A comprehensive neurovestibular assessment is an in-depth functional examination of 10 different inner-ear balance organs, thier neurologic correlates in the brain, and their integration with other body systems, that together, are responsible for your overall balance and equilibrium function.
The human balance system is incredibly complex and involves the integration of multiple different sensory inputs into highly coordinated motor outputs that allow us to maintain stable balance and vision during all sorts of dynamic movement – or even just while standing still. At the centre of this remarkable integrative system is our on-board super computer – the brain! While we are indeed focussed on assessing inner-ear function, we are also assessing numerous complex neurologic processes and brain areas that are responsible for receiving information from your inner-ears and integrating that with other systems. We divide the entire vestibular system into two major categories: “Central” and “Peripheral”. “Central” basically just means the brain, and “peripheral” means the inner-ears. The term “neurovestibular” is just referring to the fact that we are assessing both central and peripheral aspects of this incredibly complex system. In fact, one of the main goals of assessment is to differentiate central vs. peripheral disorders, because they may require vastly different treatments/interventions.
So, let’s get into a few details! When it comes to assessing peripheral function (i.e. the inner-ear structures themselves) there is a lot more going on than what most people imagine. A short video with helpful visual aids is in the works, but for now here’s a brief summary:
There are 2 major inner-ear structures on each side. One for hearing (the cochlea) and one for balance (the labyrinth, which includes the semi-circular canals and a centre vestibule). Just within the labyrinth there are 5 individual end-organs, each of which detects/codes for different types of movement. Some sense rotational accelleration – like your basic principles of flight: pitch, roll, and yaw – while others detect more linear translations and gravity – like tilting, moving straight foward/back, side to side, or up/down.
There are also 3 distinct reflexes that are generated by these organs, including two with the eyes, and another with your neck. Yes, believe it or not, your ears are in constant communication with your eyes and neck.
These reflexes also involve multiple different cranial nerves. The one that is directly connected to your inner-ears is the VIIIth cranial nerve, aka: the vestibulo-cochlear nerve. It has 3 main branches itself, 2 of which are dedicated to the labyrinth.
The point of this elaborate explanation is that there is A LOT going on in your inner-ears, and it takes a large number of different tests and a vast array of incredibly sophisticated technology to perform a truly comprehensive neurovestibular assessment.
There are very few clinics in the world that offer the breadth of testing that we provide here in one location. Our ability to assess all 10 vestibular end-organs, their associated reflex pathways, nerve branches, and neurologic correlates gives us the best possible chance of determining what is at the root of your symptoms, with the ultimate goal of setting you on the most appropriate and effective treatment path going forward. There aren’t always immediate “magic wand” solutions, unfortunately, but knowing exactly what you are dealing with, and what can or cannot be done about it, is a critical first step. Let us help you take it.
Specialized infrared video goggles and powerful software that track and analyze detailed eye movements under a variety of different test conditions. VNG goggles themselves are relatively common, and may even be found at many physiotherapy clinics. However, what differentiates our system from most others is the associated software, which is the most cost-prohibitive aspect of any VNG system. Because our clinic is dedicated to advanced vestibular diagnostics, we have invested in the most exhaustive set of advanced VNG sub-tests available from the manufacturer, and also have the ability to create custom tests if/when required. Our standard protocol includes tests for:
vHIT utilizes another kind of specialized eye-tracking goggle that employs a high speed camera and sophisticated gyroscope to precisely measure the coordination between certain head and eye movments. The stimulation of tiny little rotational sensors in your inner-ears from quick head movements produces reflexive eye movements that provide us with detailed information about the function of an extremely important reflex called the “vestibulo-ocular reflex”, or VOR. Some other traditional ways of measuring VOR function are far less objective or precise (ex. the bedside HIT), or can only stimulate a response from horizontal sensors at the equivalent of a very slow speed (ex. caloric testing). Caloric testing still has value in certain cases, so we do utilize at times, but it has largely been replaced by vHIT, which provides incredibly precise data on high-speed VOR function in the 6 different planes of movement associated with each of the semi-circular canals.
The cVEMP is an electrophysiologic response from large neck muscles called the sternocleidomastoids (SCM). These muscles receive important information from a tiny gravity sensing organ in your inner-ear called the saccule to help keep your head and neck stable during different types of movement. The response is elicited through the presentation of carefully calibrated high-intensity sounds and measured with small electrodes placed on the SCM muscles. The cVEMP is the only clinical test that directly measures saccular function and it also provides information on the inferior branch of the vestibular nerve and the lower brainstem.
The oVEMP is another electrophysiologic response similar to the cVEMP, however, it measures responses from small eye muscles and asseses a different neural pathway called the maculo-ocular reflex. The oVEMP is primarily assessing another gravity-sensing organ of the inner-ear called the utricle, as well as the superior branch of the vestibular nerve.
The ABR is an elctrophysiologic response elicited by auditory stimuli and measured through electrodes that are placed on the scalp. It is a form of EEG that provides information on the health of cranial nerve VIII – the vestibulo-cochlear nerve. While it is often used as a diagnostic tool related to hearing, it is also highly sensitive to problems with cranial nerve VIII that can cause dizziness, and is therefore included in our test battery.
Since your inner-ear contains the structures for both balance and hearing, it is common for certain balance & dizziness disorders to also have a hearing loss component. A full audiometric evaluation that assesses outer, middle, and inner-ear function as they relate to hearing is therefore also included as part of our comprehensive assessment.
Note: We do not deal with hearing aids at Alberta Balance Centre but we will let you know if that is something you should consider and offer honest, objective advice on selecting the best clinic for your hearing needs.
The Gans SOP is a clinically validated assessment that evaluates a person’s ability to utilize and integrate various sensory inputs in order to maintain postural control. It is highly sensitive to vestibular dysfunction and contains components of three other clinically validated tests of static balance function, including: The Modified Romberg test, the Clinical Test of Sensory Interaction on Balance (CTSIB), and The Fukuda Step Test.
A quick functional assessment of the VOR that bascially measures the degree of blurred vision/loss of acuity with head movement. While vHIT is a far more precise and objective diagnostic tool, this test has great utility as a quick and effective outcome measurement tool for monitoring progress with vestibular rehabilitation/gaze stabilization.
We have a variety of other functional assessement and outcome measurement tools or surveys that may be used depending on the specific case, including:
Getting to the bottom of your balance and dizziness problems, and helping restore the quality of life you deserve.
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