Traumatic Brain Injury, Part 8: Diagnosing Vestibular Dysfunction
Today our post will discuss the various diagnostic tests used to identify Vestibular Dysfunction. There are four main categories of diagnostic tests that I want to talk about. The first two are Electronystagmography and Videonystagmography. Next is Rotational Chair Testing, and there is also Dynamic Postureography. Let’s take a moment and talk about each of those in order.
Electronystagmography (ENG) is a diagnostic test that records involuntary movements of the eye caused by nystagmus. It can also be used to diagnose the cause of vertigo, dizziness or balance dysfunction by testing the vestibular system. By looking at how the eye is moving in relation to data that is provided through an electrode attached around the nose, Electronystagmography gives us an objective way to test for a vestibular dysfunction.
Another test is Videonystagmography. This is a very different kind of test. Videonystagmography (VNG) is a technology for testing the inner ear and the central motor functions of the brain, a process known as Vestibular Assessment. It involves infrared goggles which trace eye movements during visual stimulation and changes in position. Videonystagmography can help determine whether a patient or client’s dizziness is caused by a problem with the inner ear, such as benign paroxysmal positional vertigo, as opposed to some other cause such as low blood pressure, anxiety or other types of issues.
Another diagnostic tool is the Rotational Chair Test. During the rotational chair test, the chair is rotated several times, followed by a sudden stop to analyze the post rotaring nystagmus of the patient. The test measures the dizziness, the nystagmus, while slowly being turned in a chair that rotates back and forth. Rotational Chair Testing is usually ordered in addition to the ENG and VNG testing mentioned above. This is done to confirm a diagnosis and to increase accuracy. The tests determine if the semi-circular canals of the inner ear are working properly. ENG and VNG tests by themselves may be falsely positive or falsely negative if not administered properly. Rotary Chair Testing is not affected by mechanical obstructions of the ear, like ear wax, the way ENG and VNG testing may be.
The next test is a Dynamic Postureography. Postureography is a term that relates and covers all the different techniques used to try to measure postural control in a person’s upright stance in either static or stationary or dynamic moving condition. How does Postureography work? Static Postureography is done by having the person in a standing position on a fixed platform that has the instrumentation that is going to measure the patient, connected to sensors which are able to detect tiny movements of the body. Dynamic Postureography is different from Static Postureography, generally because it uses a special machine with a moveable, horizontal platform. As the patient makes small movements, the varying information transmits in real time to a computer.
Those are the various diagnostic tests used to examine a person who may suffer from Vestibular Dysfunction. As you can see, each test measures vary discreet small movements overall, whether they be of the eyes, the body, the different muscles, or the different aspects of our movement in space. All of these tests help determine what is really happening in the body at a level that we may not otherwise notice or be able to identify.
We hope you’ve enjoyed this series on Traumatic Brain Injuries. For more information and additional resources on this topic, please visit the Online Traumatic Brain Injury Resource Center located at our website, www.ericratinoff.com.