No abstract available.
Acceleration* ; Head* ; Reflex, Vestibulo-Ocular*

Dizziness is one of the most commonly presenting complaints in clinical practice. However, a systematic diagnostic approach to the dizzy patient remains challenging due to the wide range of diagnostic possibilities. As a symptom, dizziness is quite subjective and is resulted from diverse conditions. Therefore, classifying the patient's complaints into the etiology oriented categories through detailed histories should be the first step of the approach. Physicians should be acquainted with skills for the history taking and a brief but comprehensive neuro-otologic examination which can be done easily in clinical practice. This article focused on practical skills for history taking and bedside examination in the diagnostic approaches to the patient with dizziness.
Dizziness ; Humans ; Reflex, Vestibulo-Ocular ; Resin Cements

The aim of this study was to investigate the effect of flight training on vestibuloocular reflex (VOR) induced by rotational chair test in student-pilots. The study group was divided into followings; control, prepilot (student-pilots before flight training), and student-pilot (after training). Gain, phase and symmetry of eye movement induced by sinusoidal harmonic acceleration with frequencies of 0.01, 0.02, 0.04, 0.08, 0.16, 0.32 Hz. Gain and phase did not show any significant differences between control and student-pilots before flight training in all frequencies. But there were significant gain differences between control and student-pilots after flight training in 0.01, 0.04, 0.08 frequencies. And phase showed significant differences between before and after flight training in student-pilots in 0.01, 0.04 Hz. These results suggest that the flight training would be attributable to modulate the vestibular function in the student-pilots.
Acceleration ; Eye Movements ; Reflex, Vestibulo-Ocular*

BACKGROUND AND OBJECTIVES: The parameters of vestibulo-ocular reflex (VOR) are believed to indicate the quantitative value of vestibular function and the differences in them are related to the susceptibility of motion sickness. The purpose of this study was to investigate the effects of repetitive multiaxial 3-dimensional rotation training on VOR parameters. MATERIALS AND METHODS: Fifteen healthy volunteers were randomly assigned to 3 different groups according to the mode of exercise training. Aerotrim exercise was done as a method of repetitive multiaxial 3-dimensional rotation training. The changes in VOR parameters after 9 weeks of exercise training in Aerotrim training group were compared with that of other groups. RESULTS: While the values of VOR gain in Aerotrim training group after 9 weeks of exercise training were significantly lower than baseline values at rotation frequencies of 0.01, 0.04, 0.08, 0.16, and 0.32 Hz, values of VOR gain in other groups showed no difference between before and after exercise training. In all groups, there were no significant differences in VOR phase and symmetry values between before and after exercise training. CONCLUSION: This study showed that VOR parameters changed after 9 weeks of repetitive multiaxial 3-dimensional rotation training, and vestibular habituation might eventually occur. Since vestibular habituation is known to contribute to mitigating the frequency and the degree of motion sickness, we suggest that repetitive multiaxial 3-dimensional rotation training can be used as the countermeasure for student pilots or astronauts, who are often exposed to unusual motion and positional status in actual 3-dimensional space.
Astronauts ; Humans ; Motion Sickness ; Reflex, Vestibulo-Ocular

We investigated the vestibulo-ocular reflex which is followed by the change of angular acceleration in sinusoidal harmonic acceleration test. 20 normal volunteers with no evidence of previous otoneurologic disease were tested. The maximal slow phase eye velocity, gain and asymmetry were obtained in five different amplitudes of rotation, 30degrees, 60degrees, 90degrees, 120degrees and 150degrees with properly fixed conditions such as darkness and the frequency of rotation fixed at 0.05Hz. During each test, we asked the examinees to be alert and keep the eyes open. At least 5 minute interval was given between the tests and recalibrations were done before each test. The results of this test were as follows. 1) The maximal slow phase eye velocities were gradually increased according to the increment of the amplitudes of rotation with the statistical significances(p<0.05). 2) The gains were gradually decreased according to the increment of the amplitudes of rotation between the range of 30degrees and 90degrees with the statistical significances(p<0.05). 3) The asymmetries of each amplitude were the highest(13.6%) at 30degrees and the lowest(6.9%) at 120degrees, but there were no statistical significances(p>0.05). Therefore, from the above results, sinusoidal harmonic acceleration test with the frequency fixed at 0.05Hz, gain is higher when the amplitude of rotation is smaller and the pattern of the nystagmus is more evident when the amplitude of rotation is bigger. But The authors conclude that in order to get the results which are statistically significant, the amplitude of rotation should be lower than 90degrees.
Acceleration* ; Darkness ; Healthy Volunteers ; Reflex, Vestibulo-Ocular*

The results of rotation chair test were known to variable by many parameters such as eye opening and alertness, etc. The situational change in rotation chair test must be considered to interpretation of its result. But in Korea, there were no reports or articles about parameters which influence the result of rotation chair test. So, we assumed that eye opening and alertness were main parameters and took rotation chair test in neurotologically normal subjects. For evaluation of the effect of eye-open or eye-closure and alertness on the rotational vestibular stimulation, we have taken sinusoidal harmonic acceleration test in 30 otoneurologically normal subjects. The maximal slow phase eye velocity, gain and asymmetry were obtained and compared with each other in four different conditions with properly fixed conditions such as in darkness and 0.05Hz frequency. At least five minutes interval was given between the tests and recalibrations were done before each tests. The results of this test were as follows. 1) Vestibular-ocular reflex(VOR) changes according to eye open or closure. In cases of examinees which were given alerting tasks, larger gain was obtained with eyes opened than with eyes closed, and that was statistically significant(p<0.05). In cases of examinees which were not given alerting tasks, larger gain was obtained with eyes opened than with eyes closed, but that was not statistically significant(p>0.05). 2) VOR changes according to alertness. In cases of examinees which opened their eyes, larger gain was obtained with alerting tasks than without alerting tasks, and that was statistically significant(p<0.05). In cases of examinees which closed their eyes, larger gain was obtained with alerting tasks than without alerting tasks, and that was statistically significant(p<0.05). 3) There was no significant changes of asymmetry according to the conditions. Therefore, from above results, we recommend the condition in which examinees open their eyes and be given alerting tasks as one of the optimal condition in sinusoidal harmonic acceleration test.
Acceleration* ; Darkness ; Korea ; Plastics* ; Reflex, Vestibulo-Ocular*

BACKGROUND AND OBJECTIVES: Vestibulo-ocular reflex and vestibulo-spinal reflex are induced by transmatoid galvanic stimulation of vestibular system. Nystagmus and body sway are result of each reflex. Recently, videooculograph possible to record a minute ocular movement was commonly used, vestibulo-ocular reflex induced by galvanic simualtion is easily documented. The purposes of this study are to evaluate the galvanic nystagmus in nomal persons in order to better understand the physiology of the vestibular system. MATERIALS AND METHODS: Eye movement of 20 neurootologic normal subjects by both side transmstoid galvanic stimulation (40cases) were analyzing by videonystagmography. RESULT: The direction of nystagmus in fast phase was to the negative electrode. Galvanic nystagmus was occured all normal subjects when stimulus intensity was more than 2mA. There was positive correlation between slow phase velocity(SPV) and electric current but negative correlation was noted between asymmery of SPV and electric current. CONCLUSION: It is suggested that the galvanic nystagmus test could be a new diagnostic tool for evaluation of vestibular status.
Electrodes ; Eye Movements ; Humans ; Physiology ; Reflex ; Reflex, Vestibulo-Ocular

BACKGROUND: Vestibular reflexes, such as vestibulo-sympathetic reflex, have been considered as an important physiologic mechanism to maintain peripheral vascular resistance in case of orthostatic stress. Vestibular function may play an important role not only in maintaining spatial orientation, but also in determining G-tolerance. The purpose of this study was to investigate the possible contribution of vestibular function to G-tolerance. METHODS: Vestibular function was measured indirectly in 86 subjects by analyzing vestibulo-ocular reflex (VOR) using a rotating chair test. They were also exposed to +6Gz acceleration for 30 seconds with rapid onset run (1 G/sec). After G-exposure, they were classified into the Pass and the G-LOC group according to their success or failure to maintain consciousness during G-exposure. The VOR parameters of the G-LOC group were compared with those of the Pass group. RESULTS: While VOR gain values of one subset of the G-LOC group (low gain G-LOC group, N=8) were significantly lower than those of the Pass group at rotation frequencies of 0.02, 0.04, 0.08, and 0.32 Hz, VOR gain values of the other subset of the G-LOC group (high gain G-LOC group) were significantly higher than those of the Pass group at all rotation frequencies. There was no difference of VOR phase value between the Pass and the G-LOC groups. CONCLUSIONS:This study suggests the vestibular function may be involved in determining G-tolerance. According to VOR gain values, we were able to recognize two distinct G-LOC subgroups compared with the Pass group. The difference between afferent or efferent vestibular flows and target organ response can be a possible explanation for different VOR parameters of G-LOC subgroups.
Acceleration ; Consciousness ; Reflex ; Reflex, Vestibulo-Ocular* ; Unconsciousness* ; Vascular Resistance

To investigate the short-term vestibular responses in the pilots, the 4 successive velocity step tests were done on the 25 pilots, who are in active service in ROKAF (Republic of Korea Air Force), and the obtained results were compared with those of the non-pilots. As the repeated rotations might alter the vestibulo-ocular reflex (VOR), sinusoidal harmonic acceleration (SHA) test at a frequency of 0.16 Hz were also given before and after the 4 successive velocity step tests to investigate the changes of gain and phase of VOR. In the 25 pilots (mean age 31 year), the mean values of the slow cumulative eye position (SCEP), the time integral of eye velocity during nystagmus and time constants were gradually reduced with 4 successive trials. These values were significantly greater than those obtained in the 25 non-pilots. The gain of vestibulo-ocular reflex (VOR) induced by SHA test at a frequency of 0.16 Hz decreased from 0.64+/-0.04 to 0.58+/-0.03 in the pilots, while the VOR gain increased from 0.59+/-0.03 to 0.78+/-0.06 in the non-pilots. However, this result did not indicate that the pilots' gains of VOR were out of normal range. In another SHA tests in which the 30 pilots participated, the gains, phases and the symmetries of VOR lied in the very normal range in every test frequencies (0.01, 0.02, 0.04, 0.08, 0.16, 0.32 Hz). From the above results, it might be suggested that the vestibular responses of the pilots are different with those of the non-pilots.
Acceleration ; Exercise Test ; Korea ; Reference Values ; Reflex, Vestibulo-Ocular

No abstract available.
Humans ; Nystagmus, Pathologic ; Reflex, Vestibulo-Ocular* ; Wernicke Encephalopathy*