Systematic assessment of square-wave jerks in progressive supranuclear palsy: a video-oculographic study.

BACKGROUND: The presence of frequent macro-square-wave jerks (SWJs) has been recently included in the diagnostic criteria for progressive supranuclear palsy (PSP). The aim of the current video-oculographic study was to systematically assess the presence and features of SWJs during a brief fixation task in PSP, in comparison with Parkinson's disease (PD) patients and healthy controls (HC). METHODS: Thirty-eight PSP patients, 55 PD patients and 40 HC were enrolled in the study. All patients underwent a video-oculographic (VOG) examination including a 5-s fixation task, and the number, duration and amplitude of SWJs were recorded. The diagnostic performance of several SWJs parameters were then compared in distinguishing PSP from PD patients and controls. RESULTS: PSP patients showed a higher number and amplitude of SWJs compared to PD patients and controls. At least two SWJs within the 5-s fixation task were observed in 81.6% of PSP patients, 52.7% of PD patients and 25% of HC. The SWJs amplitude was the parameter showing the highest performances in distinguishing PSP from PD (AUC: 0.78) and HC (AUC: 0.88), outperforming the SWJ number and duration. The SWJ amplitude was larger in PSP-Richardson's syndrome than in PSP-Parkinsonism patients, while no difference was found between PSP patients with different degrees of vertical ocular motor dysfunction. CONCLUSIONS: This video-oculographic study provides robust evidence of larger SWJs number and amplitude in PSP than in PD patients, with some potential for differential diagnosis, supporting the inclusion of this ocular sign in PSP criteria.

Wearable Near-Eye Tracking Technologies for Health: A Review.

With the rapid advancement of computer vision, machine learning, and consumer electronics, eye tracking has emerged as a topic of increasing interest in recent years. It plays a key role across diverse domains including human-computer interaction, virtual reality, and clinical and healthcare applications. Near-eye tracking (NET) has recently been developed to possess encouraging features such as wearability, affordability, and interactivity. These features have drawn considerable attention in the health domain, as NET provides accessible solutions for long-term and continuous health monitoring and a comfortable and interactive user interface. Herein, this work offers an inaugural concise review of NET for health, encompassing approximately 70 related articles published over the past two decades and supplemented by an in-depth examination of 30 literatures from the preceding five years. This paper provides a concise analysis of health-related NET technologies from aspects of technical specifications, data processing workflows, and the practical advantages and limitations. In addition, the specific applications of NET are introduced and compared, revealing that NET is fairly influencing our lives and providing significant convenience in daily routines. Lastly, we summarize the current outcomes of NET and highlight the limitations.

Video-Oculography Assessment in Neurodegenerative Ataxias and Niemann Pick Type C.

Introduction: Deceleration of vertical saccades, an early and characteristic finding of Niemann-Pick Type C (NP-C), may help diagnosis. Our aim in this study was to demonstrate the role of video-oculography (VOG), in the differential diagnosis of ataxia syndromes, particularly of NP-C, using this technique in the evaluation of saccadic velocity and smooth pursuit gain of ataxia patients. Methods: We recruited consecutive 50 ataxia patients and 50 healthy control subjects who were age and sex-matched with the patient group. Saccadic eye movements and smooth pursuit eye movements for different angles and different directions from patients and healthy subjects were recorded by using VOG. Results: Saccadic eye movement velocity and smooth pursuit gain values of the patients were significantly lower in all directions and at all angles as compared to healthy subjects. In the patient group, 3 cases out of 50 were selected as suspected NP-C, based on the dissociation between their markedly impaired vertical saccadic velocity and near normal to slightly impaired horizontal one and relatively intact smooth pursuit eye movements; the diagnoses in all 3 cases were confirmed with positive genetic testing, and thereupon Miglustat treatment was started. Conclusion: Our findings support that cerebellar pathology in degenerative ataxia patients is associated with both impaired saccadic velocity and smooth pursuit gain, whereas in NP-C, only the impaired vertical saccades as opposed to relatively preserved other eye movements are seemingly a diagnostic marker for the entity. We conclude that recording of eye movements could be useful for differential diagnosis and monitorization of the treatment of ataxia syndromes as an easy and objective method.

Quantification of saccadic fatigability and diagnostic efficacy for myasthenia gravis.

BACKGROUND AND OBJECTIVES: The diagnostic challenge of myasthenia gravis (MG) is exacerbated by the variable efficacy of current testing methodologies, necessitating innovative approaches to accurately identify the condition. This study aimed to assess ocular muscle fatigue in patients with MG using video-oculography (VOG) by examining repetitive saccadic eye movements and comparing these metrics to those of healthy control participants. METHODS: This prospective, cross-sectional study was conducted at a tertiary care center and involved 62 patients diagnosed with MG (48 with ocular MG and 14 with generalized MG) and a control group of 31 healthy individuals, matched for age and sex. The assessment involved recording saccadic eye movements within a ± 15° range, both horizontally and vertically, at a rate of 15 saccades per minute over a 5-min period, resulting in 75 cycles. Participants were afforded a 3-min rest interval between each set to mitigate cumulative fatigue. The primary outcome was the detection of oculomotor fatigue, assessed through changes in saccadic waveforms, range, peak velocity, latency, and the duration from onset to target, with a focus on comparing the second saccade against the average of the last five saccades. RESULTS: In the evaluation of repetitive saccadic movements, patients with MG exhibited a reduced saccadic range and a prolonged duration to reach the target, compared to healthy subjects. Furthermore, a significant elevation in the frequency of multistep saccades was observed among MG patients, with a marked rise observed over consecutive trials. Receiver operating characteristic (ROC) analysis revealed the discriminative performance of multistep saccade frequency, in conjunction with variations in saccadic range and duration from onset to target achievement between the second saccade and the mean of the final five saccades, as effective in distinguishing MG patients from healthy subjects. Although alterations in peak saccadic velocity and latency were less pronounced, they were nevertheless detectable. DISCUSSION: The utilization of VOG for repetitive saccadic testing in the diagnosis of MG has demonstrated considerable diagnostic precision. This methodology affords significant accuracy in evaluating ocular muscle fatigue in MG patients, providing class III evidence supportive of its clinical application.

Non-Invasive Recording of Ocular-Following Responses in Children: A Promising Tool for Stereo Deficiency Evaluation.

Background: The ability to merge the two retinal images to perceive depth (stereopsis) plays an important role in human vision. Its proper development requires binocular alignment and good visual acuity in both eyes during childhood. Because treatments are more effective when applied early, early diagnosis is important. Unfortunately, assessing stereo deficiencies in infants and young children remains challenging. Recently, it has been shown that ocular-following responses (OFRs; reflexive, short-latency eye movements induced by the sudden motion of a large textured pattern) are sensitive to changes in interocular correlation, making them potentially useful for stereo deficiency assessments. To test this hypothesis, we measured OFRs elicited by dichoptic stimulation in children with normal and compromised stereopsis (due to amblyopia). Methods: Two groups of six children (age- and sex-matched: 3M/3F aged 7-12 yo), one with compromised stereopsis and one with normal stereopsis, were included. OFRs were recorded using a custom high-resolution video eye-tracking system. The relative differences between eye displacement induced by correlated stimuli (up-correlated-down-correlated) and anticorrelated (up-anticorrelated-down-anticorrelated) were compared. Results: We found significant differences between OFRs induced by two dichoptic conditions (correlated and anticorrelated stimuli) in most children with normal stereopsis, whereas no differences were observed in children with compromised stereopsis, indicating a lack of disparity detectors. Conclusions: OFRs might thus be exploited as a diagnostic tool for the objective identification of stereo deficiencies in children. This might lead to improved early diagnosis and treatment outcomes for conditions like amblyopia and strabismus.

Early Manifestation of Benign Paroxysmal Positional Vertigo: A Case Report.

Introduction: Benign paroxysmal positional vertigo (BPPV) is an inner ear disorder with a heterogeneous etiology, often linked to preceding infections, head injuries, or vestibular neuronitis. While it is commonly observed in the elderly, its occurrence in the pediatric population is rare. To our knowledge, there have been no reported cases of BPPV in patients younger than 5 years. Case Presentation: A 4.5-month-old female infant was admitted with episodes of paroxysmal nystagmus. Parents reported fast horizontal eye movements lasting up to 30 s, with one episode accompanied by vomiting. Comprehensive differential diagnosis was considered from epileptic nystagmus to intoxications and both central and peripheral vestibular etiologies. During the observation on ward, connection between the baby's positioning and nystagmus was identified. The diagnostic roll test confirmed a transient positional geotropic nystagmus. The diagnosis aligned with BPPV characteristics, pointing to the right lateral semicircular canal canalolithiasis. A successful Lempert roll maneuver was performed with prompt effect. To further support the diagnosis and research, we introduced a semiautomatic video-oculography method. Conclusion: This case highlights a rare instance of BPPV in an infant. The clinical findings combined with the effectiveness of the repositioning maneuvers support the diagnosis of right lateral semicircular canal lithiasis. Despite the rarity of this condition in such a young-age group, the need for thorough diagnostic evaluations is emphasized. In order to document the case, we also present a semiautomatic video analysis pipeline for analyzing abnormal eye movements in a home setting.

Automatic Video-Oculography System for Detection of Minimal Hepatic Encephalopathy Using Machine Learning Tools.

This article presents an automatic gaze-tracker system to assist in the detection of minimal hepatic encephalopathy by analyzing eye movements with machine learning tools. To record eye movements, we used video-oculography technology and developed automatic feature-extraction software as well as a machine learning algorithm to assist clinicians in the diagnosis. In order to validate the procedure, we selected a sample (n=47) of cirrhotic patients. Approximately half of them were diagnosed with minimal hepatic encephalopathy (MHE), a common neurological impairment in patients with liver disease. By using the actual gold standard, the Psychometric Hepatic Encephalopathy Score battery, PHES, patients were classified into two groups: cirrhotic patients with MHE and those without MHE. Eye movement tests were carried out on all participants. Using classical statistical concepts, we analyzed the significance of 150 eye movement features, and the most relevant (p-values ≤ 0.05) were selected for training machine learning algorithms. To summarize, while the PHES battery is a time-consuming exploration (between 25-40 min per patient), requiring expert training and not amenable to longitudinal analysis, the automatic video oculography is a simple test that takes between 7 and 10 min per patient and has a sensitivity and a specificity of 93%.

Three-dimensional analysis of per-rotational nystagmus.

BACKGROUND: Head rotation produces a vestibulo-ocular reflex (VOR). In horizontal rotation, not only lateral semicircular canals but also posterior semicircular canals are stimulated, because posterior canals cupulae are not horizontal in the sitting position. Therefore, theoretical nystagmus is horizontal and torsional. Convection of endolymph does not occur, because the centre of head rotation is a dens of the second cervical vertebra, not the center of lateral canal. Although per-rotational nystagmus is a result of VOR, whether it could be explained by the movement of cupula remains undetermined. To answer this question, we analysed per-rotational nystagmus using three-dimensional video-oculography. OBJECTIVE: To clarify whether per-rotational nystagmus is the same as the physical movement of cupula (theoretical nystagmus). MATERIALS AND METHODS: Five healthy human were evaluated. The participant's head was rotated (sinusoidal yaw rotation) manually (frequency, 0.33 Hz; amplitude, 60°). The experiment was performed in a dark, with the participant's eyes open. Nystagmus was recorded and converted into digital data. RESULTS: In all participants, the direction of nystagmus was rightward on rightward rotation and leftward on leftward rotation. In all participants, nystagmus was purely horizontal. CONCLUSIONS: Practical per-rotational nystagmus differs completely from the theoretical nystagmus. Therefore, VOR is strongly influenced by the central nervous system.

Static cervico-ocular reflex in healthy humans.

BACKGROUND: Dynamic cervico- (COR) and vestibulo-ocular reflex (VOR) contribute to stabilise visual images in the retina. The gain in dynamic COR is small in healthy individuals but increases in patients with vestibular dysfunction. Conversely, static COR has not been directly observed in healthy individuals. OBJECTIVES: To elucidate the presence of static COR and quantify it in normal individuals in the roll plane. METHODS: Eleven healthy participants were included in the study. Eye torsions were measured using video oculography to evaluate the static COR induced by lateral neck flexion during a head-upright-with-body-tilt position at 15°, 30°, and 45°. The ocular counterroll (OCR) was compared during whole-body and head tilts to assess the influence of static COR on OCR. RESULTS: Static COR was significantly observed as eye torsion in the direction opposite to the body tilt. The head tilt OCR was significantly smaller than the whole-body tilt OCR to the right side but not to the left side. CONCLUSION: Static COR exists in healthy individuals and tends to show higher amplitude as neck flexion stimulation increases.

Video Ocular Counter-Roll (vOCR): Otolith-Ocular Function and Compensatory Effect of the Neck Following Vestibular Loss.

OBJECTIVE: Assessment of recovery following vestibular loss has been limited by the lack of bedside measures in clinical settings. Here, we used the video ocular counter-roll (vOCR) test to study otolith-ocular function and compensatory effect of neck proprioception in patients at different stages of vestibular loss. STUDY DESIGN: Case-control study. SETTING: Tertiary care center. METHODS: Fifty-six subjects were recruited including patients with acute (9 ± 2 days [mean ± standard error of mean]), subacute (61 ± 11 days), and chronic (1009 ± 266 days) unilateral loss of vestibular function, as well as a group of healthy controls. We used a video-oculography method based on tracking the iris for vOCR measurement. To examine the effect of neck inputs, vOCR was recorded during two simple tilt maneuvers in all subjects while seated: 30° head-on-body tilt and 30° head-and-body tilt. RESULTS: The vOCR responses evolved at different stages following vestibular loss with improvement of the gains in the chronic stage. The deficit was more pronounced when the whole body was tilted (acute: 0.08 ± 0.01, subacute: 0.11 ± 0.01, chronic: 0.13 ± 0.02, healthy control: 0.18 ± 0.01), and the gain of vOCR improved when the head was tilted on the body (acute: 0.11 ± 0.01, subacute: 0.14 ± 0.01, chronic: 0.13 ± 0.02, healthy control: 0.17 ± 0.01). The time course of vOCR response was affected as well with reduced amplitude and slower response in the acute stage of vestibular loss. CONCLUSION: The vOCR test can be valuable as a clinical marker to measure vestibular recovery and compensatory effect of neck proprioception in patients at different stages following loss of vestibular function.

Oculomotor fatigability with decrements of saccade and smooth pursuit for diagnosis of myasthenia gravis.

BACKGROUND AND OBJECTIVES: As the efficacy of current diagnostic methods for myasthenia gravis (MG) remains suboptimal, there is ongoing interest in developing more effective diagnostic models. As oculomotor fatigability is one of the most common and diagnostic symptoms in MG, we aimed to investigate whether quantitative saccadic and smooth-pursuit fatigability analyses with video-oculography (VOG) are useful for diagnosis of MG. METHODS: A convenience cohort of 46 MG patients was recruited prospectively, including 35 with ocular and 11 with generalized MG (mean age, 50.9 ± 14.5 years; 17 females); 24 healthy controls (HCs) (mean age, 50.6 ± 16.3 years; 13 females) also were enrolled. Seventy-five repetitive saccades and smooth pursuits were recorded in ranges of 20° (horizontal plane) and 15° (vertical plane) using a three-dimensional VOG system. Based on the oculomotor range of the second saccade and smooth pursuit and the mean ranges of the last five of each, the estimated decrements (%) reflecting oculomotor fatigability were calculated. RESULTS: The baseline oculomotor ranges did not show significant difference between the MG and HCs groups. However, following repetitive saccades and pursuits, the oculomotor ranges were decreased substantially during the last five cycles compared to baseline in the MG group. No such decrements were observed in the HC group (p < 0.01, Mann-Whitney U test). Receiver operating characteristic (ROC) analysis revealed that repetitive vertical saccades yielded the best differentiation between the MG and HC groups, with a sensitivity of 78.3% and specificity of 95.8% when using a decrement with an amplitude of 6.4% as the cutoff. CONCLUSION: This study presents an objective and reproducible method for measuring decrements of oculomotor ranges after repetitive saccadic and pursuit movements. Quantification of oculomotor fatigability using VOG could be a sensitive and specific diagnostic tool for MG and allows easy, cost-effective, accurate, and non-invasive measurements. CLASSIFICATION OF EVIDENCE: This study provides class III evidence that VOG-based quantification of saccadic and pursuit fatigability accurately identifies patients with MG.

Lesion follows function: video-oculography compared with MRI to diagnose internuclear ophthalmoplegia in patients with multiple sclerosis.

BACKGROUND: Video-oculography (VOG) is used to quantify functional deficits in internuclear ophthalmoplegia (INO), whereas MRI can detect the corresponding structural lesions in the medial longitudinal fasciculus (MLF). This study investigates the diagnostic agreement of MRI compared to VOG measurements. METHODS: We prospectively compared structural MRI findings and functional VOG measures of 63 MS patients to assess their diagnostic agreement for INO. RESULTS: MRI detected 12 true-positive and 92 true-negative MLF lesions for INO compared to VOG (12 true-positive and 38 true-negative patients) but identified one-third of the MLF lesions on the wrong side. MRI ratings were specific (92.0%) to detect MLF lesions but not sensitive (46.2%) for diagnosing INO (86.4% and 63.2% by patient). Accordingly, MRI has a high positive likelihood ratio of 5.77 but a modest negative likelihood ratio of 0.59 for the probability of INO (4.63 and 0.43) with an accuracy of 82.5% (79.4%). CONCLUSION: MRI assessments are highly specific but not sensitive for detecting INO compared to VOG. While MRI identifies MLF lesions in INO, VOG quantifies the deficit. As a simple, quick, and non-invasive test for diagnosing and tracking functional INO deficits, it will hopefully find its place in the diagnostic and therapeutic pathways of MS.

Progression of Clinical and Eye Movement Markers in Preataxic Carriers of Machado-Joseph Disease.

BACKGROUND: Little is known about preclinical stages of Machado-Joseph disease, a polyglutamine disorder characterized by progressive adult-onset ataxia. OBJECTIVE: We aimed to describe the longitudinal progression of clinical and oculomotor variables in the preataxic phase of disease. METHODS: Carriers and noncarriers were assessed at three visits. Preataxic carriers (Scale for Assessment and Rating of Ataxia score < 3) expected to start ataxia in ≤4 years were considered near onset (PAN). Progressions of ataxic and preataxic carriers, considering status at the end of the study, were described according to the start (or its prediction) of gait ataxia (TimeToAfterOnset) and according to the study time. RESULTS: A total of 35 ataxics, 38 preataxics, and 22 noncarriers were included. The "TimeToAfterOnset" timeline showed that Neurological Examination Scale for Spinocerebellar Ataxias (NESSCA; effect size, 0.09), Inventory of Non-Ataxia Symptoms (INAS0.07), and the vestibulo-ocular reflex gain (0.12) progressed in preataxic carriers, and that most slopes accelerate in PAN, turning similar to those of ataxics. In the study time, NESSCA (1.36) and vertical pursuit gain (1.17) significantly worsened in PAN, and 6 of 11 PANs converted to ataxia. For a clinical trial with 80% power and 2-year duration, 57 PANs are needed in each study arm to detect a 50% reduction in the conversion rate. CONCLUSIONS: NESSCA, INAS, vestibulo-ocular reflex, and vertical pursuit gains significantly worsened in the preataxic phase. The "TimeToAfterOnset" timeline unveiled that slopes of most variables are small in preataxics but increase and reach the ataxic slopes from 4 years before the onset of ataxia. For future trials in preataxic carriers, we recommend recruiting PANs and using the conversion rate as the primary outcome. © 2022 International Parkinson and Movement Disorder Society.

Analysis of 30 patients with cupulolithiasis of the posterior semicircular canal.

BACKGROUND: The diagnostic characteristics of patients with cupulolithiasis of the posterior semicircular canal are persistent torsional nystagmus in the supine position and persistent torsional nystagmus (opposite direction) in the nose-down position, which are caused by the affected canal becoming gravity sensitive. OBJECTIVE: To investigate the clinical features of posterior cupulolithiasis. MATERIALS AND METHODS: We interviewed 30 consecutive patients with cupulolithiasis of the posterior canal and categorized them by onset time into the following four groups: (1) during sleep; (2) at the time of awakening; (3) morning; and (4) afternoon. We defined disease duration as the period from onset to the day when we detected remission of positional nystagmus. RESULTS: Time of awakening was the most common onset time. The mean disease duration was 18.2 days, and 90% of patients achieved cure within 1 month. CONCLUSIONS: Physicians should take into account the duration of nystagmus, because cupulolithiasis of posterior canal exists. The etiology of posterior cupulolithiasis is closely related to sleep, because time of awakening is the most common onset time of vertigo. Most patients with posterior cupulolithiasis cure within 1 month.

Weak nystagmus in the dark persists for months after acute unilateral vestibular loss.

Background: Weak nystagmus with fixation removed can be seen both in normal individuals and in recovery from a unilateral vestibular insult, thus its clinical significance is unclear in patients with dizziness. We thus sought to compare features of nystagmus at various stages following unilateral vestibular loss (UVL). Methods: We enrolled thirty consecutive patients after acute UVL with impaired vestibulo-ocular reflex (VOR) gain. The patients were allocated into three groups according to time from onset of symptoms: acute (1-7 days), subacute (8-30 days), and chronic (>30 days). Patients underwent video-oculography (with and without fixation) and video head impulse testing (vHIT) to determine VOR gain. We examined the relationships amongst SPV, VOR gain, and time from symptom onset across groups. Results: There were 11, 10, and 9 patients in the acute, subacute, and chronic stages of UVL, respectively. With visual fixation, only 8 patients (26.7%) demonstrated nystagmus, all from the acute group. With fixation removed, 26 patients (86.7%) exhibited spontaneous nystagmus, including 90.9%, 90%, and 77.8% of the patients from the acute, subacute, and chronic groups, respectively. Horizontal nystagmus was paralytic (i.e., fast phase contralesional) in 25 (96.7%) cases. Horizontal SPV was negatively correlated with logarithm of time from onset to examination (r = -0.48, p = 0.007) and weakly negatively correlated with ipsilesional VOR gain (r = -0.325, p = 0.08). Conclusion: In the subacute or chronic stages of UVL, paralytic nystagmus with fixation removed persisted at a low intensity. Therefore, weak nystagmus in the dark may have diagnostic value in chronic dizziness.

Measuring saccades in patients with Niemann-Pick type C: A comparison between video-oculography and a novel eye tracking test based on continuous psychophysics.

Introduction: Vertical supranuclear gaze palsy is a key feature of Niemann-Pick type C (NP-C) and is commonly quantified using video-oculography (VOG). VOG requires sitting still for long times and performing specific tasks, thus it can be challenging or impossible for patients severely affected by movement disorders or cognitive impairment. To overcome this limitation, we measure saccades of NP-C patients using a fast eye tracking test based on continuous psychophysics and compare it to VOG. Methods: Saccades of six NP-C patients and six age-matched controls were assessed using VOG and Standardized Oculomotor and Neuro-ophthalmic Disorders Assessment (SONDA). In SONDA, participants continuously track a semi-randomly moving dot on a computer screen while their gaze is being tracked. For both assessments, saccades were quantified using four conventional measures: amplitude, gain, latency, and peak velocity. Furthermore, SONDA's continuous measures were quantified with several novel spatio-temporal properties. Results: In the NP-C patients, both methods revealed reduced amplitude, gain, peak velocity, and increased latency of vertical saccades compared to horizontal saccades and compared to healthy controls. Effect sizes obtained with SONDA were overall larger than those for VOG. SONDA's spatio-temporal properties showed similar trends. Conclusion: SONDA reveals a deterioration of vertical saccades in NP-C patients that is consistent with VOG. SONDA's measures based on continuous psychophysics are consistent with traditional saccadic parameters and can potentially provide complementary information. SONDA shows larger effect sizes than VOG, suggesting that it provides robust and clinically relevant outcomes with a more intuitive task and shorter testing time.

Toward an Automatic Assessment of Cognitive Dysfunction in Relapsing-Remitting Multiple Sclerosis Patients Using Eye Movement Analysis.

Despite the importance of cognitive function in multiple sclerosis, it is poorly represented in the Expanded Disability Status Scale (EDSS), the commonly used clinical measure to assess disability, suggesting that an analysis of eye movement, which is generated by an extensive and well-coordinated functional network that is engaged in cognitive function, could have the potential to extend and complement this more conventional measure. We aimed to measure the eye movement of a case series of MS patients with relapsing−remitting MS to assess their cognitive status using a conventional gaze tracker. A total of 41 relapsing−remitting MS patients and 43 age-matched healthy controls were recruited for this study. Overall, we could not find a clear common pattern in the eye motor abnormalities. Vertical eye movement was more impaired in MS patients than horizontal movement. Increased latencies were found in the prosaccades and reflexive saccades of antisaccade tests. The smooth pursuit was impaired with more corrections (backup and catchup movements, p<0.01). No correlation was found between eye movement variables and EDSS or disease duration. Despite significant alterations in the behavior of the eye movements in MS patients, which are compatible with altered cognitive status, there is no common pattern of these alterations. We interpret this as a consequence of the patchy, heterogeneous distribution of white matter involvement in MS that provokes multiple combinations of impairment at different points in the different networks involved in eye motor control. Further studies are therefore required.

Comparison of EOG and VOG obtained eye movements during horizontal head impulse testing.

Introduction: Video head impulse testing is frequently used to evaluate the vestibular function. During this test, eye movement responses are recorded with video-oculography (VOG). However, the use of VOG can sometimes be challenging, especially due to pupil detection problems (e.g., blinking, droopy eyelids, etc.). Therefore, this study investigated whether electro-oculography (EOG), a technique that does not depend on pupil tracking but on the orientation of the corneoretinal potential, might be an alternative to VOG for quantifying eye movement responses during head impulse testing. Subjects and methods: Head impulse testing was performed in 19 healthy subjects without a prior history of vestibular symptoms. Horizontal eye movements were recorded simultaneously with EOG (using an EOG system) and VOG (using a VHIT system: ICS Impulse). The eye movement responses to each side of both techniques were compared using a concordance correlation coefficient (r c ), t-testing, and Bayes Factor (BF) paired t-testing. Results: EOG and VOG obtained eye movement traces that correlated well with each other during head impulse testing (average r c = 0.89). Average VOR gains obtained with EOG and VOG were not significantly different from each other for all subjects during left head impulses. However, VOG gains differed between both techniques regarding right head impulses. VOG showed significant VOR gain asymmetry (5% to the right), whereas EOG showed no significant asymmetry (1% to the right). Conclusion: This study demonstrated the use of EOG to record eye movements during head impulse testing for the first time. EOG and VOG obtained eye movement traces that correlated well with each other during horizontal head impulse testing. In addition, EOG showed smaller VOR gain asymmetry in healthy individuals, in contrast to VOG. These findings indicate that EOG might potentially be applicable as an alternative to VOG for collecting eye movement responses during head impulse testing. Trial registration number: 10192021-38 dated 19.10.21.

Automated nystagmus detection: Accuracy of slow-phase and quick-phase algorithms to determine the presence of nystagmus.

PURPOSE: To verify the accuracy of automated nystagmus detection algorithms. METHOD: Video-oculography (VOG) plots were analyzed from consecutive patients with dizziness presenting to a neurology clinic. Data were recorded for 30 s in upright position with fixation block. For automated nystagmus detection, slow-phase algorithm parameters included mean and median slow-phase velocity (SPV), and slow-phase duration ratio. Quick-phase algorithm parameters included saccadic difference and saccadic ratio. For verification, two independent blinded assessors reviewed VOG traces and videos and coded presence or absence of nystagmus. Assessor consensus was used as reference standard. Accuracy of slow-phase and quick-phase algorithm parameters were compared, and ROC analysis was performed. RESULTS: Among 524 analyzed VOG traces, 99 were verified as nystagmus present and 425 were verified as nystagmus absent. Prevalence of nystagmus in the sample population was 18.9%. In ROC analysis, areas under the curve of individual algorithm parameters were 0.791-0.896. With optimal thresholds for determining presence or absence of nystagmus, algorithm sensitivity (70.7-87.9%), specificity (71.8-84.0%), and negative predictive value (91.7-96.4%) were ideal, but positive predictive value (38.8-53.4%) was not ideal. Combining algorithm parameters using logistic regression models mildly improved detection accuracy. CONCLUSION: Both slow-phase and fast-phase algorithms were accurate for detecting nystagmus. Due to low positive predictive value, the utility of independent automated nystagmus detection systems is limited in clinical settings with low prevalence of nystagmus. Combining parameters using logistic regression models appears to improve detection accuracy, indicating that machine learning may potentially optimize the accuracy of future automated nystagmus detection systems.

Reliability of mobile video-oculography in multiple sclerosis patients using an iPad: A prospective validation study.

BACKGROUND: Video-oculography (VOG) could be useful for monitoring neurodegenerative diseases and multiple sclerosis (MS), as a high prevalence of subclinical eye movements abnormalities (EMA) has been previously reported, with a potential prognostic value regarding disease evolution. However, access to VOG is limited in clinical practice. OBJECTIVE: To evaluate the reliability of VOG recordings performed using eVOG, a mobile application developed on an iPad. METHOD: Patients with MS or related disease without clinically detectable EMA were enrolled in a cross-sectional study during which two VOG exams (classical VOG and eVOG) were performed on the same day. We examined reflex saccades, antisaccades, smooth pursuit and fixation. The total number of deficits, saccadic latencies and velocities, qualitative smooth pursuit were compared. RESULTS: 30 patients were included. The mean number of EMA per patient on classical VOG was 4.1 and 2.3 on eVOG. We found a statistical association between the number of EMA for each exam (r = 0.66, p < 0.0001). Saccades latencies (r = 0.57, p < 0.0001) and velocities (r = 0.45, p < 0.0001) were also well correlated. Assessing eVOG accuracy, we found a sensitivity ranging from 44% to 100% and a specificity ranging from 71% to 88.9% depending on the considered abnormality. CONCLUSION: eVOG could be an easily accessible solution to screen MS patients for the presence of EMA. We plan to use eVOG on a larger cohort of patients, in a prospective study to assess the prognostic value of subclinical EMA in MS. We also plan to investigate the use of eVOG in other neurological conditions.