New Study Examines the Effect of Chiropractic on Patients with Previous Stroke

The effects of a single session of chiropractic care on strength, cortical drive, and spinal excitability in stroke patients.

Scientific Reports 2019

Holt K, Niazi IK, Nedegaard RW, et al.

Full Text


A research team based out of the New Zealand College of Chiropractic who have been publishing a great deal on the neurophysiologic impact of chiropractic on the brain did an investigation on the impact of chiropractic adjustments on patients who have previously suffered a stroke.

The study was set up as a randomized controlled crossover trial of 12 patients with a previous history of stroke. For the first week, half the patients received an adjustment while the other half had a control maneuver of just moving the body around. Seven days later, the groups switched with the control group getting an adjustment and the intervention group getting a control.

The authors tested patients who suffered weakness in their ability to plantar flex post stroke and tested their strength on plantar flexion pre and post adjustment.

They also wanted to know if there were increases in strength, were they likely tied to a local spinal cord mechanism, or did the strength change come from the brain. To do that, they used electrodiagnostic testing to measure things called the H-Reflex and the V-Wave.

The H-reflex uses an electrical stimulation of a peripheral nerve (the tibial nerve in this case) during a sub-maximal contraction to measure excitability in the spinal motorneuron pools (influenced at the spinal cord level)

The V-Wave uses electrical stimulation during maximal contraction to measure recruitment of additional neuronal pools which is an indicator of cortical drive (influenced by the brain)

If you want to get into the weeds on these tests, you can read this paper here.

There were large and significant changes in maximum contraction of plantar flexion post adjustment while the control group showed a decrease in strength.

As far as the electrical diagnostic testing, the chiropractic group showed large and significant changes in the V-wave indicating that the strength change was likely from a brain mechanism (cortical drive).

For the H-Reflex slight change in the adjustment group that was not significant. There was also a slight decrease in V-wave change in the control group that was also not significant.

Dizziness and the Cervical Spine: Beyond Cervicogenic Dizziness

Read Time: [6 minutes]


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.

The Downside of Listening to Your Body Too Much

Historically I’ve been a big advocate of being “in-tune” with your body. For the most part, I do think that a generally healthy person can benefit from developing a better awareness of what their body is experiencing. It’s a good guide for adapting your training and developing a meditative practice like breath awareness.

In recent years, I’ve come to the conclusion that there are situations where a patient can be TOO in-tune with what their body feels, and this perception of what their body feels can actually create fear, apprehension, and further harm to their mental state and quality of life. Today we’ll discuss some of these types of situations and what a patient can do to help themselves break a negative connection with their own self-awareness.

When Listening to Your Body Goes Wrong

There’s a lot of research that shows that paying attention to inner body activities can be extremely beneficial for you. Things like being aware of your breath, meditation, counting your heart beat are all tools used in yoga and mindfulness practices that really help people a lot!

The concept of listening to your body has been popularized in the circles of fitness. It’s a phrase used to guide people in sport or exercise to recognize when their body may not be in the best state to complete a task.

It involves feeling out different aches or pains, observing where the body seems to be putting a restriction on movement, or just an inner awareness of fatigue. It’s supposed to be a guide against overtraining and possibly develop an awareness of impending injury. In cases where this is an otherwise healthy person with no history of chronic pain problems, it serves a good purpose.

However, in my experience seeing patients with chronic pain daily, a heightened attention and awareness of their own pain can be very counterproductive to a patient’s recovery and progression. Let’s talk about why.

Being In-Tune With Body Pain

It’s natural for your brain to pay attention to areas of your body that are in pain. It’s one of the ways your body protects itself whenever it has suffered an injury like a sprained ankle or a large cut on your hand. By avoiding contact of the injured body part, you are allowing your body to temporarily immobilize an area so that the natural healing responses can have time to fix the damaged tissue.

This is a necessary and completely normal response to physical injury. While this is a big generalization, the healing time for various tissues is shown in the graphic below. You can see that most minor muscle and ligament injuries can take a few days to heal while moderate to severe injuries can take several months.

Image Credit and Instagram @drcalebburgess

So even in a worst-case scenario where you have an unstable injury that needs surgery, it takes about 2 years for a tissue to heal completely. If we know that these are the general healing times for people, then what explains the pain patients can feel for several years?

However, for some people there can be problems that develop in neurological pathways that perceive pain. What seemed like a simple, straight forward injury leads to chronic or persistent pain that lasts long beyond the normally allotted time for tissues to heal.

The problem in these cases is that many of these patients will avoid movements or activities to protect an area of injury that may not need protection and avoidance. So there ends up being a cycle of injury, stopping exercise, followed by deconditioning from lack of exercise leading to more risk of injury and pain.

The brain can learn to fear movement to avoid pain creating a vicious cycle often seen in persistent pain patients.

This is the result of treating the pain issue as a muscle or joint problem, when it’s really a brain and neurologically rooted problem. The kicker is that while avoiding movement is necessary for true joint injuries, avoidance may actually make a persistent pain problem in the brain even worse.

Many times when someone suffers with persistent pain issues that have no diagnosable injury, being too aware of your body’s painful triggers can be detrimental to healing and recovery.

Pain Science

One of the more popular concepts in pain science is the idea that chronic pain can develop from factors known as hypervigilance, catastrophizing, and fear-avoidance.

  • Pain Hypervigelance – “when there is an excessive tendency to focus on pain or somatic sensation, or an excessive readiness to select pain-related information over other information from the environment.” [1]
  • Catastrophizing – “an concept where people show exaggerated thoughts and descriptions of the negative consequences of pain featuring magnification, rumination, and helplessness” [2]
  • Fear-Avoidance – a model of chronic pain that describes how people develop and maintain chronic pain as a result of attention processes and avoidant behavior based on pain-related fear. [3]

Those are nice academic definitions, but what do they mean for us? A lot of it comes down to being really fixated on how bad the pain is and avoiding anything that might be associated with the pain. And we now know that the fixation and avoidance behavior can reinforce maladaptive patterns in the way the brain is working.

So it is to say that being too focused on your pain when you are trying to heal can reinforce the cycle of staying in chronic pain.

Fostering an Anti-Fragile Mindset

One of the big things that drew me to chiropractic was a philosophical idea that the body is strong and has a remarkable ability to heal itself. It’s a mindset that I’ve had growing up while playing sports where my coaches would see someone get injured and they’d always say to just walk it off.

Obviously it’s not something you want to do with an unstable or serious injury like major sprains or a concussion. However, for things like scraping our shins, getting hit by a pitch in the back, pulling a muscle, or having a mild ankle sprain this approach trained our young minds to:

  • Understand that the pain will go away on it’s own in time
  • That our body and mind is strong enough to will away pain
  • That we aren’t fragile

Ultimately, we came away with the mental state that we will feel better and pain goes away with time. This also meant that we were pushed towards our normal activities as quickly as possible.

As a chiropractor, a big part of my job is to foster a sense of strength and resiliency in my patients. It means that I want my patients to foster a sense of independence from their pain. That means I don’t want my patients to fear doing activities or to be dependent on any intervention whether that’s a drug, massage, or even chiropractic adjustment. I want my patients to never need me, but they can certainly count on me to be there when they want to be better.


So before anyone takes my points to the extremes, let me just say this.

  • Mental state won’t cure every pain
  • Don’t avoid doctors, especially with serious injury/illness
  • Many people will still have chronic pain even without a sense of fear avoidance and catastrophizing.

So with that out of the way. Mental state can be a powerful influence on the development and resolution of pain, but it can be really, really difficult. When we know there no longer a risk of worsening an injury, in order for patients to make the next step in their recovery, we have to engage them in doing the normal activities that they have avoided.

That might mean lifting some moderately heavy objects, bending their back forward, turning their heads, or getting back into exercise. Yes, sometimes that means we have to make patients revisit their pain and forcing their brain and nervous system to adapt and stop fearing it.

It means they have to stop listening to their body for a bit, and actually push through the false alarm signal so they can adapt.

It’s not easy, and it doesn’t happen quickly. But when patients are able to get their, the whole world opens up again, and we can start to pop the bubble that they’ve lived in because their brain is free again.

Exploring the Gut-Brain Connection through the lens of concussions

It’s no longer a secret that the composition and health of your gut has an substantial impact on the health of the brain and nervous system. Research on the role the gut microbiome has exploded in the last 10 years with blockbuster studies showing that your gut bacteria composition can affect mental health conditions like depression [1] and neurological disorders like Parkinson’s Disease [2].

Although chiropractic is generally associated with bad backs and tight muscles, most chiropractors have a deep seated interest in the connection between the brain, the immune system, and the gut. While there haven’t been any hard studies on the topic, some authors are looking at this connection to see if the gut-brain axis may be a link between head injuries and neurodegenerative disease. This specific topic actually ties into all of my scientific interests in one shot, so you’ll hopefully get a lot from some of the extra content and diagrams I’m going to try to lay out in this article.

A Tale of Two Brains

Most everyone is aware of the importance of the brain in your head, but there is also a staggering number of neurons that exist in your gut. This bundle of nerves in the gut is collectively known as the enteric nervous system (ENS). There are an estimated 500 million neurons in the gut which exceeds the number of neurons in the spinal cord, and makes it the second only to the brain in terms of neural density. This has lead some scientists to affectionately call the ENS the 2nd brain, so maybe making “gut” decisions might not be such a terrible thing (jk).

The number of neurons in the gut might actually be the second most interesting thing about the ENS. The most interesting thing is that the ENS can actually function without talking to the brain if it needs to. The gut has it’s own set of interneurons and integrating centers so that it can carry out reflexes and functions without the help of the brain. In normally functioning humans, the brain does talk to the gut through the vagus nerve, but the vagus nerve can be severed and the gut will continue to work of it’s own power.

The gut is also a MAJOR producer of neurotransmitters for the body which are the chemical currency of the nervous system. The gut produces about 90% of the total serotonin in the body and about 50% of body’s dopamine which can have major implications in the function of the brain and mood [3]. We’ll get into the importance of that a little later.

Shield’s Down: The Gut and the Brain Barrier

The brain and the gut also has some similarities in that both have physiological barriers that have been topics of high interest for neurodegenerative disease. 

The gut has a barrier that keeps potentially harmful substances from getting IN to your blood stream while the brain has a barrier to keeps harmful substances in the blood OUT of the brain.

The barrier in your brain is called the blood-brain barrier and it’s fairly well established that disruption of the blood brain barrier is associated with a host of neurological disorders [4]

Intestinal permeability, also known as leaky gut, is also well supported in the literature as a driver of systemic inflammation, but has been subject to a lot of abuse from various practitioners overstating it’s prevalence and significance. While not everything is leaky gut, and not every leaky gut needs an intensive supplement regiment, intestinal permeability is a real phenomenon has the potential to create disease in the gut like Celiac, inflammatory bowel disease, and metabolic syndrome. [5]

Losing these barriers is like losing a layer of defense which can make your body more prone to attack from disease causing agents, or even the cells of your own immune system.

Neuroinflammation – Collateral damage from your Body’s Defenses

So we have these barriers in our gut and our brain that help prevent harmful substances from getting into our blood or into our brains. We know that when these barriers get disrupted that our body is more susceptible to threats from outside the body. However, the increased permeability of these barriers may be the major driving force in threats from the INSIDE of the body.

Our immune system is made up of several classes of white blood cells and proteins that patrol the body looking for any bacteria, viruses, parasites, fungi, or other organisms that may potentially harm us. While the immune system does a remarkable job protecting us, scenarios can arise when the immune system accidentally does the body harm. This is the case in autoimmune disorders like multiple sclerosis, rheumatoid arthritis, Grave’s Disease, and Crohn’s Disease.

The presence of these autoimmune reactions can be the result of an immune system that is isn’t regulated properly or has accidentally built antibodies that can inadvertantly attack the body’s own tissues. When you have a leaky gut, these immune cells can get primed to attack compounds that don’t normally harm the body (think gluten or food allergies). When there is a leaky blood-brain barrier, these immune reactions can occur in the brain and spinal cord which normally tries to keep inflammation OUT. When these reactions occur in or around the brain, it can cause neuroinflammation which can gradually deteriorate brain tissue. Some authors have suggested that post-concussion syndrome may be a form of an inflammatory brain illness, but that hypothesis hasn’t been studied extensively yet. [6]

It is something that’s worth paying attention to because many neurodegenerative disorders seem to have a link to the brain being exposed to chronic neuroinflammation, and surely chronic traumatic encephalopathy would fit that bill.

Microglia: When the Brain’s Helper Cells Go Rogue

Your brain is loaded with non-neuronal helper cells called glia. Glia help support the neurons in your brain by providing protection, insulation, and repair whenever it needs. They take up a huge chunk of brain material and actually outnumber neurons in the brain by a factor of 10.

A special type of glia exists in the brain called microglia. Microglia are macrophages inside of the brain and they help clean up dead or unnecessary debris hanging out in the brain. They play a role in protecting the brain from infections, but they also do really cool things like prune synapses that aren’t used anymore, or get rid or clean up dead brain cells after injury. [Source for graphic and summary]

Microglia can act as cells that just keep watch inside the brain, but primed and activated microglia are looking for a fight and can stimulate inflammation.

Like most immune cells, their default setting is turned to the off switch. You don’t want immune cells overly active otherwise they create a lot of inflammation. When infections or injuries arise, these cells become primed and active to help initiate the clean up and repair inside the brain.

This means that they start eating away at dead cells and recruiting other immune cells to create inflammation. Short-term inflammation is essential to healing, so we need these cells to generate inflammation for short periods of time while tissues heal. But sometimes, when a cell gets turned on, the off switch gets broken and it stays on leading to chronic inflammation.

Chronic activation of microglia has been implicated in multiple neurological diseases with autism, MS, and Alzheimer’s Disease chief among them. [7]

The Vagus Nerve – The Bridge for the Gut-Brain Connection

If you’ve been following this blog for a while, you know that I love writing about this cranial nerve because it appears to be relevant in all aspects of our health. You can comb through my previous thoughts on the vagus nerve here.

The vagus nerve provides a two-sided highway for the brain to access the gut, and for the gut to access the brain.

The vagus nerve is a specialized nerve that comes off the brain stem and is connected to many of the body’s vital organs. It has a particularly important role in the gut-brain axis because it is a primary conduit for the brain in your gut to talk to the brain in your head.

This becomes really important when we consider that the brain acts as a biological thermostat for multiple functions in the body, including regulation of the immune system. It’s been well established that changes in the your gut bacteria can dictate inflammation in the brain [8] and brain damage can influence gut permeability [9]. Many scientists suspect that the vagus nerve is a central player in these phenomenon.

How important is this bridge? Some evidence suggests that the vagus nerve may be a conduit for how rogue proteins in Parkinson’s Disease can spread into the brain.

Concussions: Disrupting the Barriers and Stirring the Pot of Inflammation

So now it’s time to put it all together. How does something like a concussion affect this entire system? Two recent review papers have gone into this concept with some detail, but here are the big ideas [1011]:

  • Traumatic brain injury (TBI) can cause dysautonomia resulting in poor functionality of the vagus nerve and poor motility of the gut.
  • Animal models have shown that experimentally induced brain injury can lead to more porous gut permeability within 3 hours of TBI.
  • TBI disrupts the blood brain barrier
  • TBI will lead to priming of microglia and neuroinflammation. Structural signs of brain injury are correlated to the amount of microglia primed in the brain
  • A disrupted gut lining after TBI is more susceptible to rogue bacteria infiltrating the blood stream and creating systemic inflammation. Systemic inflammation can further impact the brain’s microglia promoting more neuroinflammation long after TBI.

In a worst case scenario, the disruption of the gut barrier and the brain barrier allow for a persistent cycle of systemic inflammation and constant activation of brain microglia.

Image from Sundman et al. Brain, Behavior, and Immunity (2017)

Do we know if this happens in humans yet? Truthfully the answer is no. There haven’t been any experiments done that have looked at this relationship yet so it’s too early to say if this is a real phenomenon that can tie together brain injury and neurodegeneration.

So what probiotic should I take after a concussion?

So the natural question after reading this is what type of treatment do you need after a concussion? When we talk about guts, the usual line of thinking is to think about probiotics, but that probably won’t lead us to the answers people with brain injuries really need.

Remember that big cast of characters we talked about before we addressed the topic of concussion? Here’s a refresher:

  • The brain
  • The “brain” in your gut (enteric nervous system)
  • Intestinal barrier
  • Blood-brain barrier
  • Microglia
  • Vagus nerve

Brain injury is a multi-faceted injury that has wide effects on numerous parts of the body. There’s no magic potion that will specifically hit everything in a positive way. Here are some ways we’ve seen patients improve with problems in the gut-brain axis:

  • Cervical, vestibular, ocular rehabilitation with graded exercise is becoming the gold standard in concussion recovery
  • Cardiovascular exercise to improve hippocampal and global neuroplasticity
  • Correction at the craniocervical junction to improve cerebrospinal fluid dynamics, decrease stress on the blood brain barrier, and improve circulation of neuroinflammatory compounds
  • Vagus nerve stimulation to improve neuroplasticity, decrease systemic inflammation, and increase gut repair
  • Neurofeedback for plasticity and improve parasympathetic tone
  • Pre- and probiotics to repair gut permeability
  • Ketogenic/fasting type diets to decrease neuroinflammation and alter gut biome
  • Reduction of common dietary gut irritants

There’s a lot more that we could add to this list, but these are some of the most common things that we see that can help some of the more challenging patient presentations.

Will these therapies stop or prevent neurodegenerative diseases? We can’t say for sure, but they are all things that tend to improve the lives of people with early signs of neurological deterioration so time will tell if this can impact the brain injury population as a whole.

  1. Marin I, Goertz J, Ren T et al. Microbiota alteration is associated with the development of stress-induced despair behavior. Scientific Reports. 7 Article number: 43859 (2017)
  2. Sampson T, Debelius J, Thron T, et al. Gut microbiota regulate motor deficits and neuroinflammation in a model of Parkinson’s Disease. Cell. 2016 Volume 167, Issue 6.
  3. Stroller-Conrad J. Microbes Help Produce Serotonin in the Gut. Cal Tech Matters Newsletter. April 9, 2015.
  4. Zlokovic BV. The blood-brain barrier in health and chronic neurodegenerative disorders. Neuron. 2008 Jan 24;57(2):178-201.
  5. Bischoff SC, Barbara G, Burrman W, et al. Intestinal permeability – a new target for disease prevention and  therapy. BMC Gastroenterol. 2014 Nov 18;14: 189.
  6. Rathbone, AT, Tharmaradinam S, Jiang S, et al. A review of the neuro-and systemic inflammatory responses in post concussion symptoms: Introduction of the ‘post-iflammatory brain syndrome’ PIBS. Brain, Behav. Immun. 46, 1-16 (2015).
  7. Streit WJ, Mrak RE, and Grifften WST. Microglia and neuroinflammation: a pathological perspective. Journal of Neuroinflammation. 2004
  8. Fung TC, Olson CA, and Hsiao EY. Interactions between the microbiota, immune and nervous systems in health and disease. Nature Neuroscience 20, 145-155(2017).
  9. Crapser J, Ritzel R, Verma R, et al. Ischemic stroke induces gut permeability and enhances bacterial translocation in aged mice. Aging. 2016 May;8(5):1049-63.
  10. Zhu CS, Grandhi R, Patterson TT, Nicholson SE. A review of traumatic brain injury and the gut microbiome: insight into novel mechanisms of secondary brain injury and promising targets for neuroprotection. Brain Sci. 2018 Jun; 8(6):113.
  11. Sundman MH, Chen NK, Subbian V, and Chou YH. The bidirectional gut-brain-microbiota axis as a potential nexus between traumatic brain injury, inflammation, and disease. Brain Behav Immun. 2017 Nov; 66:31-44.

1 rep max squat: a future biomarker for brain health?

When people think about growing new brain cells and optimizing brain health, they think about playing games like Sudoku or Luminosity. The idea being that we need mental games to flex our mental muscle.

The problem is that mental games like Sudoku and Luminosity have failed to demonstrate any meaningful evidence that it alters brain or cogntive function. They can make you good at Sudoku-related tasks or LUminosity-related games, but that’s about it.

There is one thing that has consistently shown improvements in cognitive, cellular, and neurological measures of brain function:


A 2018 study showed that the dis-use of leg muscles was associated with decreased production of neural stem cells and decreased maturation of the supporting cells in the brain.

While this study was done in rats, it does help to explain some important phenomenon seen in humans.

Neurodegenerative Disease, Leg Exercises, and Stem Cells

Neurodegenerative diseases consist of brain and nervous system illnesses like multiple sclerosis, Parkinson’s Disease, an ALS. One of the big commonalities with this class of neurological disorders is that they they will eventually take away your independent ability to move.

Dr. Danielle Botaii, one of the authors of the study, wanted to investigate whether it was the gradual deterioration or the nervous system compromised muscular function, or if there was a possibility that loss of mobility from these diseases accelerated brain deterioration. [Source]

The study used mice and restricted the use of their hind legs and were compared to control mice who roamed normally. The researchers found that the mice who didn’t have normal use of their legs showed:

  • 70% decrease in neural stem cells compared to controls
  • Decreased maturation of support cells in the brain
  • Decreased expression of key genes for mitochondrial health

All of this to say that simply taking away the function of their legs could have significant ramifications for the ability of the brain to develop, adapt, and repair properly. With compromised stem cell production, less glial cell maturation, and worse energetics, you deal the brain a harder hand to play with. So much of our brain is built to provide action and resistance to gravity, and your legs play a huge role in that.

Squatting Your Way to a Better Brain

So the title of this article was definitely hyperbolic and click-baity. Guilty as charged. But the idea of squatting your way to better brain health sounds pretty sexy when you’re a doctor that lifts.

Working on that Snatch/Overhead Squat…..for brain health purposes

It’s super unlikely that your 1 rep max squat is going to be useful as a brain biomarker (though one can hope!), but there’s growing evidence that moving your legs frequently and often is phenomenal for your brain. One might even be able to make the case that running, jumping, squatting, and any other movement that keeps your legs strong may have more brain benefits than weight loss benefits.

There’s been ample evidence in mouse models that showed steady state running had significant effects on brain cell growth in a key memory area of the brain called the hippocampus. There’s also been compelling studies showing sedentary behavior reduced brain volume in parts of the brain which couldn’t be overcome by casual exercise.

There’s really no human evidence yet that shows that squatting will change the brain, but I feel strongly that preserving leg strength is one of those key things that differentiate those that age poorly and those that age with grace.

It’s definitely way too early, but I say we jump start the movement to 1RM for your Brain and let the evidence come in after the fact. Squat regularly and squat often friends.

Does Exercise Make you Dizzy? Here’s Why

One of the biggest complaints in people with dizziness is that they can’t exercise because exercise makes their symptoms worse. This is a particularly difficult problem in athletes who have suffered a concussion because the dizziness upon activity is preventing them from getting back to their sport.

When people have problems with dizziness on exercise, it can usually be attributed to a couple of problems.

  1. Deficient vestibulo-ocular response (VOR)
  2. Autonomic Dysfunction

Let’s break these issues down.

Deficient VOR

The vestibulo-ocular response is one of your body’s primary and important reflexes. It’s based out of an organ in your inner ear called the vestibular apparatus; the part of your ear that is really important for balance. When you turn your head, your inner ear sends a message to your eyes to move the eyes in the opposite direction.

Image result for VOR testing
The Vestibulo-ocular response in action

This reflex is fast. Really really fast. When your vestibular system is working, this reflex occurs in about 6 milliseconds.

Just for comparison, it takes your eyes 100 milliseconds to respond to something you see. That means your eyes are almost 20x more responsive to movement of your head than to vision.

Why do you need this reflex? Mainly to keep your eyes on target whenever your head moves. We don’t think about it at all because this reflex works really well, but whenever we move, our heads are bobbing all over the place.

Image result for slow motion walking head gif
Our heads move way more than we think about when we run and our eyes have to match that movement.

When this reflex is working well, your head can be moving quickly, but you still have an ability to read and focus while on the move. It doesn’t even feel like your head is bouncing around. It’s a critical neurological circuit passed on by our evolutionary ancestors that relied on hunting to survive.

When this reflex doesn’t work, our eyes move too slowly which makes it feel like the world is moving around you too quickly which can in turn produce a feeling of dizziness.

How do we know this is true? Because this is exactly what many people experience after a head injury or if they have lost the function of their inner ear from something like an infection.

But you don’t need a concussion or an infection for your VOR to become less efficient. The only thing that needs to happen is that the nerves coming from the inner ear to the brain stem start firing too little, or sometimes too much than is necessary.

Image result for vestibular nerve
The inner ear sends messages to the brainstem through a specialized nerve called the vestibulocochlear nerve. When this nerve fires too little or sometimes too much, it can affect your body’s VOR.

Autonomic Dysfunction

Another reason that someone may feel dizzy while exercising is from a problem causing blood flow issues in the brain. Blood flow in the brain is a very tightly regulated system that is maintained by blood pressure, pulse rate, and the opening and closing of key arteries. Your body is set up to prioritize maintaining a steady stream of blood and oxygen in the brain.

The brain and the nervous system control this response through a branch of the nervous system called the autonomic nervous system. The autonomic nervous system is basically the branch that controls all of your automatic bodily activities like heart rate, digestion, blood pressure, etc. Some people can have problems with this system and develop a subset of conditions called dysautonomia.

You can read more about dysautonomia and the autonomic nervous system here.

While people who get dizzy with exercise might not have a diagnosable form of dysautonomia, some of the physiology that is occurring may be similar. With dysautonomia, many patients may feel light-headed and dizzy just from going from sitting to standing. This is because the brain doesn’t have good control of the heart and blood vessels resulting in decreased blood flow to the brain or an abnormal compensation to prevent it.

Different types of dysautonomia showing various breakdown of communication between the brain and cardiovascular system.

One of the hallmark issues in sports concussion is exercise intolerance. It’s been thought that this is a result of large changes in cerebral blood flow after a head injury because the brain is struggling to regulate the opening and closing of the arteries feeding it blood. 

Exercise itself makes the brain work harder which demands increased blood flow to meet the demand. However, the brain is not adequately prepared to increase blood flow leading to an energy deficit.

When the brain is experiencing an energy deficit, the areas that are hit hardest by the deficiency are likely to produce symptoms because of a failure in adequately feeding those neurons oxygen.

Treat the Patient, Not the Symptom

Just to be clear, these aren’t the only reasons that you can get dizzy when you exercise. These are just the more common things that I’ve seen in my practice when people feel mostly fine in normal circumstances, but as soon as exercise begins the dizziness starts.

When it comes to dizziness, people like to take a one-size fits all approach by throwing a variety of maneuvers or remedies to try to fix the symptom. You may get lucky sometimes by doing an Epley maneuver for someone because they just happen to have positional vertigo, but that same maneuver may be useless for someone with an autonomic imbalance.

Fortunately, people with a pattern of dizziness that looks like an insufficient VOR or an insufficient autonomic nervous system are things that seem to respond well to our combination of craniocervical correction and functional neurological rehabilitation.

As with most problems, it comes down to identifying the nature of YOUR pattern of dizziness, then developing the right strategy that suits the patient, not the illness.

The Neurology of a Max Effort Lift

One of the keys to successfully completing a maximum effort lift is to not think so much, and just pull and push with all of your might. On the surface it seems really simple. Get this heavy object from point A to point B in a straight line, but all of the moving pieces that are involved in doing a very complex compound movement is actually pretty astounding.

When people are taught about the neurology of contracting a muscle, it’s usually in the form of a diagram like the one you see below:

Classic diagram for how the brain moves a muscle.

Right side of the brain sends a signal down the spinal cord and tells a muscle on the left to contract.

The truth is way more complicated that than. Honestly, when you want to contract just one muscle, your brain is unconsciously doing all of these calculations to figure out all the other things that need to happen for you to contract that muscle and not fall flat on your face.

You can check out my breakdown of this majestic system in my instagram story at this link: Instagram Story

Why Do We Do Balance Tests After an Atlas Correction?

One of the main components of every examination we do with new patients is a video balance test. You can see what that looks like in the video below:

It’s true that our office works with a lot of people who come in with dizziness or balance complaints, but we do this exam on people even if their complaint is low back pain, neck pain, or any other problem you can think of. Why does a chiropractor need to measure the balance of someone with back and neck pain?

The reason is that balance is a really important indicator for the function of your entire nervous system. Large chunks of your brain and spinal cord are devoted to neurons that help to keep you standing all day. When your brain is struggling, balance is one of the key functions that starts to go badly first. At it’s most extreme, you can see balance deteriorate in brain injuries and illnesses like concussion, Parkinson’s Disease, Multiple Sclerosis, and Alzheimer’s Disease.

Balance and the Nervous System

Our state of balance is the net result of multiple senses providing information to the brain. We take standing and walking for granted because it’s so automatic but it takes a ton of brain power to make standing upright work!

  • While you’re standing your foot and ankle muscles are constantly providing feedback to the brain about the angle of your ankles so you can tell if you’re standing on a flat surface or at an angle.
  • At the same time, your eyes and ears are sending messages to the brain about the location of your head. Is it moving? Is it standing still? Are you tilting? The location of your head will change the amount of muscle tension that you need to keep in your spine.
  • Meanwhile, your spine is constantly manipulating the tension in the dozens of of muscles connected to your vertebrae to help find the right balance of standing up straight and maintaining comfort.
  • All of the messages from these areas are being sent to the brain stem and the cerebellum for interpretation. Within fractions of a second, your brain is doing calculations and sending messages back to your muscles to make small little changes and adjustments as needed.

While all of this happening subconsciously, the higher level brain centers are busy with things like talking, listening, thinking about what’s for dinner, or any other thing that may be on your mind. Your brain separates these unconscious processes so you can do multiple things at once.

By measuring your balance, we can figure out what part of your nervous system may be dysfunctional. 

The 3 super systems that maintain your balance

Balance is Linked to….

The systems that come together to form your sense of balance are your vestibular, visual, and proprioceptive systems. All of these systems send signals and stimulate the brain to take action in it’s internal and external environment.

Disruptions to this system doesn’t necessarily mean that you will feel dizzy and off balance. Your body is really good at compensating when you lose one of those senses. How does your body compensate for a loss of some of your balance receptors?

By changing the posture of your body.

As your body makes these postural changes, then you may start to feel tightness in some of your back muscles in some areas more than others. It may lead to a lower hip on one side and a tilted head on another side. 

Disruptions in these systems may also contribute to problems outside the spine. The neurological connections between the vestibular system and proprioceptive systems are also related to things like your heart rate, digestive tract, and control of blood pressure.

The best part about this is that balance can change really quickly. Even within a single atlas correction.

We Measure Everything

So why do we measure balance? Because we want to measure every meaningful datapoint that may contribute to getting our patients a successful outcome.

We can and do measure someone’s pain and symptoms, but pain and symptoms is not always a good indicator of someone’s level of improvement.

You can feel a lot better after an adjustment but your balance measurements are still far from optimal. If a patient stops working when they feel better, they are leaving a lot of improvements on the table that may contribute to a long term outcome.

On the flip side, someone’s balance and posture may improve relatively quickly, but their body still experiences pain. In some of these cases their body may need more time for nerve, muscle, and other tissues to heal.

That’s why we measure everything to get a complete picture. If we only relied on one metric, we may miss the whole picture.

Chiari Symptoms, Cerebral Spinal Fluid, and the Atlas

Arnold-Chiari malformation is a condition in which portions of the brain (the brain stem or cerebellum) descend below the skull and into the spinal canal. You can see an image of a normal brain MRI and a classic Chiari malformation shown below.

Comparison of a normal appearance MRI vs one that has a herniated cerebellar tonsil characteristic of Chiari malformation

The estimated prevalence for Chiari is about 1 in 1000 people. The good news is that this issue doesn’t cause a problem in most people. Many times people will show a Chiari while getting an MRI for a problem like neck pain, and the Chiari is just an incidental finding.

When a Chiari is causing problems, it can cause non-specific symptoms like:

  • Headache
  • Balance problems
  • Drop attacks
  • Dizziness and Dyscoordination
  • Ringing in the ears
  • Muscle weakness
  • Neck pain
  • Scoliosis

Many patients are born with this brain abnormality, but things like spinal taps and head/neck trauma have been shown to cause cerebral spinal fluid abnormalities that cause the brain to descend into the spinal canal. 

Identifying the Problematic Chiari

Because Chiari symptoms are non-specific in nature and because so many Chiaris are asymptomatic, you can’t diagnose someone’s problem by symptoms or imaging alone. So how do you know if Chiari is causing your problem?

A 2007 study published in the journal Radiology showed that a cerebrospinal fluid flow study can help differentiate symptomatic vs asymptomatic patients. In this study, patients with symptomatic chiari will show blockages in cerebrospinal fluid in the area of the herniated brain tissue. You can see a video example below:

A part of your brain called the choroid plexus is constantly producing cerebrospinal fluid from circulating blood flow. In cases of chiari, the pressure from cerebral spinal fluid pushes against the skull and the brain. Since the skull is solid after childhood, the pressure from the fluid is going to compress the brainstem and cerebellum leading to the symptoms we discussed before.

Prolonged pressure from cerebrospinal fluid can force it’s way into the spinal cord creating a lesion in the spinal cord called a syrinx. These syrinxes can cause pain and loss of sensation into the arms and legs in some cases. In other cases, they are not symptomatic at all.

Image result for syringomyelia and chiari
Chiari + spinal cord syrinx

In the case that someone has chiari, syringomyelia, and chiari type symptoms, a surgical procedure to expand or remove parts of the skull and the protective covering of the brain can be done to alleviate this pressure.

Can Chiari symptoms be addressed conservatively?

This can be a tough question to answer for a few reasons.

Chiari is not symptomatic in a lot of people, and the symptoms of chiari are symptoms that commonly arise in a variety of pain and balance disorders. It’s hard to tell if a treatment actually addressed the consequences of chiari or by another reason.

Additionally, traditional chiropractic high-velocity manipulation is considered a contraindication to chiari malformations. The rationale for this is that a forceful maneuver to the neck may worsen or exacerbate the pressure to the brain stem. There’s no real data to support this, and there are even a few case studies showing no harmful effects. Plus, considering how many patients likely have an asymptomatic chiari and get chiropractic, it seems unlikely that someone with a small chiari would be an absolute contraindication.

But let’s just assume that high-velocity low-amplitude manipulation is problematic. Is there room for a low-force procedure to help?

Some of the work done by Dr. Scott Rosa using upright MRI suggests that a low-force upper cervical technique is more than just safe, but it may help patients with symptomatic chiari.

Craniocervical alignment and Spinal Fluid

There’s a theory that traumatic injuries to the neck like those seen in whiplash can cause susceptible patients with shallow skull bases to have their cerebellum protrude into the foramen magnum.

Michael Flanagan wrote about this concept and how the top of the neck called the craniocervical junction could be a potential choke point for the normal flow of cerebrospinal fluid in the brain. 

Not only can a chiari cause this blockage in spinal fluid, but misalignments in the top of the neck can create this blockage and potentially create the environment to cause or worsen a chiari after trauma. You can see a cool pre and post adjustment video from one of Dr. Rosa’s patients below.

Pre and post cerebrospinal fluid changes after upper cervical alignment

Not only has Dr. Rosa noted changes in cerebrospinal fluid movement, he has also recorded changes in the size of a chiari by using MRI scans after an adjustment. It’s actually pretty amazing to see!

Chiari Might Be More Implicated in Pain and Illness Than We Thought

Thanks to new methods of neuroimaging, scientists are able to see the how spinal fluid impacts brain motion with some startling visibility. The video you below shows how each heart beat creates a pulsing motion of cerebrospinal fluid in the brain of a patient with chiari.

New imaging technique showing the how CSF motion can move the brain

A study using this technique showed alterations in normal brain biomechanics related to changes in how the chiari affects cerebrospinal fluid pressure. The study was only done on one patient, but more work is being done to investigate this phenomenon.

There is also evidence that upright imaging may show that more patients have a chiari than anticipated in patients in whiplash.

Historically, non-specific nature of chiari symptoms have been reason to dismiss it as an entity that can cause pain and illness, but from the experience of many craniocervical chiropractors, there may be more people with this problem that can get relief from a gentle approach to the upper neck.

New Research Shows 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.