Hearing and Balance-Tests

Hearing and Balance Tests

THE COMPREHENSIVE HEARING EVALUATION

Pure tone hearing test
Speech testing
Impedance testing
Otoacoustic emission testing (OAEs)

ELECTROPHYSIOLOGIC TESTING

Auditory brainstem response test (ABR)
Auditory steady state response test (ASSR)
Electrocochleography (ECoG)
Electroneuronography (ENoG)

BALANCE TESTING

Electronystagmography (ENG)/Videonystagmography (VNG)
Vestibular autorotation test (VAT)
Computerized dynamic posturography (CDP)
Vestibular evoked myogenic potential (VEMP)

SPECIALTY EVALUATIONS

Cochlear implant evaluation
Baha® system evaluation
Auditory processing disorder test battery (APD)
ImPACT testing for concussions

THE COMPREHENSIVE HEARING EVALUATION

A comprehensive hearing evaluation consists of four components, each designed to evaluate different parts of the hearing mechanism: pure tone testing, speech testing, impedance testing and inner ear testing.  Each component is important in the overall assessment of a patient’s hearing function as well as for the screening for many other disorders.

Pure tone hearing test

In order to determine hearing sensitivity, or the softest level one can hear sounds, a pure tone hearing test is administered.  The entire hearing system (sound entering the ear through the ear canal, traveling through the middle ear to the inner ear) is tested using Air Conduction.  Inner ear function is then further examined using Bone Conduction testing.  

Speech testing

While pure tone testing measures detection of sound, speech testing examines the ability to process and understand speech.

Impedance testing

Impedance assessment consists of several different subtests.  These tests evaluate the mechanical sound transmitting properties of the middle ear structures (impedance), the pressure in the middle ear (tympanometry), and some properties of the auditory nerve and reflexes carried by the auditory nerve (acoustic reflexes).  These tests also aid in the evaluation of Eustachian tube function and the middle ear muscles. 

Otoacoustic emission testing (OAEs)

This measurement allows objective information regarding the function of the inner ear and conductive mechanism of the middle ear without requiring responses from the patient.  A healthy middle ear (normal eardrum, middle ear bones, absence of infection) is critical to obtaining accurate OAE measurements.  The inner ear, or cochlea, has different sound gathering and enhancing specialized cells.  There are two different types of hair cells – outer hair cells and inner hair cells.  The outer hair cells naturally amplify sounds coming into the ear, before sending the sounds to the brain via the hearing nerve.  The inner hair cells help to clarify sounds and then send them to the brain via the hearing nerve.  OAEs measure the outer hair cell function of the inner ear. 

ELECTROPHYSIOLOGIC TESTING

Auditory brainstem response test (ABR)

An Auditory Brainstem Response (ABR) is an examination that can only? be ordered by your physician.  This is one of many tests that may be recommended for the evaluation of dizziness, balance problems, hearing loss, ear pressure and/or ear noises (tinnitus).  The ABR test allows us to determine how well electrical impulses generated by the inner ear travel through the brainstem to the brain.  Specifically, the test helps to determine whether or not there is a blockage in the transmission of electrical signals from the ear to the brain.  A small percentage of patients may have benign growths on the nerve leading from the ear to the brain (acoustic neuroma).  This test can help determine if such a benign growth is present or if your symptoms are due to other causes. 

A second portion of this test, the Latency Intensity Evoked Function, is a series of clicks or tones that are presented at varying intensities to objectively assess an individual’s general hearing level.  For patients who cannot respond to conventional hearing tests, such as an infant, this test helps to determine ear-specific hearing in the mid to high frequencies.  

Auditory steady state response test (ASSR)

The auditory steady-state response (ASSR) is similar to an ABR, but is elicited with modulated tones that can be used to predict hearing sensitivity in patients of all ages.  The response is evoked or stimulated by the modulation, or turning on and off, of a tone.  A measurement of the neural response that closely follows the tone helps to determine hearing sensitivity.  The response is frequency-specific and can be detected objectively at intensity levels that correspond to behavioral threshold levels. 

Electrocochleography (ECoG)

ECoG is similar to the ABR, however the recording electrode is either placed in the ear canal (using a tip-trode electrode), on the eardrum (using a TM surface electrode), or on the cochlea by passing an electrode through the eardrum (using the transtympanic technique).  Once again, it is a physician-directed exam and is used to assist with the diagnosis of  Ménière’s disease and hydrops, and specifically looks at the summating potential / action potential ratio or hair cell and neural response. 

Electroneuronography (ENoG)

Electroneuronography is an electrical test used to evaluate facial nerve function when there has been an onset of paralysis due to Bell’s Palsy, trauma from an accident, herpes zoster oticus, otitis media or other causes.  Initial testing should occur between three days after onset of the paralysis to no later than three weeks after onset.  The doctor examines the results and determines if surgical decompression of the facial nerve is warranted.  The test has proven effectiveness in predicting the long-term prognosis for Bell's palsy.  It also frequently is performed when an acoustic tumor has been diagnosed.  If done preoperatively, it has been shown to be a good predictor of facial nerve function following removal of an acoustic tumor.

BALANCE TESTING

Electronystagmography (ENG)/Videonystagmography (VNG)

ENG/VNG consists of numerous sub-sets of tests used to evaluate the function of the vestibular system by evaluating a known reflex connection between the inner ear and movements of the eye.  Some of the tests specifically evaluate the inner ear and others evaluate the oculomotor or central function.  One portion of the test is comprised of bithermal caloric irrigation (performed with water or air) and this evaluates the superior vestibular nerve function, as it either warms or cools the lateral (horizontal) semicircular canal.  The results of all the tests are then interpreted by the physician for diagnosis and the physical therapist for vestibular rehabilitation. 

Vestibular autorotation test (VAT)

The Vestibular Autorotation Test (VAT) is used to evaluate both the horizontal and vertical vestibulo-ocular reflex (VOR). This natural reflex enables you to fixate on a target while the head or body moves and therefore prevents images from moving as our head and/or body moves.  The main purpose of the VOR is to allow clear vision during head movement by sending signals to move the eye muscles to compensate for the small rapid head movements that occur in everyday life.  The VAT examines the normal, everyday range of motion and speed where many balance disorders occur.  The VAT is used to determine very specific problems, aiding both the physician and physical therapist in developing an individualized treatment and recovery plain. The VAT can be used in diagnosis and also for monitoring changes during vestibular rehabilitation.

Computerized dynamic posturography (CDP)

CDP is designed to better assess a patient’s functional balance problem, allowing our physician to evaluate a patient based on the integration of the three different components of the balance system: visual, sensory (brain interpreting what the feet are telling it), and vestibular.  If the eyes, the ears and the brain do not work together properly, imbalance can result.  Various scenarios are used to stress each of the three balance system components to determine if and where the weakness lies.  The results of the test not only assist with the diagnosis of the balance problem, but also assist the physical therapist in creating a rehabilitation plan. 

Vestibular evoked myogenic potential (VEMP)

The VEMP test complements the other balance function tests and allows us to further examine the inner ear balance structures.  The VEMP tests results reflect the function of the inferior vestibular nerve and saccule.  The VEMP has been found helpful in the diagnosis of numerous labyrinthine or inner ear disorders.  The saccule, which is vertically oriented and the lower of the two otolithic organs, has a slight sound sensitivity which can be measured.  Although the cochlea has replaced the saccule as the primary organ of hearing in mammals, there is evidence that the mammalian saccule remains responsive to sound.  Vestibular evoked myogenic potentials (VEMPs) are short latency electromyograms (EMG) that are evoked by high-level acoustic stimuli and are recorded from surface electrodes over the tonically contracted sternocleidomastoid (SCM) muscle. Studies also demonstrated that there is no correlation between the VEMP and the degree of sensorineural hearing loss.  The VEMP has been found helpful in the diagnosis of numerous inner ear disorders. 

SPECIALTY EVALUATIONS


Cochlear implant evaluation

The cochlear implant evaluation consists of a series of questionnaires and tests designed to determine if a patient with a severe-to-profound hearing loss is an appropriate candidate for cochlear implantation.  The testing examines a person’s ability to hear and understand while using amplification.  The results of the test may indicate candidacy or the need for better amplification. 

Baha® system evaluation

Some individuals cannot benefit from traditional amplification and are not candidates for a cochlear implant.  For these individuals, a Baha® system, which transfers sound through the bone behind the ear, may be the solution.  Hearing testing and an in-office trial with the device are used to determine benefit and candidacy. 

Auditory processing disorder test battery (APD)

This test battery has also been referred to as a Central Auditory Processing Disorder test (CAPD).  APD testing differs from hearing testing (which is the detection of sound) as it measures the processing of auditory information once it has been heard.  The tests are designed to stress the auditory system by degrading an auditory stimulus through the introduction of distortion, competition, time alteration or background noise.  This test battery is comprised of several special tests designed to assess the various auditory functions of the brain.  The selection of tests will depend upon a number of factors, including the age of the individual, the specific auditory difficulties reported, the native language and cognitive status of the individual.  For the most part, children under the age of 7 years are not candidates for this type of diagnostic testing.  In addition, auditory processing assessments may not be appropriate for children with significant developmental delays or children with hearing loss.

ImPACT testing for concussions

ImPACT testing is a user-friendly computer based testing program specifically designed for the management of concussion injuries. It was developed to help evaluate the recovery process following a concussion.  The ImPACT program evaluates and documents multiple aspects of neurocognitive functioning including verbal and visual memory, brain processing speed, reaction time and post-concussive symptoms.  It can be used for athletes who have suffered from concussions, but also individuals involved in motor vehicle accidents or anyone suffering from a head injury. 

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