Early detection of hearing loss, combined with early intervention, significantly reduces communication delays that commonly accompany hearing loss.

Center for Audiological and Vestibular Services - Vestibular Services - Evaluation

A battery of tests are used to evaluate the causes of dizziness and imbalance, including:

• Electronystagmography (ENG)

This is the most commonly used test to evaluate the vestibular system (balance portions of the inner ear, nerve, and brain). When the head is in motion, the inner-ear balance organs send signals to the eye muscles to keep vision in focus. Therefore, eye movements can be used to evaluate the balance system. Electrodes are taped near to the eyes, and a computer records results as patients follow a moving light with their eyes and as they sit and lie in different positions. Each ear canal also is irrigated with small amounts of warm and cool water (caloric test) as the patient lies on an examination table. The water causes a temperature change that creates eye movements (nystagmus) that can be measured and compared for each ear. The patient's physician uses the information obtained from the ENG, along with information from other clinical tests, to make a diagnosis and recommendations for treatment. This type of ENG cannot be used with infants, very small children, or if there is a perforation (hole) in the eardrum. In these cases, rotary chair is the most appropriate test.

• Videonystamography

This test is similar to the ENG, except that specialized video goggles with infrared cameras, rather than conventional electrodes, are used to measure eye movements.

• Posturography

In a normal system, balance is accomplished with the teamwork of three systems: vision, proprioception (sensors in muscles and joints), and the vestibular system (balance portions of the inner ear and brain). Posturography evaluates the interrelationship of all three parts of the balance system. This test may be used to evaluate balance in older children and adults. During posturography, the patient stands barefoot on a small platform surrounded on three sides by a padded wall. The platform and wall move slightly and the patient is asked to maintain balance. The patient wears a safety harness for support. A computer records the patient's shift in body weight and sway and these results are analyzed for patterns of imbalance. Posturography results should be interpreted in conjunction with the results of other clinical and vestibular tests.

• Monitored Fistula Test

In some patients, a small tear may occur in the membrane that separates the middle ear from the inner ear. This condition is known as a perilymphatic fistula (PF). When a fistula occurs, the inner ear's natural fluid (perilymph) leaks out, disrupting inner ear function and resulting in hearing loss and dizziness or imbalance, particularly during pressure changes, such as flying. This test is indicated when a patient's balance or dizzy complaints are related to pressure changes, such as flying, sneezing, blowing the nose or physical exertion. During a monitored fistula test, positive and negative air pressure is introduced to each ear canal. The audiologist monitors the patient for abnormal eye movements (nystagmus) or balance changes on the posturography platform in response to these pressure changes. If a fistula is present, eye movements (nystagmus), balance changes and/or dizziness may occur when the air pressure is changed.

• Rotary Chair Test

This test provides another means of assessing inner ear function and is often better tolerated than the ENG. Rotary chair testing can be used to test patients of all ages, including infants. The patient sits in a chair in a small, dark booth. Small children and infants sit on a parent's lap for this procedure. Electrodes are attached near the eyes and the computer-driven chair rotates gently back and forth at several acceleration rates. This motion stimulates the inner balance system and causes eye movements (nystagmus) that are recorded by a computer and monitored with an infrared camera. Unlike the ENG, rotary chair testing cannot provide specific diagnostic information about each ear individually. The rotary chair test is particularly useful when confirming a suspected loss of inner ear balance function in both ears and determining the extent of residual function. It is also a reliable method of monitoring the effects of ototoxic medications on the inner balance system over time.