause of the spasm (a worn pain of ancient dentures causing his bite to be ‘overclosed’) and release the muscles. One happy father-in-law.

“So what about food intolerances,” I can hear readers scream, “Or hormones!” Pretty much the only other pain sensitive structures in the brain are the blood vessels, particularly the muscular wall of arteries, quite of few of which run within … yes, the dura. Anything that causes pressure on the dura – such as the changing diameter of an artery – can trigger pain, particularly if the dura is already under tension from the external causes we’ve been discussing. 

This fits well with the concept many chiropractors use of a ‘physiological adaptive range’ within which things can go wrong without causing pain but as different factors erode that ‘healthy’ range (diet, lifestyle, trauma, illness, environment), it can tip you over the edge.  Get as many of those things right as possible, and you not only get rid of the symptoms but restore enough of the adaptive range for you to soak up the daily pressure of living without it triggering a headache.

This is part of the reason that chiropractors don’t just train in diagnosis and physical therapy but also in nutrition and psychology – which makes a chiropractor a good place to start if you’ve got a headache.

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