What Causes Headaches and Migraines?

 

Persistent headaches and migraines can be incredibly disabling. You can be otherwise fit and healthy, yet find yourself limited in work, exercise, hobbies and everyday life because of recurring headaches or migraines. In fact, headache disorders are one of the leading causes of disability worldwide, ranking among the highest causes of years lived with disability.

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If you've been living with persistent headaches or migraines, you've likely already seen a range of healthcare professionals—GPs, physiotherapists, chiropractors, neurologists and others. You may have tried pain medications, Botox, nerve blocks or various manual therapies. While these treatments can help reduce symptoms, many people continue searching for a long-term solution because their headaches keep coming back.

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One of the biggest barriers to managing headaches and migraines is understanding why they occur in the first place. Once you understand what may be driving your symptoms, it becomes much easier to recognise your triggers, understand your condition and develop effective long-term management strategies.

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Understanding Brainstem Sensitisation

 

One of the key concepts within the Watson Headache® Approach is brainstem sensitisation, also known as central sensitisation.

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The brainstem is located at the base of the brain where it joins the spinal cord. It acts as one of the body's major communication centres, constantly receiving information from different areas before sending it to the brain for processing.

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Some of the main inputs into the brainstem include:

• The upper cervical spine (C0/C1, C1/C2 and C2/C3 joints and surrounding muscles)

• The jaw (temporomandibular joint)

• The eyes

• The ears and vestibular (balance) system

• The nose and throat

• The vagus nerve, which supplies the heart, lungs, digestive system and contributes to the body's stress response

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Under normal circumstances, the brainstem accurately processes this information and the brain responds appropriately.

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However, research suggests that in many people with persistent headaches and migraines, this system becomes sensitised.

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Importantly, this does not mean the brain is damaged or that something sinister is occurring. Instead, it is better thought of as a change in the way the nervous system processes information—a signal processing problem.

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Rather than interpreting information normally, the brainstem begins to amplify incoming signals. Information from the neck, jaw, eyes or other structures is interpreted as being more threatening than it really is, causing the nervous system to produce pain more easily.

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Pain is designed to protect us. Normally, it acts as a warning system to alert us to actual or potential tissue damage.

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A useful analogy is a smoke alarm. If your toaster catches fire, you would expect the alarm to sound because there is genuine danger. However, if the alarm went off simply because your toast was slightly burnt—or even before you had put the bread into the toaster—it would be far too sensitive.

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The alarm isn't broken; it has simply become overprotective. Brainstem sensitisation works in much the same way.

People with persistent headaches or migraines often have an alarm system that is triggered far more easily than it should be. Everyday inputs that should cause little or no pain are amplified, resulting in headaches or migraines.

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This helps explain why seemingly harmless things such as:

• Bright lights

• Strong smells

• Mild neck stiffness

• Looking at a computer screen

• Poor sleep

• Stress

can trigger significant headaches or migraines.

 

These factors are often referred to as triggers, but they are rarely the entire cause. More commonly, they are the final stimulus that activates an already sensitive nervous system.

 

For example, many women notice their migraines occur around their menstrual cycle. Hormones clearly influence the nervous system, but hormones affect both sides of the brain equally. So why does one person consistently develop a migraine behind only one eye?

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Within the Watson Headache® model, hormones are considered one factor that increases the sensitivity of the brainstem. If the upper cervical joints are already irritated, hormonal changes may simply be the final trigger that pushes the nervous system beyond its threshold, resulting in a headache or migraine.

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Understanding Referred Pain

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Another important concept is referred pain.

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Referred pain occurs when pain is felt in one part of the body even though the source of the problem is somewhere else.

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A classic example is someone having a heart attack. The heart is the structure being affected, yet the person may experience pain travelling down their left arm. There is nothing wrong with the arm itself—the brain is simply interpreting the incoming signals differently.

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The same principle applies to headaches.

 

The brainstem receives information from the upper neck, jaw, eyes, ears, vestibular system and vagus nerve. Because these structures all communicate with the same region of the brainstem, irritation from any one of them can sometimes be experienced as pain elsewhere.

 

For example, a stiff or irritated joint in the upper neck may produce pain in the temple, forehead or behind the eye. Likewise, temporomandibular joint (TMJ) dysfunction can sometimes present as a headache rather than jaw pain.

 

At our clinic, we commonly find that dysfunction within the upper cervical spine is one of the major contributors driving brainstem sensitisation in people with persistent headaches and migraines.

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This also helps explain why headaches and migraines are often associated with symptoms such as:

• Ringing in the ears (tinnitus)

• Dizziness

• Nausea or vomiting

• Visual disturbances or spots in vision

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In many cases, these structures are not damaged. Instead, they all send information into the same sensitised brainstem, where the signals may be amplified and misinterpreted.

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Why Does the Brainstem Become Sensitised?

 

There is rarely one single cause.

Instead, several factors can gradually increase the sensitivity of the nervous system over time.

These may include:

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Genetics
Some people are genetically predisposed to developing headaches or migraines. It is common to find a family history of migraine.

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Trauma
A significant injury, such as whiplash or a fall affecting the neck, may increase irritation of the structures feeding into the brainstem and contribute to sensitisation.

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Persistent Neck Pain
Long-standing neck pain that has gone untreated or only partially improved can gradually increase the sensitivity of the brainstem. Many people initially experience only neck pain before eventually developing recurrent headaches.

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Stress, Poor Sleep and Hormonal Changes
These factors may not directly cause headaches, but they can increase the sensitivity of the nervous system, making headaches or migraines more likely to occur.

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The encouraging news is that sensitisation is not permanent.

 

Once the factors driving the sensitivity are identified and addressed, many people experience significant improvements in their headache frequency, intensity and quality of life.

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Key Takeaways

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Headaches and migraines are complex, but several important principles help explain why they occur:

• Persistent headaches and migraines are often associated with increased sensitivity within the brainstem.

• This sensitised nervous system can amplify normal information from the neck, jaw, eyes and other structures, producing pain more easily.

• Head pain is often referred pain, meaning the source may not actually be inside the head.

• Genetics, trauma, persistent neck pain, stress, poor sleep and hormonal changes can all contribute to brainstem sensitisation.

• By identifying and treating the factors driving sensitisation, many people can significantly reduce the frequency and severity of their headaches.

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Ocean is trained in the Watson Headache® Approach and has experience assessing and treating persistent headache and migraine conditions. If you'd like to find out whether your neck may be contributing to your headaches, book an assessment with our clinic.