Dizziness and the Cervical Spine: Beyond Cervicogenic Dizziness

Read Time: [6 minutes]

Outline:

The cervical spine has been a known source of dizziness since the 1950’s with a classification as cervical vertigo. While the true spinning sensation of vertigo is not common with cervical spine issues, a feeling of imbalance, disorientation, light headedness, swaying, and unsteadiness have all been linked to problems in the cervical spine, especially the craniocervical junction.

Cervicogenic vertigo has a contentious history as a legitimate clinical entity. This stems from the fact that cervicogenic vertigo has no distinct biomarker and remains a diagnosis of exclusion; a leftover diagnosis when a more obvious inner ear cause doesn’t exist.

Cervicogenic vertigo may or may not exist as it’s own unique clinical entity, but there’s little doubt that the cervical spine plays a key role in balance and equilibrium. In this article, we’ll talk about how a dysfunctional cervical spine can be causing dizziness, and how cervical spine interventions can be a useful therapeutic option for people with dizziness disorders of many types.

The Anatomy of Cervicogenic Dizziness

While the diagnosis of cervicogenic vertigo has been contentious, the anatomical connections linking the cervical spine to symptoms of dizziness are not.

Neck Muscles, Ligaments, and Joint Receptors

The neck is loaded with receptors that help the brain know where the head is in relation to the body. These receptors come from the small suboccipital muscles, the cervical discs, the cervical joints, and the cervical ligaments. The receptors from the suboccipital muscles in particular have an unusual amount of density when compared to the rest of the spine [Source]. When you move your neck, these receptors help to control how fast and how far you move your neck. They are also receptors that are very active even if your head isn’t moving because we spend most of our time with our head up fighting gravity. All of these signals are transmitted to the brain which has to make constant decisions about where to put the head next.

Image result for upper cervical spine ligaments and muscles

When you have an injury like a whiplash or head trauma, the muscles and ligaments of the neck are susceptible to injury, and that injury takes away one of the methods that your brain uses to keep track of the head. If your brain can’t tell where your head is in space, then dizziness and a sense of imbalance is the result.

Cerebellum and Vestibular Nuclei

The cerebellum and vestibular nuclei are 2 really important parts of the brain that play a role in dizziness and balance problems originating from the neck.

The vestibular nuclei is the routing center for the signals traveling from your inner ear through the vestibular nerve. The primary job of the vestibular nuclei is to take the information coming from your ears and to calculate where the head is in space and to move the eyes appropriately in response to these signals. While the bulk of the input into the vestibular nuclei is coming from the ears, the vestibular nucleus also receives afferents from the cerebral cortex, visual centers, spinal cord, and cerebellum. It takes in all of this information and calculates where the head is in space based on what you see (visual), head direction (inner ear), and proprioception (muscle and joint activity).

Image result for cerebellum and vestibular nuclei

The cerebellum is generally thought of as a subdivision of the brain that aids in coordination of muscle movements. However, the cerebellum has an large chunks of real estate devoted to eye movements and modulation of the vestibulo-ocular response. The cerebellum also plays a role in how the vestibular system impacts the spinal muscles via the vestibulospinal tract.

These regions of the brain are important because the same muscles, ligaments, and joint receptors we discussed earlier have direct and indirect connections to the vesibular nuclei and the cerebellum.

The Vertebral Artery

The vertebral artery passes through the transverse foramina in the cervical spine. At the level of C1 and C2, the vertebral artery takes on a more tortuous path into the skull to supply the brain stem and cerebellum with oxygen. Most clinicians think of the vertebral artery as a potential source for arterial dissection that can cause stroke. However, there are documented cases of transient vertebrobasilar insufficiency caused by rotation of the neck. This syndrome has been named Bow-Hunter Syndrome or rotational vertebral artery vertigo (RVAO). [Source]

Studies have shown that decreases in blood flow from the vertebral artery can cause transient ischemia through the vertebral artery when the neck is turned in rotation. It’s not known whether the ischemia is affecting the brain stem/cerebellum, or if the ischemia is hitting the labyrinthe itself because of the way the artery branches out toward the peripheral vestibular apparatus.

Beyond Cervicogenic Dizziness

Therapies for the cervical spine can make an impact on cervicogenic dizziness. These therapies can commonly include cervical exercises, osteopathic manipulation, upper cervical chiropractic approaches, and other manual therapy techniques. The use of these modalities has largely been associated in patients who have reported dizziness following a trauma to the neck such as whiplash disorder [Source].

Is there a role to play for cervical spine-based therapies for other causes of dizziness and imbalance?

While there’s limited evidence to pull from, there are numerous anecdotes and case reports of patients with motion sickness, Meniere’s-like illness, and vestibular migraine showing improved outcomes while receiving care focused on addressing cervical spine dysfunction.

Let me be clear, I have no supporting research to support what I’m going to say next. These are just observations from 8 years of working with dizzy patients.

Many patients with feelings of dizziness but do not have full peripheral vestibular loss likely have problems of central processing of sensory information. Plastic changes in the central nervous system that can promote a sense of dizziness can include:

  • Inapporpriate Sensory re-weighting for balance
  • Inappropriate afferentation into the vestibular nuclei and cerebellum
  • Anxiety related to pathologies or activities that promote dizziness
  • Decreased cellular activity in key sensory areas of the brain due to disrupted hemo/hydrodynamics

Simplified flowchart showing the way sensory information contributes to balance

By understanding some of the interconnected nature of the senses that produce a feeling of balance, we can leverage treatments to create neuroplastic changes in the central nervous system that may help a person adapt when vestibular function is compromised.

When it comes to dizziness, there are so many anatomical players and varying degrees of compromise, we can’t rely on one thing to fix all types of dizziness. By using the cervical spine to help stimulate the proprioceptive system, we might be able to help some patients compensate with a deficit where they weren’t able to before. We may also be removing one extra stressor to the balance system that was preventing the body from compensating appropriately.

Concussion + Neck Injury = Longer Recovery

If you’re a reader of our blog, then you’re aware of our stance that an injury strong enough to concuss is strong enough to also injure the neck. You can read some of our thoughts on this subject here:

2 Reasons Why Your Concussion Symptoms Aren’t Going Away

Head Injury, Chronic Dizziness, Concentration Problems, and the Atlas – A Case Study

What a 10 mph car accident does to the neck

You can find a lot more by using the search tool on the website, but that should get you started.

After years of research, we now know that injuries to the neck can mimic symptoms seen in concussion. This is a big reason why patients with chronic whiplash look really similar to patients with post-concussion syndrome when you’re just looking at symptoms alone [source]. However, many clinicians have suspected that when patients have both a neck injury and a brain injury, that it can take longer for the patient to recover and return to sport.

A study published in the Journal of Head Trauma Rehabilitation is helping to shed light on this concept. THe study looked at patients in a multidisciplinary pediatric concussion clinic with sports related concussion. A total of 246 patients were included and were assessed for neck pain, headache, dizziness, and abnormal cervical spine exam findings. Out of the 246 patients with concussion, 80 met the criteria for a neck injury.

When reviewing the data, the authors found that patients with a neck injury took an average of 28.5 days to make a clinical recovery compared to 17 days for the patients who only showed physiologic brain injury alone. Patients with neck injury were also almost 4 times more likely to experience delayed recovery (longer than 4 weeks) from their symptoms.

So just to summarize, if you have a neck injury + concussion:

  • It will take on average 10 days longer to make a clinical recovery than a concussion alone
  • You are 4 times more likely to have symptoms beyond 30 days than a concussion alone

So you might be saying….well…maybe some of these neck injuries were really serious ones. Like the ones you might see where people have to wear a neck brace and get carted off the field. Obviously people with severe neck and spinal cord injuries can drastically skew the number of days it takes for people to recover and some may not recover at all.

The authors actually accounted for these types of injuries. One patient had a compression fracture and 5 patients had spinal cord injury or cord neuropraxia. All of these patients were taken out of the data analysis. So that leaves us with patients with a neck injury, but an injury that compromises the spinal cord.

Protect the Neck

The role of the neck has become a growing area of research in the field of head trauma. One study looking at the relationship between neck strength and risk for concussion showed that for every pound of increase in neck strength, there was a 5% reduction in risk of concussion. Another study shows a rehabilitation program that includes treating the neck in patients with post-concussion symptoms can accelerate a patients return to normal activity.

The neck is a neurologically important and inherently mobile area that can be prone to injury. When it is injured, people with a combination of brain and neck injuries may have higher levels of sensitivity than patients with more routine neck pain. That means that people who suffer concussions and neck injuries may benefit from more precise and gentle care than approaches that take a more aggressive style of treatment.

 

Why Is Cranio-facial Pain So Much Worse Than Everything Else?

Read time: 7-8 minutes

Outline:

  • Pain is weird
  • Chronic head and face pain and suicidality
  • Why head and face pain feels worse
  • The neuroscience of suffering

Pain is complicated. It’s even more complicated as a clinician because the expectation from years and years of conditioning is that when you have pain, then something about that painful body part must be damaged to cause it. When people are in pain, doctors are typically trained to identify things like a ruptured disc, broken bone, or torn muscle to validate a patients’ sense of suffering.

In this model, the more damage that is present = more pain. Less damage = less pain.

However, the experience of pain can be way more complex than finding damaged tissue. The experience of pain is an emotional response to ‘painful’ sensory receptors called nociceptors. While tissue damage can cause a lot of nociceptors to fire, and trigger increased pain, but it is far from the only factor in the pain equation. but it is taken into the context of cultural, social, cognitive, and experiential factors.

Which takes us to an important point.

The amount of pain you experience can also depend on what body part is injured. As we’ll see today, there are hardwired circuits in your brain that can make the experience of pain in the head/face a different and perhaps worse experience then pain from the body as a whole.

Chronic Facial Pain and Suicidality

Chronic pain is a known risk for suicidal ideation, and has been documented in numerous studies [source]. These thoughts have a higher chance of turning into behavior when you have chronic pain and a co-morbid mental health disorder [source].

This effect seems most pronounced when the source of the pain is coming from the head or face. Two disorders in particular are highly associated with suicidal thoughts and behavior; trigeminal neuralgia and cluster headaches. Trigeminal neuralgia has a high enough association that it was historically dubbed the suicide disease, while cluster headache has been known to be called the suicide headache.

Both of these illnesses are associated with some of the most intense pain that human beings can experience. The severity of the pain combined with the chronicity of the pain lead to a sense of despair because these disorders can be difficult to treat, so there is always a fear of the next attack.

Scientists have recently uncovered some neurological pathways that might explain why conditions like trigeminal neuralgia and cluster headaches can cause such disproportionate suffering compared to other body pains.

The Trigeminal Complex and the Limbic System

It’s been known that pain experienced in the head and face activate the emotional centers of the brain more than pain felt in the periphery of the body [source]. From an evolutionary standpoint, a higher state of pain in the head and neck region may have served a  purpose so that there would be extra vigilance in protecting this region of the body from injury. What was unknown was weather this heightened sense of protection was derived from a psycho-social factors, or if it was something that was hard wired into our nervous system.

Duke University scientists may have some answers. A 2017 study in Nature Neuroscience showed that sensory neurons in the head and face have a direct pathway to the emotional circuits in the brain.

Scientists identified a direct, monosynaptic connection between sensory fibers of the trigeminal nerve into a part of the brainstem called the parabrachial nucleus. The parabrachial nucleus has direct connections into the emotional hub of the brain in the amygdala, which is highly tied to fear and avoidance behavior.

Why is this important? Because monosynaptic connections are way more powerful sensory stimuli than indirect pathways.

Think of it this way:

Let’s say you were mailing a time-sensitive package that needed to get to it’s destination as soon as possible. Would you choose to overnight it by plane, or would you choose regular first-class mail?

Cranio-facial pain uses direct and indirect pathways that tap into the brain’s emotional responses to pain.

You probably chose to overnight it right? Why? Because it’s going to get there faster, and because the person receiving it is going to perceive that package as more important because it was sent with all of this overnight labeling implying it’s importance.

These monosynaptic pathways are like your overnight deliveries, where the indirect pathways are like ground shipping.

Our brains place a higher priority on signals coming from these monosynaptic pathways.

While other body regions only use an indirect path to the parabrachial nucleus, the trigeminal distribution uses both indirect AND direct pathways to stimulate this emotional hub.

That means that firing from nociceptive pain fibers in the trigeminal distribution, or even pathways that share trigeminal distribution will have a higher chance of driving an emotional response than pain fibers from the shoulder, back, hip, etc.

The Emotional Brain’s Influence On Pain

How big of an influence does emotion make in the experience of pain? In this study, the researchers stimulated pain receptors in the paw or in the face of mice using a chemical called formalin. Using a technique called optogenetics, researchers can selectively express brain activity in a mouse model using different light frequencies.

When light activated the direct pathway, the mice showed more intense avoidance behavior to the formalin on the face. When light was used to knock out this pathway, the mice didn’t react as strongly.

So you have the same amount of pain stimulus, the same mouse, and it experiences pain differently because the path to the parabrachial nucleus was turned off.

It suggests that our emotional brain’s connection to a painful stimulus plays a substantial role in the experience of pain.

Biology vs Psychology

There’s always a debate about nature vs nurture when confronted with the struggles of human existence. In recent years, it has evolved into a debate between biomechanical/orthopedic search to treat identifiable lesions vs a biopsychosocial approach which generally tends to lean heavily on the psycho and social components of the pain experience.

Here is some evidence that suggests that the two are inseparably linked together.

The experience of pain is intimately tied to our thoughts, memories, expectations, and current mental state. If the experience of pain is tied to some of these neural circuits, then changing our mind activating our different neural circuits in the brain can change our experience of pain.

It also means that fear/avoidance behavior, and repetitive responses to painful stimuli may create plasticity in the neural circuits that may reinforce the same pain over and over again.

Changing thoughts and behavior can have a significant impact on the perception of pain and the feelings of suffering for a persistent pain patient.

That doesn’t mean that we are just telling people in the midst of a terrible trigeminal neuralgia or cluster headache attack that they have to suck it up and think differently about their pain.

It means that when people have persistent pain disorders, in the process of treating patients with various interventions, we have to help and guide a patient through the process of re-framing their pain and illness.

This is really hard for patients with persistent pain. It means that sometimes we are walking a line where a patient may feel like we are telling them that the pain is just in their head. Sometimes it means that the patient is going to ask the same question, or tell you the same symptom over and over again because they’re looking for you to just understand that what they are feeling and that know that they’re being heard.

Trying to help a patient disassociate themselves from their chronic pain emotionally is challenging. After all, most of us didn’t become doctors and therapists to be a patient’s psychologist. However, empowering a patient with a stronger belief in the resilience of their body can be extremely fulfilling, and in my opinion puts people on the path to recovery while they’re in the process of receiving quality care.