Research in Vestibular Science

Original Articles

Difference of Cervical Vestibular Evoked Myogenic Potentials between Bone-Conduction and Air-Conduction in Patients with Nonspecific Dizziness: Yong-Hwi An, Jung Ho Choi, Seung Yeon Jeon, Hyun Joon Shim; Res Vestib Sci. 2022;21(4):93-98. Published online December 15, 2022; DOI: https://doi.org/10.21790/rvs.2022.21.4.93

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Abstract PDF: Objectives
This study was performed to evaluate the difference of the cervical vestibular evoked myogenic potentials (cVEMP) stimulated by bone-conduction (BC) and air-conduction (AC) in patients with nonspecific dizziness.
Methods
Twenty-eight dizzy patients (56 ears) and 15 subjects (30 ears) as normal control was enrolled. Responses of BC- and AC-cVEMP were recorded sequentially in both groups. cVEMP parameters including latencies, inter-latencies intervals, amplitudes, and interaural amplitude asymmetry were analyzed and compared.
Results
Among the patients with nonspecific dizziness, AC-cVEMP responses were clearly detected in all 56 ears while BC-cVEMP responses were detected in 32 ears (57.1%). Amplitudes of BC-cVEMP were significantly smaller than those of AC-cVEMP in all patients with BC-cVEMP response. There was no difference in latencies, inter-latencies intervals, and interaural amplitude asymmetry ratios between BC- and AC-cVEMP. There was no significant difference in BCand AC-cVEMP between the dizzy and control groups.
Conclusions
BC-cVEMP is not clinically useful in comparison to AC-cVEMP for the evaluation of nonspecific dizziness. An effective stimulation tool for BC is necessary to provoke more reliable responses of BC-cVEMP.

Effect of Korean Red Ginseng on Early Vestibular Function Restoration after Unilateral Labyrinthectomy: Jiyeon Lee, Mi Joo Kim, Gyu Cheol Han; Res Vestib Sci. 2020;19(3):79-88. Published online September 15, 2020; DOI: https://doi.org/10.21790/rvs.2020.19.3.79

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Abstract PDF: Objectives
Vertigo is a common condition. Definitive treatment is to induce vestibular compensation. Currently, no medications have been discovered that enhance vestibular functional restoration. The current study was conducted to evaluate the ability of ordinary Korean red ginseng (KRG) to induce vestibular compensation.
Methods
Twelve Sprague-Dawley rats were divided into two groups. Five rats (KRG group) were fed KRG extract (100 mg/kg) for 2 weeks before undergoing unilateral labyrinthectomy (ULx). The remaining seven rats (control group) were untreated before ULx. After surgery, all animals were housed in the same environment without being fed additional extract. To evaluate vestibular function, gain of the horizontal nystagmus to 0.2 Hz with a peak velocity of 100°/second sinusoidal rotation was compared and analyzed before ULx as well as 3 and 7 days after surgery.
Results
Before the operation, gain of the control and KRG group were 0.81±0.05 and 0.88±0.08, respectively, with 0.2-Hz stimulation. This value decreased to 0.43±0.08 and 0.53±0.08, respectively on 3 days after operation (p=0.047), and it was 0.40±0.06 and 0.68±0.11, respectively on 7 days after surgery. The difference of gain between the two groups was statistically significant at each 3 and 7 days (p＜0.05). By confirming c-Fos protein expression in medial vestibular nuclei, the functional effect of KRG causing vestibular modulation was confirmed.
Conclusions
Rats treated with KRG showed more rapid and complete recovery after acute vestibular loss compared to untreated animals. Therefore, KRG could be one of candidate for the useful medication of vestibular diseases.

Reviews

Vestibular Rehabilitation after Traumatic Head Injury with Dizziness: Sung Kyun Kim, Seok Min Hong; Res Vestib Sci. 2019;18(2):32-37. Published online June 15, 2019; DOI: https://doi.org/10.21790/rvs.2019.18.2.32

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Abstract PDF: The vestibular symptoms such as dizziness and imbalance that occurred after traumatic head/brain injury were caused by a combination of central factors such as abnormalities of white matter, diffuse axonal injury and microhemorrhage, and peripheral factors like decreased vestibulo-ocular reflex caused by the energy transmitted to the semicircular canal and otolith organs. These symptoms can affect on the patient's overall physical, cognitive, emotional, and quality of life. There have been reports that vestibular rehabilitation for the treatment of dizziness and imbalance after head trauma can promote vestibular compensation, stabilize of the gaze movements, and also affect the treatment outcomes of the associated injuries. The frequency, duration, and number of people participating in vestibular rehabilitation varied with each study, and physical therapy, occupational therapy, cognitive counseling, medication treatment, duration of treatment for associated injuries were also variable. Most studies have shown that many patients who get the vestibular rehabilitation have a significantly reduced time to return to work and sports activities, and may be able to speed up the recovery of vestibular symptoms. However, further research is needed on its long-term effects. In addition, patients with traumatic head/brain injuries are more susceptible to injuries of other organs as well as vestibular disorders, therefore consideration of treatment planning for associated injuries including precise evaluation mental support, and cognitive therapy is expected to be more effective with vestibular rehabilitation therapy.

Vestibular Histopathology in Temporal Bone: Sung Il Nam; Res Vestib Sci. 2018;17(4):130-133. Published online December 21, 2018; DOI: https://doi.org/10.21790/rvs.2018.17.4.130

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Abstract PDF: There are a number of reports on the pathologies of vestibular disorders. However, these studies included only a few examples, which were not quantitative but merely anecdotal or descriptive. However, a single tissue section may be relevant to a specific disease in multiple ways. The histopathological characteristics of common peripheral vestibulopathies, including benign paroxysmal positional vertigo, Ménière’s syndrome, labyrinthitis, vestibular neuritis, and ototoxicity, have been described. A recent study validated a new quantitative method for determining vestibular otopathology. Detailed quantitative analyses of vestibular pathology are required to obtain a deeper understanding of the vestibular system. Such studies will likely reveal the pathophysiological causes of specific diseases by elucidating the correlations between structural and functional features. Therefore, histopathological studies of vestibular disorders should be performed.

Case Report

Spontaneous Recovery of Vestibulo-Ocular Reflex Gain after Bilateral Complete Vestibular Loss Following Head Injury: Ga Young Park, Eun Wook Chung, Jong Sei Kim, Won Ho Chung; Res Vestib Sci. 2012;11(4):146-153.

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Abstract: Dizziness is a frequent complication of head injury and objective evidence of vestibular dysfunction in the dizzy patient following head injury has been reported in literatures. However, there is no report about bilateral spontaneous recovery of caloric response after complete loss of bilateral vestibular function following head injury. A 27-year-old male patient who presented with continuous dizziness and disequilibrium following head injury was diagnosed as diffuse axonal injury after brain magnetic resonance image and bilateral complete loss of vestibular function after caloric and rotary chair test. He showed gradual improvement of dizziness, vestibulo-ocular reflex gain and left caloric response at 2 months after vestibular exercise. After another 4 months, his caloric function was fully recovered, and dizziness disappeared at 16 months after the onset of dizziness. We present this case with reviews of previous literatures about dizziness following head injury and diffuse axonal injury.

Central Vertigo in Non-vascular Disease: Sang Ho Hwang, Keun Su Kim; Res Vestib Sci. 2010;9:128-132.

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Abstract PDF: Vertigo, defined as an illusion f the movement, always indicates an imbalance within the vestibular system. The same sensation can result from lesions in such diverse locations as the inner ear, the visual-vestibular interaction centers in the brainstem and cerebellum, or the subjective sensation pathways of the thalamus or cortex. While vascular disorders are most common causes of central vertigo, a wide variety of diseases can be causes of non-vascular central vertigo including tumor, multiple sclerosis, cerebellar ataxia syndromes, epilepsy, and migraine. The clinical manifestation and differential diagnosis of cerebellar ataxia, vestibular epilepsy and vestibular migraine will be discussed in detail.

Original Articles

Changes of Vibration-Induced Nystagmus by Age in Normal Subjects: Yong Soo Jung, Hong Ju Park, Jung Eun Shin, Jae Yoon Ahn, Ga Hyun Park, Hi Boong Kwak, Yeo Jin Lee, Jin Seok Yoo; J Korean Bal Soc. 2007;6(2):186-191.

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Abstract PDF: Background and Objectives: It has been reported that vibration applied either on the mastoid or on the sternocleidomastoid (SCM) muscles induces nystagmus in normal subjects. The aims of the study were to characterize the direction and velocity of slow-phase eye movement which is induced by vibration in normal subjects and to propose the mechanism of vibration-induced nystagmus (VIN) in normal subjects. Materials and Method: We recorded eye movements during unilateral 100-Hz vibration on the mastoid bone and SCM muscles in 56 normal subjects. The subjects were divided into 4 groups in ages (20s, 30s, 40s, 50~60s). The directions of VIN, the degree of maximal slow-phase eye velocities were analyzed according to age. Positive value means slow-phase velocity (SPV) to the right side. Results: In 20s, vibration on right/left mastoids induced SPV of 1.2±2.0°/sec, 0±2.1°/sec and on right/left SCM muscles, 1.1±1.9°/sec, -1.2±2.5°/sec. In 30s, vibration on right/left mastoids induced SPV of 3.3±3.8°/sec, -0.3± 1.4°/sec and on right/left SCM muscles, 2.8±4.2°/sec, -1.0±1.5°/sec. In 40s, vibration on right/left mastoids induced SPV of 0±1.7°/sec, -0.2±1.2°/sec and on right/left SCM muscles, 0±1.8°/sec, 0±1.0°/sec. In 50~60s, vibration on the right/left mastoids induced SPV of -1.3±1.3°/sec, 1.2±1.3°/sec and on right/left SCM muscles, -0.6±0.9°/sec, 0.9 ±1.5°/sec. The directional preponderance of the slow-phase eye movement to the vibrated side was statistically significant in 20s and 30s, however, the preponderance of the slow-phase eye movement changed into the non-vibrated side in 50~60s. Conclusion: The proprioceptive input, changing major rotator from the inferior oblique muscle to the sternocleidomastoid muscles might explain the change of the directional preponderance of the slow-phase eye movements in normal subjects according to ages. Although this directional preponderance is not consistent in all age groups, it is still important in discriminating normal responses from abnormal responses which can be induced by vibration.

Role of the Peripheral Vestibular System on Neuroplasticity Induced by Hypergravity Stimulation: Jae Hyo Lee, Gyoung Wan Lee, Han Su Park, Jae Hee Lee, Dong Ok Choi, Myoung Ae Choi, Byung Rim Park; J Korean Bal Soc. 2006;5(2):213-223.

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Abstract PDF: Background
and Objectives: Altered environmental gravity, including both hypo- and hypergravity, may result in space adaptation syndrome. To explore the characteristics of this adaptive plasticity, the expression of immediate early gene c-fos mRNA in the vestibular system following an exposure to hypergravity stimulus was determined in rats. Materials and Method: The animals were subjected to 2 G force (two-fold earth's gravity) stimulus for 3 hours, and were examined at post-stimulus hours 0, 2, 6, 12, and 24. Real time reverse transcription-polymerase chain reaction (RT-PCR) was adopted to analyze temporal changes in the expression of c-fos mRNA.
Results
The hypergravity stimulation produced the expression of c-fos mRNA in the vestibular ganglion, medial vestibular nucleus, inferior vestibular nucleus, hippocampus, vestibulocerebellum, and vestibular cortex. The peak expression occurred at hour 6 in the animals hypergravity-stimulated for 3 hours. Bilateral labyrinthectomy significantly attenuated the degree of up-regulation in c-fos mRNA expression. MK-801, an NMDA receptor antagonist, also significantly attenuated the degree of up-regulation in c-fos mRNA expression.
Conclusion
These results indicate that the adaptive neuroplasticity in response to an altered gravity occurs in the vestibular-related organs in the central nervous system, in which peripheral vestibular receptors and NMDA receptors play an important role. Key Words : Hypergravity, Neuronal plasticity, Vestibule, c-fos gene

A Promotive Effect of Low Level Laser on Hair Cell Viability in Postnatal Organotypic Culture of Rat Utricles: Sun Young Oh, Kwang Dong Choi, Jae Moon Kim, Jei Kim, Seong Ho Park, Ji Soo Kim; J Korean Bal Soc. 2006;5(1):35-43.

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Abstract PDF: Background
and Objectives: To culture and maintain mammalian hair cells is still a big challenge. In this study, long-term organotypic culture of rat utricular maculae was established to study vestibular hair cell. The effects of low level laser on hair cell viability in postnatal organotypic culture of rat utricles were investigated. Materials and Method: Uticular explants were prepared from postnatal 2 to 7 rats and cultured. To improve hair cell survival, the utricles were irradiated daily with low level laser. Whole-mount utricles were stained with FM1-43 which is known to be an efficient marker to identify live hair cells in cultured tissues. Such cells visualized directly through tissue culture dish with cover glass bottom by Confocal laser scanning microscope at specific time points.
Results
The explanted utricular hair cells were cultured for up to 31 days in in vitro culture system. In low level laser irradiation group, utricular hair cells were more survived at 24 DIV and 31 DIV.
Conclusion
These results suggest that low level laser promotes hair cell viability in utricular explants. Key Words : Organotypic culture, Low level laser, FM 1-43, Utricle

Morphologic Change of the Vestibular Organ in the Na+-K+-2Cl- Cotransporter Deficiency Mouse: Ju Hyoung Lee, Jae Young Choi, Sang Ho Jung, Won Sang Lee; J Korean Bal Soc. 2006;5(1):21-28.

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Abstract PDF: Background
and Objectives: The Na+-K+-2Cl- cotransporter-1 (NKCC1) is a member of the cation-coupled chloride transporter that participates in salt transport and cell volume regulation in diverse tissues. NKCC1 deficient mice exhibit deafness, and have structural alterations in the cochlea. In addition to hearing loss, NKCC1-deficient mice show a shaker-waltzer behavior, which suggests a vestibular system defect. This study investigated the morphology of the vestibular system of NKCC1-deficient mice. In addition, this study evaluated whether NKCC1 mRNA and its protein are expressed in human vestibular end organs. Materials and Method: NKCC1-deficient and wild type mice aged 4~5 weeks were sacrificed. Their heads were cut in the midsagittal plane, fixed and decalcified. For light microscopy, 5 m sections were cut, and stained with hematoxylin and eosin. Human vestibular end organs were harvested during acoustic tumor surgery via translabyrinthine approach. Some of these end organs were used for the total mRNA extraction and the remainder was used for immunostaining. RT-PCR was performed for NKCC1.
Results
The scala media of the cochlear of the NKCC1-deficient mice were collapsed but the bony labyrinth of the cochlea appeared unaffected. However, the semicircular canals (SCCs) were much smaller than those in the wild type. Furthermore, the SCCs were completely missing in some NKCC1-deficient mice. NKCC1 mRNA was expressed in both human macula and crista ampullaris and its protein was expressed mainly in the transitional and dark cell area of the human crista ampullaris.
Conclusion
NKCC1 may be essential for maintaining the vestibular morphology and its function in mice and NKCC1 is well expressed in human vestibular end organs. Key Words : Ion transport, Vestibule, Knockout mouse

Reviews

The Optimization of Galvanic Vestibular Stimulation according to Evoked Nystagmus: Gyu Cheol Han, Dong Kyu Kim, Ju Hyoung Lee, Chang Hyoun Cho, Dong Young Kim, Heung Eok Cha; J Korean Bal Soc. 2004;3(2):386-394.

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Abstract PDF: Background
and Objectives : The aim of this study were to observe the nystagmus of normal general populations on galvanic vestibular stimulation, to set a new korean standard for galvanic vestibular stimulation. Materials and Method : We recruited 10 healthy adults and they were stimulated by 1,2,3 mA monaural monopolar, monaural bipolar, binaural monopolar, binaural bipolar galvanic vestibular stimulation through carbon-rubber electrode and Ag-AgCl electrode. We evaluated galvanic stimulating nystagmus and after galvanic stimulating nystagmus on sitting position through Frenzel goggle and video-nystagmography.
Results
: We detect stimulating and after-stimulating nystagmus on 1,2,3 mA monaural monopolar, monaural bipolar, binaural monopolar, binaural bipolar galvanic vestibular stimulation. The nystagmus on galvanic vestibular stimulation was directed to the negative electrode side and after-galvanic stimulating nystagmus was directed to opposite side. The greater current, the more occurrence of nystagmus was found. We detect nystagmus mostly on monaural bipolar vestibular stimulation through carbon-rubber electrode. We thought most effective Galvanic vestibular stimulation was 2 mA monaural bipolar vestibular stimulation through carbon-rubber electrode in consideration of increased pain and discomfort on 3 mA monaural bipolar vestibular stimulation in spite of high occurrence of nystagmus.
Conclusion
: Galvanic vestibular stimulation evoked different nystagmus according to stimulation, stimulated site. We thought 2 mA monaural bipolar vestibular stimulation through carbon-rubber electrode was most effective, stable galvanic stimulation. Specifity and sensitivity of 2 mA monaural bipolar vestibular stimulation were 100%, 100% respectively. Galvanic vestibular stimulation is useful to evaluate vestibular function.

Comparison of Vestibule-ocular Reflex of Eccentric Rotation with Centric Rotation in Normal Subjects: Byung Han Cho, Seung Yeun Jang, Ho Suk Choi, Seung Chul Lee, Kyu Sung Kim; J Korean Bal Soc. 2004;3(2):351-335.

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Abstract PDF: Background
and Objectives : Conventional vestibular rotation testing with the head centered on the axis stimulates the semicircular canals evoking compensatory eye movements. By placing subjects off from the axis of rotation, the otolithic organ may also be simultaneously stimulated by additional linear acceleration forces. In the present study, we compared the rotation with subjects placed on axis to those placed in an eccentric position. Materials and Method : In the eccentric rotation, the head of subject was facing outward and placed eccentrically for 33cm on naso-occipital axis. Slow harmonic acceleration test and velocity step test were performed.
Results
: The sinusoidal eccentric rotation at 0.32, 0.64 Hz produced a significantly higher vestibulo-ocular reflex gain than did on axis rotation. In velocity step test, initial slow component velocity was significantly higher in eccentric rotation than in centric rotation.
Conclusion
: These finding suggest that the gain enhancement due to eccentric rotation is a result of tangentiallinear acceleration, probably sensed by the otolithic organ. This study raises the possibility of using eccentric rotation for the diagnosis of the patients with otolithic dysfunction.

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