Research in Vestibular Science

Sun Young Oh

15 Articles

Diagnosis of Benign Paroxysmal Positional Vertigo: Sun Young Oh; Res Vestib Sci. 2013;12(3):73-78.

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Abstract: Benign paroxysmal positional vertigo (BPPV) is a clinical syndrome characterized by brief recurrent episodes of vertigo triggered by changes in head position with respect to gravity. BPPV is the most common cause of recurrent vertigo, with a lifetime prevalence of 2.4%. In this review article, the diagnosis of BPPV involving the posterior, horizontal and anterior semicircular canal are described.

Initiation of Smooth Pursuit in Acute Cerebellar Infarction: A Preliminary Study: Tae Ho Yang, Sun Young Oh; Res Vestib Sci. 2013;12(2):47-53.

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Abstract: Background and Objectives: The cerebellar lesion causes an initiation deficit of smooth-pursuit eye movement depending on the location of the lesion. We investigated the initiation of smooth pursuit in patients with cerebellar infarction and in healthy subjects, using step-ramp stimuli. Materials and Methods: Ten patients with cerebellar infarction documented by brain magnetic resonance imaging and fifty healthy subjects are recruited. To estimate the initiation of smooth pursuit, the onset latency and initial acceleration during the first 100ms of the horizontal smooth pursuit were estimated using the step-ramp target stimuli (5°/sec, 10°/sec, and 20°/sec). Results: In healthy subjects, onset latency of pursuit was shortened and initial acceleration was increased as target velocity was increasing. In patients with unilateral cerebellar infarction, the onset latency of ipsilesional smooth pursuit was significantly delayed at the target velocities of 10°/sec and 20°/sec. For the fast target velocity of 20°/sec, there was significant decrease of the initial acceleration of contralesional pursuit. Conclusion: In comparison with the healthy subjects, the patients with unilateral cerebellar lesions showed significant delay of pursuit onset and decrease of initial eye acceleration in the fast target velocity. These results support that the cerebellar lesions affect not only steady-state smooth pursuit gain but also the processing time required to initiate smooth pursuit, i.e., onset latency and initial acceleration. More extensive study is needed to confirm the role of cerebellum for parametric adjustment of each component of smooth pursuit.

Ocular Vestibular Evoked Myogenic Potentials Produced by Stimulation With Bone-conducted Vibration in Healthy Subjects: Tae Ho Yang, Sun Young Oh, Tae Woo Kim, Byoung Soo Shin, Jun Young Lee, Seul Ki Jeong, Man Wook Seo; Res Vestib Sci. 2012;11(3):97-104.

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Abstract: Background and Objectives: To provide the empirical basis for using ocular vestibular evoked myogenic potentials (oVEMPs) in response to bone-conducted vibration (BCV) stimulation to indicate vestibular function in normal subjects. Materials and Methods: In response to bone-conducted tone burst (90 dB nHL and 100 dB nHL with frequencies 500 Hz and 1,000 Hz, the oVEMPs were measured in 45 healthy controls. The early negative component (n10) of the oVEMP to brief BCV of the forehead and at each mastoid process is recorded by surface electromyography electrodes just beneath the eyes. We used a hand-held vibrator (Bruel and Kjaer 4810 Mini-Shaker) placed on the forehead, in the midline at the hairline (Fz) and at each mastoid process and quantified the individual differences in n10 magnitude, latency and symmetry to Fz and mastoid BCV at each frequency. Results: In normal subjects, n10 responses were symmetrical in the two eyes during Fz and both mastoid stimuli and the latencies of the onset were consistent among subjects. Response rate is similar between Fz and mastoid stimuli. However, at each stimulation site, response rate is higher on 500 Hz than on 1,000 Hz stimulation. During the mastoid stimuli, the onset latency is slightly shorter and amplitude is larger than the Fz stimuli. The average amplitudes decreased with age and average latency (to peak) increased slightly with increasing age. Conclusion: Clear oVEMP responses to bone-conducted Fz and mastoid stimuli were evoked from normal subjects. It is concluded that bone-conducted stimuli as well as air conduction can evoke myogenic potentials from the ocular muscles.

Pathophysiology of Vestibular Migr: Sun Young Oh, Tae Ho Yang; Res Vestib Sci. 2012;11(3):81-87.

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Abstract: Vestibular migraine (VM) is an increasingly recognized cause of episodic recurrent vertigo. However, the pathophysiology of VM is still a matter of speculation. An understanding of the relationship between migraine and the vestibular system increases knowledge of the pathogenesis of both migraine and vertigo. The pathophysiology of VM has been known to be related to cortical spreading depression, neurotransmitters (i.e., serotonin, noradrenaline, dopamine, calcitonin gene-related peptide) and calcium ion channel disorder. Moreover, VM is related with Meniere's disease, benign paroxysmal positional vertigo, motion sickness, cerebellar dysfunction, or comorbid psychotic disorder. This review refines recently proposed pathophysiological concept for VM and relationships between migraine and other related disorders.

Downbeat, Gaze-evoked and Perverted Head-shaking Nystagmus Associated with Dapsone Toxicity: Tae Woo Kim, Sun Young Oh, Ha Cheol Choi, Byoung Soo Shin, Man Wook Seo, Young Hyun Kim; Res Vestib Sci. 2009;8(2):161-163.

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Abstract PDF: Dapsone is an agent commonly used to treat leprosy and its most common adverse effect is a hemolytic anemia. We present a patient who showed transient downbeat, bilateral horizontal gaze-evoked nystagmus (GEN), and perverted head-shaking nystagmus after taking a large dose of dapsone. These oculomotor abnormalities are assumed to be a reversible vestibulocerebellar dysfunction caused by over-dose of dapsone.

Metronidazole-induced Reversible Cerebellopathy: Ha Cheol Choi, Sun Young Oh, Byoung Soo Shin, Man Wook Seo, Young Hyun Kim; Res Vestib Sci. 2009;8(2):132-136.

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Abstract PDF: Metronidazole is a nitroimidazole antibiotic used for anaerobic infections, protozoan infections, and Helicobacter pylori infections. It may produce rare but well known neurological adverse effects including peripheral neuropathy, encephalopathy, cerebellar dysfunction, and seizures. We describe three patients with metronidazole-induced reversible cerebellar dysfunctions characterized by abnormal oculomotor findings, dysmetria, and ataxia. The diagnosis of metronidazole toxicity was made clinically and supported by the brain MRI findings. The neurological signs and abnormal signal intensity on MRI resolved after discontinuation of metronidazole.

Clinical Features and Treatment Pattern of Migrainous Vertigo in Korea: A Nationwide Prospective Multicenter Study: Seong Ki Ahn, Kyusik Kang, Ja Won Koo, Kyu Sung Kim, Beom Gyu Kim, Byung Kun Kim, Ji Soo Kim, Kyoung Ho Park, Shi Nae Park, Eun Ho Park, Hong Ju Park, Jae Yong Byun, Myung Whan Suh, Ki Bum Sung, Sun Young Oh, Chung Ku Rhee, Tae Kyeong Lee, Seong Hae Jeong, Won Ho Chung, Chang Il Cha, Sung Won Chae, Eui Kyung Goh; Res Vestib Sci. 2009;8(2):122-131.

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Abstract PDF: Background and Objectives It is being increasing recognized that the morbidities of migraine and balance disorders are interrelated. In fact, migrainous vertigo (MV) is one of frequent causes of recurrent vertigo in patients presenting to specialized dizziness clinics. Nevertheless, not many studies have reported clinical manifestations and treatment. Therefore, the aim of study was designed to assess clinical features and treatment patterns by a nationwide multicenter study. Materials and Methods Patients between 9 and 74 years of age who visited 17 Korean tertiary referral centers and 1 clinic from February to March 2009 were investigated using two forms of questionnaires. Results Overall, 318 patients with MV were enrolled. MV was responsible for ~8.45% of visits to the specialized dizziness clinics. One hundred seventy-five of these patients had definite MV and were included in assessing the clinical features. Vertigo characteristics of patients with definite MV were various. Vertigo was regularly as-sociated with headache in 87% of the patients. The duration of vertigo ranged from seconds to days. For the treatment patterns, an acute and prophylactic therapies were carried in most clinics. There were no differences in either acute or prophylactic therapies between department of neurology and otorhinolaryngology. Conclusions The results of this study suggest that MV the clinical features of MV also varies in Korea. In addition, most clinics provide similar patterns of practice in treatment for MV. The syndrome of MV deserves further research activity as it is relatively common and clinically relevant.

Two Cases of Methyl Bromide Intoxication Mimicking Bickerstaff’s Brainstem Encephalitis: Jin Young Seo, Byoung Soo Shin, Man Wook Seo, Young Hyun Kim, Sun Young Oh; J Korean Bal Soc. 2008;7(2):199-203.

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Abstract PDF: Background: Methyl bromide is toxic to the central and peripheral nervous systems. Two patients with occupational exposure to this agent are described. Case: Two cases of previously healthy young men were involved. They had worked in a fumigating plant spraying fruits using methyl bromide for several months before admission. They showed general weakness, severe ataxia, bilateral dysmetria and bilateral lateral gaze limitation. And gaze-evoked nystagmus was observed in one of them. Brain MRI showed symmetrically increased signal intensity lesions including the brainstem, cerebellum and splenium of corpus callosum. After conservative treatment, they gradually improved over the next few weeks. Conclusions: Symmetry and topography of our patients’ clinical and radiographic abnormalities support the proposal that methyl bromide exposure can produce symptoms similar to Bickerstaff’s brainstem encephalitis. Key words: Methyl bromide, Acute intoxication, Bickerstaff’s brainstem encephalitis

Two Cases of Congenital Ocular Motor Apraxia Associated With Cerebellar Vermian Dysplasia: Jin Young Seo, Yeon Hee Lee, Byoung Soo Shin, Man Wook Seo, Young Hyun Kim, Sun Young Oh; J Korean Bal Soc. 2008;7(1):63-67.

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Abstract PDF: Congenital ocular motor apraxia is a rare syndrome characterized by rotational head thrusts that attempt to compensate for the lack of voluntary eye movements. We describe the clinical, oculographic and magnetic resonance imaging features of two children with congenital ocular motor apraxia.

Third Nerve Palsy in Idiopathic Hypereosinophilic Syndrome: Report of Two Cases: Mi Hye Lim, Byoung Soo Shin, Young Hyun Kim, Sun Young Oh; J Korean Bal Soc. 2007;6(2):234-238.

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Abstract PDF: The idiopathic hypereosinophilic syndrome (IHES) is a heterogenous spectrum of disorders, characterized by a long lasting hypereosinophilia without identifiable underlying cause and by the presence of various end-organ dysfunction. The neurologic manifestations of IHES can be encephalopathy, organic psycho syndrome and polyneuropathy and in rare cases polymyositis. Central nervous system involvement is the second mostclinically important complication of the hypereosinophilic syndrome as it is associated with chronic disability and a poor prognosis. In this report, we describe two patients of IHES who presented anisolated third nerve palsy with pupillary involvement and were improved by corticosteroid therapy. They satisfied the criteria of IHES and the third cranial nerve was the only site of neurologic involvement. Early recognition of neurologic involvement in IHES and prompt treatment could lead to good outcome.

Tilt Suppression of the Post-rotatory Nystagmus in Cerebellar Nodular Lesions: Sun Young Oh, Kwang Dong Choi, Jung Eun Kim, Ja Won Koo, Ji Soo Kim; J Korean Bal Soc. 2007;6(2):161-166.

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Abstract PDF: Background and Objectives: Head tilt at the end of step rotation about a vertical axis decreases the time constant (TC) of the post-rotatory nystagmus, which is known as tilt-suppression of the vestibulo-ocular reflex (VOR). Tilt suppression of the VOR is mediated by the cerebellar nodulus and ventral uvula and is eliminated after surgical ablation of those structures. However, studies on the tilt suppression of the VOR have been sparse in humans with cerebellar lesions. Materials and Methods: Five patients with circumscribed cerebellar lesions involving the nodulusor ventral uvula underwent recording of spontaneous and positional nystagmus, and the VOR. To evaluate tilt suppression of the VOR, the participants pitched their head forward at the end of step rotation about a vertical axis both in the clockwise and counter-clockwise directions. Results: The VOR gain was increased in a patient with infarction in the territory of the medial posterior inferior cerebellar artery while the gain of visually enhanced VOR was normal in all the patients. The time constants of perand post-rotatory nystagmus was increased in a patient with increased VOR gain and the tilt suppression of the post-rotatory nystagmus was impaired in two patients, either uni- or bilaterally. Spontaneous downbeat and central positional nystagmus were frequently accompanied. Conclusions: Nodular lesion may impair tilt suppression of the VOR. Measurement of tilt suppressive effect of the VOR may provide a valuable tool for evaluating the nodular dysfunction.

Novel Mutation in FRMD7 Gene in X-linked Congenital Nystagmus: Sun Young Oh, Byoung Soo Shin, Man Wook Seo, Chang Seok Ki, Jeong Min Hwang, Ji Soo Kim; J Korean Bal Soc. 2007;6(2):155-160.

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Abstract PDF: Background and Objectives: Congenital nystagmus (CN) is an ocular oscillation that usually manifests during early infancy. To report a novel mutation in FERM domain containing 7 (FRMD7) gene in a Korean family with CN. Materials and Methods: Genomic DNA was prepared from peripheral blood leukocytes and direct sequencing of the entire coding and adjacent intronic regions was performed to detect sequence variation of FRMD7 gene, where mutations were found recently in patients with familial CN. The family showed an X-linked pattern of inheritance without father-to-son transmission. Results: Three family members with CN exhibited two sequence variations which were a novel mutation (c. 875T>C; Leu292Pro) and a polymorphism (c. 1403G>A; Arg468His, dbSNP rs#6637934). The proband was hemizygous for both variations and his mother and maternal grandmother were heterozygous carriers. Conclusion: This study provides an additional evidence for mutations in FRMD7 as a common cause of X-linked CN and expands its mutation spectrum.

Isolated Positional Downbeat Nystagmus: Central or Peripheral Positional Nystagmus?: Sun Young Oh; J Korean Bal Soc. 2006;5(2):235-241.

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Abstract PDF: Background
and Ojbectives: Nystagmus produced by static placement of the head in different orientations is termed positional nystagmus and in most instances the cause is a peripheral vestibular disorder, as in benign paroxysmal positioning vertigo (BPPV). However, the physiologic basis of the isolated positional downbeat nystagmus has not been fully understood. The goal was to find a possible pathomechanism of dizzy patients who showed isolated positional downbeat nystagmus (pDBN). Materials and Method: Twelve consecutive patients with isolated positional DBN and 50 normal volunteers underwent evaluation of spontaneous, head-shaking and positional nystagmus, smooth pursuit, saccades, and VOR. The patients with focal neurologic signs, abnormal hearing, caloric paresis or acute lesion on brain imaging were excluded.
Results
Positional downbeat nystagmus was developed during lying down, straight head-hanging and/or Dix-Hallpike position. Perverted head-shaking nystagmus was observed in seven patients (58.3%). Gait disturbance revealed in six patients. Other cerebellar manifestations including saccadic dysmetria and gaze-evoked nystagmus were not observed. The gains of VOR were increased than normal controls. However, the gains of visual enhancement and visual cancellation of the VOR were not different from controls and OKN/OKAN were normal. The mean VOR time constants did not differ between patients and normal controls. However, tilt suppression of the post-rotatory nystagmus was impaired in the patients (p<0.01). All patients showed normal findings in head thrust test, caloric response, BAEPs, and brain imaging.
Conclusion
Isolated positional downbeat nystagmus (pDBN) in patients complained intermittent dizziness showed frequently accompanied perverted head-shaking nystagmus (HSN) and increased gain of VOR and impaired tilt suppression. This finding tells us that isolated positional downbeat nystagmus (pDBN) reflects pathologic central nystagmus results from cerebellar (uvulonodular) dysfunction. Key Words : Nystagmus, Positional vertigo, Vestibulo-ocular reflex

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

Convergence-Retraction Nystagmus: Analysis with 3-dimensional Oculography: Ji Soo Kim, Kwang Dong Choi, Sun Young Oh; J Korean Bal Soc. 2005;4(1):5-12.

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Abstract PDF: Background
and Objectives : Convergence-retraction oscillations are rhythmic or arrhythmic jerks of dysjunctive eye movements associated with backward displacement of the eyeballs during the convergence phase. Oscillations in convergence-retraction oscillations have been proposed to be consisted of opposed adducting saccades immediately followed by slow abducting glissades without latency. However, dynamic characteristics of convergence oscillations accompanying retraction have not been studied, and pathomechanism of these eye movements remains to be elucidated. This study was to get insights on the pathomechanisms of convergence-retraction oscillations by using 3-dimensional recording of eye movements. In particular, we intended to clarify whether the nystagmus originates from instability of vergence eye movement or of saccades. Materials and Method : Seven consecutive patients with convergence-retraction oscillations were recruited. All the patients received full neurological and neuro-ophthalmological evaluation by the senior author. Some of the patients underwent 3-dimensional recordings of convergence-retraction oscillations with video-oculography or magnetic search coil technique.
Results
: Wave forms of convergence-retraction oscillations were varied. The onset of convergent eye movements was either synchronous or asynchronous between both eyes. The initial directions of eye movement was same (conjugate) or opposite (disjunctive). In some, vergence eye movements occurred only in one eye (unilateral). Convergence phase of one eye was commonly consisted of multiple steps while the other eye attained final position with a single step. The following divergent eye movements commonly overshoot the orbital midposition and were followed by correcting convergent eye movements. The velocity-amplitude relationship of convergent eye movements, which was analyzed in typical pairs of vergence oscillations, did not differ between both eyes. Divergent eye movements are slower than convergent eye movements. The both convergent and divergent eye movements were slower than the microsaccades of similar amplitudes.
Conclusion
: Quantitative analyses of convergence-retraction oscillations revealed various patterns of wave forms. The amplitude-velocity relationships of the disjunctive eye movements suggest that the slowed saccades may be due to co-contraction of the agonist and antagonist, or due to enhanced vergence eye movements by the accompanying saccades.

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