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Original Articles
- Development of An Algorithm for Slippage-Induced Motion Artifacts Reduction in Video-Nystagmography
- Yerin Lee, Young Joon Seo, Sejung Yang
- Res Vestib Sci. 2022;21(4):104-110. Published online December 15, 2022
- DOI: https://doi.org/10.21790/rvs.2022.21.4.104
- 1,540 View
- 58 Download
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Abstract
PDF - Objectives
The slippage of the video-nystagmography devices causes motion artifacts in the trajectory of the pupil and thus results in distortion in the nystagmus waveform. In this study, the moving average was proposed to reduce slippage-induced motion artifacts from the real-world data obtained in the field.
Methods
The dataset consists of an infrared video of positional tests performed on eight patients with a lateral semicircular canal benign paroxysmal positional vertigo. The trajectories of the pupil were obtained from the video with binarization, morphological operation, and elliptical fitting algorithm. The acquired data was observed and the section where the slippage occurred was labeled by an otolaryngologist. The moving average with windows of various lengths was calculated and subtracted from the original signal and evaluated to find the most adequate parameter to reduce the motion artifact.
Results
The period of nystagmus in the given data was found to be ranged from 0.01 to 4 seconds. The slippages that appeared in the data can be categorized into fast and slow slippages. The length, distance, and speed of trajectories in the slippage ranges were also measured to find the characteristics of the motion artifact in video-nystagmography data. The shape of the nystagmus waveform was preserved, and the motion artifacts were reduced in both types of slippages when the length of the window in moving average was set to 1 second.
Conclusions
The algorithm developed in this study is expected to minimize errors caused by slippage when developing a diagnostic algorithm that can assist clinicians.
- Assessment of the Vestibuloocular Reflex in Patients with Unilateral Chronic Middle Ear Disease Using the Video Head Impulse Test: A Preliminary Study
- Gi-Sung Nam, Wonyong Baek, Sung-Il Cho
- Res Vestib Sci. 2022;21(3):80-85. Published online September 15, 2022
- DOI: https://doi.org/10.21790/rvs.2022.21.3.80
- 2,109 View
- 51 Download
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Abstract
PDF
- Objectives
This study aims to investigate the usefulness of the video head impulse test (vHIT) as a method for evaluating vestibular function in patients with unilateral chronic middle ear disease.
Methods
Nineteen patients with various unilateral middle ear diseases including chronic otitis media (COM), COM with cholesteatoma, and adhesive otitis media successfully underwent preoperative vHIT. The gain of vestibuloocular reflex (VOR) and the presence of corrective saccades were compared between the affected ear and the healthy ear.
Results
A total of eight male and 11 female patients with a mean age of 43.1 years were included in this retrospective study. Twelve ears had COM, four had COM with cholesteatoma, and three had adhesive otitis media. A positive history of vertigo or dizziness was reported in 36.8% of the cases. The VOR gain of the affected ears and the healthy ears were 0.97±0.16 vs. 1.00±0.08 in the horizontal canal, 0.91±0.11 vs. 0.87±0.11 in the anterior canal, and 0.87±0.17 vs. 0.99±0.12 in the posterior canal, respectively. Only VOR gain of the posterior canal was significantly decreased compared with healthy ears.
Conclusions
The average VOR gains in the patients with chronic middle ear disease were within the pre-defined values of normality; however, when compared quantitatively, posterior canal gain of affected ears was significantly decreased compared to healthy ears. Our results can be explained by the anatomical proximity of the ampulla of the posterior canal and middle ear space.
- 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
- 10,122 View
- 230 Download
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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.
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