Vestibular dysfunction examination method

The vestibule is part of the human inner ear organ tissue. The vestibule function is mainly to sense external information, such as: its own movement, external stimulation to the body, etc., so as to achieve the purpose of regulating the balance of the human body. However, when there is a problem with the vestibular function of the human body, the body's balance cannot be adjusted normally. The main symptoms include loss of balance when walking, leaning to one side, and frequent feeling of dizziness. This article briefly introduces several examination methods for vestibular dysfunction.

There are mainly the following inspection methods:

Balance function check

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

①Angbai test. Also known as the eyes closed upright examination method. The subject closes his eyes, stands upright with his feet together, and stretches his arms out to the sides and raises them to shoulder level. When there is a lesion in the labyrinth, the body will deviate to the affected side; when the head turns, the direction of the deviation will change accordingly. When there is a lesion in the cerebellum, it will lean toward the affected side or backward, and the direction of leaning will not change with the rotation of the head.

②Wrong pointing position test. The examiner and the examinee sit opposite each other, each stretch out one arm, with the index finger extended and the other four fingers clenched into a fist. The examiner's hand is facing downward and the examinee's arm is facing upward. Ask the subject to raise his arm and then move it downward, with his index finger touching the examiner's index finger. Try it with your eyes open first, then check with your eyes closed. People with lesions in the labyrinth cannot point to the intended target correctly when closing their eyes, and the index fingers of both hands are deviated toward the affected side. When there is a lesion in the cerebellum, the index finger of the affected side deviates toward the affected side, while the index finger of the healthy side can correctly touch the examiner's index finger.

③Babinski-Weil test. Ask the subject to close his eyes and walk 5 steps forward from the starting point, then 5 steps backward, and repeat 5 times. Observe the deviation angle between the last walking direction and the starting direction to determine the vestibular function status of both sides. If the deviation angle is greater than 90° to the right, it means that the right vestibular function is weakened; if the deviation angle is greater than 90° to the left, it means that the left vestibular function is weakened.

④Dynamic position electrogram. Many countries use dynamic positional electrogram to examine patients with vertigo. The method is to ask the subject to stand on a balance function meter, and connect electrodes around the eyes to the recorder. Tracings are used to distinguish peripheral from central disease. This is a new inspection instrument.

Rotation test

The most commonly used method is the Barrani method. The subject sits in a Jones swivel chair with the head tilted forward 30° and fixed on a headrest to keep the lateral semicircular canal in a horizontal position. Ask the subject to close his eyes and rotate the swivel chair clockwise first, 10 times within 20 seconds, and stop immediately after 10 turns. Ask the subject to gaze into the distance and calculate the duration of nystagmus. After 10 minutes, rotate counterclockwise 10 times and calculate the nystagmus time. Chinese scholars have calculated the normal values, which are that the average duration of nystagmus in the clockwise direction is 23 seconds, and the average duration of nystagmus in the counterclockwise direction is 22 seconds.

Hot and cold water test

There are many methods, such as the Barani method, the Kobrak method and the Halpic method. Most hospitals in China use the Halpic method. When using this method, the subject lies supine on a couch with the head raised 30° (the line connecting the outer canthus and the apex of the external auditory canal is perpendicular to the bed surface). The bucket is suspended above the head at a distance of 60 cm, and the diameter of the water outlet pipe is 4 mm. Each ear was stimulated with 30°C cold water and 44°C hot water for 40 seconds, with an interval of 5 to 10 minutes between each stimulation. The subject stares at a point on the roof. The level of nystagmus was used as the recording standard for observation. A stopwatch was used to calculate the time from the start of water irrigation to the disappearance of nystagmus. Chinese scholars have calculated that the normal average values ​​of the Halpick method for hot and cold water tests are: 24 for cold water, 143 for hot water, and the average latency period (the time from the start of water injection to the onset of nystagmus) is 29. This method can provide a reference for differentiating peripheral or central vestibular diseases. In recent years, some people in China have applied the binaural simultaneous cold and hot water test in clinical practice, and believe that this method is more sensitive than the binaural alternating cold and hot water test.

Hot and cold air test

Using air instead of water as a stimulus to induce nystagmus is a newer method for examining vestibular function. This method has the advantages of being easy to operate, more comfortable for the subjects, applicable to patients with tympanic membrane perforation, and not requiring the collection of outflowing water.

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

DC test

The bipolar method is generally used. The subject sits upright in a chair with his eyes looking straight ahead. Soak the gauze-wrapped electrode with normal saline, place it on the tragus on both sides, turn on the current, gradually increase the current as indicated by the milliammeter, and observe the current intensity at which nystagmus occurs. The cathode is the stimulation side. The nystagmus is rotary and directed toward the cathode. The current should be increased or decreased slowly to prevent excessive stimulation and violent reactions. According to statistics of 50 normal people, the normal average value of nystagmus is 3 mA when the current is between 1 mA and 6 mA. If nystagmus only occurs when the current is above 4 mA, it means that the function is weakened. If no nystagmus occurs when the current exceeds 10 mA, the vestibular function disappears. The direct current test is performed directly on the 8th cranial nerve. Therefore, in peripheral diseases such as Meniere's disease, the direct current test is normal, while in cases of central vestibular diseases such as acoustic neuroma, nystagmus will only occur when the direct current test exceeds 4 mA, and the reaction may even disappear. Therefore, when the vestibular nerve is suspected to be diseased, a direct current test should be performed, which can be helpful in differential diagnosis.

Head position nystagmus examination

Nystagmus occurs when the head is in one or more positions but not in other positions. The pathogenesis is not yet fully understood. According to ear pathology and clinical research, it is mostly caused by lesions of the utricle maculae and the ridge of the posterior semicircular canal ampullary ridge. Before the examination, explain in detail to the examinee that dizziness and nausea may occur during the examination and that the examinee should not close his eyes, so as to obtain the examinee's cooperation and ensure the accuracy of the examination results. The patient is examined sitting upright on a low couch. The examiner supports his head with both hands and pushes him into a supine position with his head hanging over the edge of the couch to observe whether nystagmus occurs. After 10 seconds, help the person sit upright and observe for another 10 seconds. Turn the subject's head to the right, push him/her to lie on his/her back with his/her head hanging over the edge of the couch, facing the right, and observe for 10 seconds. Have the patient sit upright with the head still turned to the right, and observe for 10 seconds. Using the same method, observe the subject for 10 seconds each time when his head is turned to the left supine position and the upright position, for a total of 6 head positions. Each change to a new head position must be completed within 3 seconds. If nystagmus occurs, its direction, amplitude, and type should be noted, and a stopwatch should be used to calculate the latency and duration of nystagmus. In addition, attention should be paid to whether the nystagmus is fatigue-type. Repeat the above test, taking a few minutes to observe whether nystagmus occurs each time at that specific location. If no nystagmus occurs during repeated examinations, it is called fatigue-type (peripheral head position) nystagmus. If a weaker nystagmus is detected after re-examination and it no longer occurs after several consecutive examinations, it is called the gradual fatigue type. Nystagmus that remains constant in intensity each time after repeated examinations is called non-fatiguing (central head position) nystagmus.