Besides hearing tests, audiologists can also perform tests (audiology exams) to diagnose balance disorders. Surprisingly enough, the ear plays an important role in balance. The inner ear is made up of the cochlea, used for hearing, and the semicircular canals, which are used for balance. The semicircular canals are made up of three canals, the horizontal, the posterior and the superior. Each canal is filled with liquid, known as endolymph and lined with tiny hairs. Whenever you move your head, the fluid within the canal moves as well. The fluid movement activates the hairs, which sends an electrical impulse to the brain. The three canals all sit at different angles, leading to each being responsible for a different sense of directional balance. The superior canal is responsible for detecting side-to-side movements, like moving your head towards your shoulder. The posterior canal detects forward and backwards motions, like sit-ups. The horizontal canal senses up and down movement, such as nodding your head.
In order to determine the cause of your unexplained episodes of dizziness your audiologist will review your medical history and complete a physical exam, which includes examining how you walk and keep your balance while standing. Then, they may order a series of tests.
The first test will involve measuring your eye movements by asking you to following a moving object with your eyes. If there is a chance you may be suffering from benign paroxysmal positional vertigo (BPPV), a Dix-Hallpike maneuver may be performed. The audiologist will move your head and then ask you to lie down; they will then observe your eye movements for 45 seconds.
Vestibular testing is a category of tests used to determine if there is something wrong with the part of the inner ear responsible for balance.
Computerized dynamic posturography measures how well you can balance on a moveable platform while also looking at different visual stimuli. You will be attached to a safety harness to make sure that if you become dizzy, you do not fall.
Vestibular evoked myogenic potential (VEMP) evaluates the function of the saccule, a section of the middle ear that helps maintains balance by translating head movements into neural impulses which are sent to the brain. These neural impulses also cause the sternocleidomastoid (SCM) neck muscles to relax. The VEMP test starts with you lying down and then raising your head, which flexes the SCM neck muscles. A loud tone is played to stimulate the saccule, and how much your neck muscle relaxes is measured.
A rotational chair test can be used to diagnose bilateral vestibular loss and consists of three parts: the chair test, the optokinetic test and the fixation test. Your level of dizziness during each test is measured by recording eye movement. The chair test measures your level of dizziness while being slowly turned in a motorized chair. The optokinetic test measures how dizzy you become while viewing moving stripes. The fixation test measure dizziness while you are being rotated and the dot you are instructed to look at is also rotating.