Compression of the brainstem and spinal cord injury risk – Cervical spine instability and Atlantoaxial instability

Ross Hauser, MD

Upper cervical instability is a primary focus of the Hauser Neck Center at Caring Medical Florida. Every day we are making discoveries in patients who have bizarre and disabling neurological symptoms that have gone undiagnosed or unresolved by their local primary care doctors or even other well-known specialty clinics.

Discussion points of this article:

Upper cervical instability and atlantoaxial instability a problem with many names

Many people we see have a diagnosis that describes similar problems. While the problems can be similar the diagnosis tag can be somewhat confusing in describing the same problem. You may have a diagnosis for:

In the medical literature, atlantoaxial instability generally refers to the connection between the atlas and the dens of axis, which we refer to as dens atlantoaxial instability (DAAI). This is important because dens atlantoaxial instability is more of a surgical lesion, whereas facet atlantoaxial instability can often be treated by conservative measures such as chiropractic care, physiotherapy, and injections.

The caption of the image below reads: Schematic of upper cervical region from posterior (rear) view, Facet joints of C0-C2 are stabilized by capsular ligaments. OIt is these ligaments that are primarily strengthened by Prolotherapy injections (explained below) to stabilize the spinal segments.

Facet joints of C0-C2 are stabilized by capsular ligaments

C1-C2 Rotatory Subluxation: “this condition often goes undiagnosed, or the diagnosis is delayed and the outcome is worse.”

Researchers in Spain lead by the University of Valladolid, published a July 2022 study in the journal Diagnostics (27) that sought to help doctors understand
C1-C2 Rotatory Subluxation. Here are some of the learning points and suggestions:

“The atlantoaxial joint C2 (axis) with the anterior arch of C1 (atlas) allows (the neck and head) 50% of cervical lateral rotation. It is responsible for precise and important movements that allow us to perform precise actions, both in normal and working life.

Due to low incidence in adults, this condition often goes undiagnosed, or the diagnosis is delayed . . .with a poor prognosis just because of the late diagnosis and the outcome is worse. The correct approach and treatment of atlantoaxial dislocation requires a careful study of the radiological findings to decide the direction and plane of the dislocation.

In almost a century, surgery techniques have not evolved.

The C1-C2 rotatory subluxation has different and varied etiologies (causes) that determine the therapeutic approach to be followed. Common in all of them is pain, inflammation, torticollis, and in more advanced cases, neurological complications. . . when studying and recognizing the different surgical treatment options, there are numerous techniques available, all of them leading to stabilization. However, there is a relevant fact: the techniques have not evolved at all since they were introduced (starting in 1930) up to the present day and until today.”

As alluded to in the citation above, the structure in the human body most important to be in stable alignment is the atlas. Since the atlas is supported by a sea of ligaments and weighs only 2 ounces, yet “supports” the cranium, which weighs a whopping 10-12 pounds, it is prone to misalignment, causing the myriad of potential symptoms discussed in this article.  Sometimes the atlas is 2-3 inches forward from where it should be due to breakdown of the cervical curve, thus making its improper positioning responsible for much of the symptoms and syndromes related to cervical instability.

The atlas’s 3-dimensional orientation is so important that multiple branches of chiropractic have been formed to realign its malrotations, including orthospinology, Grostic procedures, atlas orthogonal, the National Upper Cervical Chiropractic Association (NUCCA), and others. The medical literature is filled with with case reports and studies to show that improving atlas subluxations will lessen symptoms of high blood pressure, migraine headaches, neck pain, and a host of systemic symptoms and illnesses. There is no bone in the body that is more neurologically protected and the atlas is also the “headquarters” for the vagus nerve.

The stability of the atlas has one primary weak link, the atlantoaxial capsular ligaments

The stability of the atlas has one primary weak link, the atlantoaxial capsular ligaments, because they are normally “loose” or “stretched” to allow head rotation. The atlantoaxial joint lies between the very stable atlanto-occipital joints (stabilized because of the large convex occipital condyles and concave superior articular facets of the atlas) and the C2-C3 joints, which are stabilized by its intervertebral disc and a myriad of muscles that connect to the large C2 spinous process. The medial atlantoaxial joint is stabilized by the stronger transverse and alar ligaments (compared to the capsular ligaments). It is the atlantoaxial capsular ligaments that are continuously stretched. Facet atlantoaxial instability is easy seen by motion videography (digital motion x-ray). DMX or digital motion x-ray is a motion x-ray and it is discussed below.

Stability or prevention of the anterior translation of the atlas (the atlas is floating or moving forward of the cervical spine)

Stability or prevention of the anterior translation of the atlas (the atlas is floating or moving forward of the cervical spine) is performed by the capsular ligaments posteriorly (in the rear) and the transverse ligament anteriorly (in the front). The transverse ligament connects along the expanse of the anterior arch of the atlas. Capsular ligament injury of C1-C2 results in facet atlantoaxial instability, whereas injury of the transverse and alar ligaments causes dens atlantoaxial instability. Injury to the atlantoaxial capsular ligaments causes a dramatic increase in lateral bending and axial rotation motion (43% and 159%, respectively), whereas transverse ligament disruption significantly increases the anterior atlanto-dens interval. This was demonstrated in a February 2019 paper in the Journal of neurosurgery. Spine, (21) from the University of Utah. In this paper the researchers examined contradictory evidence regarding the relative contribution of the key stabilizing ligaments of the occipitoatlantal  joint.

For a detailed discussion of the many health challenges instability in this portion of the neck can cause please see my article: Symptoms and conditions of Craniocervical and Cervical Instability

In this article, we briefly review, compression of the brainstem symptoms of dizziness, fainting, blurred vision, visual and auditory disturbances, flushing, sweating, tearing of the eyes, runny nose, vertigo, numbness, tingling, difficulty swallowing or talking, and drop attacks. In the video below, Ross Hauser, MD discusses how upper cervical instability impacts the brain stem and leads to many of the symptoms that we help in our clinic, as well as our approach to resolving the issue without surgery or a lifetime of medication.

What causes Atlantoaxial instability or Craniocervical instability?

In the cervical spine, the body will always choose stability over motion to protect the adjacent neurovasculature structures. The cervical spondylosis process starts with its loss of structural integrity. Uneven forces exerted on the vertebral bodies cause osteophyte (hone spurs) formation and facet hypertrophy, the condition even being called “degenerative instability.” (24) Cervical facet joint osteoarthritis, degenerative disc disease, and ponticulus posticus, while very different conditions, illustrate the lengths at which the body will go to protect key blood vessels and nerves. While the overgrowth of bone in the facet joints and degeneration in the cervical discs attempt to protect the carotid arteries, vagus nerves, and cervical spinal nerves, ponticulus posticus serves to do the same and protect the vertebral artery and cranial nerve I (suboccipital nerve). Yet there are more people with these findings on MRI that are asymptomatic vs. symptomatic, including up to 78% of people in their 20s. (25,26)

The vagus nerve and Atlantoaxial instability

The vagus nerves are the most important nerves in the body. The vagus nerves are most vulnerable to stretch and traction, but also compression in the cervical region, as they lie in a specific space called the carotid space.

The caption of the image below reads: Carotid sheath compression from ligamentous cervical instability (LCI). This is the primary mechanism by which ligamentous cervical instability causes human illness as it obstructs the primary outflow of the brain causing “brain illness” and interferes with the vagus nerve signal transmission leading to body illness.

Carotid sheath compression from ligamentous cervical instability

The carotid space is a paired space  (on left and right side of neck) defined by the carotid sheath, a connective tissue boundary in the neck, that is made by the superificial, middle, and deep layers of the cervical fascia. Extending from the jugular foramen at the skull base to the aortic arch at the thoracic inlet, the carotid space is divided craniocaudally into the supra- and infrahyoid regions. The suprahyoid portion of the carotid space contains the internal carotid artery, the internal jugular vein, cranial nerves 9 through 12, the ansa cervicalis, the sympathetic plexus and deep cervical lymph nodes.

The anatomical layout of the carotid sheath is shown below. The image caption reads: View looking up showing the position of the atlas and carotid sheath contents to the jugular and carotid foramen. Atlas misalignment, especially displacement anterior can kink the carotid sheath contents particularly the carotid artery, internal jugular vein and vagus nerve.

The anatomical layout of the carotid sheath

Below the level of the hyoid, (the bone that supports the back of the tongue) the ansa cervicalis (a loop of the first 3 cervical nerves) and cranial nerves 9, 11, and 12 have exited the carotid sheath in the front, leaving thus only cranial nerve 10. The internal jugular vein and the common carotid artery are also contained within the infrahyoid carotid space. The vagus nerve is thus the only cranial nerve in the infrahyoid carotid space. Typically the vagus nerve lies in the posterior groove between the jugular vein and carotid artery. In the infrahyoid carotid space, the vagus nerve is between the ansa cervicalis which is embedded in the anterior carotid sheath and the sympathetic plexus which is posterior.

The carotid sheath contents including the vagus nerve (one on each side) because of its location and length is very vulnerable to tissue strain by deformations or deviations from the normal stable cervical lordotic curve

The cervical spine is divided into two parts – the upper and the lower cervical spine.

The cervical spine is divided into two parts – the upper and the lower cervical spine. The upper cervical spine contains C0 (the occiput or base of the skull) and C1 and C2 (the atlas and axis, respectively). Instability of the upper cervical spine is often referred to as “atlanto-axial instability.” Ligament injury can happen to any part of the neck, but an injury to the upper part of the neck may cause unique symptoms. These include neck pain, headaches, dizziness, vertigo, fatigue, numbness and tingling of the face and tongue, tinnitus, nausea/vomiting, balance difficulties, drop attacks, difficulty swallowing, and migraines.

Craniocervical instability or Atlantoaxial instability can be caused by many factors. Trauma injury, congenital defects (defects from birth), and arthritis. A commonality among these causes is the possibility and extent of cervical ligament damage. Again, standard x-rays and MRIs are normal after these types of injuries because instability and ligament injury is usually not evident. Once these imaging studies come back normal, there is often not much else traditional medicine can offer the patient in terms of relieving lingering neck pain and instability. The focus of this article will therefore concentrate on the impact of cervical spine ligament injury and how addressing this injury can help alleviate pain and symptoms.

A patient will come into our clinics, they will describe a daily, emotional battle with the symptoms of “suspected” or “suspicious” atlantoaxial instability. They will tell us about:

The patient will then relate a long, confusing, frustrating medical history that includes MRIs, CT Scans, Physical therapy, and countless medications.

In some patients, an MRI will reveal that the Atlantoaxial joint between C1-C2 has subluxed or moved out of place. Some of these patients will reveal to us that they have been recommended for cervical fusion surgery. Some patients will tell us that their doctors have recommended waiting on the surgery until “things get really bad.”

When Atlantoaxial instability symptoms extend beyond neck-related.

Mechanical stability is the spine’s ability to maintain its alignment and to provide protection to the neural (nerves), vascular (blood) and other structures it encloses during physiological loading (stress on the neck) so that there is no harm to any of these tissues and no symptoms are produced. Clinical ligamentous cervical instability is an inability of the cervical ligaments to maintain individual, adjacent, or global vertebral alignment when subjected to increased forces by various postures, positions, and/or motions that alter bony, soft tissue, and/or neurovascular alignment and function such that symptoms result.

The potential seriousness of clinical ligamentous cervical instability is amplified when one considers that all major neurovascular structures from the body that enter and leave the brain and brainstem, including the autonomic ganglia, do so through the neck. The neck is thus a conduit for fluid and nerve flow that run the body through the brain and brainstem. clinical ligamentous cervical instability can disrupt this fluid and nerve flow, and the neurology that results can explain many of the chronic symptoms, disorders, syndromes and diagnoses that plague people.

It is important to realize that unchecked cervical instability could damage the cervical spinal cord, as with each facedown posture of looking at a cellphone, the vertebrae move anterior, thus narrowing the spinal canal. If it were not for muscle tension and spasm, and other compensatory mechanisms that stop excessive cervical motions from injuring vital neurovascular structures, spinal cord damage could occur. If the ligament injury does not heal and the excess motions and forces continue in the neck, degenerative breakdown of the adjacent vertebral segments occurs in the disc, facet, and uncovertebral joints, as well as the vertebral endplates. (21) This degeneration can be manifested as a clicking, grinding, or popping sensation as the person moves or manipulates their own neck. Motion will eventually be limited as bridging osteophytes occur on the facet joints, along with disc degenerations, ultimately fusing the joint. (22) Unfortunately, this degenerative fusion then causes excessive neck motions to occur in the adjacent vertebral motion segment, increasing its stress and potential for becoming unstable. (23)

Why someone can have neck-related symptoms but NOT have neck pain. Part 1: Jugular vein

A summary transcript and explanatory notes of this video is available here: Why someone can have neck-related symptoms but NOT have neck pain. Part 1

Why is instability more common in C1-C2 than C3-C7?

The cervical spine is typically divided into the upper cervical region (C0-C2) and lower cervical region (C3-C7). The susceptibility to the instability of the occiput-C1 and C1-C2 joints is elevated due to the fact that these areas of the spine are the only areas that do not contain intervertebral discs. The upper cervical spine consists of the Cranio junction, atlantoaxial joint, and craniovertebral junction. The atlantoaxial joint provides about 50% of the motion in the cervical spine, enabled by the peg (C2) – ring (C1) anatomy. The upper cervical vertebrae (C0-C2) are suspended in “a sea of ligaments” whereas the lower cervical vertebrae (C3-C7) are stabilized by the intervertebral discs.

The lower cervical region

The cervical spine is interconnected by C0-C7 and as mentioned above, stabilized by different structures. I just noted that the lower cervical vertebrae (C3-C7) are stabilized by the intervertebral discs. A May 2022 paper in the journal World neurosurgery (19) comes to us from combined findings from the Yamaguchi University Graduate School of Medicine in Japan and the University of Toledo in Ohio. In this paper the importance of the intervertebral discs in maintaining cervical spine stability at C2-C7 is noted.

“Soft tissue cervical spine injury  have the possibility of causing cervical segmental instability which can lead to spinal cord injury. There is a lack of certainty in assessing whether soft tissue cervical spine injury is unstable or not. This biomechanical study aimed to investigate the risk factors of soft tissue cervical spine injury.”

The question that is sought answered is, how much does soft tissue injury cause risk for spinal cord compression or injury. In this study computer models were used to assess the cervical spine ligaments at (C2-C7) .

Three soft tissue injury models were simulated at C4-C5: (a) posterior ligament complex (PLC) injury (PLCI), (b) Intervertebral disc with anterior longitudinal ligament  injury, and (c) when all the injuries were involved. For the Intervertebral disc and combined posterior ligament complex (PLC) injury, Intervertebral disc with anterior longitudinal ligament  injury, models, the range of neck motion increased (more instability) at the injury level in extension (by 101%) and left/right axial rotations (more than 30%) compared to the control model. The Intervertebral disc and Intervertebral disc with anterior longitudinal ligament  injury models showed an increase of more than 50% in annular and nucleus stresses at the injury level in extension and left/right rotations compared to the intact model. The posterior ligament complex  showed similar stresses as the intact model except for flexion. The facet contact forces of Intervertebral disc and combined injury models increased more than 100% compared to other models in all motions. The researchers concluded “In cervical spine injury, all soft tissues have a key role in stabilizing cervical spine, but Intervertebral disc (keeping the disc in place) is the most important component of all.” Keeping the disc in place is the role of the cervical spine ligaments.

The challenges of diagnosis

A July 2021 paper from the Mayo Clinic Arizona, Department of Neurological Surgery begins: (2)

“Painful atlantoaxial (C1-2) osteoarthritis has been described over 40 years ago. The condition may cause severe pain symptoms and disability related to unilateral suboccipital pain and, in some cases, occipital neuralgia. One of the greatest challenges with atlantoaxial (C1-2) osteoarthritis is making the diagnosis. Diagnosis is commonly missed or delayed when headaches are treated in isolation or when pain is attributed to subaxial spondylosis.”

Let’s note that occipital neuralgia is coming under more intense observation as previously a 2015 paper (3) reported:

“Atlantoaxial osteoarthritis, either in isolation or in the context of generalized peripheral or spinal arthritis, presents most commonly with neck pain and limitation of cervical rotational range of motion. Occipital neuralgia is only rarely attributed to Atlantoaxial osteoarthritis.”

The condition that is the most perplexing for patients and their doctors to figure out is upper cervical instability.

The reasons why this condition goes undiagnosed by traditional medical doctors and health care professionals are manifold including:

There is no gold standard for making the diagnosis of upper or lower cervical instability. Let’s start with a 2005 study in the medical journal Physical Therapy (4). Here physical therapists correlated the following symptoms with cervical instability:

As a definitive physical examination diagnostic tool has not been developed, cervical instability will continue to be diagnosed primarily through a combination of clinical findings including history, subjective complaints, and manual examination methods. I would add that when available, the definitive diagnosis is confirmed with some type of motion x-ray or MRI examination of the neck which then is correlated with the person’s symptoms and physical examination. Generally, the diagnosis of upper and lower cervical instability is made on clinical grounds, along with associated signs and symptoms in the upper cervical spine. These include muscle tightness, tension, and tenderness. In range of motion testing, crepitation or clicking in the neck can be palpated or heard. Some patients have locked in the neck. Pain is typically worse with movement and better with immobilization or rest. Referral of pain from the upper cervical area to the mastoid, occiput, temporal and frontal areas is common. Tenderness over the suboccipital musculature and spinous process of the axis with palpation are common findings. The general major criteria we use at Caring Medical for diagnosing cervical instability based on patient history includes:

It can also include these more specific (minor) criteria:

When Atlantoaxial instability the problems become neurologic-like.

Some of the symptoms described above would be considered neurologic-like in nature. Loss of balance, vision problems, involuntary muscle spasms to name a few. When you understand that the following nerve or nerve centers run within a few millimeters of the atlas and axis vertebrae it is easier to understand these symptoms as being caused by herniation of compression on these nerves.

  1. C2 nerve root which becomes the greater and lesser occipital nerves.
  2. Glossopharyngeal, vagus, spinal accessory, and hypoglossal, all of which are contained at some point in the carotid sheath.
  3. Superior cervical sympathetic ganglia.
  4. Upper cervical spinal cord (and its connections to the trigeminal nerve).
  5. Brainstem

It is extremely important to understand the key role that the stability and alignment of the atlas and axis have on the proper neurological function of the human body. When there is atlantoaxial instability and/or atlantoaxial subluxation (malalignment) most if not all of the above nerves or nerve centers will not function properly. It is not too much to add that the brain will not function properly either, as the arterial, venous and cerebrospinal fluid flow would also be affected.

For some who did not have a positive MRI reading for Atlantoaxial joint subluxation, they will tell us that they have been recommended for counseling and for mental illness screening. They have been told it may be “all in your head.”

What the physical therapists say: MRI can confuse the issue.

The most common symptoms or physical or muscular manifestation of Atlanto-axial instability or upper cervical instability re: muscle tension in the neck, headache, weakness in holding the head up, relief of major symptoms with laying down or wearing a cervical collar, and a clicking grinding or popping sensation in the neck. An inability to hold a self or chiropractic cervical adjustment is another sign.

Upper cervical instability, including the occiput-C1 and C1-C2 joints, often goes unnoticed because the diagnosis is difficult to confirm without a motion x-ray or MRI. This is simply because the reliability and validity of joint integrity tests performed upon physical examination as well as radiographic studies are still under debate. The most common tests done on physical examination to try and diagnose ligament damage of the upper cervical spine include the Sharp Purser, Anterior Shear, and cervical distraction with various movements including flexion, rotation, and lateral flexion.

What is generally found on physical examination is muscle guarding, because the patient does not want the clinician to even touch the upper cervical area because of the sensitivity and pain. There is sometimes no correlation between the measure of hypermobility or subluxation of the vertebrae and the presence of clinical or neurological signs and symptoms in mild to moderate instability cases.

The problems of accurate diagnosis were noted

In the study cited above from 2005, physical therapists correlated the following symptoms with cervical instability: intolerance to prolonged static postures, fatigue and inability to hold head up, improvement in symptoms with external support (collar), frequent need for self-manipulation, feeling of instability, shaking or lack of control of the head, episodes of acute attacks, sharp pain with sudden movements.

A few years later in 2009, a paper published in the Journal of Manual and Manipulative Therapy (5) tried to address the challenges of matching a patient’s symptoms with what appeared on an MRI. The problems of accurate diagnosis were noted:

“Information gathered from the patient history, physical examination, and advanced testing augments the decision-making process and is proposed to improve the probability of diagnostic and prognostic accuracy. However, these findings may provide inconsistent results and can lead to errors in decision-making. The purpose of this study was to examine the relationship between common clinical complaints and specific findings on magnetic resonance imaging (MRI) in patients with chronic neck dysfunction.

What we had here in this study was a lack of consistency in interpretation of what the MRI seemed to suggest and what was wrong with the patients.

Of note was the fact that when there was less fluid around the spinal cord, symptoms could be correlated. The image of less fluid suggested spinal cord compression.

A December 2013 study brings us closer to 2021 by the way that the same problems seen 8 years ago are still problems today. Here is a paper from the journal Physical Therapy. (6)

“Patients with neck pain, headache, torticollis, or neurological signs should be screened carefully for upper cervical spine instability, as these conditions are “red flags” for applying physical therapy interventions. However, little is known about the diagnostic accuracy of upper cervical spine instability tests.”

MRI does see cord compression plays a major role in Cervical spondylotic myelopathy

In 2021 a paper published in the medical journal Cureus (7) citing this 2009 research continued: “Cervical spondylotic myelopathy is the most common cause of spinal cord dysfunction. Magnetic resonance imaging (MRI) remains the imaging modality of choice, but its findings are not completely specific for clinically significant Cervical spondylotic myelopathy.  . . (The researchers then suggested) the MRI parameters such as canal and cord size of the cervical spine are an objective reflection of compression on the spinal cord. Correlations observed indicate cord compression that plays a major role in the pathophysiology of cervical spondylotic myelopathy.”

What are we seeing in this image? It is an image of less Cerebrospinal Fluid surrounding the spinal cord. It is an image suggesting spinal cord compression

In the image below we have three cross-sections of an upper cervical spinal cord MRI.

Cervical instability can be difficult to diagnose. This is largely due to the low reliability and validity of radiographic studies including functional (motion) radiographs and many clinical examination measures that are still under debate and are rather questionable. Unfortunately, there is often no correlation between the hypermobility or subluxation of the joint, clinical signs or symptoms, or neurological signs or symptoms. Sometimes there are no symptoms at all which further broadens the already very wide spectrum of possible diagnoses for cervical instability. However, this is not the case for those of us who are skilled in recognizing cervical joint instability.

The effect of atlas misalignment on upper cervical spinal canal space.

In the image below is a comparison between normal atlas alignment and misalignment. In the Misalignment, the axial canal space for the upper spinal cord and/or brainstem and cerebrospinal fluid is severely compromised when the atlas misaligns. Symptoms can range from suboccipital and head pain and pressure to severe neurological compromise. Please see our article on treatments for Atlas displacement c1 forward misalignment.

There is no gold standard for making the diagnosis of upper or lower cervical instability on clinical grounds so it must be suspected so the right radiographic analysis can be made.

There is no gold standard for making the diagnosis of upper or lower cervical instability on the clinical ground’s so it must be suspected so the right radiographic analysis can be made. A 2017 mini-review paper published in the Journal of Spine (8) offers common guidance in what to look for in patients with suspected upper cervical instability. These are many of the symptoms we see here in our patients and are symptoms you are likely yourself suffering from. Here is what the authors published:

“Diagnosis of Atlanto-axial instability is based upon careful history, a detailed neurological exam, and imaging of the upper cervical spine. The most common clinical features are neck pain and suboccipital headache, with the caveats that headache is present in 50% of patients with EDS (doctors should look for Ehlers-Danlos Syndrome as a possible component of the patient’s challenges) and that moderate pain is a common occurrence for most EDS patients.

There may be symptoms referable to the vertebral artery blood flow, including visual changes, as well as headache associated with the vertebral artery itself. Syncopal (fainting or passing out) and presyncope (the feeling that you are going to faint or pass out) events are frequent.

Other symptoms include dizziness, nausea, sometimes facial pain, dysphagia (difficulty in swallowing), choking, and respiratory issues. There is usually improvement with a neck brace. (Note: Please see our Caring Medical article: Cervical collars – why do they help some people and not others?).

Examination often demonstrates tenderness over C1-C2, altered mechanics of neck rotation, hyperreflexia, dysdiadochokinesia (dysdiadochokinesia is an inability to perform rapid alternative movements – for example, as used to test for dysdiadochokinesia, your ability to tap the palm of one hand with the fingers of the other and then flipping the palm over so the fingers can tap the back of the hand), hypoesthesia (loss of sensation) to pinprick.

What this mini-review reveals are the challenges we see of a neurologic-like nature.

It is not all in your head, it is all in your neck – let’s get to some answers – The c2 vertebra is moving and causing basilar invagination

Lightheadedness or dizziness if a very common symptom, for which people often get a lot of x-rays, MRIs, EKGs, and blood tests. It is an extremely common complaint when people come to Caring Medical with neck complaints. There are many reasons for a person with upper cervical instability to have lightheadedness or dizziness. The most likely cause is a decrease in sympathetic nerve fiber firing on blood vessels causing vasodilation. Another reason is carotid sinus syncope. In this condition, a sharp moving of the neck causes a vasodepressor response, and the blood pressure and pulse rate become dangerously low so blood supply to the brain is diminished and lightheadedness, fainting, or severe fatigue can result.

In March 2019, a team of neurosurgeons wrote in the medical journal World Neurosurgery, (9) about cervical instability and osteoarthritis. What they found was the degenerative condition of the cervical spine could result in hypermobility of the atlantoaxial segment (excessive rotation, possible subluxations) and cause overstress in the transverse ligament and the lateral atlantoaxial joints.

The surgeons noted: “These changes explain the pathogenesis of atlantoaxial dislocation and basilar invagination associated with osteoarthritis.”

In other words, the c2 vertebra is moving and causing basilar invagination, (reducing the size of the opening in the skull (the foramen magnum) where the spinal cord passes into the brain. This excessive motion is caused by an overstressing (wear and tear) degeneration of the transverse ligament. This is causing the symptoms we alluded to earlier including balance issues, vision issues, headache, hearing issues, among others.

Atlantoaxial instability (AAI or C1-C2 instability) causes some of the most common symptoms people with illness and injury experience but are unaware that it is from their neck. Case studies will be presented along with an explanation of the neurology involved.

Atlantoaxial instability is the abnormal, excessive movement of the joint between the atlas (C1) and axis (C2). This junction is a unique junction in the cervical spine as the C1 and C2 are not shaped like cervical vertebrae. They are more flattened so as to serve as a platform to hold the head up. The bundle of ligaments that support this joint is strong bands that provide strength and stability while allowing the flexibility of head movement and allow unimpeded access (prevention of herniation or “pinch”) of blood vessels, nerves that travel through them to the brain and the spinal cord itself.

Understanding how the Atlas and its ligaments support your head and how damage to those ligaments causes the symptoms of neck pain, limited head and neck motion, and possibly sensory issues.

Above, we have a picture of the Greek mythological titan Atlas. Atlas was ordered by the king of the Greek gods Zeus, to hold the sky in the heavens (later the earth in the heavens as depicted in the art). The C1 vertebra is therefore aptly named the Atlas as it holds the weight of your head as Atlas in mythology holds “the weight of the world.”

A little bit of pretending helps us understand the role of cervical ligaments in Atlantoaxial instability and how the weight of the world can damage our neck.

If Atlas’s right arm is injured, the weight of the world will fall on the left hand. With this extra burden and stress, the left arm will eventually suffer fatigue, wear and tear, and weaken. With both arms injured and weakened the earth (your head) will wobble between the right and left arm.

If Atlas’s right leg is injured, he will shift his weight to his left leg. The earth will tilt towards his left leg. With this extra burden and stress, the left leg and left arm will eventually be injured. Atlas himself will wobble and have balance issues.

To fix Atlas’s problems, you need to fix his cervical ligaments. His supporting structures keep the globe steady.

To fix your Atlantoaxial instability, you need to fix your cervical ligaments.
When ligaments are ignored, Occipitoaxial fusion becomes the treatment

Fixing the ligaments is usually not the first choice among more traditional doctors. Fusion surgery is. In the above picture, if we cemented Atlas’s feet to the ground do you think his knees and hips would suffer? When your C1-C2 cervical vertebrae are fused to limit atlantoaxial instability and related symptoms, the force and energy in your neck movements are going to be transferred to those vertebrae below the fusion. In many patients, all this accomplishes is transferring the atlantoaxial instability to the lower cervical vertebrae.

The following research highlights these problems:

Surgery is often aimed at fixing the instability by fusing vertebral segments together.

Destabilization of C0-C1 or C1-C2 joints can lead to extremes of instability with severe life-threatening neurologic sequelae that necessitate surgical consult. On several occasions, we have stopped a person in the middle of a motion x-ray examination because of how severe the instability was on the exam. Patients or athletes with serious symptoms after head or neck trauma including dysarthria, diplopia, dysphagia, drop attacks, paraesthesias, or weakness in the limbs (especially the legs) necessitate surgical consultation. If radiographic analysis confirms significant upper cervical instability, then surgical fusion is performed. But the vast majority of people with a myriad of symptoms do not meet the criteria for surgical fusion, yet they are sent to fusion surgery anyway.

In a study (July 2018) published in the Archives of Orthopaedic and Trauma Surgery, (10) doctors examined occipitoaxial fusion for atlantoaxial instability. Surgery is often aimed at fixing the instability by fusing vertebral segments together. In the case of C1-C2 instability, these two vertebrae are fused posteriorly to limit their amount of movement. However, it may limit motion so much that patients become completely unable to move that portion of their neck. In addition, fusion operations can accelerate the degeneration of adjacent vertebrae as the motion in the neck is distributed more on these issues. For example, if you fuse the C1 and C2 vertebrae together, extra motion is placed on the remaining vertebrae during normal neck movement, accelerating the degeneration process and further contributing to chronic neck pain.

Adjacent segment degeneration after cervical fusion surgery was 32.8%

A 2019 study published in the International Orthopaedics (11) found Adjacent segment degeneration after cervical fusion surgery was found in 32.8% of patients.  Of those approximately 1/4-1/3 of progressed to adjacent segment disease.

Study findings: More than 1/3rd patients had complications after occipitoaxial fusion for atlantoaxial instability

This type of surgery, with its high complication rate and similar procedures, may not even be necessary. 

Cervical spine ligament weakness is why many cervical neck pain patients do not have a successful surgery.

Doctors at the University of Waterloo in Canada published research in the Spine Journal (12) where they were attempting to define a new clinical scoring system for patients with cervical neck instability. The scoring system would help identify the role of cervical ligaments in difficult to treat neck pain and instability.

This is what came out of this research:

Surgery, unless a life-threatening or extreme situation, should never be considered until the problems of the cervical ligaments are addressed.

Cervical ligament injury should be more widely viewed as a key, if not THE key, to atlantoaxial instability treatment

In a 2015 paper appearing in the Journal of Prolotherapy, our staff along with our co-writer Paul Fisher wrote that cervical ligament injury should be more widely viewed as a key, if not THE key, to chronic neck pain and various cervical neck related disorders including atlantoaxial instability treatment. In our opinion, in many patients, cervical ligament injury is underlying pathophysiology (the cause of) atlantoaxial instability and the primary cause of cervical myelopathy (disease). (13)

This was a continuation in the series of published research Caring Medical is producing on the problems of cervical instability including the 2014 article Chronic Neck Pain: Making the Connection Between Capsular Ligament Laxity and Cervical Instability led by Danielle Steilen. (14)

In that research, our team suggested that the cervical capsular ligaments are the main stabilizing structures of the facet joints in the cervical spine and that they are a major source of chronic neck pain. The instability these injuries create often reflects a state of instability in the cervical spine and is a symptom common to a number of conditions including disc herniation,

In the upper cervical spine (C0-C2), this can cause a number of other symptoms including, but not limited to, nerve irritation and vertebrobasilar insufficiency with associated cervical vertigo, dizzinesstinnitus, facial pain, arm pain, and migraine headaches.

An overstressed transverse ligament may be the culprit to your myriad of symptoms

In June 2017, German researchers publishing in Zeitschrift für Orthopädie und Unfallchirurgie (Journal of Orthopedics and Trauma Surgery) also saw the connection of damaged cervical ligaments and chronic neck problems. Here is what they wrote:

The German team set out to investigate in human cadaver studies, fracture and displacement of the odontoid process and ruptures and tears of the transverse ligament. After examination and compilation of data, the researchers concluded:

The scientific and anatomical explanation to supporting the weight of the head on the atlas

Above I describe in metaphorical terms cervical instability at C1-C2. Let’s be a little more medical in this description.

The C1 (atlas) and C2 (axis) articulation involve 3 separate joints (AA joints): two lateral flat horizontal oriented facet joints (one on each lateral mass) and the medial atlanto-dens joint. Let’s briefly discuss the image below.

What are we seeing in this image?

For many of the neurologic, vascular, psychiatric-like problems we see, there is an issue with possible compression of the brainstem / spinal cord. In the illustration below we see clearly that the brainstem and spinal cord slip neatly into the space provided by the proper alignment of the C1-C2 atlas/axis. The key here is a properly aligned C1-C2.

What are we seeing in this image?

As mentioned, in the illustration above we see clearly that the brainstem and spinal cord slip neatly into the space provided by the proper alignment of the C1-C2 atlas/axis. The key here is a properly aligned C1-C2. In the image below we see the right posterior or to the rear malrotation of the C2. What this means is that the C2 is rotating to the right below the C1. This rotation shows cervical ligamentous or cervical ligament laxity. The problem is the cervical ligaments are not holding the C2 and C1 in proper alignment to each other.

What are we seeing in this image below? A wandering C1.

The basic understanding that this article is trying to present is that the brainstem and spinal cord slip neatly into the space provided by the proper alignment of the C1-C2 atlas/axis. In the image below we see wandering C1 vertebrae. What this means is that the C1 is moving back and forth in an unnatural motion on the C2 and causing compression to the spinal cord, arteries, veins, and nerves. This image here is the image generated by a digital motion x-ray (DMX).

The primary ligamentous support of the lateral or side facet joints of C1-C2 are the capsular ligaments; whereas the atlanto-dens joint is held together by the transverse ligament and its back-up the alar ligaments.

The C1-C2 atlantoaxial joint provides 50% of cervical spine rotational mobility as the arch of C1 rotates around the dens of C2. The atlantoaxial joint when stable allows some flexion but
almost no lateral flexion. Lateral flexion in this joint is one of the hallmark signs of facet atlantoaxial instability (FAAI). In other words, you should not be able to touch your shoulder with your ear without moving your arm up to meet your head.

In the medical literature, generally, atlantoaxial instability refers to the connection between the atlas and the dens of the axis, which we refer to as dens atlantoaxial instability (DAAI). This is important because dens atlantoaxial instability is more of a surgical repair type lesion; whereas, facet atlantoaxial instability can more often be treated by conservative measures such as chiropractic care, physiotherapy, and Prolotherapy.

Stability against the anterior translation of the atlas (the C1 wandering over the C2) is by the capsular ligaments posterior (in the back) and the transverse ligament anteriorly (in the front).  Capsular ligament injury of C1-C2 results in facet atlantoaxial instability whereas injury of the transverse and the alar ligament causes dens atlantoaxial instability. Injury to the atlantoaxial capsular ligaments causes a dramatic increase in lateral bending and axial rotation motion; whereas transverse ligament disruption significantly increases the anterior atlanto-dens interval. The anterior atlanto-dens interval is the horizontal distance between the C1-C2. The more distance, the more displacement, the more “wandering,” the more compression.

Another thing that can happen is cervical instability can cut off the blood supply to the brainstem which is the vertebral artery.

In my article, Vertebrobasilar insufficiency, I discuss the complexity and challenges of cervical neck instability treatment which we find fully displayed in the controversies and confusions surrounding the diagnosis of vertebrobasilar insufficiency, also called vertebrobasilar artery insufficiency or Bow Hunter Syndrome. Here patients may suffer from symptoms that include dizziness, fainting, blurred vision, visual and auditory disturbances, flushing, sweating, tearing of the eyes, runny nose, vertigo, numbness and tingling, difficulty swallowing or talking, and drop attacks. Please refer to that article for a review of current research.

In this illustration the vertebral artery is clearly seen weaving its way through C1-C2. If the C1-C2 are moving and hypermobile, they could press on and compress the vertebral artery. This could cause the sensation of lightheadedness and feeling faint.

In this illustration, the vertebral artery is clearly seen weaving its way through C1-C2. If the C1-C2 are moving and hypermobile, they could press on and compress the vertebral artery. This could cause the sensation of lightheadedness and feelings of faintness. This is seen in the x-ray below.

In this x-ray, when the patient looks down, a 6 mm space opens between the C1-c2. When the patient looks up, 0 mm, no space. Everything between those two surfaces is compressed.

In this x-ray, when the patient looks down, a 6 mm space opens between the C1-c2. When the patient looks up, 0 mm, no space. Everything between those two surfaces is compressed.

Cervical Spine Stability and Restoring Lordosis

The cervical spine has a natural curve. It acts as a spring or shock absorber for the head. When this curve is gone because of injury, Joint Hypermobility Syndrome, or degenerative cervical disc disease, not only are the arteries and nerves between the vertebrae not protected from the impact of walking or running or jumping or a bumpy car ride, they are subjected to compression from cervical spine instability caused by cervical ligaments that have also been damaged by injury or wear and tear and no longer hold the neck in correct alignment.

The cervical spine has a natural curve. It acts as a spring or shock absorber for the head. When this curve is gone, injury, Joint Hypermobility Syndrome, or degenerative cervical disc disease

The cervical spine has a natural curve. It acts as a spring or shock absorber for the head. When this curve is gone, injury, Joint Hypermobility Syndrome, or degenerative cervical disc disease

Digital motion X-Ray C1 – C2

The digital motion x-ray is explained and demonstrated below. This is one of our tools in demonstrating cervical instability in real-time and motion. Most injuries to the upper or lower cervical spine are not identified by standard or static x-rays, CT scans, or MRIs. Functional or dynamic imaging technology, which images a person while joints are under stress or in extremes of motion is more sensitive in diagnosing instability. Digital motion x-rays or stress cervical radiographs are obtained using open-mouth projections in neutral, left, and right cervical lateral flexion as well as rotation to reveal a significant lateral offset of one of the lateral masses of C1 on C2.

The clinical signs of upper cervical instability can vary from no symptoms or relatively diffuse complaints to signs and symptoms of extreme importance or seriousness. When clinical symptoms are present, assessing the degree of instability by objective means including digital motion x-ray helps in determining the treatment course.

 

  • Digital Motion X-ray is a great tool to show instability at the C1-C2 Facet Joints
  • The amount of misalignment or “overhang” between the C1-C2 demonstrates the degree of instability in the upper cervical spine.
  • This is treated with Prolotherapy injections (explained below) to the posterior ligaments that can cause instability.
  • At 0:40 of this video, a repeat DMX is shown to demonstrate correction of this problem.

The challenges of cervical instability are many. Fixing cervical neck instability is not something that can be treated simply or easily, it takes a comprehensive non-surgical program to get the patient’s instability stabilized and the symptoms abated. We believe that if you have been going from clinician to clinician, practitioner to practitioner, doctor to doctor, there is a good likelihood that you have problems of cervical neck instability coming from weakness and damage to the cervical ligaments.

Summary and discussion

In this article and video summary, we see that cervical spine instability can have a terrible impact on the quality of life in patients where brain stem compression is occurring. This is not a new problem. Neck instability and the symptoms I describe above have been linked together for a long time. In 1998 doctors at the Department of Neurosurgery, University of California, San Francisco reported on a strange case (16) of a 41-year-old woman, post-surgery who had flexion-induced compression (every time she pointed her chin down towards her chest) of the upper cervical spinal cord causing symptoms of brainstem compromise in the absence of radiographic evidence of osseous instability. (Nothing was showing up on MRI and there was no calcification of the soft tissue). Still, the patient experienced postsurgical instability with dynamic compression by the C3 vertebral body, which caused brainstem compromise. The patient was then sent to a more comprehensive second surgery to fix this problem. A little over two years after this second surgery the patient was reported asymptomatic.

The point of this research was to make fellow surgeons aware that following a C3 decompression surgery, with continued patient symptoms and no obvious reason for it, surgeons should look for cervical spine instability causing pressure on the brainstem. The patient in this case study had a subsequent C2 – C6 fusion.

This study is demonstrated to highlight that more than 20 years later, unknown problems of upper cervical instability continue to confuse patients and doctors. The patients we see in our offices still suffer from many of the same problems whether these symptoms resulted post-surgical or they have not had surgery yet without radiological evidence that something is wrong with them.

Video summary
In this video, Ross Hauser MD discusses how upper cervical instability can affect the brain stem.

As you may be aware, the spinal cord enters the brain through the foramen magnum, the hole in the base of the skull. Once through, the brainstem connects with the brain. This does not always occur. Sometimes, the brainstem does not make it all the way through the foramen magnum. The brainstem may end its journey to the brain in the cervical spine, short of the foramen magnum opening.

This is one reason that the brain stem can be affected by upper cervical instability.

Transcranial Doppler to test blood flow

Video at (1:05) in Caring Medical Florida, we document the blood flow of the vertebral artery with Transcranial Doppler. So our ultrasound machines can measure blood flow to the vertebral artery and then we can move a person through a range of motion to see if the blood supply goes down (is reduced). Please see our article Using Transcranial Doppler & Extracranial Doppler Ultrasound Testing at the Hauser Neck Center for further information and explanations.

We document the blood flow of the vertebral artery with Transcranial Doppler. So our ultrasound machines can measure blood flow to the vertebral artery and then we can move a person through a range of motion to see if the blood supply goes down

We document the blood flow of the vertebral artery with Transcranial Doppler. So our ultrasound machines can measure blood flow to the vertebral artery and then we can move a person through a range of motion to see if the blood supply goes down

(Video at 1:35 ) The lower part of the brainstem is called the medulla oblongata and is where Cranial Nerve X or the Vagus Nerve, Cranial Nerve IX or the glossopharyngeal nerve, Cranial Nerve XI or the spinal accessory nerve, and Cranial Nerve XII or the hypoglossal nerve all originate.

Upper cervical instability, by causing a decrease in neurologic function of the lower part of the brainstem can affect the nerves.

Symptoms may be seen as:

(Video at 2:23 ) A connection to constant nausea

(Video at 2:45 ) Heart palpitations and arrhythmias

(Video at 3:35) Respiratory rate

The Curve of the Cervical Spine

(Video at 4:05) The cervical curve

The Horrific Progression of Neck Degeneration with Unresolved Cervical Instability. Cervical instability is a progressive disorder causing a normal lordotic curve to end up as an “S” or “Snake” curve with crippling degeneration.

The Horrific Progression of Neck Degeneration with Unresolved Cervical Instability. Cervical instability is a progressive disorder causing a normal lordotic curve to end up as an “S” or “Snake” curve with crippling degeneration.

  • The cervical instability from ligament injury causes the cervical spine curve to change, from a normal “C” curve to the opposite, a reversal of the curve. See the progression illustration below.
  • This curve reversal causes stretching on the spinal cord, the cervical spine, with its now unnatural curve, is yanking and pulling on the brain stem and the whole brain. That traction, or pull on the brain stem, can also affect the brainstem as well have cranial nerve function.
  • To get the brainstem and all the nerves working correctly one has to address and tighten the ligaments in the back of the neck as well as get the cervical curve back to its normal lordotic configuration.

"S" cervical curve. Cervical spine instability from cervical ligaments can cause hypermobility of the cervical vertabrae. This leads to a loss of the natural curve or lordosis and eventual cervical kyphosis and an "S" curve.

“S” cervical curve. Cervical spine instability from cervical ligaments can cause hypermobility of the cervical vertebrae. This leads to a loss of the natural curve or lordosis and eventual cervical kyphosis and an “S” curve.

Treatment Prolotherapy

The clinical signs of upper cervical instability can vary from no symptoms or relatively diffuse complaints to signs and symptoms of extreme importance or seriousness. When clinical symptoms are present, assessing the degree of instability by objective means including digital motion x-ray helps in determining the treatment course. It can guide which ligaments need to be injected with Prolotherapy. Destabilization of C0-C1 or C1-C2 joints can lead to extremes of instability with severe life-threatening neurologic sequelae that necessitate surgical consult. On several occasions, we have stopped a person in the middle of a motion x-ray examination because of how severe the instability was on the exam. Patients or athletes with serious symptoms after head or neck trauma including dysarthria, diplopia, dysphagia, drop attacks, paraesthesias, or weakness in the limbs (especially the legs) necessitate surgical consultation. If radiographic analysis confirms significant upper cervical instability, then surgical fusion is performed. But the vast majority of people with a myriad of symptoms do not meet the criteria for surgical fusion. So what are those suffering people to do?

The way we do this at Caring Medical is with Prolotherapy treatments.

We have published dozens of papers on Prolotherapy injections as a treatment in difficult to treat musculoskeletal disorders. Prolotherapy is an injection technique utilizing simple sugar or dextrose. We are going to refer to two of these studies as they relate to cervical instability and a myriad of related symptoms including those mentioned above in relation to the brainstem. It should be pointed out that we suggest in our research that “Additional randomized clinical trials and more research into its (Prolotherapy) use will be needed to verify its potential to reverse ligament laxity and correct the attendant cervical instability.” Our research documents our experience with our patients.

In the above research, we have made the case that the complexity of your problems may be caused by cervical instability caused by weakened and damaged cervical spine ligaments. Now we will begin to make the case that your symptoms may be alleviated on a long-term more permanent basis with the use of Prolotherapy.

Prolotherapy is a regenerative injection technique that utilizes substances as simple as dextrose to repair and regenerate damaged ligaments.

In 2015, Caring Medical published findings in the European Journal of Preventive Medicine investigating the role of Prolotherapy in the reduction of pain and symptoms associated with increased cervical intervertebral motion, structural deformity, and irritation of nerve roots.

Twenty-one study participants were selected from patients seen for the primary complaint of neck pain. Following a series of Prolotherapy injections, patient-reported assessments were measured using questionnaire data, including a range of motion (ROM), crunching, stiffness, pain level, numbness, and exercise ability, between 1 and 39 months post-treatment (average = 24 months).

We concluded that statistically significant reductions in pain and functionality, indicate the safety and viability of Prolotherapy for cervical spine instability. (18)

Summary and contact us. Can we help you? How do I know if I’m a good candidate?

Lightheadedness or dizziness is a very common symptom, for which people often get a lot of x-rays, MRIs, EKGs, and blood tests. It is an extremely common complaint when people come to Caring Medical with neck complaints. There are many reasons for a person with AAI to have lightheadedness or dizziness. The most likely cause is a decrease in sympathetic nerve fiber firing on blood vessels causing vasodilation. Another reason is carotid sinus syncope. In this condition, a sharp moving of the neck causes a vasodepressor response, and the blood pressure and pulse rate become dangerously low so blood supply to the brain is diminished and lightheadedness, fainting, or severe fatigue can result. When AAI is present, various afferent or sensory nerves may not send the right signals to the brain stem, as even the glossopharyngeal nerve is extremely close to the atlas and axis. This could then cause the NTS to sense that blood pressure is too high and cause an overstimulation of the vagus nerve and account for the low blood pressure and pulse. For more information please see my article Ross Hauser, MD Reviews Cervical Spine Instability and Potential Effects on Brain Physiology.

The general major criteria we use at Caring Medical for diagnosing cervical instability based on patient history includes:

It can also include these more specific (minor) criteria:

In our experience, someone who has four of the major criteria and at least four of the minor criteria has cervical instability and typically needs treatment with Prolotherapy. There are exceptions to this, of course, and each case needs to be evaluated on its own merits.

We hope you found this article informative and it helped answer many of the questions you may have surrounding your neck pain. Just like you, we want to make sure you are a good fit for our clinic prior to accepting your case. While our mission is to help as many people with chronic pain as we can, sadly, we cannot accept all cases. We have a multi-step process so our team can really get to know you and your case to ensure that it sounds like you are a good fit for the unique testing and treatments that we offer here.

Please visit the Hauser Neck Center Patient Candidate Form

References

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This page was updated August 2, 2022

 

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