Because the hearing and balance functions of your inner ears are closely related, it is important to comprehensively evaluate the hearing and balance systems whenever either system is affected.
Basic Comprehensive Audiogram
Basic Comprehensive Audiogram is a hearing test that is administered in a soundproof room and requires foam ear inserts or a set of headphones. You will be able to see the audiologist who is administering the tests and you will have voice contact through a microphone. A series of beeps/tones are presented to evaluate the softest levels one can hear at certain frequencies/pitches. In addition, a series of words are also presented to determine the softest level one can understand words along with a scored percentage of speech discrimination abilities. These tests will be repeated at certain intervals to determine stability, patterns of deterioration and/or patterns of improvement.
The following tests are administered by inserting a probe into the outer ear canal. The patient will feel pressure changes and sounds while measurements are determined.
- Tympanogram is a mechanical test to determine eardrum movement, middle ear fluid, eardrum perforations, function of middle ear bones, etc.
- Acoustic Reflex Testing is used to measure the middle ear muscles and bones response to intense sound.
- Acoustic Reflex Decay is used to measure the sustainability of the middle ear muscle contraction.
This test measures early electrical response of the inner ear and hearing nerve. It is helpful in cases of inner ear pathologies. During this test a soft electrode is deeply placed in the outer ear canal with other electrodes placed on forehead. These electrodes are fed into a computer where sound signals are emitted to the patient’s ears. These impulses of sound are computerized and evaluated.
Auditory Brainstem Response (ABR)
This test evaluates the electrical conduction of the hearing nerve and brainstem pathways. It measures the speed of the electrical impulses that are carried along the acoustic (hearing) nerve and brainstem. During this test, insert electrodes are placed deep in the ear canal and on the patient’s forehead. The patient then relaxes or sleeps as sounds are given through earphones placed over the patient’s ears. These impulses of sound are tracked electronically and recorded as they travel from the inner ear to the brain.
Otoacoustic Emissions (OAE)
Sounds must pass through external, middle and inner ear structures within the hearing system before the brain decodes them. This test is used to monitor the function of the outer hair cells within the organ of hearing in the inner ear. You will sit in a chair and a small probe will be placed in your ear canal. A series tones are generated which will stimulate the outer hair cells in different regions within the organ of hearing. These hair cells generate an acoustic response, which is measured by the probe. The response is averaged over time and is graphed on the computer screen.
Vestibular Evoked Myogenic Potentials (VEMP)
Vestibular Evoked Myogenic Potential (VEMP) is used to determine the integrity of a sensor in the inner ear.
The cVemp testing procedure consists of placing electrodes to the middle third of the anterior (front) neck muscles (sternocleidomastoids) and the forehead. With the patient in a supine (laying back) position, the patient is instructed to hold their head up with no support surface using their anterior neck muscles thus creating a muscle contraction. Tones are then repetitively presented to each ear. Patients are instructed to contract their neck muscles during acoustic stimulation, and relax between sound stimulation.
The oVemp test is performed by introducing tones into the ear as well. However, electrodes are placed around the eye to measure eye muscle contraction.
Moving Platform Pressure Test (PPT)
Under normal conditions, changes in pressure outside the body do not cause balance disturbances because the inner ear is sealed. When a microscopic opening is present, the balance system of the inner ear that is affected will be abnormally stimulated when pressure changes occur. This causes certain symptoms and postural responses that can be recorded.
While you stand on the Computerized Dynamic Posturography platform, and ear probe that is connected to a pressure device is inserted into the ear canal to enable the presentation of air pressure changes. Changing the air pressure in the ear canal causes a corresponding change of pressure in other parts of the ear as well. If a defect is present, certain symptoms or postural changes may result and these may help verify inner ear dysfunction.
Computerized Dynamic Posturography (CDP)
Posturography tests the interrelationship of all parts of the balance system – the inner ear, vision, and muscles and joints. This test can help determine if one or more of these three systems is abnormal.
To perform the test, you will be asked to stand on a platform surrounded on three sides with a panel painted with pink clouds, blue sky and ocean. You will be fitted with a safety harness, which will prevent you from falling if you should lose your balance during the test. To fit this harness, you need to wear pants.
Electronic sensors and computer monitors record shifts in your body weight that occur while you maintain your balance. These gauges are mounted under the platform. Body sway is also recorded. At times, the platform and/or walls may also move slightly so that your responses to these changes can be monitored. All information is then analyzed by computer to determine the function of your balance system.
Vestibular Autorotation Test (VAT)
Rotation tests evaluate how inner ear control of eye movement is working. Rotation (turning) of the head stimulates part of the inner ear, which then sends messages to the brain, which then causes the eyes to move in a certain direction. This reflex permits clear vision during head motion. The VAT gives information about the faster response of the inner ear while the rotating chair test provides information about the slow speed responses of this system.
This test takes place seated, while the patient moves their head side to side or up and down and focuses on a spot on the wall.
Rotational Chair Testing
Rotation tests also evaluate how your systems of eye movement are working. Rotation of the head stimulates part of the vestibular system known as the vestibular-ocular reflex. This reflex responds to rotation by generating eye movements that allow you to maintain clear vision as your head moves.
Testing takes place in a darkened booth. A microphone and speaker in the booth allow you to have voice contact with the technician, who is seated at the computer console just outside the door.
The patient is seated in a computerized chair that turns gently from left to right. For your safety, you will be securely harnessed in the chair and your head will be restrained against a headrest. Your eye movements are recorded as the chair turns by goggles.
During testing, the technician will ask you a series of simple questions. This is called “tasking”. Tasking is designed to keep your mind busy so that you stay alert during testing.
One easily measured response of the balance system is nystagmus – a rapid, involuntary eye movement. By stimulating the inner ear and nervous system and then carefully measuring eye movements, the physician can learn a great deal about any abnormalities in the vestibular system. This procedure is called VNG, short for videonystagmography, and it means the video recording of eye movements. VNG testing is really a battery of tests that contribute significantly to the information the doctor needs for diagnosis.
During these tests, your eye movements are recorded by placing goggles around the eyes. The goggles record your eye movement. Your eye movements will be recorded and analyzed during the following stimuli:
- Light Targets
- Pressure Changes
- Sound stimuli
- Thermal Stimulation
Blood studies may be performed to rule out conditions such as anemia, diabetes, hypothyroidism, infections or other conditions that may be interfering with the coordination of brain impulses.
Radiographic Studies (CT Scans, MRI, etc.)
If there is reason to suspect that dizziness could stem from a tumor or cyst, the patient may undergo a CT scan or MRI. X-ray pictures are taken of the brain from several different angles. These images are then combined by a computer to give a detailed view that may reveal the damaging growth. CT scans may be helpful in evaluating inner ear structural abnormalities even if the MRI is normal.
Tympanic Membrane Displacement (TMD)
By measuring eardrum movement in response to different sounds, this test gives information about inner ear fluid and spinal fluid pressure. This procedure is non-invasive, well tolerated, and does not cause dizziness.