What Is Involved in Vestibular Testing?

When the balance of the human body is impaired, such as walking to one side, etc., it is necessary to perform a vestibular function test to determine whether the vestibular apparatus is diseased, and the degree and nature of the lesion. By observing the spontaneous signs caused by vestibular lesions, or by inducing the vestibular response with some physiological or non-physiological stimulus, it is helpful to infer the degree and location of vestibular lesions. Vestibular function is one of the three main factors that maintain the body's balance. The organs responsible for vestibular function are called vestibular organs, which are located in the inner ear and include 3 semicircular canals (external, superior, and posterior semicircular canals), an oval capsule, and a balloon. There are cystic spots in the oval capsule and the balloon, or otoliths. These are the vestibular peripheral receptors. The balloon and balloon are statically balanced (such as sitting or standing).

Vestibular function test

Dizziness can be caused by inner ear disease, central disease, and many systemic diseases. Inner ear diseases such as

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There are the following:

Vestibular function test

The main symptoms of balance disorders are sideways, misalignment, walking or writing disorders. The following inspection methods are commonly used.

Ang white test. Also known as closed-eye upright inspection. The subject closed his eyes, his feet were placed side by side, his arms stretched straight to the sides and shoulders flat. When there is a lesion in the labyrinth, it will fall to the affected side; when the head is turned, the direction of the fall will change. When there is a lesion in the cerebellum, it will fall to the affected side or the back, and will not change the direction of the fall with the rotation of the head position.

Wrong finger level test. The examiner sat opposite the examinee, each with one arm extended, the index finger extended, and the other four fingers fisted. The back of the examinee's hands is down, and the examinee's arms are up. Ask the examinee to raise his arm and move it downward, and touch the index finger of the examinee with his index finger. Open your eyes first and then close your eyes. If you have a labyrinthine lesion, you can't point the target correctly when you close your eyes, and both index fingers are deflected toward the affected side. When there is a lesion in the cerebellum, the index finger on the affected side is deviated, and the index finger on the healthy side can correctly contact the index finger of the examiner.

Babinski-Weir test. Ask the subject to close their eyes and walk 5 steps forward from the starting point, then back 5 steps, and repeat 5 times. Observe the deflection angle between the direction of the last walk and the starting direction to determine the functional status of the vestibule on both sides. If the deviation angle to the right is greater than 90 °, the right vestibular function is weakened; if the deviation is greater than 90 ° to the left, the left vestibular function is weakened.

Dynamic position electrogram. In many countries, dynamic position electrograms are used to check vertigo patients. The method is to instruct the subject to stand on a balance function meter, connect electrodes around the eyes and connect them to the tracing device. Use tracing to distinguish peripheral or central disease. This is a new inspection instrument.

Vestibular function test rotation test

The most commonly used method is the Barani method. The subject was seated in a Jones chair with his head tilted 30 ° forward, and his head was fixed on the headrest so that the outer semicircular canal was maintained in a horizontal position. Make the subject close their eyes, rotate the swivel chair clockwise first, rotate 10 times within 20 seconds, and stop immediately after 10 turns. Ask the subject to stare into the distance and calculate the nystagmus time. After 10 minutes, rotate 10 times counterclockwise to calculate the nystagmus time. The normal value calculated by some Chinese scholars is that the average time for nystagmus rotated clockwise is 23 seconds, and the average time for nystagmus rotated counterclockwise is 22 seconds.

Vestibular function test hot and cold water test

There are many methods, such as the Barney's method, the Kobrak method, and the Halpic method, and many hospitals in China use the Halpic method. When using this method, make the subject lie on a couch and raise the head by 30 ° (the line connecting the apex of the external condyle and the external auditory canal is perpendicular to the bed surface). The bucket is suspended 60cm above the head, and the diameter of the outlet pipe is 4mm. Each ear was stimulated with cold water at 30 and hot water at 44 for 40 seconds, 5-10 minutes apart. The subject stared at the roof a little. Grade horizontal nystagmus was used as the recording standard for observation. Use the stop meter to calculate the time from the start of irrigation to the disappearance of nystagmus. Some Chinese scholars have calculated that the normal average value of the cold and hot water test of the Halpic method is: cold water is 24, hot water is 143, and the incubation period (the time from the start of irrigation to the appearance of nystagmus) is 29 on average. This method can provide a reference for identifying peripheral or central vestibular disease.

In recent years, there have been clinical trials of using both ears in hot and cold water in China, and this method is considered to be more sensitive than the alternative ears cold and hot water test.

Vestibular function test hot and cold air test

Using air instead of water as a stimulus to induce nystagmus is a newer method of vestibular function testing. This method has the advantages of simple operation, more comfortable subject, can be applied to patients with tympanic membrane perforation, and does not need to collect the outflow of water.

The analysis of the results of the hot and cold air test is the same as the hot and cold water test.

Vestibular function test DC test

The bipolar method is generally used. The subject is sitting in a chair, his eyes looking straight ahead. The electrodes covered with gauze were soaked with physiological saline, placed on the tragus respectively on both sides, and the current was switched on. The current was gradually increased under the instruction of the milliamp meter, and the nystagmus occurred when the current intensity reached. The cathode is the stimulation side. The nystagmus is rotating and faces the cathode. The current should be increased or decreased slowly to prevent excessive stimulation and a violent response. According to the statistics of 50 normal people, the normal value of nystagmus at 1 to 6 mA was 3 mA. If the nystagmus does not appear above 4 mA, the function is weakened. If there is no nystagmus over 10 mA, the vestibular function disappears.

The direct current test is directly applied to the 8th cerebral nerve. Therefore, in peripheral diseases such as Meniere's disease, direct current tests are normal, while in cases of central vestibular lesions such as acoustic neuromas, direct current tests exceed 4 milliamps before nystagmus occurs and the response disappears. Therefore, when a lesion of the vestibular nerve is suspected, a direct current test should be performed, which has certain help in differential diagnosis.

Vestibular function test head nystagmus

There was nystagmus when the head was in one or more positions, but no nystagmus in other positions. The pathogenesis is not fully understood. According to ear pathology and clinical research, most of them are caused by oval plaque lesions and posterior semicircular canal ridge lesions.

Explain the dizziness and nausea that may occur during the inspection to the subject in detail before the inspection. Do not close your eyes to obtain the cooperation of the subject to ensure the accuracy of the inspection results. After inspection, take the head upright and sit on a low couch. The examiner supports his head with both hands, pushes to lie on his back, and hangs his head on the side of the couch. After 10 seconds, sit up and watch for another 10 seconds. Turn the subject's head to the right, push to lie on his back, hang his head on the couch, face to the right, and observe for 10 seconds. Sit back straight, still turn your head to the right, and observe for 10 seconds. In the same way, when the subject turns his head to the left supine position and the upright position, observe each for 10 seconds, and check the movements of the six head positions every time the new head position is changed within 3 seconds. If nystagmus occurs, pay attention to its direction, amplitude and type, and calculate the latency and nystagmus time of the nystagmus with a stopwatch. In addition, it is necessary to pay attention to whether the nystagmus is fatigue type. Repeat the check with the method above, and observe whether nystagmus appears at this particular position every few minutes. If there is no repeated nystagmus, it is called fatigue type (peripheral head position) nystagmus. Check again, weaker nystagmus appears, and those who no longer appear after several consecutive inspections are called gradual fatigue. Repeated examinations, each time a nystagmus with constant intensity is called a non-fatigue type (central head position) nystagmus.

Head nystagmus is a pathological sign that can be caused by many central and peripheral diseases, such as changes in blood circulation in the brain, intracranial tumors, traumatic brain injury, Meniere's disease, and so on.

Vestibular function nystagmus electrogram

The nystagmus was recorded with an electronysmograph. The physiological basis is the use of electronic instruments to record the potential changes between the cornea and the retina. The back of the eyeball and the retina are negatively charged, while the front of the eyeball and the cornea are positively charged, so the movement of the eyeball causes a potential change, which is called the Moeller principle.

Electronystagmogram (ENG) is an objective record of nystagmus, which is more accurate than the naked eye. Fast and slow phase time and nystagmus frequency can be measured according to records.

Measuring nystagmus intensity is most reliable with slow phase angular velocity. The measurement method is to take the average frequency, amplitude and slow phase angular velocity of the nystagmus within 10 seconds of the reaction climax period to measure its intensity, also known as the extreme peak value.

In some countries, the nystagmograph has a computer. After the inspection, the computer quickly prints out various data. At present, China uses many calculations by hand, and only a few units have started to connect computers to the nystagmograph.

Vestibular function test

There is no reliable way to check otoliths separately. The parallel swing frame test is a test that makes the otoliths receive the maximum stimulation and the semicircular canals receive the minimum stimulation. However, the equipment is complicated and expensive, and the inspection methods are cumbersome and cannot be widely used. Although the arc ruler method has shortcomings in theory and practical application, it is simple and easy to perform and can roughly estimate the functional status of the otolith.

ellipse capsule examination. The subject was seated on a chair, and the arc ruler was turned to the vertical position, and the head positions were checked in normal head position, 30 ° forward tilt of the head, and 150 ° backward tilt. The arm swings left and right on the horizontal plane, pointing to the midpoint of the arc ruler. Check the left sac with the left hand and the right sac with the right hand.

Function is normal: no deflection is indicated on any head position. Hyperfunction: The index finger is below the midpoint, and it appears as mild hyperthyroidism when it is tilted 30 ° in front of the head; it is moderate hyperthyroidism when it appears in the normal head position; Reduced function: The index finger is biased above the midpoint, which is most obvious when the head is tilted forward 30 °.

balloon examination. Turn the arc ruler to the horizontal position. In the normal head position, the head is tilted 105 ° to the left shoulder (check the right balloon) or the head is tilted 105 ° to the right shoulder (check the left balloon). The subjects were instructed to use their two index fingers to swing up and down on the sagittal plane, pointing to the midpoint of the arc ruler.

Function is normal: In any head position, the indication is not skewed. Hyperfunction: When the head is tilted 105 ° to the right shoulder, the left and right index fingers are biased to the left, which is the left balloon hyperfunction. When the head is tilted to the left and shoulders by 105 °, the index fingers of the left and right hands are biased to the right, which is the right balloon function. Functional weakening: When the head is tilted to the right and shoulders by 105 °, the index fingers of the left and right hands are biased to the right, which weakens the function of the left balloon. When the head is tilted to the left and shoulders by 105 °, the left and right fingers are biased to the left, which weakens the function of the right balloon.