Research in Vestibular Science

Man-Wook Seo

8 Articles

Two Cases of Myasthenia Gravis Showing Fatigibility Presenting with Decreased Gain of Smooth Pursuit: Ju-Hee Chae, Hyun-June Shin, Byoung-Soo Shin, Man-Wook Seo, Sun-Young Oh; Res Vestib Sci. 2019;18(2):54-58. Published online June 15, 2019; DOI: https://doi.org/10.21790/rvs.2019.18.2.54

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Myasthenia gravis (MG) is an autoimmune disease caused by autoantibodies to the acetylcholine receptors of the neuromuscular junction characterized by weakness and abnormal fatigability of the muscles. Therefore, the diagnosis of MG depends on the recognition of this distinctive pattern of fatigable weakness. Previous studies presented the diagnostic efficacy of saccadic eye movements in patients with ocular MG. We here in report 2 patients of ocular MG showing the fatigue effects during repetitive sustained smooth pursuit, and the effects of the administration of edrophonium on myasthenic smooth pursuit. Changes in smooth pursuits reflecting peripheral and secondary central mechanisms were demonstrated.

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Tracking Eye Movements for Diagnosis in Myasthenia Gravis: A Comprehensive Review
Minh N. L. Nguyen, Anneke van der Walt, Joanne Fielding, Meaghan Clough, Owen B. White
Journal of Neuro-Ophthalmology.2022; 42(4): 428. CrossRef

Visuospatial Dysfunction in Patients With the Right Vestibular Neuritis: Seung-Ho Jeon, Ko-Woon Kim, Hyun-June Shin, Byoung-Soo Shin, Man-Wook Seo, Sun-Young Oh; Res Vestib Sci. 2019;18(1):19-23. Published online March 15, 2019; DOI: https://doi.org/10.21790/rvs.2019.18.1.19

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Abstract PDF

Acute vestibular neuritis (VN) is characterized by acute/subacute vertigo with spontaneous nystagmus and unilateral loss of semicircular canal function. Vestibular system in human is represented in the brain bilaterally with functional asymmetries of the right hemispheric dominance in the right handers. Spatial working memory entails the ability to keep spatial information active in working memory over a short period of time which is also known as the right hemispheric dominance. Three patients (patient 1, 32-year-old female; patient 2, 18-year-old male; patient 3, 63-year-old male) suffered from acute onset of severe vertigo, nausea and vomiting. Patients 1 and 2’s examination revealed VN on the right side showing spontaneous left beating nystagmus and impaired vestibular ocular reflex on the right side in video head-impulse and caloric tests. Patient 3’s finding was fit for VN on the left side. We also evaluated visuospatial memory function with the block design test in these 3 VN patients which discovered lower scores in patients 1 and 2 and the average level in patient 3 compare to those of healthy controls. Follow-up block design test after resolved symptoms showed within normal range in both patients. Our cases suggest that the patients with unilateral peripheral vestibulopathy may have an asymmetrical effect on the higher vestibular cognitive function. The right VN can be associated with transient visuospatial memory dysfunction. These findings add the evidence of significant right hemispheric dominance for vestibular and visuospatial structures in the right-handed subjects, and of predominant dysfunction in the hemisphere ipsilateral to the peripheral lesion side.

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The Differential Effects of Acute Right- vs. Left-Sided Vestibular Deafferentation on Spatial Cognition in Unilateral Labyrinthectomized Mice
Thanh Tin Nguyen, Gi-Sung Nam, Jin-Ju Kang, Gyu Cheol Han, Ji-Soo Kim, Marianne Dieterich, Sun-Young Oh
Frontiers in Neurology.2021;[Epub] CrossRef

원활추종운동 이득감소로 근피로도를 확인한 중증근무력증 2예: Ju-Hee Chae, Hyun-June Shin, Byoung-Soo Shin, Man-Wook Seo, Sun-Young Oh; Received April 9, 2019 Accepted June 3, 2019 Published online June 3, 2019; [Accepted]

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Abstract: Myasthenia Gravis (MG) is an autoimmune disease caused by autoantibodies to the acetylcholine receptors of the neuromuscular junction characterized by weakness and abnormal fatigability of the muscles. Therefore, the diagnosis of MG depends on the recognition of this distinctive pattern of fatigable weakness. Previous studies presented the diagnostic efficacy of saccadic eye movements in patients with ocular MG. We here in report two patients of ocular MG showing the fatigue effects during repetitive sustained smooth pursuit, and the effects of the administration of edrophonium on myasthenic smooth pursuit. Changes in smooth pursuits reflecting peripheral and secondary central mechanisms were demonstrated.

Visuospatial dysfunction in patients with the right vestibular neuronitis: Seung-Ho Jeon, Sun-Young Oh, Ko-Woon Kim, Hyun-June Shin, Byoung-soo Shin, Man-Wook Seo; Received August 3, 2018 Accepted October 1, 2018 Published online October 1, 2018; [Accepted]

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Abstract: Acute vestibular neuritis is characterized by acute/subacute vertigo with spontaneous nystagmus and unilateral loss of semicircular canal function. Vestibular system in human is represented in the brain bilaterally with functional asymmetries of the right hemispheric dominance in the right handers. Spatial working memory entails the ability to keep spatial information active in working memory over a short period of time which is also known as the right hemispheric dominance. Three patients (Pt 1, 32-year-old female; Pt 2, 18-year-old male; Pt 3, 63-year-old male) suffered from acute onset of vertigo. Pt 1 and 2’s examination revealed vestibular neuritis (VN) on the right side showing spontaneous left beating nystagmus and impaired vestibular ocular reflex (VOR) on the right side in video head-impulse and caloric tests. Pt 3’s finding was fit for VN on the left side. We also evaluated visuospatial memory function with the block design test in these three VN patients which discovered lower scores in Pt 1 and 2 and the average level in Pt 3 compare to those of healthy controls. Follow up block design test after resolved symptoms showed within normal range in both patients. Our cases suggest that the patients with unilateral peripheral vestibulopathy may have an asymmetrical effect on the higher vestibular cognitive function. The right VN can be associated with transient visuospatial memory dysfunction. These findings add the evidence of significant right hemispheric dominance for vestibular and visuospatial structures in the right-handed subjects, and of predominant dysfunction in the hemisphere ipsilateral to the peripheral lesion side.

Clinical Significance of Perverted Head-Shaking Nystagmus: Tae-Ho Yang, Byung-Soo Shin, Man-Wook Seo, Sun-Young Oh; Res Vestib Sci. 2017;16(4):119-128. Published online December 15, 2017; DOI: https://doi.org/10.21790/rvs.2017.16.4.119

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Abstract PDF: Objectives
We investigated clinical significance of head shaking nystagmus (HSN) and perverted HSN (pHSN) in patients with peripheral and central vestibular disorders. Methods: We reviewed medical records of 822 consecutive subjects who were referred to a dizziness clinic. We performed neurologic examination including video-oculography in darkness for 60 seconds before, during and for 100 seconds after head-shaking. HSN was considered to develop when post-head-shaking nystagmus last at least 5 beats with latency from end of head-shaking of no more than 5 seconds, and a velocity at least 3°/sec. Results: In control group (n=45), there were observed spontaneous nystagmus (SN) in 2.2%, HSN in 17.8%, pHSN in 6.7%. In patients with peripheral vestibular disorder group (n=397), there were observed SN in 14.1%, HSN in 40.6%, pHSN in 9.8%. In patients with central vestibular disorder group (n=217), there were observed SN in 17.5%, HSN in 24.0%, pHSN in 13.4%. In unspecified dizziness group (n=208), there were observed SN in 1.9%, HSN in 13.0%, pHSN in 1.9%. pHSN was frequently observed in central vestibular disorders such as stroke, vestibular migraine, cerebellar ataxia, and vertebro-basilar insufficiency. However, pHSN was also observed at higher rate than expected in peripheral vestibular disorders including benign paroxysmal positional vertigo especially involving vertical canals, Meniere disease and even in unilateral vestibulopathy. Conclusions: Our results show that perverted HSN in dizzy populations was frequently observed not only in cases of central vestibular disorders but also in peripheral disorders. Perverted HSN can develop by any conditions that cause difference in vestibular velocity storage in vertical component of vestibular-ocular reflex.

Brain Hypometabolism in Cerebellar Ataxia, Neuropathy, Vestibular Areflexia Syndrome: Byoung-Min Jeong, Byoung-Soo Shin, Man-Wook Seo, Ji-Yun Park, Hwan-Jeong Jeong, Sun-Young Oh; Res Vestib Sci. 2017;16(4):156-160. Published online December 15, 2017; DOI: https://doi.org/10.21790/rvs.2017.16.4.156

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Abstract PDF: Cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS) is a slowing progressive ataxic disorder characterized by bilateral vestibulopathy, cerebellar ataxia and somatosensory impairment. Autonomic dysfunction is recently considered as a core feature in CANVAS in addition to these symptoms. In most cases, patients with CANVAS show cerebellar atrophy in brain imaging, but some cases show minimal or no atrophy of cerebellum. Brain (18F)-fluoro-2-deoxy-D-glucose positron emission tomography (¹⁸F-FDG PET) study can be a complimentary tool to diagnosis CANVAS in cases of no structural abnormality such as cerebellar atrophy. Hereby, we present a case of CANVAS with minimal atrophy of cerebellum but showing a prominent hypometabolism in cerebellum, thalamus and posterior cingulate cortex in ¹⁸F-FDG PET.

Four Cases of Wernicke’s Encephalopathy with Impaired Horizontal Vestibular Ocular Reflexes: Hyuk-Su Jang, Byoung-Soo Shin, Man-Wook Seo, Sun-Young Oh; Res Vestib Sci. 2017;16(2):57-63. Published online June 15, 2017; DOI: https://doi.org/10.21790/rvs.2017.16.2.57

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Abstract PDF: Wernicke’s encephalopathy (WE) is a neurological disorder induced by a dietary vitamin B1 (thiamine) deficiency which is characterized by encephalopathy, gait ataxia, and variant ocular motor dysfunction. In addition to these classical signs of WE, a loss of the horizontal vestibulo-ocular reflex (VOR) is being reported as the major underdiagnosed symptoms in WE. In this retrospective single center study, we report four cases of WE initially presented with impaired horizontal VOR in addition to the classical clinical presentations, and imaging and neurotological laboratory findings were described.

Four Cases of Wernicke’s Encephalopathy with Impaired Horizontal Vestibular Ocular Reflexes: Hyuk su Jang, Sun-Young Oh, Byoung-Soo Shin, Man-Wook Seo; Received April 24, 2017 Accepted June 2, 2017 Published online June 2, 2017; [Accepted]

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Abstract: Wernicke's encephalopathy (WE) is a neurological disorder induced by a dietary vitamin B1 (thiamine) deficiency. It is characterized by encephalopathy, gait ataxia, and some variant of oculomotor dysfunction which are the classic triad of WE. However, a complicating factor of WE identification may not be associated with the classical clinical triad in up to 90% of patients. In recent years, a loss of the horizontal vestibulo-ocular reflex (VOR) is being reported as the major underdiagnosed symptoms in WE. In this retrospective single center study, we describe four cases of WE presented mainly impaired horizontal VOR in addition to the classical clinical presentations, and imaging and neurotological laboratory findings were described.

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