Assessment technology
Eye movement technology
Finding the right solution starts with understanding the problem. Neurological conditions are not always clearly defined, which means the assessment does not always give a clear answer. The best type of assessments are those which are repeatable and reliable. At BrainBalanz, we want to ensure you that your diagnosis is clear – that’s why we use objective measurements for eye-movements, head motion and balance.
Eye-tracking is a useful measurement due to the many distinguishing brain areas which relate to various eye movements. Infra-red cameras are used to measure particular eye motions, including:-
- Saccades: quickly moving the eye from one target to another
- Pursuits: tracking a target as it is moving
- Fixation stability : fixating the gaze on a stationary target
The accuracy and quality of eye movements is measured by the camera, which then computes the data into meaningful information which can be compared to age-related normal values.
Eye movement is a very useful insight into brain function and is used in many types of neurological assessments. It should be noted that the motion of the eye is different to clarity of image. Motion is controlled by the 6 muscles behind the eye, which in turn are controlled by certain parts of the brain. Visual acuity relates the clarity of the image as it is focused on the retina.
See how eye-tracking is done.
Head movement technology
Pictured here are the ICS IMPULSE goggles, made by the international company, Natus. These goggles don’t exactly measure head movement; however, they assist the clinician by recording the eyes responses to various movements and positions of the head. The direct connection between the motion sensors in the inner ear (vestibular system) and the eye muscles enables clinicians to strategically move the head of the patient whilst observing for normal or abnormal eye responses.
The ICS IMPULSE goggles then gives the clinician the opportunity to replay the video of the head/eye motion, using slow-motion if necessary, and carefully distinguish between a variety of problems with the peripheral or central vestibular system in the inner ear and brain. Video recordings are then stored as a file and marked as a certain date for the purpose of reviewing in the future.
Another advantage of using the ICS IMPULSE goggles is the “vison-denied” feature. When using this feature, the clinician may remove the patient’s vision by placing an eye patch under the goggle lens. The infrared camera has the ability to continually capture footage of the eye movements (visible on the clinician’s computer) whilst the patient is unable to see anything.
This type of sensitized test is often performed so that eye motion is examinable whilst the patient is unable to fixate on a target. The “vision-denied” testing procedures are not crucial for the diagnosis of the most common cause of vertigo, BPPV, but it is crucial for diagnosing and measuring other causes of dizziness.
Body movement technology
Anybody who has suffered dizziness or vertigo will understand that impaired balance is entwined with the condition. This is because the function of balance relies on the parts of the brain which are also responsible for the symptoms of dizziness and vertigo.
From a safety perspective balance is a very important measurement. This is particularly true for the older client who may be at a risk of falling. The measurement of balance can be repeated in a reliable and standardised manner by using force-plate technology. A digital force-plate can be used as a way of measuring postural sway, and therefore, balance. The patient is directed to stand on the plate and remain as stationary as possible.
Movement is then detected by the force-plate and converted into direction and distance, to give an overall score. The more the patient moves, the higher the score, but the worse the balance, I.e. the better your balance, the less movement you make, the lower your score.
Scores are taken as an average over three attempts and are compared with age-related norms. Although balance is not an indication of function for any specific brain-region, it is a an indication of overall brain function, and is a useful measurement in the dizziness/vertigo clinic.
Balance can also be measured by how much movement can be made without letting the feet lift from the floor. This test is called the “limits of stability” test and requires the patient to move in all directions as much as possible, without losing balance or lifting the foot. In contrary to the “standing still” test, the better score on the “limit of stability” test is the score which indicates maximum movement in all directions, and is therefore the highest score.
