Research in Vestibular Science

Case Reports

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.

Citations

Citations to this article as recorded by

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

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.

Original Articles

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.

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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