Relationship Between Motion Sickness Susceptibility and Vestibular Test Results.

Objective: There is no test parameter with high sensitivity and specificity for the diagnosis of motion sickness. The aim of this study was to demonstrate a correlation between vestibular function tests and motion sickness. In addition, our secondary aim is to evaluate the sensitivity of the skull vibration-induced nystagmus test (SVINT) in the diagnosis of motion sickness. Methods: A total of 44 young adults aged 19-25 who had no hearing loss, complaints of dizziness/vertigo, or any diagnosed neurological disease were included. According to the motion sickness susceptibility questionnaire-short form (MSSQ-SF), participants were divided into the motion sickness group (21±1.38 years) and control group (20.5±1.18 years). Mean MSSQ-SF score for the motion sickness group is 78.18±12.2 and for control group 19.09±17.08. Ocular and cervical vestibular evoked myogenic potential tests, SVINT, video head impulse test, and oculomotor tests were performed. Results: The only significant difference between the groups was in n1-p1 amplitudes in the left ocular vestibular evoked myogenic potential test (p=0.014). None of the other parameters differed between the two groups (p>0.05). Conclusions: There was no significant relationship between motion sickness susceptibility and the results of any vestibular function test. Performing diagnostic tests for motion sickness in an environment that creates significant sensory conflict may yield different results. This study contributes to the literature in terms of evaluating the vestibular system using a comprehensive test battery and is the first to use the SVINT test in motion sickness.

Deep Learning-Based Nystagmus Detection for BPPV Diagnosis.

In this study, we propose a deep learning-based nystagmus detection algorithm using video oculography (VOG) data to diagnose benign paroxysmal positional vertigo (BPPV). Various deep learning architectures were utilized to develop and evaluate nystagmus detection models. Among the four deep learning architectures used in this study, the CNN1D model proposed as a nystagmus detection model demonstrated the best performance, exhibiting a sensitivity of 94.06 ± 0.78%, specificity of 86.39 ± 1.31%, precision of 91.34 ± 0.84%, accuracy of 91.02 ± 0.66%, and an F1-score of 92.68 ± 0.55%. These results indicate the high accuracy and generalizability of the proposed nystagmus diagnosis algorithm. In conclusion, this study validates the practicality of deep learning in diagnosing BPPV and offers avenues for numerous potential applications of deep learning in the medical diagnostic sector. The findings of this research underscore its importance in enhancing diagnostic accuracy and efficiency in healthcare.

Downbeat nystagmus: a clinical and pathophysiological review.

Downbeat nystagmus (DBN) is a neuro-otological finding frequently encountered by clinicians dealing with patients with vertigo. Since DBN is a finding that should be understood because of central vestibular dysfunction, it is necessary to know how to frame it promptly to suggest the correct diagnostic-therapeutic pathway to the patient. As knowledge of its pathophysiology has progressed, the importance of this clinical sign has been increasingly understood. At the same time, clinical diagnostic knowledge has increased, and it has been recognized that this sign may occur sporadically or in association with others within defined clinical syndromes. Thus, in many cases, different therapeutic solutions have become possible. In our work, we have attempted to systematize current knowledge about the origin of this finding, the clinical presentation and current treatment options, to provide an overview that can be used at different levels, from the general practitioner to the specialist neurologist or neurotologist.

Complete and Immediate Resolution of See-Saw Nystagmus Following Pituitary Macroadenoma Resection: Case Report and Review of the Literature.

See-saw nystagmus (SSN) is a rare form of nystagmus characterised by alternating elevation with incyclotorsion of one eye and concomitant depression with excyclotorsion of the other eye, often due to abnormalities involving the midbrain and parasellar region. Herein, we highlight a rare case of pendular SSN, which demonstrated complete resolution following resection of a pituitary macroadenoma. A patient in their 40s was identified to have SSN and was diagnosed with a pituitary macroadenoma. They underwent an endoscopic endonasal transsellar approach for resection of the pituitary adenoma. Their nystagmus resolved immediately after surgery. From a review of the literature, resolution and/or significant improvement in SSN occurred in 74% of cases following treatment, with 100%, 86% and 50% following treatment for medication-induced, neurological infarcts, and mass-effect aetiologies of SSN, respectively. SSN is a rare entity with a wide array of aetiologies. Identification of the causative aetiology and appropriate treatment can lead to significant improvement or resolution of the nystagmus in most cases.

Sustained bias of spatial attention in a 3 T MRI scanner.

When lying inside a MRI scanner and even in the absence of any motion, the static magnetic field of MRI scanners induces a magneto-hydrodynamic stimulation of subjects' vestibular organ (MVS). MVS thereby not only causes a horizontal vestibular nystagmus but also induces a horizontal bias in spatial attention. In this study, we aimed to determine the time course of MVS-induced biases in both VOR and spatial attention inside a 3 T MRI-scanner as well as their respective aftereffects after participants left the scanner. Eye movements and overt spatial attention in a visual search task were assessed in healthy volunteers before, during, and after a one-hour MVS period. All participants exhibited a VOR inside the scanner, which declined over time but never vanished completely. Importantly, there was also an MVS-induced horizontal bias in spatial attention and exploration, which persisted throughout the entire hour within the scanner. Upon exiting the scanner, we observed aftereffects in the opposite direction manifested in both the VOR and in spatial attention, which were statistically no longer detectable after 7 min. Sustained MVS effects on spatial attention have important implications for the design and interpretation of fMRI-studies and for the development of therapeutic interventions counteracting spatial neglect.

A Novel Homozygous ACBD5 Variant in an Emerging Peroxisomal Disorder Presenting with Retinal Dystrophy and a Review of the Literature.

Introduction: Acyl-CoA binding domain containing 5 (ACBD5) deficiency is a newly defined inborn peroxisomal disorder with only 7 patients reported to date. Herein, we report a patient with ACBD5 deficiency who was diagnosed after a complicated diagnostic process. Case Presentation: A 6-year-old male patient was admitted with complaints of neuromotor regression and visual disturbances. He had spastic paraparesis dominated with axial hypotonic posturing and horizontal nystagmus. His very-long-chain fatty acid levels were within normal ranges with a slightly elevated C26:0/C22:0 ratio. Brain magnetic resonance imaging revealed white matter involvement. Clinical exome sequencing displayed a novel homozygous intronic splice site variant (c.936 + 2T>G) in the ACBD5 (NM_145698.5) gene. Conclusion: With this report, a novel variant in ACBD5 deficiency was described. Macular dystrophy was demonstrated with optical coherence tomography imaging for the first time in the literature in ACBD5 deficiency. In order to contribute to the knowledge about the clinical, biochemical, and genetic spectrum of ACBD5 deficiency, new patients need to be defined.

Crossed VEP asymmetry in a patient with AHR-linked infantile nystagmus and foveal hypoplasia.

INTRODUCTION: Infantile nystagmus and foveal hypoplasia associated with AHR gene defects is a newly recognized and rare disorder. Our aim was to present a patient with a novel biallelic AHR pathogenic variant with electrophysiological evidence of chiasmal misrouting. MATERIALS AND METHODS: Complete ocular examination, fundus imaging, visual evoked potentials (VEP) and full-field electroretinography were performed at initial presentation. Genetic testing was performed by whole exome sequencing. RESULTS: Female patient of 6 years old presented a reduced best corrected visual acuity, an infantile nystagmus and a grade III typical foveal hypoplasia without ocular hypopigmentation. A crossed asymmetry was discovered on pattern onset/offset VEP. Genetic testing put in evidence a novel homozygous variant in AHR: c.2242del, p. (Gln748Lysfs*5). During 11-years follow-up period, BCVA gradually improved. There was no evidence of retinal degeneration. CONCLUSION: AHR gene defects could be associated with infantile nystagmus, foveal hypoplasia and chiasmal misrouting.

Parinaud Syndrome in a Patient With Microangiopathic Lesions in the Bilateral Gangliocapsular Region and Left Thalamus.

Parinaud syndrome, which most commonly involves the dorsal midbrain, has classical features of upward gaze paralysis, convergence-retraction nystagmus, and pupillary light near dissociation. A 62-year-old male presented to the Eye department with diminution of vision and symptoms of dry eye with associated difficulty in walking. Examination revealed nystagmus while performing convergence test. An MRI revealed lesions in the thalamic and gangliocapsular regions. Microangiopathies involving the thalamus and gangliocapsular region can lead to Parinaud syndrome. In our case, microangiopathies were most probably hypertensive.

Vestibular Assessment with the vHIT and Skull Vibration-Induced Nystagmus Test in Patients with Nonprogressive Vestibular Schwannoma.

Background: Our primary objective was to monitor nonprogressive unilateral vestibular schwannomas (VSs) to assess the efficiency of rapid bedside examinations, such as the video head impulse test (vHIT) and skull vibration-induced nystagmus test (SVINT), in identifying vestibular damage. Methods: An observational study was conducted from March 2021 to March 2022 on all adult patients (>18 years old) with a confirmed nonprogressive VS (no active treatment). The SVINT (using a 100 Hz vibrator with two (SVINT2) or three (SVINT3) stimulation locations) and vHIT (for the six semicircular canals (SCCs)) were performed on all patients. The asymmetry of function between the vestibules was considered significant when the gain asymmetry was greater than 0.1. Rapid and repeatable assessment of VSs using two- and three-stimulation SVINT plus vHIT was performed to quantify intervestibular asymmetry. Results: SVINT3 and SVINT2 triggered VIN in 40% (24/60) and 65% (39/60) of patients, respectively. There was significant asymmetry in the vestibulo-ocular reflex (VOR), as shown by a VS-side gain < healthy-side gain in 58% (35/60) of the patients. Among the patients with significant gain asymmetry between the two vestibules according to the vHIT (VS-side gain < healthy-side gain), the proportion of patients expressing vestibular symptomatology was significantly greater than that of patients without any symptoms [67% (29/43) vs. 35% (6/17), respectively; p = 0.047]. Conclusions: The SVINT2 can be combined with the vHIT to form an interesting screening tool for revealing vestibular asymmetry. This work revealed the superiority of mastoid stimulation over vertex stimulation for SVINT in patients with unilateral vestibular loss.

Dissociated cerebellar contributions to feedforward gait adaptation.

The cerebellum is important for motor adaptation. Lesions to the vestibulo-cerebellum selectively cause gait ataxia. Here we investigate how such damage affects locomotor adaptation when performing the 'broken escalator' paradigm. Following an auditory cue, participants were required to step from the fixed surface onto a moving platform (akin to an airport travellator). The experiment included three conditions: 10 stationary (BEFORE), 15 moving (MOVING) and 10 stationary (AFTER) trials. We assessed both behavioural (gait approach velocity and trunk sway after stepping onto the moving platform) and neuromuscular outcomes (lower leg muscle activity, EMG). Unlike controls, cerebellar patients showed reduced after-effects (AFTER trials) with respect to gait approach velocity and leg EMG activity. However, patients with cerebellar damage maintain the ability to learn the trunk movement required to maximise stability after stepping onto the moving platform (i.e., reactive postural behaviours). Importantly, our findings reveal that these patients could even initiate these behaviours in a feedforward manner, leading to an after-effect. These findings reveal that the cerebellum is crucial for feedforward locomotor control, but that adaptive locomotor behaviours learned via feedback (i.e., reactive) mechanisms may be preserved following cerebellum damage.

Assessments of Subjective Visual Gravity and Spontaneous Nystagmus in Patients With Vestibular Neuritis.

OBJECTIVE: This study aimed to assess the correlation between the spontaneous nystagmus (SN) and the subjective visual vertical/horizontal (SVV/SVH) among patients with vestibular neuritis (VN) at the different head positions. STUDY DESIGN: Case-control study. SETTING: Affiliated Sixth People's Hospital, Shanghai Jiao Tong University School of Medicine. METHODS: This study evaluated the SVV/SVH in both healthy subjects and patients with VN. These evaluations were performed in 5 different head positions: upright, 45° tilt to the left, 90° tilt to the left, 45° tilt to the right, and 90° tilt to the right. Additionally, the intensity of SN, as measured by slow-phase velocity, was recorded. RESULTS: In patients with VN, a significant correlation was observed between SN and SVV/SVH in an upright position. The intensity of SN was higher when the head was tilted 90° toward the affected side compared to other positions. The SVV/SVH displayed an ipsiversive shift, when the head was tilted toward both the lesion and unaffected sides, exhibiting a contraversive direction. Furthermore, the changes in position-induced SN were consistent with the displacements of SVV and SVH caused by head tilt. CONCLUSION: The presence of SN in patients with VN was observed to vary across different head position. These variations could potentially be attributed to the diverse activation patterns of the mechanical properties of otolith organs that are induced by head tilts.

Evolution of Hyperventilation-Induced Nystagmus in Acute Unilateral Vestibulopathy-Interpretative Model and Etiopathogenetic Hypotheses.

Hyperventilation induces metabolic changes that can elicit nystagmus (hyperventilation-induced nystagmus, HVIN) in various vestibular disorders, revealing vestibular imbalance and bringing out central or peripheral asymmetries. In acute unilateral vestibulopathy (AUVP, namely vestibular neuritis), hyperventilation can induce different patterns of nystagmus (excitatory, inhibitory, or negative), disclosing or modifying existing static vestibular asymmetries through its ability to invalidate compensation or increase peripheral excitability. In this context, we followed the evolutionary stages of HVIN in AUVP across 35 consecutive patients, with the goal of assessing alterations in the oculomotor pattern caused by hyperventilation over time. In the acute phase, the incidence of the excitatory pattern (and the strongly excitatory one, consisting of a reversal nystagmus evoked by hyperventilation) was significantly higher compared to the inhibitory pattern; then, a progressive reduction in the incidence of the excitatory pattern and a concomitant gradual increase in the incidence of the inhibitory one were observed in the follow-up period. Assuming the role of the ephaptic effect and the transient loss of vestibular compensation as opposing mechanisms, i.e., excitatory and inhibitory, respectively, the oculomotor pattern evoked by hyperventilation is the result of the interaction of these two factors. The data obtained allowed us to hypothesize an interpretative model regarding the pathogenetic aspects of responses evoked by hyperventilation and the etiologies of the disease: according to our hypotheses, the excitatory pattern implies a neuritic (viral) form of AUVP; instead, the inhibitory (and negative) one can be an expression of both the neuritic (viral) and vascular forms of the disease.

Vertical infantile nystagmus: Explanation of why the direction of nystagmus is vertical.

This case report presents a rare case of infantile nystagmus syndrome (INS) in which the direction of infantile nystagmus (IN) was vertical. A 66-year-old woman was referred to our department for investigation of abnormal eye movements. She showed a disordered field of view with a homonymous hemianopia in the lower left quadrant and vertical gaze-evoked nystagmus, but there were no other abnormal neurological findings. She did not complain of an oscillopsia. Imaging revealed that the cause of hemianopia was atrophy and low cerebral blood flow in the right occipital lobe. The vertical nystagmus became strong when attempting to fixate to stationary targets. A reversed optokinetic nystagmus response was observed in the vertical optokinetic nystagmus test. From these eye movements, we diagnosed her nystagmus as vertical IN. Patients with INS see everything by saccades. IN consists of the alternate appearance of saccades and preceding slow eye movements. For these eye movements, a wide visual field is necessary. In this case, vertical IN was caused by the wider vertical than horizontal visual field resulting from homonymous hemianopia. Therefore, the direction of IN is horizontal in most patients with INS because their horizontal visual field is the widest field.

Electroretinography in congenital nystagmus patients with a normal fundus examination.

PURPOSE: To identify the ophthalmic causes of congenital nystagmus with normal eye examination by electroretinography (ERG). STUDY DESIGN: Retrospective observational study. METHODS: We reviewed the medical records of patients younger than 6 months of age who presented between June 2008 and November 2011 with nystagmus and no other neurological signs following an otherwise normal eye examination. A complete ophthalmic examination and ERG (Nicolet Bravo system; Nicolet Biomedial & RETIscan; Roland Instruments), fundus photography, and Ishihara color test were performed to identify any ophthalmic causes of congenital nystagmus. RESULTS: Thirty-three patients met the criteria. Rod dysfunction was diagnosed in 4 patients (12.1%), cone dysfunction in 2 patients (6.1%), and cone-rod dysfunction in 1 patient (3.0%). The results of ERG were negative in 2 patients (6.1%). Idiopathic infantile nystagmus was diagnosed in the remaining 24 patients (72.7%) based on their normal ERG examination. CONCLUSIONS: In Korean congenital nystagmus patients with a normal fundus examination, achromatopsia and Leber's congenital amaurosis are uncommon causes. ERG is needed to make a definite diagnosis and provide prognostic information in congenital idiopathic nystagmus patients with a normal fundus examination.

Paraneoplastic Syndrome Case Presented As Nystagmus and Ataxia.

The incidence of paraneoplastic syndrome (PNS) is on the rise, attributed to the growing detection of antibody modalities in both the serum and cerebrospinal fluid (CSF). PNS can occur as different neurological symptoms. The revised guidelines streamline the diagnostic approach but identifying PNS still requires the detection of neurological manifestations concurrent with cancer, along with the presence of specific PNS autoantibodies.

Pediatric Benign Paroxysmal Positional Vertigo: Degree of Nystagmus and Concurrent Dizziness Differs from Adult BPPV.

Background: Benign paroxysmal positional vertigo (BPPV) is characterized by brief, intense episodes of vertigo triggered by abrupt changes in head position. It is generally accepted as being most common in adults, while it is regarded as rare in children. It is necessary to compare the disease between pediatric and adult patients for a better understanding of the disease's characteristics and its natural history. This study aimed to identify the clinical characteristics of BPPV in children and compare them with those of adult BPPV patients. Methods: All children ≤ 18 years old who were diagnosed with BPPV were selected by searching the electronic database of our hospital. Clinical features were identified by medical record review. For adult patients, we collected data from patients > 19 years of age. Results: A total of 30 pediatric (13.65 ± 4.15 years old) and 264 adult patients (60.86 ± 13.74 years old) were included in the study. Among pediatric patients, the lateral canals were involved in 80% and the posterior canals in 16.67%. In adult patients, the lateral and posterior canals were involved similarly (p = 0.007). The degree of nystagmus in pediatric patients was 6.82 ± 12.09, while in adults it was 15.58 ± 20.90 (p < 0.001). The concurrent dizziness disorder was higher in the pediatric group and recurrence was higher in the adult group. In the regression analysis, it was found that adult patients had a stronger nystagmus with a value of 6.206 deg/sec, and the risk of concurrent dizziness disorder was found to be 5.413 times higher in the pediatric group (p < 0.05). Conclusions: BPPV occurs in pediatric patients with lower prevalence, but it cannot be overlooked. In the pediatric group, a relatively high proportion of patients demonstrated lateral canal involvement, weaker nystagmus, and additional dizziness disorder.

Internuclear ophthalmoplegia following radial artery cardiac catheterization approach: An unusual presentation.

Internuclear ophthalmoplegia (INO) may happen following percutaneous coronary intervention and angiography. However, no reports of INO during radial artery angioplasty were reported yet. We report a rare case in a 47-year-old man presenting with diplopia after radial artery angioplasty. Although the symptoms were resolved after 60 days, diagnosing this obstacle is necessary to reduce the patient and physician's anxiety.

Digital biomarkers from gaze tests for classification of central and peripheral lesions in acute vestibular syndrome.

Acute vestibular syndrome (AVS) is characterised by a sudden vertigo, gait instability, nausea and nystagmus. Accurate and rapid triage of patients with AVS to differentiate central (potentially sinister) from peripheral (usually benign) root causes is a challenge faced across emergency medicine settings. While there exist bedside exams which can reliably differentiate serious cases, they are underused due to clinicians' general unfamiliarity and low confidence interpreting results. Nystagmus is a fundamental part of AVS and can facilitate triaging, but identification of relevant characteristics requires expertise. This work presents two quantitative digital biomarkers from nystagmus analysis, which capture diagnostically-relevant information. The directionality biomarker evaluates changes in direction to differentiate spontaneous and gaze-evoked (direction-changing) nystagmus, while the intensity differential biomarker describes changes in intensity across eccentric gaze tests. In order to evaluate biomarkers, 24 sets of three gaze tests (left, right, and primary) are analysed. Both novel biomarkers were found to perform well, particularly directionality which was a perfect classifier. Generally, the biomarkers matched or eclipsed the performance of quantitative nystagmus features found in the literature. They also surpassed the performance of a support vector machine classifier trained on the same dataset, which achieved an accuracy of 75%. In conclusion, these biomarkers simplify the diagnostic process for non-specialist clinicians, bridging the gap between emergency care and specialist evaluation, ultimately benefiting patients with AVS.