Balance and fall risk – Cervical Instability and Vagus Nerve Impairment

Ross Hauser, MD

Nine out of 10 people that come to the Hauser Neck Center have balance issues. Most of my patients come in and their balance is terrible. Some of these patients know what’s causing it, they may have double vision and gaze instability. A clue that the balance problems are coming from neck instability may be problems with motion when driving in a car. In fact, any sort of motion, especially driving in a car, that makes your balance and sense of equilibrium worse is likely going to be from your neck.

Our bodies are filled with what I call balance reflexes. They are working all the time. For instance, you are watching this video now. Your brain is getting so much input from so many sources that require balance. Your brain needs balance from your visual input so that both images of me arrive in your brain at the same time. If they do not, then blurry, double, or “slow motion” vision occurs. Balance requires more than the images arriving to the brain at the same time.

What is good balance? For someone who does not have good balance, it would be being able to watch this video without distressing sensations like light-headedness, dizziness, vertigo, or the sensation as if you’re going to fall over.

For good balance there is:

  • Eye and vision input.
  • Hearing Input.
  • Spinal cord input
  • Ligament input.

All working in coordination. There are many different ways doctors check for balance. In the office I have patients walk and observe their gait. I get a good medical history and we do our neck stability vitals to work on figuring out the cause of the imbalance. Most times it is many factors that are contributing to the imbalance. For some, loss of sensation or weakness on one side of their bodies can be a major factor.

What are we seeing in the image below? An example of an increase in imbalance during gait

The image is adapted from a September 2019 paper in the European spine journal (1) led by noted researcher J C Le Huec at the University of Bordeaux in France. In this paper, the “well-defined” parameters of gait are discussed in regard to aging. Factors include pelvic incidence, sacral slope, and pelvic tilt. The cervical parameters are the upper (O-C2) and lower cervical curvatures (C2-C7), the C7 slope, the spino-cranial angle and the vertical cervical offset (C2-7 sagittal vertical axis (the distance from the posterosuperior corner of C7 to a vertical line from the center of the C2 vertebra), At the thoracic and lumbar level, they are, respectively, kyphosis and lordosis. The OD-HA (odontoid hip axis) angle is the most efficient parameter to analyze the global balance.

pelvic incidence, sacral slope, and pelvic tilt

The illustration below helps explain these parameters. The caption reads:

OD-HA measurement odontoid hip axis figure. A: 3D drawing of the OD-HA angle from dens of C2 access and vertical line through hip access. B. OD-HA 2D x-ray, lateral view. It informs on the efficiency of compensating mechanisms as its value is normally plus two degrees to minus 5° in asymptomatic patients independently of age global spine shape in the presence or absence of compensating mechanisms all over the place.

OD-HA measurement the odontoid hip axis figure.

In this paper, these measurements were used as a study guide. In this illustration below, a more simple graphic demonstrates what all these measurements and angles mean when it comes to your body compensating for your balance issues.

Compensation mechanisms for anterior segment imbalance – the problems the pelvis can create

In the image below we see that problems in the pelvis can contribute to cervical hyperlordosis, reduction in thoracic kyphosis, lumbar retrolisthesis, hyperextension of the lumbar segments, pelvic retroversion, bending of the knees and stretching of the ankles.

Compensation mechanisms for anterior segment imbalance - the problems the pelvis can create

A brief summary of the illustrations above and balance problems.

The traditional way doctors learn about proper balance is that a person’s center of gravity has to go through their feet. In the above research and illustrations, the focus is on the aging patient. As a person gets older, degenerative changes shift their center of gravity. This is seen in research that suggests an older person leans forward over time on a treadmill, they are tilting forward. Their center of gravity is no longer between their legs. In its simplest terms, you could say proper balance starts with proper posture. The worse the posture, the worse the balance.

As you age and your joints become unstable, your body develops all these compensatory motions. We see patients who have Atlas misalignment, upper cervical instability, and they will tell us that their “head is not on straight.” This is a big problem because of gaze instability. If you are tilting your head so that you can “see straight” and have level gaze stability, the whole spine may adjust to provide this gaze stability.

Back to the problem of balance.

As the body tries to balance itself, the research has demonstrated along with our illustrations, that as people age they start leaning forward.

In the image below we simply see a patient whose center of gravity is far forward. This would make them a fall risk because of balance disorders.

In the image we simply see a patient whose center of gravity is far forward

Cervical instability and the vagus nerve

Above we looked at the structural aspects which could lead to problems with gait and balance and could lead to greater fall risk. Now we will explore the neurologic aspect. A connection we often see in patients is that their cervical spines are in a moderate to severe degenerative stage. This can cause pressure on the nerves and blood vessels that travel from the brain to the body.

Much of the research surrounding the vagus nerve and gait focus on Parkinson’s disease. Parkinson’s disease is a neurologic motor skill degenerative disease. As noted in a June 2021 paper in the journal Frontiers in Neurology (2), the vagus nerve may play a crucial role in the pathogenesis of Parkinson’s disease (PD). It has been hypothesized that α-synuclein aggregates (neural proteins) form in the enteric nervous system (our gastrointestinal system has its own nervous system, the enteric nervous system which works with the vagus nerve provides central coordination of everything related to the digestive tract, including sensation, absorption, motility, and even sphincter control.) These harmful proteins aggregating within the enteric nervous system can spread via the autonomic nervous system to the central nervous system.” This would cause the motor and mobility problems often seen in Parkinson’s patients.

One final note on Parkinson’s disease.  When the Enteric-vagal system is not functioning properly there is growing evidence that enteric nervous system dysfunction is involved at least in part in the etiopathogenesis (origins) of autism spectrum disorders, amyotrophic lateral sclerosis, transmissible spongiform encephalopathies (the human form of “mad cow disease.” A human cannot get Mad Cow Disease) Parkinson disease and Alzheimer disease.  The mechanisms of such are debated but do include the transport of harmful substances or organisms from the gut to the brain via the vagus nerve. (3)

Transcutaneous auricular vagus nerve stimulation

I am using the example of Parkinson’s disease to demonstrate an aspect of gait degeneration or improvement when the vagus nerve is stimulated. In an October 2022 paper (4) published in the journal Movement Disorders, researchers noted that previously published studies found that transcutaneous cervical vagus nerve stimulation (VNS) can improve gait symptoms in Parkinson’s disease. The results were on 12 patients with idiopathic (of unknown origin) Parkinson’s disease who had walking difficulties but could still walk on their own. Among the walking characteristics, the researchers measured were gait speed, stride length, number of steps, mediolateral sway (balance between steps), and swing amplitude (the swing of the leg forward). The researchers reported stride length, swing amplitude, gait speed, and gait time showed significant changes after transcutaneous auricular (at the ear) VNS but not with transcutaneous cervical vagus nerve stimulation (at the neck). The researchers do note however, “. . .despite our results being in line with recent noninvasive cervical VNS experiments, it is still not possible to draw a firm conclusion. . . Nonetheless, given the manageability of the portable commercialized transcutaneous auricular VNS devices, they may be considered a valuable tool in the neuromodulation landscape of Parkinson’s Disease.

What I would like to focus on here is that gait abnormalities can be not only impacted by structural causes but by disruptions to the vagus nerve causing disrupted or distorted messages from getting back and forth between the brain and the muscles of the body needed for locomotion.

Cerebellar tonsillar ectopia.

A brief discussion of Cerebellar tonsillar ectopia at (9:40)

The cerebellum is key to balance one might even say that’s the balance center of the brain so anything that causes a stretch compression of the cerebellum can cause balance problems. While the brain stem and cerebellum are normally protected inside the cranium, in some genetic conditions such as Arnold Chiari malformations, the cerebellum and/or brain stem can extend into the foramen magnum and are affected by cervical conditions, especially related to atlantoaxial (C1-C2) instability.

Another lesser-known condition called cerebellar tonsillar ectopia can occur which again involves the cerebellar tonsils blocking vital structures in the foramen magnum, but this condition generally occurs with a trauma such as a whiplash injury. Sometimes Arnold Chiari malformations or cerebellar ectopia can cause symptoms by themselves, but I find that symptoms most often occur with upper cervical instability.

What are we seeing in this image?

Normal anatomy versus Chiari malformation of the cerebellum. With the size of the posterior fossa too small, the cerebellar tonsils may herniate through the foramen magnum of the skull into the spinal canal. The tonsils block the flow of cerebrospinal fluid and may cause fluid buildup inside the spinal cord, called a syrinx. This can cause many issues including balance issues.

For more detailed discussions on this topic please see my article Cerebellar tonsillar ectopia herniation and Chiari 1 malformation and Injury and abnormalities at the cervicomedullary junction.

Normal anatomy versus Chiari malformation of the cerebellum. With the size of the posterior fossa too small, the cerebellar tonsils may herniate through the foramen magnum of the skull into the spinal canal. The tonsils block the flow of CSF and may cause fluid buildup inside the spinal cord, called a syrinx. 

If the cerebellum is stressed a person’s balance can get so bad that the neurologist will say they have ataxia. Ataxia is a group of disorders caused by damage to the cerebellum such as the above Cerebellar tonsillar ectopia.

Let’s look at research that connects cerebellar pressure or compression to movement and balance disorders.


A brief introduction to Meniere’s Disease

Meniere’s disease is a disorder of the inner ear that causes spontaneous episodes of vertigo – a sensation of a spinning motion – along with fluctuating hearing loss, ringing in the ear (tinnitus), and sometimes a feeling of fullness or pressure in the ear.  Meniere’s disease comprises symptoms related to the Eustachian tube, the upper cervical spine, the temporomandibular joints, and the autonomic nervous system. Please see my companion article Ear pain, ear fullness, sound sensitivity, tinnitus, Meniere’s Disease, and hearing problems caused by neck instability and Meniere’s Disease and Fluid build up in the ears – Chronic cerebrospinal venous insufficiency.

A 2021 study (2) wrote: “Vestibular vertigo of Meniere’s disease and Benign Paroxysmal positional vertigo (BPPV – dizziness caused by moving your head) and cervicogenic dizziness (dizziness traced to neck pain) are classified as separate entities. Cervicogenic dizziness is not considered the domain of Otolaryngologists, as it is mainly related to neck proprioceptors (neck movements). Headache and neck pain, have been found to be associated with both Meniere’s disease and Benign Paroxysmal positional vertigo, so is cervicogenic dizziness.”

The doctors of this study then sought to make a connection and an association between cervical signs and symptoms in patients with Vestibular Vertigo of Meniere’s disease, Benign Paroxysmal Positional Vertigo, and cervicogenic dizziness.

  • “Most of the Meniere’s Disease patients  (80% for unilateral and 88.23% for bilateral), Benign Paroxysmal Positional Vertigo (75%for right-sided BPPV, 66.67% for left-sided BPPV) and cervicogenic dizziness (90%) had associated symptoms of neck pain or headache and were found to be positive for neck tightness and/or asymmetry of the shoulder.
Proper Eustachian Tube function vs. dysfunction. In this illustration the proper opening of the Eustachian Tube is shown to require the action of the tensor veli palatini and the levator veli palatini muscles innervated by the vagus and trigeminal nerves. When these muscles do not operate normally, fluid builds up in the middle ear potentially causing the problems of ear discomfort, ear fullness, pressure, pain, dizziness and even partial or complete hearing loss.
Proper Eustachian Tube function vs. dysfunction. In this illustration, the proper opening of the Eustachian Tube is shown to require the action of the tensor veli palatini and the levator veli palatini muscles innervated by the vagus and trigeminal nerves. When these muscles do not operate normally, fluid builds up in the middle ear potentially causing problems of ear discomfort, ear fullness, pressure, pain, dizziness, and even partial or complete hearing loss.

In the image below the neck-eye reflexes are described.

These reflexes keep the head balanced while a person is watching moving objects or the body or head is in motion.

  • The reflex vestibulo-ocular (VOR) causes eye gaze stabilization during head motion
  • The reflex cervico-ocular (COR) helps the eyes to move in relation to neck rotation, (because of cervical ligament and facet joint proprioceptors – neurons that sense motion.)
  • The reflex vestibulocollic (VCR) helps to stabilize the head in space when the body moves.
  • The reflex cervicalcollic (CCR) muscles tightened to stabilize the head (because of cervical ligament and facet joint proprioceptors – neurons that sense motion.)

Potentially all these reflexes are impaired with ligament cervical instability causing symptoms of vertigo, dizziness, Nystagmus, Oscillopsia, visual disturbance, and poor balance.

neck-eye reflexes


For treatment options please continue with our article: Treatments for Neck Pain and Cervical Instability: A review of upper cervical instability and symptom treatment with Ross Hauser, MD

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1 Le Huec JC, Thompson W, Mohsinaly Y, Barrey C, Faundez A. Sagittal balance of the spine. European spine journal. 2019 Sep 1;28:1889-905. [Google Scholar]
2 Horsager J, Walter U, Fedorova TD, Andersen KB, Skjærbæk C, Knudsen K, Okkels N, von Weitzel-Mudersbach P, Dyrskog SE, Bergholt B, Borghammer P. Vagus Nerve Cross-Sectional Area in Patients With Parkinson’s Disease—An Ultrasound Case-Control Study. Frontiers in neurology. 2021 Jun 22;12:681413. [Google Scholar]
3 Rao M, Gershon MD. The bowel and beyond: the enteric nervous system in neurological disorders. Nature reviews Gastroenterology & hepatology. 2016 Sep;13(9):517-28. [Google Scholar]
4 Marano M, Anzini G, Musumeci G, Magliozzi A, Pozzilli V, Capone F, Di Lazzaro V. Transcutaneous auricular vagus stimulation improves gait and reaction time in Parkinson’s disease. Movement disorders. 2022 Oct;37(10):2163. [Google Scholar]

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