Slow Phase Velocity Research Articles

A study of the effect of hot and cold gas perfusion sequence on caloric test results

Objective: To study whether the warm/cold air injection sequence affects the test results in the caloric test, and provide a basis for the specification and quality control of the caloric test. Methods:Video nystagmography and warm and cold air stimulation apparatus were applied for caloric test. Thirty healthy volunteers （60 ears） were divided into two groups of 15 （30 ears） each. The first group was given cold air stimulation followed by warm air stimulation, and the second group was given heat followed by cold. The differences in nystagmus maximal slow phase velocity （SPV）, semicircular canal paresis （CP） and dominant preponderance （DP） were compared between the two groups of subjects under different perfusion sequences of caloric test. Results:The intensity of nystagmus evoked by subjects in group 1 （cold first and then warm） and group 2 （warm first and then cold） were similar. Paired t-test showed that intra-group analysis of the SPV values of the two groups, comparison of the intensity of nystagmus evoked by different temperatures of the same ear or different sides of ear with the same temperature, the difference was not statistically significant （all P>0.05）. Independent samples t-test showed that between-group analysis of SPV values of two groups, the intensity of nystagmus induced by the same and different temperature stimuli in the ipsilateral ear, the difference was not statistically significant （all P>0.05）. Independent samples t-test showed that the CP values of the two groups were analyzed between groups, and the difference was not statistically significant （all P>0.05）. Independent samples t-test showed that DP values of both groups were in the normal range and the difference was not statistically significant （all P>0.05）. Conclusion:Different perfusion sequences of warm and cold air do not affect the results of caloric tests, and the order of warm and cold air stimulation is not the normative and quality control research direction of caloric test.

Caloric Stimulation with Water and Air: Responses by Age and Gender.

Introduction: The caloric test is a well-known valuable clinical instrument that can evaluate and quantify the functional status of both lateral semicircular canals. The American National Standard Institute (ANSI) does not include air as a standard method for caloric stimulation due the lack of published data to determine response variability comparable to water. Due the controversy about air irrigators, it is worthwhile to evaluate the presence of differences between the two irrigation methods in caloric response. The goal is to compare, by age group, the post caloric responses with water and air according gender and age. Materials and Methods:Individuals without otoneurologic complaints were selected and divided in groups. All were submitted to caloric bithermal stimulation with water at temperatures of 44°C and 30°C (Micromedical Technologies, Inc., USA) and air at temperatures of 50°C and 24°C (Micromedical Technologies, Inc., USA). Results:91 subjects were evaluated (46 men and 45 women) with a mean age of 43 years old. The caloric response was similar between genders (P=0,958) and no statistical difference was observed comparing both stimulus (P=0,93). It was identified that the Slow-Phase Velocity (SPV) was lower for the group older than 60 years comparing to the other groups. Conclusion:For the caloric test, the stimulus with air was confirmed as similar as stimulation with water, including absolute values. Lower values for SPV were found for elderly population.

Horizontal nystagmus is gravity-dependent in patients with vestibular neuritis

ObjectiveHorizontal nystagmus can be observed in the acute stage of vestibular neuritis, Although the direction of the nystagmus is gravity independent, its intensity can be influenced by gravity. In this study, we compared the slow phase velocity (SPV) of horizontal nystagmus in different head positions in patients with vestibular neuritis to analyze the static effects of gravity on horizontal nystagmus. MethodsThe study enrolled 22 vestibular neuritis patients with spontaneous horizontal nystagmus (9 men, 13 women; median age 40 years). The deficits were right-sided in 9 patients and left-sided in 13. The nystagmus was recorded in the sitting, supine, right and left ear down positions. The intensity of spontaneous nystagmus in the sitting versus while supine position, and SPV in affected ear down (AED), healthy ear down (HED), and supine positions were compared. The position-induced nystagmus was calculated to quantify the effect of head positions on nystagmus. ResultsThe nystagmus intensity in the supine position had no statistic difference than when sitting, with a median value of 6.3°/s and 5.6°/s, respectively(P = 0.355). SPV in AED had a median value of 7.8°/s, which was greater than when supine (P = 0.008) and HED (4.8°/s) (P < 0.001). Position-induced nystagmus in left and right ear-down positions were 1.4°/s and –1.4°/s respectively, which were significantly correlated (Spearman's ρ = −0.848, P < 0.001). ConclusionsThe nystagmus intensity in vestibular neuritis is gravity dependent; it's greater in AED than in supine and HED, and the effect of head position on nystagmus was nearly symmetrical in left and right ear-down positions.

The Skull Vibration-induced Nystagmus Test (SVINT) for Vestibular Disorders: A Systematic Review.

To determine the specificity and sensitivity of the skull vibration-induced nystagmus test (SVINT) for detecting vestibular hypofunction. The Cochrane Library, MEDLINE, PubMed, EMBASE, and SciELO. A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Databases were searched using a comprehensive search strategy including the terms "Vibration-induced nystagmus" or "SVINT" or "skull vibration-induced nystagmus test" or "skull vibration-induced nystagmus" from inception to May 2020. A total of 79 articles were identified, and 16 studies met the inclusion criteria. The methodology for performing the SVINT and determining positivity is varied. Most authors refer to reproducibility, sustained response, ending with withdrawal of stimulus, nondirection changing, and response in more than one point of stimulation, as necessary for a positive test. Only seven studies included a slow phase velocity of 2 degrees/s or 2.5 degrees/s as a criterion. Most studies employed 100 Hz stimulus for 10 seconds, while longer duration is suggested for pediatric patients. For partial and total unilateral vestibular loss, positivity varied from 58 to 60%, and 93 to 100%, respectively. Sensitivity ranged from 50 to 100%, and specificity from 62 to 100%. Importantly, the SVINT may decrease with time but does not usually disappear, hence, can provide information of past/compensated vestibular events. The SVINT can be used in pediatric and adult patients. It provides information regarding unilateral vestibular loss, acute, or compensated. It is a quick, safe, and noninvasive test, and is complementary to the dynamic vestibular and positional tests.

Pre-ataxic Changes of Clinical Scales and Eye Movement in Machado-Joseph Disease: BIGPRO Study.

The pathological burden of spinocerebellar ataxia type 3, also known as Machado-Joseph disease (SCA3/MJD), accumulates before the beginning of symptoms. Our study aims at validating biomarkers for disease progression since pre-ataxic periods. We report on baseline findings of clinical scales and oculomotor neurophysiology. Ataxic (Scale for the Assessment and Rating of Ataxia > 2.5) and at 50% risk subjects were included. The latter were subdivided into noncarriers, pre-ataxic carriers near (PAN), or pre-ataxic carriers far from (PAFF) ataxia onset (AO), with 4 years from the predicted age at onset being the cutoff. The subjects were assessed by Neurological Examination Score for Spinocerebellar Ataxia (NESSCA), International Cooperative Ataxia Rating Scale (ICARS), Inventory of Non-Ataxic Signs (INAScount), Composite Cerebellar Functions Score and SCA Functional Index, and video-oculography, including the regression slope of vestibulo-ocular reflex gain (VORr), main sequence of volitional and reflexive vertical saccades, slow-phase velocity of central and gaze-evoked (SPV-GE) nystagmus, and vertical pursuit gain. Correction for multiple comparisons was performed; the threshold for statistical significance was P < 0.05. A total of 35 ataxic, 14 PAN, 24 PAFF, and 22 noncarriers were included. All variables showed significant differences between groups and correlated to time to onset or time after onset, among all 73 SCA3/MJD carriers; none significantly changed with age in controls. NESSCA, ICARS, INAScount, VORr, main sequence of volitional saccades, and SPV-GE not only distinguished PAN from controls but also correlated with time left to AO. Clinical scales and video-oculography variables were already altered in pre-ataxic SCA3/MJD carriers and worsened with time. NESSCA, ICARS, INAScount, VORr, main sequence of vertical volitional saccades, and SPV-GE are good candidates to measure preclinical changes in SCA3/MJD. © 2021 International Parkinson and Movement Disorder Society.

Vestibular Function After Bilateral Simultaneous Cochlear Implantation.

Thanks to the advantages of hearing-in-noise and spatial orientation, currently bilateral cochlear implantation (CI) became popular for patients with profound hearing loss. The aim of this study was to investigate vestibular function in bilateral simultaneous CI recipients. Retrospective analysis. University hospital. Sixteen patients with profound hearing loss were included. Bilateral simultaneous CI with flexible electrode using round window approach. Vestibular function was evaluated using both objective and subjective measures in the subjects preoperatively and 4 months postoperatively. Differences were analyzed preoperatively and postoperatively. Preoperative vestibular tests revealed that 8 subjects (50%) had abnormal caloric test results, 11 ears (34.4%) had abnormal ocular vestibular-evoked myogenic potential results, 6 ears (18.8%) had abnormal cervical vestibular-evoked myogenic potential results, 7 ears (21.9%) in the anterior semicircular canal, and 6 ears (18.8%) in the posterior semicircular canal had gain loss. However, surgery significantly decreased the sums of the maximal slow-phase velocities evidenced by caloric test (p ‹ 0.05). Cervical vestibular-evoked myogenic potential abnormal rate significantly increased to 53.1% after surgery (p ‹ 0.05). The postoperative changes regarding ocular vestibular-evoked myogenic potential, video head impulse test (vHIT), and Dizziness Handicap Inventory (DHI) were not significant among all the patients. Patients diagnosed as large vestibular aqueduct syndrome showed significantly higher DHI scores than others (p ‹ 0.05). Spearman's correlation analysis revealed that DHI moderately correlated with the dysfunction of semicircular canals evidenced by vHIT (r = 0.702; p < 0.001), weakly correlated with caloric (r = 0.352; p = 0.048). However, no correlation was found between DHI and VEMPs. The monosyllabic and disyllabic word recognition score significantly improved from 0 to 60.4 ± 14.3% (p < 0.05) and from 0 to 63.3 ± 14.5% (p < 0.05) respectively. There was no correlation between the improvement of word recognition score and the change of vestibular tests. The study showed preservation of utricle function, vestibular function at high frequency after bilateral simultaneous CI. However, operation significantly affected vestibular function at low frequency and saccule function. Patients with large vestibular aqueduct syndrome showed dramatically higher DHI scores than others. DHI moderately correlated with vHIT and weakly correlated with caloric.

Diagnostic Value of Straight Head Hanging in Posterior Canal Benign Paroxysmal Positional Vertigo.

Background and PurposeTo determine the diagnostic value of straight head hanging (SHH) in benign paroxysmal positional vertigo involving the posterior semicircular canal (PC-BPPV).MethodsWe retrospectively included 62 patients (age=56.2±15.0 years, 47 female) with unilateral PC-BPPV who underwent both the Dix-Hallpike maneuver and SHH before receiving canalith repositioning therapy (CRT) between September 2017 and July 2020 at the Dizziness Center of Seoul National University Bundang Hospital in South Korea (16 patients, 25.8%) or the Neurology Outpatient Clinic of Aerospace Central Hospital in China (46 patients, 74.2%). SHH was performed before (n=29, group A) or after (n=33, group B) the Dix-Hallpike maneuver.ResultsTorsional upbeat nystagmus typical of PC-BPPV was induced during SHH in 52 (83.9%) patients, and the incidence of this type of positional nystagmus did not differ between the groups A and B (79.3% vs. 87.9%, p=0.569). The maximum slow-phase velocity of the induced upbeat nystagmus was higher during SHH than during the Dix-Hallpike maneuver toward the lesion side [range=2.0–60.0°/s (median=18.5°/s) vs. range=2.7–40.0°/s (median=13.4°/s), p<0.001]. Reversal of the positional nystagmus was observed upon resuming the sitting position after SHH in 47 (75.8%) patients and after the Dix-Hallpike maneuver in 54 (87.7%) patients, with no significant difference between the groups (p=0.082).ConclusionsSHH is effective for diagnosing PC-BPPV. Given its simplicity, SHH may be performed before the Dix-Hallpike maneuver, and CRT may be attempted thereafter when the typical positional nystagmus for unilateral PC-BPPV is induced during SHH.

Proton Bunch Self-Modulation in Plasma with Density Gradient.

We study experimentally the effect of linear plasma density gradients on the self-modulation of a 400GeV proton bunch. Results show that a positive or negative gradient increases or decreases the number of microbunches and the relative charge per microbunch observed after 10m of plasma. The measured modulation frequency also increases or decreases. With the largest positive gradient we observe two frequencies in the modulation power spectrum. Results are consistent with changes in wakefields' phase velocity due to plasma density gradients adding to the slow wakefields' phase velocity during self-modulation growth predicted by linear theory.

Spontaneous Direction-Changing or Reversing Positional Nystagmus without Changing Head Position during Head-Roll/Head-Hanging Maneuvers: Biphasic Positional Nystagmus

Background and ObjectivesConflicting mechanisms have been reported about spontaneous reversal of positional nystagmus during head-roll maneuver in patients with benign paroxysmal positional vertigo (BPPV). The objective of this study is to review the reports about the characteristics and possible mechanisms of reversing positional nystagmus and to present seven new cases.Subjects and MethodsSeven cases (5 males, 2 females; 4 left-sided, 3 right-sided) were recruited among 732 patients with BPPV seen outpatient clinic between 2009 and 2019. Diagnosis of lateral canal canalolithiasis was confirmed when transient geotropic nystagmus was documented during head-roll test. Reversing positional nystagmus was analyzed in each case and clinical characteristics of the patients were documented.ResultsThe age of patients was ranging between 30 to 64 years (46.44±10.91). Duration of symptoms was short (21.34±19.74). Six of them had a story of head trauma. Initial latency was short. First, intense geotropic nystagmus was observed following provocative head-roll position on the affected side. There was short “silent phase”. Then, a longer second-phase of reversed nystagmus was noted. Total duration of nystagmus was 78.40±6.82 seconds. Maximal slow phase velocity was 24.05±6.34 deg/sec. All patients were cured with barbeque maneuver.ConclusionsIpsilateral reversing positional nystagmus during head-roll maneuver is due to lateral canal canalolithiasis. Mechanism is likely to be due to endolymphatic double flow. Bilateral cases may be due to simultaneous co-existence of canalolithiasis and cupulolithiasis. Longer recording of nystagmus is recommended not to miss the cases with spontaneous direction-changing positional nystagmus.

Nystagmus characteristics of healthy controls.

BACKGROUND:Healthy controls exhibit spontaneous and positional nystagmus which needs to be distinguished from pathological nystagmus.OBJECTIVE:Define nystagmus characteristics of healthy controls using portable video-oculography.METHODS:One-hundred and one asymptomatic community-dwelling adults were prospectively recruited. Participants answered questions regarding their audio-vestibular and headache history and were sub-categorized into migraine/non-migraine groups. Portable video-oculography was conducted in the upright, supine, left- and right-lateral positions, using miniature take-home video glasses.RESULTS:Upright position spontaneous nystagmus was found in 30.7% of subjects (slow-phase velocity (SPV)), mean 1.1±2.2 degrees per second (°/s) (range 0.0 – 9.3). Upright position spontaneous nystagmus was horizontal, up-beating or down-beating in 16.7, 7.9 and 5.9% of subjects. Nystagmus in at least one lying position was found in 70.3% of subjects with 56.4% showing nystagmus while supine, and 63.4% in at least one lateral position. While supine, 20.8% of subjects showed up-beating nystagmus, 8.9% showed down-beating, and 26.7% had horizontal nystagmus. In the lateral positions combined, 37.1% displayed horizontal nystagmus on at least one side, while 6.4% showed up-beating, 6.4% showed down-beating. Mean nystagmus SPVs in the supine, right and left lateral positions were 2.2±2.8, 2.7±3.4, and 2.1±3.2°/s. No significant difference was found between migraine and non-migraine groups for nystagmus SPVs, prevalence, vertical vs horizontal fast-phase, or low- vs high-velocity nystagmus (<5 vs > 5°/s).CONCLUSIONS:Healthy controls without a history of spontaneous vertigo show low velocity spontaneous and positional nystagmus, highlighting the importance of interictal nystagmus measures when assessing the acutely symptomatic patient.

Effect of the Epley Maneuver and Brandt-Daroff Exercise on Benign Paroxysmal Positional Vertigo Involving the Posterior Semicircular Canal Cupulolithiasis: A Randomized Clinical Trial.

Objective: To investigate the therapeutic efficacies of the Epley maneuver and Brandt-Daroff (BD) exercise in patients with benign paroxysmal positional vertigo involving the posterior semicircular canal cupulolithiasis (PC-BPPV-cu).Methods: We conducted a randomized clinical trial to evaluate the therapeutic effect of the Epley maneuver and BD exercise in patients with PC-BPPV-cu. Patients were randomly assigned to undergo the Epley maneuver (n = 29) or BD exercise (n = 33). The primary outcome was an immediate resolution of positional nystagmus within 1 h after a single treatment of each maneuver on the visit day. Secondary outcomes included the resolution of positional nystagmus at 1 week, the change of maximal slow phase velocity (mSPV) of positional nystagmus, and dizziness handicap inventory (DHI) immediately and at 1 week.Results: Immediate resolution occurred in none of 29 patients in the Epley maneuver group and only 1 of 33 patients in the BD exercise group. The Epley maneuver and BD exercise had an equivalent effect at 1 week in treating PC-BPPV-cu in terms of resolving positional nystagmus (48 vs. 36%, p = 0.436) and the decrease of mSPV and DHI.Conclusion: Neither the Epley maneuver nor BD exercise has an immediate therapeutic effect in treating PC-BPPV-cu. Clear classification of PC-BPPV should be required at the time of different pathology and different treatment response.

Influence of Aging on the Retina and Visual Motion Processing for Optokinetic Responses in Mice.

The decline in visual function due to normal aging impacts various aspects of our daily lives. Previous reports suggest that the aging retina exhibits mislocalization of photoreceptor terminals and reduced amplitudes of scotopic and photopic electroretinogram (ERG) responses in mice. These abnormalities are thought to contribute to age-related visual impairment; however, the extent to which visual function is impaired by aging at the organismal level is unclear. In the present study, we focus on the age-related changes of the optokinetic responses (OKRs) in visual processing. Moreover, we investigated the initial and late phases of the OKRs in young adult (2–3 months old) and aging mice (21–24 months old). The initial phase was evaluated by measuring the open-loop eye velocity of OKRs using sinusoidal grating patterns of various spatial frequencies (SFs) and moving at various temporal frequencies (TFs) for 0.5 s. The aging mice exhibited initial OKRs with a spatiotemporal frequency tuning that was slightly different from those in young adult mice. The late-phase OKRs were investigated by measuring the slow-phase velocity of the optokinetic nystagmus evoked by sinusoidal gratings of various spatiotemporal frequencies moving for 30 s. We found that optimal SF and TF in the normal aging mice are both reduced compared with those in young adult mice. In addition, we measured the OKRs of 4.1G-null (4.1G–/–) mice, in which mislocalization of photoreceptor terminals is observed even at the young adult stage. We found that the late phase OKR was significantly impaired in 4.1G–/– mice, which exhibit significantly reduced SF and TF compared with control mice. These OKR abnormalities observed in 4.1G–/– mice resemble the abnormalities found in normal aging mice. This finding suggests that these mice can be useful mouse models for studying the aging of the retinal tissue and declining visual function. Taken together, the current study demonstrates that normal aging deteriorates to visual motion processing for both the initial and late phases of OKRs. Moreover, it implies that the abnormalities of the visual function in the normal aging mice are at least partly due to mislocalization of photoreceptor synapses.

Design of a resonant Luneburg lens for surface acoustic waves

In this work we employ additive manufacturing to print a circular array of micropillars on an aluminium slab turning its top surface into a graded index metasurface for surface acoustic waves (SAW). The graded metasurface reproduces a Luneburg lens capable of focusing plane SAWs to a point. The graded index profile is obtained by exploiting the dispersion properties of the metasurface arising from the well-known resonant coupling between the micropillars (0.5 mm diameter and variable length ∼3 mm) and the surface waves propagating in the substrate. From the analytical formulation of the metasurface’s dispersion curves, a slow phase velocity mode is shown to arise from the hybridisation of the surface wave with the pillar resonance. This is used to compute the radial height profile corresponding to the refractive index given by Luneburg’s equation. An initial validation of the lens design, achieved through ray theory, shows that ray trajectories have a strong frequency dependence, meaning that the lens will only work on a narrow band. An ultrasonic experiment at 500 kHz where plane SAWs are generated with a piezoelectric transducer and a laser scanner measures the out of plane displacement on the metasurface, validates the actual lens performance and the manufacturing technique. Finally, comparison between the ray analysis and experimental results offers insight into the behaviour of this type of metasurface especially in the proximity of the acoustic bandgaps and highlights the possibility for acoustic shielding.

Alexander's Law During High-Speed, Yaw-Axis Rotation: Adaptation or Saturation?

Objective: Alexander's law (AL) states the intensity of nystagmus increases when gaze is toward the direction of the quick phase. What might be its cause? A gaze-holding neural integrator (NI) that becomes imperfect as the result of an adaptive process, or saturation in the discharge of neurons in the vestibular nuclei?Methods: We induced nystagmus in normal subjects using a rapid chair acceleration around the yaw (vertical) axis to a constant velocity of 200°/second [s] and then, 90 s later, a sudden stop to induce post-rotatory nystagmus (PRN). Subjects alternated gaze every 2 s between flashing LEDs (right/left or up/down). We calculated the change in slow-phase velocity (ΔSPV) between right and left gaze when the lateral semicircular canals (SCC) were primarily stimulated (head upright) or, with the head tilted to the side, stimulating the vertical and lateral SCC together.Results: During PRN AL occurred for horizontal eye movements with the head upright and for both horizontal and vertical components of eye movements with the head tilted. AL was apparent within just a few seconds of the chair stopping when peak SPV of PRN was reached. When slow-phase velocity of PRN faded into the range of 6–18°/s AL could no longer be demonstrated.Conclusions: Our results support the idea that AL is produced by asymmetrical responses within the vestibular nuclei impairing the NI, and not by an adaptive response that develops over time. AL was related to the predicted plane of eye rotations in the orbit based on the pattern of SCC activation.

Positioning Velocity Matters in Central Paroxysmal Positional Vertigo: Implication for the Mechanism.

Objectives: To elucidate the mechanism of paroxysmal central positional nystagmus (CPN) by determining the effects of head rotation velocity on the intensity of paroxysmal downbeat nystagmus induced during straight head hanging (SHH).Methods: We recruited 21 patients with paroxysmal downbeat CPN induced during SHH at the Dizziness Center of Seoul National University Bundang Hospital from September 2018 to July 2019. Twenty-one patients had manual SHH at two different lying velocities, the fast (routine) and slow, and they also underwent SHH at different rotation velocities of 10, 20, 30, and 40 °/s using a motorized rotation chair. Induced nystagmus was recorded using video-oculography and the maximum slow phase velocity (SPV) and time constant (TC) of the induced paroxysmal nystagmus were analyzed.Results: During manual SHH, paroxysmal downbeat nystagmus was invariably induced during routine SHH (fast lying down), but absent or minimal during slow positioning. During motorized SHH, the median of maximum intensity of downbeat nystagmus increased from 7.6 °/s (0–16.9) to 14.0 °/s (0–32.5), 16.5 °/s (0–44.6), and 19.1 °/s (0–55.2) as the rotation velocity increased from 10 to 20, 30, and 40°/s (P < 0.001, P < 0.001, P = 0.004; linear mixed models). In contrast, the TCs of paroxysmal downbeat CPN remained unchanged (P = 0.558, P = 0.881, P = 0.384, linear mixed models).Conclusions: The dependence of nystagmus intensity on head rotation velocity supports a disinhibited and exaggerated inhibitory rebound of the canal signals as the mechanism of paroxysmal CPN.

Episodic Vestibular Syndrome with Hyperventilation-Induced Downbeat Nystagmus.

Hyperventilation-induced downbeat nystagmus (HV-DBN) has been reported in cerebellar disorders and explained by a loss of the inhibitory cerebellar output via a metabolic effect on cerebellar Ca2+ channels. The aim of this study was to determine the clinical characteristics and underlying pathogenesis of episodic vestibular syndrome (EVS) with HV-DBN. Of 667 patients with EVS, we recruited 22 with HV-DBN and assessed their clinical characteristics, video-oculographic findings, and the results of molecular genetic analyses. The age at symptom onset was 47.5 ± 13.0years (mean ± SD), and there was a female preponderance (n = 15, 68%). The duration of vertigo/dizziness attacks ranged from minutes to a few days, and 11 patients (50%) fulfilled the diagnostic criteria for vestibular migraine. HV-induced new-onset DBN in 8 patients, while the remaining 14 showed augmentation of spontaneous DBN by HV. The maximum slow-phase velocity of HV-DBN ranged from 2.2 to 11.9°/s, which showed a statistical difference with that of spontaneous DBN (median = 4.95, IQR = 3.68-6.55 vs. median = 1.25, IQR = 0.20-2.15, p < 0.001). HV-DBN was either purely downbeat (n = 11) or accompanied with small horizontal components (n = 11). Other neuro-otologic findings included perverted head-shaking nystagmus (n = 11), central positional nystagmus (n = 7), saccadic pursuit (n = 3), and horizontal gaze-evoked nystagmus (n = 1). Gene expression profiling with a bioinformatics analysis identified 43 upregulated and 49 downregulated differentially expressed genes (DEGs) in patients with EVS and HV-DBN and revealed that the downregulated DEGs were significantly enriched in terms related to the ribosome pathway. Our results suggest that the underlying cerebellar dysfunction would be responsible for paroxysmal attacks of vertigo in patients with EVS and HV-DBN.

Skull vibration-induced nystagmus in vestibular neuritis

Background As described by Dumas, an 80–100 Hz vibration applied to the mastoid produces a horizontal nystagmus, with quick phases beating away from the affected side in patients with unilateral vestibular loss (UVL). Aim/objectives To elucidate the characteristics of skull vibration-induced nystagmus (SVIN) in patients suffering from vestibular neuritis and how these characteristics are related to information provided by the video head impulse test (vHIT). Material and methods Sixty-three patients were enrolled to perform a vHIT to measure the gain in both ears. SVIN was induced with stimulation at 30 Hz, 60 Hz, and 100 Hz. The slow phase velocity (SPV) of the SVIN was measured. Results The SVIN test was positive in 25/63 patients at 30 Hz, 36/63 at 60 Hz and 46/63 at 100 Hz. Mean gain difference between both ears to obtain a positive SVIN at 30 Hz was observed to be 0.38 ± 0.25, decreasing to 0.35 ± 0.23 at 60 Hz, and 0.31 ± 0.24 at 100 Hz (p = .025). We found a significant positive linear correlation between the gain asymmetry measured using horizontal vHIT and SPV in SVIN at 100 Hz. Conclusions and significance There is a close relationship between the difference in the gains of both ears as measured using VHIT and the SPV of the nystagmus induced by SVIN at 100 Hz.

Ictal downbeat nystagmus in Ménière disease: A cross-sectional study.

To determine the mechanism of ictal downbeat nystagmus in Ménière disease (MD), we compared the head impulse gain of the vestibulo-ocular reflex (VOR) for each semicircular canal between patients with (n = 7) and without (n = 70) downbeat nystagmus during attacks of MD. We retrospectively analyzed the results of video-oculography, video head-impulse tests, and cervical vestibular-evoked myogenic potentials (VEMPs) in 77 patients with definite MD who were evaluated during an attack. Pure or predominant downbeat nystagmus was observed in 7 patients (9%) with unilateral MD during the attacks. All 7 patients showed spontaneous downbeat nystagmus without visual fixation with a slow phase velocity ranging from 1.5 to 11.2°/s (median 5.4, interquartile range 3.7-8.5). All showed a transient decrease of the head impulse VOR gains for the posterior canals (PCs) in both ears (n = 4) or in the affected ear (n = 3). Cervical VEMPs were decreased in the affected (n = 2) or both ears (n = 2) when evaluated during the attacks. Downbeat nystagmus disappeared along with normalization of the VOR gains for PCs after the attacks in all patients. During the attacks, the head impulse VOR gains for the PC on the affected side were lower in the patients with ictal downbeat nystagmus than in those without (Mann-Whitney U test, p < 0.001), while the gains for other semicircular canals did not differ between the groups. Downbeat nystagmus may be observed during attacks of MD due to an asymmetry in the vertical VOR or saccular dysfunction. MD should be considered in recurrent audiovestibulopathy and ictal downbeat nystagmus.

Nystagmus during an acute Ménière’s attack: from prodrome to recovery

Objective We are currently undertaking a clinical investigation to evaluate the diagnostic capability of a system for detecting periods of pathological dizziness. This article presents an analysis of the data captured during an acute attack of Ménière’s disease. Design The Continuous Ambulatory Vestibular Assessment (CAVA) device is worn by patients in the community, and continuously records eye and head movement data (vestibular telemetry). Study sample A 53-year-old lady with a fifteen-year history of left-sided unilateral Ménière’s disease. Results The patient wore the device nearly continuously for thirty days. The data revealed a three-hour long attack of vertigo consisting of four separate phases of nystagmus. The duration, beat-direction and slow phase velocity of the nystagmus evolved through time. The first phase contained isolated nystagmus beats which preceded the patient’s record of the vertigo attack onset but coincided with anticipation of an impending vertigo attack. Conclusions CAVA provides a unique insight into the physiological parameters present during episodes of dizziness. Here, it has provided the first full example of an acute Ménière’s attack, including a period of prodrome. These findings have implications for the prediction of vertigo attack onset, for the diagnosis of Ménière’s disease and other diseases resulting in dizziness.

Impact of cochlear implantation on the function of the three semicircular canals

ObjectiveTo assess the effect of cochlear implantation on the function of the semicircular canals (SCC) and on experienced vestibular symptoms. Second, to determine the relation between vestibular test results.DesignRetrospective cohort study assessing absolute and categorised results of caloric irrigation test, video Head Impulse Test (vHIT) and Dizziness Handicap Inventory (DHI) before and after cochlear implantation.Study sample: 192 patients, aged ≥7 years old, without preoperative areflexia.ResultsMean maximum slow phase velocity decreased with 3.1°/s and 4.7°/s for warm and cold caloric irrigation respectively. About 37.4% of the patients deteriorated one or more categories on caloric testing. Complete caloric postoperative areflexia was found in 6.2%. Mean vHIT gain decreased with 0.06, 0.04 and 0.05 for anterior, lateral and posterior SCC, respectively. Seven patients (7.7%) acquired an abnormal gain value for the anterior SCC. Only mean score on DHI’s physical subdomain rose significantly (1.4 points). Overall, 9.0% of the patients deteriorated one or two categories on DHI. Only few weak correlations were found between caloric test, vHIT and DHI shifts.ConclusionsAlthough mean objective and subjective-physical vestibular deteriorations were significant, its clinical impact seems limited. However, 9% of patients experience vestibular deterioration, thus, advocate assessment. Vestibular test results show no or merely weak mutual correlations.