You may have heard about Vertigo as a balance disorder. So what is Vertigo? It is a condition that affects the patients’ sense of balance, coordination, & orientation. Vertigo patients often report feeling dizzy anytime they move their heads in certain ways, motion sickness, nausea, & a general sense of being unbalanced & disoriented. Vertigo is a common health concern among middle aged people, although anybody of any age can experience Vertigo.
If you suffer from vertigo or your doctor suspects that you suffer from vertigo, then they might give you some tests to find out for sure. These tests can be clumped together in a category of tests called vestibular assessment tests. Vestibular Assessment tests measure the functioning & health of the body’s vestibular system. These tests serve an important role in helping your doctor determine the course of your vertigo treatment.
To understand the different aspects of vestibular assessment tests, we have to understand how the balance system in a human body works. Without getting into too much detail, let us just tell you that the human balance system is quite complex. It works by receiving inputs from various sensory systems like the vestibular, visual, somatosensory, & central nervous system.
When there is a disturbance or disorder in any of these systems, it causes problems with the body’s balance. Vertigo primarily results from an issue in the inner ear that houses the vestibular system. Since the inner ear is also involved in hearing, some vertigo patients might also experience hearing issues along with dizziness, poor balance, & headaches.
In this article, we take a look at the various tests that make up the vestibular assessment checklist.
Electronystagmography test (ENG test) &/or the Videonystagmography test (VNG test)
The ENG test is a test used to measure the functioning of your vestibular system. It measures the nystagmus of your eyes, which are the jerky movements of your eyes in response to head movements, with the help of electrodes placed on either side of your skin. These electrodes measure the degree of your nystagmus while the doctor moves your head in different directions, & feed the data to a computer programme.
In the test, you will be required to sit in a dark room with electrodes attached to either side of your head. Your doctor will then move your head while asking you to keep your focus on an object/light in front of you.
In a person with a healthy Vestibular system, there shouldn’t be any nystagmus, or if there is, it should be very less or negligible. However, in people suffering from inner ear issues & vertigo, nystagmus will be present, & the degree of it will depend on how advanced the condition is, coupled with other factors.
The VNG test is similar to the ENG test, with the only difference being that it uses tiny cameras fitted in the goggles that the patient wears before starting the test. These cameras record the eye movements in response to the head movements & feed the data to a computer programme. The programme then generates adequate test results by comparing the received nystagmus values with normal values.
The ENG/VNG tests also consist of a caloric test, in which war, & cold air/water is introduced in your ears to check for appropriate nystagmus in your eyes. Your doctor then carefully studies the test results & based on those, advises appropriate vertigo treatment procedures & medications to you.
Rotation tests are another part of vestibular assessment tests that are used to determine the functioning of the vestibular system. There are various versions of this test; auto head rotation, computerized rotary chair, & screening test. The patient sits in a motorized chair with their head secured. They are then rotated in different directions & it is measured whether their eyes stay fixed on the target or not.
The test measures the health & functioning of the patient’s vestibular system, the coordination between the eye & head movements, the timing of the movements, & their symmetry. Another common rotary chair test requires the patient’s chair to be rotated rapidly in one direction at constant speed for one minute. The doctor then quickly decelerates the chair while the patient’s nystagmus is measured.
One advantage of the rotary chair tests is that they provide more information about the functioning of the patients’ vestibular system to the doctors than the ENG/VNG tests.
Vestibular Evoked Myogenic Potential (VEMP)
VEMP test is used to determine if the various vestibular organs & associated nerves in the vestibular system are functioning properly. The test measures the responses from different muscles in the neck & around the eyes. VEMP test uses adhesive, skin-fitted electrodes similar to those used in ENG test, along with earphones, similar to those used during a hearing test.
When sound is played through these earphones, the vestibular organs are stimulated which results in a response from activated muscle groups. This response is then recorded via skin electrodes & the results are fed into a computer programme.
Computerized Dynamic Post urography (CDP)
CDP test determines the patient’s ability to maintain balance & upright posture under various environmental conditions. Whether or not a person is able to maintain postural stability depends on the sensory information received from the body’s muscles/joints, eyes, & the inner ear. The CDP test determines the relationship between these three aspects of maintaining balance & the body’s ability to maintain balance under different conditions. The test may also be used to determine the response to vertigo treatment in patients undergoing vestibular rehabilitation therapy for their vertigo diagnosis.
The CDP test involves the patient standing still on an upright platform. The platform may be still, or moving, or the patient might be required to focus their gaze on a fixed or moving target throughout the duration of the test.
There are pressure gauges installed under the platform that measure sway or difference in body weight each time the patient moves in response to a platform shift. The patient also wears a safety harness so as to avoid any falls in case they lose their balance or become dizzy during the test.
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Besides these tests, there are also audiometry tests that are carried out to determine the patient’s hearing.
These tests can involve testing the patient’s ability to hear sounds at different frequencies to determine their range of hearing. While some other tests determine the ability of a patient’s auditory sensors to distinguish various sounds from each other.
All of these tests form a vestibular assessment checklist & will be used to determine the functioning of your vestibular system. Not all of these tests may be necessary for every single patient, & the decision to administer certain tests should be taken by a vertigo specialist or an expert only.