Audiology Testing  

Audiology StaffThe Audiology Department at the Silverstein Institite consists of five doctors of Audiology.  The Audiologists perform all the Hearing and Inner Ear testing for hearing loss, dizziness and balance problems. 

All patients with ear or dizziness complaints need basic hearing and balance tests depending upon the diagnosis. These may need to be repeated. Usually tests done at other facilities must be repeated to determine their accuracy and to determine whether any changes have occurred.

Audiological Assessment

The audiological assessment consists of a hearing test and immittance audiometry. The hearing test is a subjective test performed to assess the function of the auditory system. The patient is seated in a sound treated room with headphones or ear inserts placed on or in their ears. The patient is instructed to respond to a series of tones to determine the presence or absence of a hearing loss as well as the type and degree of hearing loss. The patient is also given a series of words to determine their ability to discriminate speech. Immittance audiometry is an objective test measuring the status of the middle ear and reflexes of the auditory muscle. A probe is placed in the ear canal via a headset. The tympanogram graphs the movement of the eardrum (tympanic membrane) in response to changes in pressure. This test is very helpful in determining whether there is fluid in the middle ear and whether the eardrum and bones of hearing are functioning normally. Acoustic reflexes are elicited with loud tones. Acoustic reflex decay testing assesses whether the reflex can be maintained for 10 seconds. The absence or presence of these reflexes is significant for diagnosis of tumors growing on the hearing nerve.

Electronystagmography (ENG) (VNG)

This test consists of a series of tests to determine problems within the vestibular (balance) portion of the inner ear. The inner ear and the eye muscles are intimately connected in the brainstem so that eye movements can be used to determine the status of the semicircular canals. Either electrodes are placed near the eyes or goggles with cameras are used to record eye movement. The eye movement is recorded throughout the test. Tracking tests require the patient to follow various targets. In the positional testing, the patients are required to move into various positions to determine if positional vertigo occurs. Caloric testing provides the physician with essential information regarding the function of each individual balance system. Different temperatures of air are used to stimulate the balance system in the inner ear. This may cause a sensation of spinning for a few seconds which is normal. If stimulation is successful the eyes move back and forth (nystagmus) which is recorded and measured. The tracing is read similar to an EKG done for the heart. A reduced or absent response indicates pathology within the vestibular system.

Balance Testing using the Balance Master

Balance testing is done using a computerized balance platform to assess the entire balance mechanism. To balance normally we need input from the eyes, the inner ear, and the proprioceptive system (nerve endings in the muscles and joints) to the brain. The brain organizes the information and sends messages to the limbs and body to keep us in balance. This is an unconscious mechanism. The patient is placed on a platform that measures body sway with the eyes open and closed. Each input is tested individually to determine if they are working normally. Then the eye input and the proprioceptive system is removed to see if the patient can balance using the inner ear only. The balance master is an important study to help the doctor make a proper diagnosis.

Brainstem auditory evoked response (BAER)

The Brainstem Auditory Evoked Response is an objective measure of the electrical activity of the auditory nerve pathway from the inner ear to the brainstem. In this test, a clicking sound is presented to one ear at a time. The electrical activity of this signal is recorded by electrodes and averaged over 2000 signals. The averaged response is displayed as a waveform that contains peaks, which correspond to various points along the neural pathway. The time between these peaks are measured and compared to normative data. A delay in a response can indicate a growth on the hearing nerve. The BSER is also helpful in the diagnosis of demyelinating diseases (multiple sclerosis) of the brain, tumors (acoustic neuroma) of the eighth cranial nerve (hearing and balance nerve) and vascular lesions (strokes) of the brain stem. Threshold testing can be done to determine if hearing is present in an individual or person unable to perform a conventional hearing test. It can also give information as to whether hearing may be present in infants that are in a high-risk group for having auditory dysfunction. BSER is also used in the operating room to monitor auditory function while an acoustic neuroma is being removed.

Electrocochleography (ECoG)

This test is usually done in conjunction with the BSER test since it requires the same type of electrode setup and stimulus. ECoG is an objective test that records potentials, which determine the pressures within the inner ear. A ratio of these potentials is calculated. A large ratio may indicate an increase of pressure in the inner ear indicating Meniere’s disease.

Otoacoustic Emissions (OAE)

This test is done to check the response of the outer hair cells in the cochlea. After sound is introduced into the ear, the ear emits minute sounds which can be heard with a computer. The presence of Otoacoustic emissions means that the hair cells are functioning and are able to respond to sound in a normal way. This test helps diagnose whether the pathology is in the hair cells or in the hearing nerve.

Summary

Combined, these tests give a complete picture of how the inner ear is functioning and provide information necessary to make an accurate diagnosis of hearing and balance/dizziness problems.