There are three types of headaches that I encounter in practice most often -- migraine, cervicogenic and tension headaches -- along with the chronic, residual effects of head trauma, which are collectively known as post-concussion syndrome.
While the etiologies of each of these conditions is complex and not well understood by the medical establishment, research indicates that they share certain underlying characteristics, namely that like other disorders causing wide-spread symptoms such as fibromyalgia or complex regional pain syndrome, they are believed to be the result of an over-active nervous system that has developed a heightened sensitivity to pain and usually manifest after trauma, such as a car accident, or infection.
A survey into the pathophysiology of migraines in the Journal of Neuroscience in 2015 describes the development of migraines as follows:
As a consequence of the disease itself or its genetic underpinnings, the migraine brain is altered structurally and functionally. These molecular, anatomical, and functional abnormalities provide a neuronal substrate for an extreme sensitivity to fluctuations in homeostasis, a decreased ability to adapt, and the recurrence of headache.
From the perspective of an Upper Cervical Specific chiropractor whose sole objective is to restore function by removing a neurologic, biomechanical and physiologic compromise at the level of the lower brainstem/upper spinal cord so that the body can regain its ability to adapt to stressors both external and internal in order to maintain homeostasis, the assessment above is fitting. As I've written before, an upper cervical subluxation engages the body's sympathetic nervous system, making it exceedingly susceptible to stimuli which then manifests as pain.
Current research indicates migraine pain originates in the brainstem and travels through cranial nerves thus corroborating the multifarious symptomatology associated with migraines. Decreased levels of serotonin, a mood and focus regulating neurotransmitter released from the Raphe nuclei of the brainstem, has also been implicated. Characteristic of these headaches is a deep-seated, pulsating pain, usually on one side of the head that can last for days and can be accompanied by nausea, vomiting and sensitivity to light and sound as part of auras or the migraine episode itself.
Cervicogenic headaches meanwhile are well-documented to be a problem of the upper cervical spine. Research shows that restricted joints, especially those of the top two vertebrae, send increased nociceptive signals and decreased mechanoreceptor signals to the brain, leading to both pain and feelings of dizziness. Cervicogenic headaches are characterized by a dull ache, deep in the sub-occipital area that radiates in a horn-like pattern around one side of the head, usually along the path of the third occipital nerve, and stopping behind one eye. Any motion of the head will usually make this headache worse as the cerebellum and brain have a difficult time interpreting the conflicting balance information coming from the joints, ears and eyes.
Tension headaches, meanwhile, were thought to be caused by tight, constricted muscles in the neck and upper body which lead to compensatory patterns above, mostly as a result of stress. However, as in the case of the other two types of headaches, the theory of heightened pain sensitivity, has recently become more widely accepted. Tension headaches are characterized by the feeling of a uniform, tight grip around the front and/or back of the head and tenderness in the neck and upper back muscles. They share characteristics with both migraines and cervicogenic headaches as both visual stimuli and neck motion can make them worse.
Lastly, head trauma is such a big topic that it deserves it's own blog post but I'll address the key points here. Today, head trauma, of which traumatic brain injuries or TBI is a subset, result mostly from sports, automobile or military combat accidents and are categorized as mild, moderate or severe. Symptoms include but are not limited to initial loss of consciousness, headaches, dizziness, insomnia, chronic fatigue, visceral organ problems, mood disorders, cognitive decline, loss of personality and more. Once these symptoms become chronic, they are collectively labeled "post-concussive syndrome".
Recently, studies have been conducted on the brains of athletes suspected to have died as a result of head trauma and its sequela of symptoms. A common pathophysiologic feature found in the brain of all these athletes, as well as in Alzheimer's and dementia patients, is a buildup of Tau protein, which gives structural support to the fragile axons of brain neurons. As a result of constant concussive forces or perhaps a single large-enough trauma, Tau protein phosphorylation becomes uninhibited and the protein spreads across the brain like a spider's web. This is of course but one pathological pathway of head trauma but because of possible NFL lawsuits it's been in the news a lot the last few years. Furthermore, it also very clearly illustrates how an upper cervical subluxation can create and perpetuate the pain pathways involved in headaches and head trauma.
Severe-enough head trauma can not only damage brain tissue but also injure other sensitive anatomy such as cranial nerves and neck tissue. However, as a UC Specific chiropractor my greatest concern when it comes to head trauma is that it's not possible to sustain a traumatic brain injury without also acquiring an upper cervical subluxation and it is the latter -- that goes undetected by the medical community -- that is pervasive, insidious and in some cases lethal. Most people are already carrying an upper cervical problem and an additional impact only makes it worse. In other words, incurring an upper cervical subluxation without head trauma is a common occurrence but sustaining head trauma without also incurring an upper cervical subluxation is highly unlikely.
Especially in the case of brain injury, the brain is highly dependent on oxygen, glucose and proper nerve impulses delivered by the blood stream and afferent nerve fibers for proper function and repair as well as flow of cerebrospinal fluid to help get rid of wastes such as Tau protein. However, an upper cervical subluxation can not only inhibit all of those repair mechanisms but also lead to symptoms of its own including many of the symptoms associated with the aforementioned headaches and head trauma. It occludes the 3mm space between the brainstem/spinal cord and neural canal, for example, reducing thermodynamic flow of blood and cerebrospinal fluid while at the same time creating stress on the lower brainstem and other afferent and efferent nerve structures and restricting joint motion, which has a detrimental impact on the vestibulocochlear system leading to the feelings of dizziness so often ascribed to headaches and head trauma. Research published in 2007 in the Journal of Neuroscience attributes the relaying of balance signals from the body to the cerebellum to the lateral cuneate nucleus of the brainstem, helping us further understand the role of the upper neck in these injures and validating what we as UC Specific chiropractors observe clinically.
Once the brain is no longer in control and the body loses the ability to adapt and respond to stressors, symptoms set in and disease manifests like fire alarms going off demanding we do something. And this is the case not only for headaches and head trauma but for health problems in general.
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