The advanced neurological testing procedures listed below allow us to pinpoint brain impairments that may be responsible for your post concussive symptoms as well as limiting function and cognition.
Video Nystagmography VNG
VNG is a computerized system used in the assessment of the oculomotor system (nervous system control of moving your eyes) and the function of those areas of your brain controlling these movements.
The Video Nystagmography (VNG) test is comfortably performed in our office. We simply place special goggles with an infrared camera on your head to record and measure your eye movements in both light and dark conditions.
Specific areas and pathways of the brain are activated during different types of eye movements. During the test computer software is recording and graphing your precise eye movements as you follow the visual target with your eyes. By measuring your recorded eye movements and displaying them on the computer screen you can see your own eye movements and how they compare to normal measurements.
The following eye movements are measured by VNG:
- Gaze Stability: It is essential that the brain stabilizes the gaze of the eyes for proper equilibrium and balance. One of the most common ocular motor deficiencies seen in concussion cases is poor gaze stability. This can be seen on the VNG tracing.
- Pursuits: Pursuits are slow and steady eye movements that allow you to track a moving object. Good smooth pursuits are essential to everyday functions but are particularly important to athletes. The pursuit mechanism is commonly altered in concussion.
- Saccades: Saccades are fast eye movement used to shift a person's gaze from one object to another. Saccades need to be fast and accurate. A concussion can alter the speed and accuracy of a person's saccades causing multiple symptoms.
- Optokinetics (OPK): This is an essential eye movement that allows for visual function as the surrounding visual environment passes by. When these are dysfunctional it can indicate poor brain function.
- Vestibular Ocular Reflex: When you move your head your eyes should move equally in the opposite direction if this reflex is functioning properly. When this reflex is disrupted by concussion it also can create many symptoms especially dizziness and poor gait.
The VNG eye movement tracings provide invaluable neurologic information concerning specific areas of your brain affected by concussion. We are experts at analysing these specific eye movements and determining if they have been disrupted in their proper function. We correlate the VNG findings with our other testing and examination procedures to develop a specific therapeutic program for each individual
Saccadometry
We measure your saccades using saccadometry. Saccades are quick movements of your eyes that allow you to voluntarily move your eyes quickly from one object to another or to react by moving your eyes to a suddenly appearing target reflexively. Saccades can be measured using a device called a saccadometer. The saccadometer is strapped around a patient's head using an elastic headband. Within the unit, there is a laser that projects targets onto the wall that a patient will look at quickly or saccade to. The saccadometer will measure the eye movements at the same time.
Studies have shown this test to be a very accurate way to detect brain dysfunction caused by concussion. This test cannot be altered voluntarily by the athlete because you cannot consciously control the speed of your eye movement during each saccade; your eyes move as fast as they can. The purpose of your saccadic eye movement is to aim the part of your eye with the best vision (fovea) at the thing you want to see most, and then hold your eye there as you examine it.
Saccades are the only human physiological function that uses every area of the brain. It is for this reason that we can evaluate a person's saccades to determine what areas of the brain are not functioning up to par after a concussion.
Some of the brain areas you use in controlling saccades involves three main cortical areas: the frontal eye fields, the parietal eye fields, and the supplementary eye fields; and several subcortical areas in the basal ganglia, thalamus and brainstem.
An area of your brain known as the superior colliculus creates an environmental grid that allows you to know where your body is in space. When you move your eyes quickly using a saccade, your brain computes an exact position of the target within that grid for your eyes to saccade to. Concussion can affect areas of brain that form that grid. If the grid is faulty the saccadic mechanism will be off and this can be measured using saccadometry.
Saccadometry very precisely measures these aspects of saccades:
- Latency: This is the reaction time taken for the saccade to fire or activate after a new stimulus or target is presented. A normal reaction time should be less than 200ms. People who have had a concussion or suffer from neurodegenerative disorders such as Alzheimer's and Parkinson's disease have pathological long saccadic latency times that are greater than 200ms.
- Velocity: The speed of a saccade is highly related to health of areas in the brain stem commonly affected by head injury.
Accuracy: The ability to make the eyes stop and land directly on the target they are saccading to or looking toward is essential to a person functioning in their environment accurately. If the saccade overshoots or undershoots the target it may indicate that the cerebellum or the area of the brain that makes the environmental grid may have been affected by the concussion. Concussion patients with these accuracy areas affected can have serious issues with balance, gait, equilibrium, movement and this may cause dizziness and nausea.
The saccadometer computerized graph shows leftward saccades that are generated by the right brain hemisphere as red and the rightward saccades that are generated by the left brain as green. This can be very useful in determining what side of the brain has been most affected by the concussion
ImPACT (Immediate Post-Concussion Assessment and Cognitive Testing):
Most post-concussion sufferers we treat are aware of or have been given an ImPACT test. If necessary, we will perform one at our office to get a closer look at how the concussion may have affected the neurocognitive aspects of brain function
CAPS™ Balance Testing
We use Computerized Assessment of Postural Stability (CAPS™) testing performed in our office for assessing how well your brain perceives your body position in space.
When a person’s brain is injured almost always their perception of where their body is positioned in space is disturbed affecting their balance. Important areas of the brain react to information that they receive from the nervous system’s sensors or receptors in the body. The brain uses this information to create a somotopic or body map that allows us to have good balance and function as we move through our environment. A concussion can damage these important areas of the brain causing a person to have an altered sense of where they are in space. This deficit can be devastating to a senior’s ability to walk and can be just as bad for the concussed athlete’s balance and body control needed for them to get back to the sport they love.
The CAPS balance and posture stability test uses an extremely sensitive force platform and specially designed software that can measure the otherwise imperceptible and undetectable changes in a person’s balance or what is known as their center of pressure and limits of stability. A person’s center of pressure is closely related to a person’s center of gravity and a person’s limit of stability is how far they can move off of this center without falling. The CAPS will generate a report that quantifies a person’s balance and stability. This will provide an objective score that can be compared to normative data for the patient’s age, height, gender or prior CAPS baseline. This test is essential in diagnosing the effects of the concussion and can be used to monitor progress through care. For more information go to: https://www.vestibtech.com/TBI.html
