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The Craniocervical Junction and Headache Disorders

 

Headaches disorders are amongst the most common conditions that people seek treatment from a doctor. While most people will experience a headache of some form,  there are those who develop chronic and repetitive bouts with headaches of different types.

Unlike people who may struggle with an occasional stress headache or feel the effects from an alcohol induced hangover, people with these chronic headaches have a neurological disorder. These headache disorders can stem from:

  • Migraines
  • Cluster headache
  • Post-traumatic/Post-concussive headache
  • Chronic pain/Temporomandibular joint disorders
  • Tension headache
  • Chronic daily headache
  • And more

Each headache has unique characteristics that help to make an effective diagnosis for effective treatment. However, when we look at the reality of a daily patient interaction, we see that people with these headache disorders can have traits that overlap. (Remember this point because this is something I’ll come back to later)

That makes these headaches  extremely burdensome on the patient, but it can also be challenging for a doctor or therapist to find effective solutions. This is particularly challenging considering the rise of medication overuse headaches as a clinical entity in 2004.

Medication overuse headaches were once classified as rebound headaches because of the way headaches could come back with a vengeance after the pain-relieving effects of a medication wore off. It became re-classified in part due to the alarming number of patients showing a regression in their headache symptoms after prolonged and frequent use of medication. While the physiology of this disorder is widely unknown, it does show characteristics of physical dependency as seen with drug withdrawals.

As drug therapies become less effective for this subset of headache patients, there has become a growing need to identify non-pharmacologic strategies to help patients with headache disorders. For many of these patients, a possible solution might lie in the neck.

Headaches and the Cervical Spine

The concept of neck problems contributing to headache disorders isn’t new. Cervicogenic headache is a term coined in 1983 to describe patients suffering from simultaneous head and neck pain [1]. The term has grown to have diagnostic criteria that include:

  • Single sided head pain radiating from the top of the neck
  • Aggravation by specific neck positions
  • Reduced upper cervical motion or painful range of motion
  • Presence of muscular trigger points
  • Normal imaging
  • Unresponsiveness to pharmacologics

Cervicogenic headache does have a contentious history as a distinct clinical entity. Critics have argued that the soft nature of the diagnostic criteria. In the past, cervicogenic headaches seemed to be diagnosed by the effectiveness of cervical spine therapies in relieving the headache. You can see how this complicates the study of these headaches as a distinct clinical entity. In recent years, nerve blocks or ablations in targeted areas of the cervical spine have been used to determine if the cervical spine is the cause of the headache, but these also require more invasive procedures to make an assessment [2].

Headaches originating from the neck seems to have the biggest role in chronic headaches that begin after a concussion or whiplash. Headaches that emerge after these injuries are commonly classified as cervicogenic headache.The neurophysiologic effects of a concussion tend to disappear 7-14 days after the trauma but the ligament and muscle injuries from a head injury can persist leading to a default diagnosis of cervicogenic headace. The study of cervicogenic headache has revealed quite a bit about the physiology of how the neck can play a role in head pain, even those associated with migraine headache [3].

One problem with this idea is that fact that a traumatic injury can sometimes lead to patients who have never suffered a migraine before, can display migrainous symptoms after an injury [4]. This is also complicated by the fact that conservative cervical spine interventions like spinal manipulation and manual therapy appear to be effective in cervicogenic headache [5], but not in migraine [6] in clinical trials.

What do these headaches have in common? How are they different? Can we use their similarities to develop effective treatment strategies for headaches that are resistent to medications?

The Physiology of Headache Pain

There’s a common source for pain related to the head and neck. That source is a bundle of neurons located in the brain stem called the trigeminocervical nucleus (TCN). This nucleus is a hub for nociceptors in the brain. Nociceptors are receptors that transmit information about noxious stimuli to the brain, usually in the form of tissue injury.

While the feeling of pain is far more complex than the sheer amount of nociception your brain receives, for the sake of simplicity in this article, we will say that nociceptors are fibers that carry pain signals. Your TCN is a major player in head AND neck pain.

Head and neck pain pathway

This area in the brain stem is like the Grand Central Station for all of the pain sensing fibers in the head and neck. From the trigeminal nerve you have pain sensing fibers from the face, jaw, teeth, arteries, and meninges, while the neck has fibers from the joints, ligaments, muscles, and skin coming from C1, C2, and C3 nerve roots. All of these fibers converge onto TVN which has to decide if it’s worth going up to the big kahuna at the top of the brain called the cerebral cortex.

For neurovascular headaches like migraine and cluster headaches, it’s suspected that the pain carrying fibers from the arteries in the brain or the outer covering of the brain called the meninges getting irritated by pulsing arteries. These fibers are carried to the  TVN by the trigeminal nerve. For cervicogenic headaches, it’s suspected that the pain generators are coming from the muscles, nerves, or joints from the upper neck.

These overlapping structures allow for some of the referred pain patterns seen in migraine patients expressing neck pain, and also for cervicogenic dysfunction to lead to headaches. It also means that if 2 pieces of anatomy share a neurological pathway, then sometimes treating one area can lead to relief in another.

Interventions in the Cervical Spine and Headache Outcomes

So we know that the convergence of these neural fibers allows for some overlap of pain sensation regardless of the type of headache. What does the research say about treating headaches with cervical spine interventions?

The answer seems to match what you think it would be.

For cervicogenic headaches, recent studies seem to support the idea that addressing the neck with spinal manipulation can be helpful and even provide some relatively long term impact. A 2016 paper showed that upper cervical and thoracic manipulation helped cervicogenic headache patients at 3 months compared to exercise and mobilization [7]. A review paper of several studies on cervicogenic headache and manipulation seems well in favor of treating the neck compared to controls [8].

For migraines, the evidence isn’t so favorable for manual intervetions. There aren’t that many clinical trials to look at, and the ones that are available appear to show no effect [9]. From a pathophysiological standpoint it makes sense because they seem to be clinically distinct entities. However, the clinical experience of people like myself who practice in an upper cervical model of chiropractic have had a much different experience.

There is some evidence that suggests that cervical spine problems may be present as a sub-type of migraine patients [10]. There is also evidence that greater occipital nerve blocks [11] and non-invasive vagal nerve stimulation in the neck [12] can decrease the frequency of headache days and may effectively abort a migraine attack.

A 2016 study by Woodfield studied 11 patients with chronic migraines showing improvements in migraine frequency while receiving a vectored correction to the atlas vertebra [13]. The study also showed some significant effects in intracranial compliance in patients with cerebrovenous drainage abnormalities.

Case Study on NUCCA atlas procedure on venous drainage routes in a migraine patient.

While the concept of cerebrospinal venous abnormalities have been a controversial topic in multiple sclerosis, it may provide insight into some patients with chronic migraine. Multiple studies have documented venous drainage abnormalities in migraine patients and even mTBI, but the significance behind these observations are unknown [13] [14] [15].

Where To Go From Here?

There’s still a lot to learn about the anatomy and physiology of headache disorders. When you consider that migraine headaches are the most common neurological disease in the world.

Predicted research dollars compared to diseae burden

Lots of work needs to be done to understand what treatments will work for which patients, but there’s still some hope that treating the neck may be a key strategy to help people with chronic headache disorders.

 

 

 

Ligament Injury: A Hidden Injury in Spinal Trauma

 

This guest post is brought to you by my friend and colleague Dr. Francisco Colon. Dr. Colon has been doing a lot medical-legal speaking on the role that ligament injury may play in pain after spinal trauma. He was kind enough to share a bit of his expertise in finding these soft tissue injuries that many physicians may be missing on a routine work up. You can find out more about Dr. Colon and his practice at his practice website Cordero Family Chiropractic

Ligament damage to the knee is something most of us have heard of in some regard. Either from personal experience or somebody we know. Detecting ligament damage to the knee is fairly easy to do. Any physician MD, DO, DC and most experienced nurses can easily test for ACL, PCL, and lateral ligament stability by applying basic orthopedic tests. Knee injuries are also well understood and addressed by health care professionals. In that regard, if you develop or acquire a ligament injury to the knee odds are any competent practitioner can easily test for, and send out for the right diagnostic images in order to get conclusive evidence. Unfortunately, this is not the case for ligament injury of the cervical and or lumbar spine.

Doctors have been playing around with x-ray technology since mid-to-late 1890’s. And we have a lot to show for 120 plus years of application and research. And since very early on physicians understood the role x-ray technology would play in detecting ligament damage to the spine. In fact, according to Yochum & Rowe’s Essentials of Skeletal Radiology: “In 1919 A. George called attention to the relevance of ascertaining alignment to detect post-traumatic cervical injuries”. When spinal anatomy is not in proper alignment with George’s line we call that a “break” or “step deformity”. In more scientific terms this is known as an anetrolisthesis or retrolisthesis depending on whether a vertebra slid forward or backwards in reference to the segment below it.

George's line

George’s lines drawn on a neutral lateral cervical x-ray. Looking for signs of a break or step.

As seen in the illustration George’s line can be seen from a side or lateral view of any portion of the spine and normally has an arch like shape. Since the moment it was described by A. George and in his book “A Method for More Accurate Study of Injuries to the Atlas and Axis” we have understood that there are 4 reasons and only 4 reasons for a break in this line. These are: dislocation, fracture, ligament laxity, and degenerative changes. These reasons have not changed since 1919. And the one we will focus on today is ligament laxity as a result of trauma.

Spotting Hidden Ligament Injuries

The most common reason for ligament damage to the knee is forceful trauma. It is the exact same for the ligaments of the spine. But unlike the knee, damage to the ligaments of the spine have  much more severe consequences and are the likely result of acceleration-deceleration injuries such as whiplash. More so, the American Medical Association indicates that “when routine x-rays are normal and severe trauma is absent ligament alteration is rare” (page 379 Guides to the Evaluation of Permanent Impairment 5th edition). In other words it takes a significant amount of force to overstretch and damage these ligaments. The AMA guides go on to say that when there is a break in adequate alignment and “severe trauma” is present flexion and extension x-rays are indicated.

George’s line is useful in identifying really gross ligament injuries, but remember that ligaments are supposed to hold things together in movement. If you sprain an ankle, the ankle doesn’t hurt nearly as much when it is neutral, but it hurts a whole lot when the ligament is stressed by movement. We can’t rely strictly on a neutral x-ray for ligament injuries, so we have to see what they look like when the neck moves.

Flexion and extension x-rays images taken of the side of the spine while the region (cervical, thoracic or lumbar) is in full flexion and also in extension (bending forward and bending back). From a practical standpoint this is the best way to stress the stabilizing ligaments of the spine. In the knee we can easily stress ligaments by manually applying pressure as it is a single superficial and large joint. Unfortunately the spine is not as easily tested and to avoid checking ligaments of the neck through the use of the “choke-hold method” a true professional will opt for x-rays.

 

Flexion stress x-ray may reveal injury to the posterior longitudinal ligaments

Flexion stress x-ray may reveal injury to the posterior longitudinal ligaments

 

 

extension x-ray

Extension stress x-ray may reveal injury to the anterior longutitudinal ligament.

It is also important to note that unlike the knee MRI and CT are will not show ligament damage as 99% of these images are taken in a neutral and recumbent position. This position will not stress the ligament structures enough to elicit evidence of Alteration of Motion Segment Integrity (AOMSI). In fact, standard trauma screening protocols miss discoligamentous injuries in an acute setting at a rate of 44% when CT is present and normal according to Alhilali and Fakhran. In a 2015 study titled Delayed or Missed Diagnosis of Cervical Instability after Traumatic Injury: Usefulness of Dynamic Flexion and Extension Radiographs, by: Gi Yeo, Jeon and Woo Kim discuss the following:

“In discoligamentous injury, 30%of patients with ligamentous disruption displayed a negative result on static radiographies and CT scan…Dynamic flexion extension radiographies are often recommended for patients complaining of neck pain or tenderness after an acceleration-deceleration mechanism injury, especially for patients presenting persistent symptoms in the absence of abnormal findings on standard 3-view radiograph including antero-posterior, lateral, and open mouth views…”

And they conclude:

“Dynamic flexion and extension radiographies are required to exclude the possibility of cervical instability in the patient with cervical trauma in initial or follow up studies. However the examination should be performed carefully to avoid neurologic deterioration.”

In short, the literature suggests that trauma protocols currently have many short comings and the knowledge practitioner should utilize dynamic flexion extension studies to document ligament damage. Concern for neurologic deteriorating has great validity as discussed in the British Journal of Radiology by Harison and Ostlere 2005 “Timely diagnosis of these injuries is imperative, as risk for neurologic sequelae is 10 times higher in patients with cervical injury missed on initial screening.”

The proposed mechanism for neurological deterioration that is expected with these injuries was evidenced and documented in a 2006 SPINE article by Nabili, Jiayong, Quaise Et.AL whereby it was documented that every millimeter of retrolisthesis allowed by ligament instability represents a 12% encroachment in the foramen. It is therefore evident that this hidden injury of the spine one that is very common place in trauma, one that is very easily overlooked and one with severe implications when undiagnosed.

Dr. Francisco Colón was born and raised in Puerto Rico. Dr. Colón decided to study chiropractic at Life University in Marietta, GA. In his last year of studies Dr. Francisco was part of a selected delegation of chiropractic students and Doctors that traveled to a hospital in China to educate and to provide chiropractic care. After graduating Life University in early 2010 Dr. Francisco moved to Miami where he practiced for 3 years with one of South Florida’s most successful chiropractic centers. Dr. Francisco has served a wide range of patients from the new born and healthy to the high performance athlete and the ill. He is committed to his new community of the Palm Beaches and will work hard to preserve the high quality of care that patients have received and have grown to expect from Cordero Family Chiropractic.

Rectus Capitis Posterior Minor in Headache Disorders

Neck muscles have been a source of suffering for patients for a long time. In recent years, one neck muscle in particular is getting a lot of attention in the world of head injury.

Meet the rectus capitis posterior minor (RCPMi)

Image Credit: Duke Univeristy Learning labhttps://web.duke.edu/anatomy/Lab01/Lab2_new2014.html

Yep. It’s that tiny little muscle deep in the middle of your neck. It connects from the top bone in your neck called the atlas, and it connects into the head via connective tissue called the myodural bridge. But more on that later.

All in all, the the RCPMi is not much bigger than the end of your pinky finger, but it’s capable of wreaking havoc on people with neck problems including concussion.

Headaches, Trauma and the Rectus Capitis Posterior Minor

The RCPMi has been considered a muscle of importance in chiropractic literature for a long time. It’s only been a recent phenomenon where more mainstream medical science has started to look at its role in headaches and trauma. Two such studies examined the RCPMi in 2016.

The first study was published in the American Journal of Neuroradiology. They saw that patients with atrophy in the RCPMi had more severe concussion symptoms and a worse prognosis. You can check out the abstract here:

Effect of the suboccipital musculature on symptom severity and recovery after mild traumatic brain injury

The second study was published in the presigious headache journal, Cephalgia. The authors found that patients with chronic headache tended to have more hypertrophy in the RCPMi than controls. You can check out that abstract here:

Correlation between chronic headaches and the rectus capitis posterior minor muscle

In case you weren’t paying attention, you should probably find those 2 outcomes to be a little strange.

On one hand, having smaller RCPMi had worse outcomes with concussion symptoms. On the other hand, having larger RCPMi was more likely to be associated with chronic headaches.

Granted we are dealing with 2 different conditions, but one of the biggest problems with chronic concussive symptoms is chronic headache. It would seem like there should be some overlap. What gives?

How Can That Small Muscle Cause So Many Problems?

There’s a few unique things about these muscles.

  1. The RCPMi does not connect into bone like most muscles do. It connects into a piece of tissue called the myodural bridge. That means it has a direct link into the outer covering of the brain which is known to be very sensitive to pain.
  2. The RCPMi is too small to provide much in the way of meaningful movement of the head and neck. Inside the belly of this small muscle are abnormally large amounts of prorioceptors called muscle spindles. Proprioceptors help provide feedback to the brain about joint position and movement.
  3. Changes in the RCPMi can deform the myodural bridge which changes movement in cerebral spinal fluid. Abnormal movement of this fluid is associated with headache.

So as you can see, even though the RCPMi is small it carries a large baggage of neurology with it.

What’s Happening in Headaches and Concussions?

This is where things get a little interesting, because we don’t really know how this muscle is causing problems. More evidence is showing that there is a correlation between this muscle and headaches, but we don’t really know anything about causation yet.

With that being said, this is mostly just speculation on my part, so here it goes.

In my office we are always striving to create symmetry in the structural positioning of the head and neck.

When the head and neck shift, it creates asymmetrical force production in the suboccipital muscles. Image Credit: Daniel O. Clark uppercervicalillustrations.com

When there is an injury like a trauma or whiplash, you create injury in some of these small muscles of the neck. When these muscles are injured, the brain loses some critical feedback mechanisms that helped to maintain proper positioning of the head and neck.

The injury also creates asymmetrical tension on the myodural bridge. This abnormal tension on the dura stimulates the sensitive pain receptors in this tissue leading to head and neck pain. There have even been cases where cutting this muscle can relieve a patient of chronic headache.

That same tension on the dura may also be creating abnormal flow of cerebral spinal fluid which may lead to chronic effects of brain physiology.