Research in Vestibular Science

Horizontal nystagmus with velocity-increasing waveforms in delayed post-hypoxic leukoencephalopathy: a case report: Eugene Jung, Suk-Min Lee, Seo-Young Choi, Kwang-Dong Choi; Res Vestib Sci. 2024;23(3):111-113. Published online September 15, 2024; DOI: https://doi.org/10.21790/rvs.2024.016

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Abstract PDF Supplementary Material: Abnormal eye movements in unconscious patients serve as crucial diagnostic instruments, offering insights into the function of the central nervous system. Understanding these movements can aid in diagnosing the cause of unconsciousness, localizing brain lesions, and predicting outcomes. We report a patient who presented with spontaneous horizontal nystagmus unaffected by light in delayed post-hypoxic encephalopathy. Video-oculography showed exponentially increasing slow phases, with an amplitude ranging from 3° to 9° and a frequency of 0.5 Hz. Based on the results of oculography and neuroimaging, persistent horizontal nystagmus in our patient may be ascribed to an unstable neural integrator, possibly caused by disrupted cerebellar feedback mechanisms for horizontal gaze holding.

Fluctuating high-frequency hearing loss with vertigo: is it Menière’s disease? A case report: Minho Jang, Dong-Han Lee, Jiyeon Lee, Chang-Hee Kim; Res Vestib Sci. 2024;23(3):106-110. Published online September 15, 2024; DOI: https://doi.org/10.21790/rvs.2024.011

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Abstract PDF Supplementary Material: This study describes an unusual case of fluctuating unilateral high-frequency hearing loss with vertigo resembling Menière’s disease. The current diagnostic criteria for definite Menière’s disease include audiometrically documented low- to medium-frequency sensorineural hearing loss on at least one occasion before, during, or after an episode of vertigo. This case presented a diagnostic dilemma. Brain MRI was nonspecific, and a bithermal caloric test showed unilateral weakness of 44% on the affected side. The results of electrocochleography and cervical vestibular evoked myogenic potential tests were within the normal ranges. Persistent geotropic or ageotropic positional nystagmus was observed during each vertigo attack; the mechanism underlying this characteristic nystagmus needs further investigation.

Smartphones versus goggles for video-oculography: current status and future direction: Pouya Barahim Bastani, Shervin Badihian, Vidith Phillips, Hector Rieiro, Jorge Otero-Millan, Nathan Farrell, Max Parker, David Newman-Toker, Ali Saber Tehrani; Res Vestib Sci. 2024;23(3):63-70. Published online September 15, 2024; DOI: https://doi.org/10.21790/rvs.2024.009

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Abstract PDF: Assessment of eye movements is the cornerstone of diagnosing vestibular disorders and differentiating central from peripheral causes of dizziness. Nonetheless, accurate assessment of eye movements is challenging, especially in the emergency department and primary care settings. To overcome this challenge, clinicians objectively measure eye movements using devices like video-oculography (VOG) goggles, which provide a video recording of the eye and quantified eye position traces. However, despite the value of VOG goggles in studying eye movements, barriers such as high prices and the need for dedicated operators have limited their use to subspecialty clinics. Recent advancements in the hardware and software of smartphones have positioned them as potential alternatives to VOG goggles that can reliably record and quantify eye movements. Although currently not as accurate as VOG goggles, smartphones can provide a cheap, widely available tool that can be used in various medical settings and even at home by patients. We review the current state and future directions of the devices that can be used for recording and quantifying eye movements.

Arnold-Chiari Malformation Presented with Spontaneous Down-Beating Nystagmus and Gait Disturbance: Minbum Kim, Youn Jin Cho; Res Vestib Sci. 2023;22(4):132-136. Published online December 15, 2023; DOI: https://doi.org/10.21790/rvs.2023.22.4.132

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Abstract PDF Supplementary Material: Arnold Chiari malformation is a disease which is characterized by herniation of a portion of the cerebellum through the foramen magnum. Symptoms vary depending on the extent of the affected area, including posterior neck pain, upper limb pain, paralysis, paresthesia, weakness, dizziness, and ataxia. Among the patients presenting with dizziness, nystagmus is frequently observed, which is primarily characterized by down-beating nystagmus. We experienced a 42- years-old female patient presented with vertigo and gait disturbance, who were diagnosed with type 1 Arnold-Chiari malformation and treated by surgical decompression.

A Comparative Analysis of the Vestibulocochlear Function in Patients with Isolated Semicircular Canal Hypofunction Using a Video Head Impulse Test: Yu Jung Park, Min Young Lee, Ji Eun Choi, Jae Yun Jung, Jung Hwa Bahng; Res Vestib Sci. 2023;22(2):34-45. Published online June 15, 2023; DOI: https://doi.org/10.21790/rvs.2023.22.2.34

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Abstract PDF: Objectives
The objective of this study was to analyze vestibulocochlear function results in patients identified with isolated semicircular canal (SCC) hypofunction using the video head impulse test (vHIT).
Methods
A retrospective review was conducted on the clinical records of 123 patients diagnosed with isolated SCC hypofunction based on vHIT results. Among these patients, 72 had isolated posterior SCC (PSCC) hypofunction, 25 had isolated lateral SCC (LSCC) hypofunction, and 26 had isolated anterior SCC (ASCC) hypofunction. Descriptive analyses were performed on various vestibulocochlear tests including pure tone audiometry, sinusoidal harmonic acceleration (SHA), spontaneous nystagmus (SN), head-shaking nystagmus (HSN), caloric testing, and cervical vestibular evoked myogenic potential, with results analyzed separately for each SCC hypofunction group.
Results
The study found that 66.0% of the evaluated patients exhibited abnormal results in at least one vestibulocochlear function test. PSCC hypofunction patients showed a significantly higher incidence of hearing loss compared to ASCC and LSCC hypofunction patients. LSCC hypofunction patients exhibited higher rates of corrective saccade, phase asymmetry of SHA, and SN abnormalities compared to other SCC hypofunction patients. Additionally, the rates of corrective saccade and phase asymmetry of SHA were also higher in LSCC hypofunction patients. ASCC hypofunction patients demonstrated significantly higher rates of normal corrective saccade, phase lead of SHA, and SN.
Conclusions
The analysis of this study suggests that even in cases where vHIT indicates isolated SCC hypofunction, additional vestibulocochlear function tests should be conducted to identify any associated vestibulocochlear dysfunctions. This highlights the importance of comprehensive evaluation to accurately diagnose and manage patients with SCC hypofunction.

Light Cupula: Recent Updates: Dong-Han Lee, Chang-Hee Kim; Res Vestib Sci. 2023;22(2):23-33. Published online June 15, 2023; DOI: https://doi.org/10.21790/rvs.2023.22.2.23

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Abstract PDF: Benign paroxysmal positional vertigo (BPPV) is the most common cause of positional vertigo and nystagmus. Direction-changing positional nystagmus (DCPN), which refers to the change in the direction of nystagmus with different head positions, is a well-known characteristic of horizontal semicircular canal BPPV. The supine head roll test is commonly used to diagnose horizontal canal BPPV. However, persistent geotropic DCPN observed during this test cannot be explained by conventional mechanisms of canalolithiasis or cupulolithiasis. The concept of a “light cupula” has been proposed to account for this unique nystagmus. In this review, we summarize the historical background, clinical features and diagnostic methods, presumed mechanisms, and treatment approaches of the light cupula phenomenon based on the available literatures up to date.

Visual Fixation-Induced Hemi-Seesaw Nystagmus: Hyun Sung Kim, Eun Hye Oh, Jae-Hwan Choi; Res Vestib Sci. 2023;22(1):19-22. Published online March 13, 2023; DOI: https://doi.org/10.21790/rvs.2023.22.1.19

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Abstract PDF Supplementary Material

Seesaw nystagmus (SSN) is characterized by conjugate torsional nystagmus with opposite vertical components in the two eyes. The waveform may be pendular or jerk (hemi-seesaw nystagmus, HSSN), in which the slow phase corresponds to one half-cycle and the quick phase to the other. Pendular SSN and HSSN have distinct clinical presentations and underlying causes. The pathophysiology of pendular SSN may be instability of visuovestibular interactions, while the underlying mechanism for HSSN may be related to the ocular tilt reaction or an imbalance in vestibular pathways. We report a patient with HSSN due to unilateral mesodiencephalic infarction that becomes apparent during visual fixation only.

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Midbrain lesion-induced disconjugate gaze: a unifying circuit mechanism of ocular alignment?
Maximilian U. Friedrich, Laurin Schappe, Sashank Prasad, Helen Friedrich, Michael D. Fox, Andreas Zwergal, David S. Zee, Klaus Faßbender, Klaus-Ulrich Dillmann
Journal of Neurology.2024;[Epub] CrossRef

The Head-Bending Test in Posterior Semicircular Canal Benign Paroxysmal Positional Vertigo: Sol-lim Choi, Hyun-Sung Kim, Jae-Hwan Choi, Eun Hye Oh; Res Vestib Sci. 2022;21(4):99-103. Published online December 15, 2022; DOI: https://doi.org/10.21790/rvs.2022.21.4.99

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Abstract PDF: Objectives
This study aimed to investigate clinical significance of a head-bending test in benign paroxysmal positional vertigo (BPPV) involving the posterior semicircular canal (PC-BPPV).
Methods
We retrospectively recruited 256 patients with unilateral PC-BPPV between January 2016 and December 2021, and assessed the clinical characteristics of patients showing head-bending nystagmus (HBN).
Results
Of 256 patients, 138 (53.9%) showed HBN. Most patients (n=136, 98.6%) had downbeat nystagmus with (n=38) or without (n=98) torsional component. The remaining two patients had pure upbeat and torsional nystagmus, respectively. The torsional component was directed to the contralesional side in all. Between patients with and without HBN, there were no significant differences in clinical characteristics such as age, lateralization, types of BPPV (canalolithiasis or cupulolithiasis), and success rate of repositioning maneuver.
Conclusions
Head-bending test may be useful in predicting the diagnosis and lateralization of PC-BPPV.

Auto-Pattern Recognition for Diagnosis in Benign Paroxysmal Positional Vertigo Using Principal Component Analysis: A Preliminary Study: O-Hyeon Gwon, Tae Hoon Kong, Jaehong Key, Sejung Yang, Young Joon Seo; Res Vestib Sci. 2022;21(1):6-18. Published online March 15, 2022; DOI: https://doi.org/10.21790/rvs.2022.21.1.6

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Abstract PDF

Objectives
The aim of this study was to develop a filtering algorithm for raw nystagmus images and a diagnostic assistive algorithm using a principal component analysis (PCA) to distinguish the different types of benign paroxysmal positional vertigo (BPPV).
Methods
Fifteen video clips of clinical data with typical nystagmus patterns of BPPV (13 cases) and with normal nystamgmus (two cases) were preprocessed when applied the thresholding, morphology operation, residual noise filtering, and center point extraction stages. We analyzed multiple data clusters in a single frame via a PCA; in addition, we statistically analyzed the horizontal and vertical components of the main vector among the multiple data clusters in the canalolithiasis of the lateral semicircular canal (LSCC) and the posterior semicircular canal (PSCC).
Results
We obtained a clear imaginary pupil and data on the fast phases and slow phases after preprocessing the images. For a normal patient, a round shape of clustered dots was observed. Patients with LSCC showed an elongated horizontal shape, whereas patients with PSCC showed an oval shape at the (x, y) coordinates. The scalar values (mm) of the horizontal component of the main vector when performing a PCA between the LSCC- and PSCC-BPPV were substantially different (102.08±20.11 vs. 32.36±12.52 mm, respectively; p=0.0012). Additionally, the salar ratio of horizontal to vertical components in LSCC and PSCC exhibited a significant difference (16.11±10.74 mm vs. 2.61±1.07 mm, respectively; p=0.0023).
Conclusions
The data of a white simulated imaginary pupil without any background noise can be a separate monitoring option, which can aid clinicians in determining the types of BPPV exhibited. Therefore, this analysis algorithm will provide assistive information for diagnosis of BPPV to clinicians.

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Development of An Algorithm for Slippage-Induced Motion Artifacts Reduction in Video-Nystagmography
Yerin Lee, Young Joon Seo, Sejung Yang
Research in Vestibular Science.2022; 21(4): 104. CrossRef

Dissociated Vertical-Torsional Nystagmus in Vestibular Nucleus Lesion: Hyun-Sung Kim, Eun Hye Oh, Jae-Hwan Choi; Res Vestib Sci. 2022;21(1):19-23. Published online March 15, 2022; DOI: https://doi.org/10.21790/rvs.2022.21.1.19

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Abstract PDF: Dissociated vertical-torsional nystagmus is a unique form of nystagmus characterized by conjugate torsional but disparate vertical components. It has been mainly reported in internuclear ophthalmoplegia or medial medullary lesion involving the medial longitudinal fasciculus (MLF). The patterns of the nystagmus may be explained by a disruption of vestibulo-ocular reflex pathways from vertical semicircular canal or utriculo-ocular reflex within the MLF, but it is debatable. We described a dissociated upbeat-torsional nystagmus in a patient with vestibular nucleus infarction without involvement of MLF.

Vascular Origin of Central Vertigo: Brainstem: Sun-Uk Lee; Res Vestib Sci. 2021;20(1):1-6. Published online March 11, 2021; DOI: https://doi.org/10.21790/rvs.2021.20.1.1

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Various neurotologic findings can be observed in stroke involving the brainstem. Analyses of the neurotologic findings are important in brainstem stroke since it can have negative diffusion-weighted image, as well as, presenting with acute vestibular syndrome in isolation without any associated neurologic deficits. In this review we discuss the neurotologic findings from lesion involving (1) the medial vestibular nucleus, (2) nucleus prepositus hypoglossi, (3) inferior cerebellar peduncle, (4) medial longitudinal fasciculus, (5) rostral interstitial nucleus of the medial longitudinal fasciculus, (6) interstitial nucleus of Cajal, and (7) middle and (8) superior cerebellar peduncles. It is important to recognize these specific neurotologic findings depending on the neural structures involved that may guide early detection and proper management.

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A Case of Ramsay Hunt Syndrome Showing Central Findings due to Brainstem Involvement
Min Hyuk Lee, Min-Beom Kim
Research in Vestibular Science.2023; 22(4): 120. CrossRef

Neurotological Findings in a Patient with Glufosinate Ammonium Intoxication: Ji Young Kim, Joo Yeon Ham, Seong-Hae Jeong; Res Vestib Sci. 2020;19(4):138-140. Published online December 15, 2020; DOI: https://doi.org/10.21790/rvs.2020.19.4.138

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Abstract PDF Supplementary Material: The upward deviation could be explained by loss of inhibitory inputs from the cerebellum onto the brainstem anterior semicircular canal projections for upward vestibulo-ocular reflex, which would lead to an upward bias in static eye position. Therefore, upward gaze deviation has been reported in comatose patients after resuscitation and diffuse cerebrocerebellar damage sparing the brainstem. Herein, we report a patient with ingestion of glufosinate ammonium presented with cerebellar ataxia and ocular motor findings suggestive of cerebellum involvement such as upward gaze tendency, spontaneous downbeat, gaze-evoked nystagmus, perverted head impulse test, and impaired smooth pursuit.

Positional Audiometry in Patients with Light Cupula: A Preliminary Study: Jiyeon Lee, Dong-Han Lee, Jung Eun Shin, Chang-Hee Kim; Res Vestib Sci. 2020;19(3):89-94. Published online September 15, 2020; DOI: https://doi.org/10.21790/rvs.2020.19.3.89

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Abstract PDF

Objectives
Light cupula is characterized by persistent geotropic direction-changing positional nystagmus in a supine head-roll test. The purpose of this study is to investigate if hearing level is influenced by the change of head position in light cupula under the assumption that relative density difference similarly occurs between the tectorial membrane and endolymph.
Methods
Twelve patients with unilateral light cupula who underwent positional audiometry were included in this study. Pure tone thresholds were compared among three head positions.
Results
Hearing threshold in pure tone audiometry (PTA) of the affected ear was not different from that of the healthy ear. PTA thresholds of the affected side were not significantly different in three head positions; upright seating, cochlear apex-up, and cochlear apex-down positions.
Conclusions
Although positional change of nystagmus direction is the most significant clinical feature of light cupula, positional change of hearing level was not observed in those patients. The lack of positional influence on hearing may be explained as follows: (1) the heavier endolymph phenomenon occurs only in the vestibular end organ without involving the cochlea; (2) the light cupula phenomenon is more likely to occur due to light debris mechanism rather than heavier endolymph or lighter cupula mechanism; and (3) the effects of light cupula could be modified by outer hair cells, which work for tuning in the cochlea, even though light tectorial membrane or heavy endolymph occurs.

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Light cupula phenomenon: a systematic review
Nilüfer Bal, Melike Altun, Elif Kuru, Meliha Basoz Behmen, Ozge Gedik Toker
The Egyptian Journal of Otolaryngology.2022;[Epub] CrossRef

Atypical Presentation of Acute Vestibular Syndrome with Ramsay Hunt Syndrome: Bong-Hui Kang, Yong-Woo Lee, Jae-Il Kim; Res Vestib Sci. 2020;19(1):16-21. Published online March 15, 2020; DOI: https://doi.org/10.21790/rvs.2020.19.1.16

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Abstract PDF: Ramsay Hunt syndrome is an acquired paralysis of the face specifically caused by a varicella-zoster virus infection in the facial nerve. Other cranial nerves including vestibulo-cochlear disturbance can be affected. Herein we reported a case of Ramsay Hunt syndrome with atypical vestibular syndrome. Although central vestibular signs including direction changing post head-shaking nystagmus or normal head impulse test are generally meaningful, clinicians need to be careful to interpret them because some findings can be observed not only in cases of central disorders but also in peripheral disorders. Clinical findings such as distinct ear pain and close observation of vesicles are important to diagnose Ramsay Hunt syndrome.

Positional Hemiseesaw Nystagmus in Ataxia with Oculomotor Apraxia Type 2 due to a Novel Senataxin Gene Mutation: A New Phenotype: Sung-Hee Kim, Ja-Hyun Jang, Ji-Soo Kim; Res Vestib Sci. 2020;19(1):12-15. Published online March 15, 2020; DOI: https://doi.org/10.21790/rvs.2020.19.1.12

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Ataxia with ocular motor apraxia type 2 (AOA2) is an autosomal recessive disorder that is characterized by adolescent-onset gait ataxia, peripheral neuropathy, ocular apraxia, and cerebellar atrophy. A 19-year-old male with AOA2 from a novel SETX mutation showed distinct oculomotor abnormalities that included spontaneous and gaze-induced downbeat nystagmus, impaired smooth pursuit, and reversed catch-up saccades during horizontal head impulse tests, as well as peripheral neuropathy involving the lower extremities and mild slowing of frontal processing. He also showed positional hemiseesaw nystagmus in the supine and straight head-hanging positions. Positional hemiseesaw nystagmus is a new manifestation of hereditary cerebellar ataxia and may be explained by a gravity-dependent position-induced error in estimating the tilt in the roll plane due to dysfunction of the tilt-estimator circuit.

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A Case of AOA2 With Compound Heterozygous SETX Mutations
Hee Jin Chang, Ryul Kim, Minchae Kim, Jangsup Moon, Man Jin Kim, Han-Joon Kim
Journal of Movement Disorders.2022; 15(2): 178. CrossRef

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