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Original Articles
- Influence of Head Position in Rotation Test
- Jeong Seok Choi, Jae Eun Kim, Kyu Sung Kim, Hoseok Choi
- Res Vestib Sci. 2011;10(2):52-55.
- 1,681 View
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Abstract
PDF - Background and Objectives: Rotation test is a widely used method to evaluate the function of the vestibular system. Generally, the head position to be tilted forwards 30° during rotation is preferred in order to bring the horizontal semicircular canals into the plane of rotation, thus ensuring maximum response. However literatures do not provide a clear reference concerning head position during the rotation test. So, we evaluated the vestibuloocular reflex (VOR) induced by sinusoidal rotation in the horizontal plane in the two different head positions: the head tilted forward 30° and with the head upright. Materials and Methods: A total of 20 men with no known neuro-otological disorders and 9 guinea pigs were studied. The rotations of slow harmonic acceleration on various frequencies were performed with the subject’s head in the upright position and in the 30 pitched down position. Computerized electronystagmography in human and magnetic coil in guinea pigs were used to measure the maximum velocity of slow component of horizontal nystagmus and to calculate gain, phase and symmetry of VOR responses. Results: In both groups, results showed no significant differences in gain, phase and symmetry. Conclusion: In the two different head positions, there were no significant differences in gain, phase and symmetry. The posture of head upright is more comfortable for the patient and gives enough response for the evaluation of vestibular function.
- Head Position Dependency of Induced Nystagmus to Ice Water Irrigation in peripheral vestibulopathy
- Byung Yoon Choi, Ja Won Koo, Seung Ha Oh, Sun O Chang, Chong Sun Kim
- J Korean Bal Soc. 2003;2(2):175-180.
- 1,746 View
- 8 Download
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Abstract
PDF
- Background
s and Objectives: The direction of caloric nystagmus depends on the head position as long as vestibular function is remaining but the it does not depend on head position change in the lateral semicircular canal (SCC) plugged ear, which is attributed to thermoconvection in the lateral SCC. So determination of head position dependency using ice water test is recommended in the evaluation of peripheral vestibulopathy in which dead labyrinth is suspected. Since ice water test in prone position is frequently skipped and neglected in many vestibular laboratories, we investigated the importance and necessity of evaluating head position dependency for the candidates of ice water test and estimated the amount of head position non-dependent component in discussion. Materials and method: From January through September 2003, 25 patients, who showed no nystagmus during warm irrigation, were included in this study. Following forty milliliter of ice water irrigation in supine & prone position, the maximum slow phase eye velocity (SPEV) and direction of nystagmus were assessed using video nystagmography system.
Result
Eleven cases showed head-position dependency and were interpreted as hypofunction of lateral SCC. Fourteen cases did not show head position dependency suggesting the absence of end organ function. However, in the latter group, 6 patients, who showed definite nystagmus to ice water irrigation in supine position, can be midinterpreted as hypofunction if ice water test in prone position is not performed.
Conclusion
Evaluation of head position dependency in ice water irrigation is an important procedure in the determination of lateral SCC function and can provide valuable information when vestibular ablative procedures are considered.
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