Drawing the curtain on dizziness & balance disorders
Dr Ryan Bonney
What is balance?
Our sense of balance is an ever-changing, dynamic feature of our nervous system. It appears to be more of an OUTPUT rather than an INPUT – meaning that the information entering our nervous system is processed, modulated, compensated for, and finally spits out a motor response – BALANCE!
This reflects our brain’s understanding of where we are in space, which changes depending on our environment, the ground beneath us, our ability to see, our footwear, how well our nerves ‘sense’ our surroundings, the strength of our muscles, and even our current mood!
Balance tends to deteriorate across our lifetime; but once we hit 50 years of age things can start to really drop off…
Another term bandied around is “sensorimotor control”, and a way to explain what this refers to, would be the process by which the central nervous system combines (or integrates) incoming sensory information from different parts of the body – namely the spine, the vestibular (inner ear) system, and vision – to form a working body schema.
So, it really refers to the way in which the nervous system constructs a sensory representation of the body in the brain – a ‘virtual body’ if you like.
Input Pathway from Receptor to Brainstem to Cortex
- Receptors: these initiate ‘first contact’ with the environment, and examples include our: inner ear hair cells, muscle and joint receptors, and retina in our eye.
- Sensory pathways then bring signals into the brainstem
- Vestibular nuclei is an important region in the brainstem where all 3 types of input converge
- Higher areas of cortical perception (where you perceive your position and motion in space). N.B. These ‘higher areas’ can drastically change things depending on what they deem to be important in your survival as an organism.
Our balance centres are always firing, even when just sitting or standing still.
In fact, there are 1.5 million action potentials (little electrical discharges) every second from each inner ear!
What is dizziness?
The dizzy spectrum may range from something as subtle as continuously bumping your elbow on a doorframe, all the way to frank vertigo – where the world is (or you are) spinning in circles.
Here are a few examples:
- Vertigo – a sensation of spinning that is the hallmark of inner ear disease. The illusion of self-motion results from an imbalance in vestibular signals
- Near-faint dizziness –diffuse cerebral ischaemia
- Cervicogenic dizziness –disturbance of normal proprioceptive input from the cervical spine due to injury or degenerative change
- Psychophysiological dizziness – impaired central integration of sensory signals, mostly related to anxiety or other psychological conditions
- Hypoglycaemic dizziness – inadequate brain glucose
- Disequilibrium – loss of vestibulospinal, proprioceptive, cerebellar or motor function
- Ocular dizziness – a visual/vestibular mismatch due to impaired vision
- Drug-induced dizziness – side-effects of medications (especially anti-depressants), recreational drugs, cerebellar toxicity, and/or alcohol
What might cause these experiences?
“Sensory mismatch” – is a key term that describes what happens when our visual, vestibular, and proprioceptive inputs are not speaking the same language i.e., what our eyes see does not agree with what our inner ear is telling us, and this may be different again from what our feet are reporting to our brainstem.
This can come about by damage to the actual neural components of our orientation system – whether that be the receptors, nerves (‘highways’ that these signals travel in), or the actual brain itself. These issues will often cause a spinning sensation to occur.
An example here might be an inner ear infection, where the hair cells that report head position are compromised; a brain tumour, that obstructs the normal function of that lobe; or even sudden blindness, where the visual system can no longer provide accurate information.
Or it might come about by disruption to energy substrates supplying the neural circuitry for orientation (ischaemia, hypoglycaemia, anaemia, hyperventilation etc.). These issues will often create a feeling of light headedness.
An example here might include diabetes, where the excess sugar damages the nerves of the feet which begin to then lose feeling; a panic attack, which upsets the balance of carbon dioxide to oxygen and leaves the sufferer giddy; or a worker who has had meeting after meeting and hasn’t been able to snatch a spare minute to eat that muesli bar in their bag!
Why do I feel so darn lousy when I’m dizzy?
Well, when these conflicting signals all arrive at the same juncture, they pass this information to a very important area called the parabrachial nucleus. This nucleus essentially drives behaviour and our emotional response to what is happening.
When everything is speaking the same language, all is well in the world from a feeling point of view; however, if a sensory mismatch occurs, then a very real feeling of being “ill at ease”, or “not myself, or not quite right”, or “foggy”, or simply “anxious” can arise.
This is because the fight or flight systems in our nervous system, those ancient systems that helped us escape the sabre tooth tiger or fight off the marauding tribe… these are the same systems that are now activating as the brain desperately tries to make sense of this Da Vinci Code of sensory data now presented to it! And the only suitable action to take is crawl into our cave (or bed) until things settle down and we can function once more.
How might a chiropractor help with dizziness?
Chiropractors are trained to be experts in the diagnosis and management of spinal disorders. As you’ve (hopefully) learnt so far, the spine, along with the inner ear and vision, plays a massive role in the maintenance of good balance.
My colleague (Dr Joshua Hallett) and I have both completed post-graduate training in further refining these assessments.
Three common presentations to our practice are:
Whiplash-Associated Disorders (WAD)
40-80% of neck traumatised patients will experience vertigo, particularly following whiplash, where around 50% of whiplash sufferers experience dizziness.
This is due (in part) to damage to the joint capsules and supporting muscles, which then impairs feedback to the brainstem. Patients will often complain of catching, mild blurriness of vision, and being off-balance.
Thankfully, gentle cervical spine manipulation has been shown to improve neck repositioning and decrease the above symptoms.
Cervicogenic Dizziness
…Illusory motion, or an altered perception of orientation deriving from disturbance of the neck. A sensory mismatch between visual, vestibular, and cervical inputs.
The cervical spine has an extraordinarily rich proprioceptive system, connecting directly onto the brainstem nuclei.
The severity of dizziness is often related to the severity of neck discomfort and restriction.
And importantly, degeneration in the absence of trauma can also cause dizziness.
“Sensorimotor retraining” exercises, as well as strengthening any discovered weaknesses can prove very useful in controlling this dizziness.
Benign Paroxysmal Positional Vertigo (BPPV)
The most common cause of vertigo!
Small crystals (no, not the fortune teller kind) called “otoconia” dislodge from their regular sites in the inner ear, and drift into canals that tell the brain where we are in space.
2.4% of the population will have this condition at any one time, and up to 75% of women between the ages of 50-85 years will experience BPPV at least once.
Amazingly, there is a simple manoeuvre that we have been trained in that has an 85% (for the most common BPPV) success rate… with almost immediate results!
These episodes are generally triggered by postural change e.g., turning over in bed, getting a haircut etc.
Thankfully, they typically only last 15-20 seconds, but can be quite violent – often resulting in vomiting and disabling spinning.
Summary
As we age, our inner ear sensors decline, and so our brain MUST rely more on our proprioceptors (i.e., all the information we get from our skin, joints & muscles when we move).
If we then become more sedentary – and God forbid – our vision also deteriorates… well this is a recipe for poor balance.
Much more can be said on these topics, especially on the diagnosis and management of such disorders, but that is beyond the scope of this article.
The good news is that we can train this system! And whether we can help using manual therapy, or perhaps you need to see a dietitian, psychologist, or an exercise physiologist; our team at Connect Healthcare will triage you appropriately to ensure you get the right care.
So as mentioned previously, if any of this information has resonated with you personally, or you know of someone who might be suffering with dizziness or balance difficulties, please send them our way!
References
- Palmgren, P et al. Head Repositioning Accuracy and Posturography Related to Cervical Facet Nerve Blockade and Spinal Manipulative Therapy in Healthy Volunteers: A Time Series Study. Journal of Manipulative and Physiological Therapeutics (2009)
- Treleaven J, et al. Sensorimotor Function and Dizziness in Neck Pain: Implications for Assessment and Management. Journal of Orthopaedic and Sports Physical Therapy (2009)
- Balaban C, et al. Neurologic bases for comorbidity of balance disorders, anxiety disorders and migraine: neurotherapeutic implications. Expert Review of Neurotherapeutics (2014)
- Meisingset I, et al. Evidence for a general stiffening motor control pattern in neck pain: a cross sectional study. BMC Musculoskeletal Disorders (2015)
- Brito LBB, et al. Ability to sit and rise from the floor as a predictor of all-cause mortality. The European Journal of Cardiovascular Prevention and Rehabilitation (2014)
- https://www.cdi.edu.au/