Clinical Saccadometry: Establishing Evaluative Standards Using a Simplified Video Oculography Protocol in the Adult Population.

BACKGROUND: Saccadometry is an advanced ocular motor test battery that allows for the functional evaluation of the varied brain regions and circuits involved in the generation of fast, purposeful, and accurate saccadic eye movements. The test battery is composed of prosaccade (PS) and antisaccade (AS) tests that progressively increase cognitive demand. Existing saccadometry protocols qualitatively describe trends across the lifespan, but have not been widely adopted by clinicians. PURPOSE: The aims of this study are to design an efficient and simplified clinical saccadometry protocol using video oculography (VOG) equipment and establish associated evaluative standards across the lifespan. STUDY SAMPLE: Data were reported on 273 adults ages 18 to 69 years. RESULTS: Evaluative data on four measures: directional error rate (DE), latency (Lat), peak velocity (Vel), and accuracy (Acc) during PS and AS measurements were provided. Age-group differences were found in Lat (p < 0.01) and Vel (p = 0.04) during PS and age-group differences were found in DE (p = 0.04), Lat (p < 0.01) and Vel (p < 0.01) during AS. Gender differences were found in DE (p = 0.01) and Lat (p < 0.01) during AS. CONCLUSIONS: This study established a standardized and time-efficient protocol with evaluative standards for individuals ages 18 to 69 years old to enable the use of saccadometry as an objective measure in the clinic. Saccadometry allows clinicians to look beyond the traditional saccade test and evaluate complex oculomotor and cognitive functions that will better help clinicians differentiate between peripheral and central diagnoses.

Application of supervised machine learning algorithms for the evaluation of utricular function on patients with Meniere's disease: utilizing subjective visual vertical and ocular-vestibular-evoked myogenic potentials.

BACKGROUND: Research on the otolith organs remains inconclusive. OBJECTIVES: This study seeks to further elucidate utricular function in patients with Meniere's disease (MD) in three ways: (1) We aimed to disambiguate the role of the Subjective Visual Vertical (SVV) and Ocular Vestibular Evoked Myogenic Potential (o-VEMP) tests regarding which utricular subsystem each is measuring. (2) We sought to characterize the acute and chronic state of MD by identifying differences in the relationship of SVV and o-VEMP results across patients with acute and chronic MD. (3) We attempted to find a machine-learning algorithm that could predict acute versus chronic MD using SVV and o-VEMP. METHODS: A prospective study with ninety subjects. RESULTS: (1) SVV and o-VEMP tests were found to have a moderate linear relationship in patients with acute MD, suggesting each test measures a different utricular subsystem. (2) Regression analyses statistically differed across the two patient populations, suggesting that SVV results were normalized in chronic MD patients. (3) Logistic regression and Naïve Bayes algorithms were found to predict acute and chronic MD accurately. SIGNIFICANCE: A better understanding of what diagnostic tests measure will lead to a better classification system for MD and more targeted treatment options in the future.

Diagnostic value of refixation saccades in the Video Head Impulse Test (vHIT) in unilateral definite Meniere's disease.

Introduction: We currently interpret the video Head Impulse Test (vHIT) results mainly based on the gain value.Aim: The purpose of this study is to evaluate vHIT results for both gain and re-fixation saccades on unilateral definite Meniere's disease (MD) subjects in comparison with normal healthy subjects.Materials and Methods: Forty unilateral definite MD subjects and age-matched healthy subjects were recruited. Pure tone audiometry, the caloric test, and the vHIT test were performed on MD subjects. The vHIT test was performed on healthy subjects.Results: The velocity regression gain (VRG) of the affected ear in patients with MD is significantly lower than of those in healthy subjects. The total percentage of refixation saccades is significantly higher in patients with MD when compared to healthy subjects. VRG values were not well-correlated with the percentage of refixation saccades. VRG asymmetry values are also not well-correlated with the percentage of unilateral canal weakness. A moderately stronger correlation between the percentage of refixation saccades and percentage of unilateral canal weakness, with an r2 of 0.474.Conclusions: The present study suggests that while VRGs are still a diagnostic parameter of detecting MD, the presence of refixation saccades can also have diagnostic value, especially with normal VRGs, in detecting MD.

Evaluation of the utricular function with the virtual-subject visual vertical system: comparison with ocular vestibular-evoked myogenic potentials.

Introduction: The subjective visual vertical (SVV) is the most frequently assessed modality of verticality perception and has been measured in a variety of clinical situations, including peripheral vestibular lesions.Aim: The main objectives are (1) to collect normative data of Virtual SVV™ from healthy subjects, and (2) to study the correlation between Virtual SVV™ and ocular vestibular-evoked myogenic potentials (o-VEMP) on healthy subjects.Materials and methods: Forty-three healthy subjects were recruited. Air conduction (AC)-elicited oVEMPs and bone conduction (BC)-elicited oVEMPs were measured. BC stimuli were produced with a RadioEar B-81 High Output Bone Transducer. Virtual SVV™ were also measured.Results: Virtual SVV™ data from our healthy subjects were consistent with previously published normative SVV data. Normal Virtual SVV™ data did not correlate with normal AC-elicited and BC-elicited oVEMPs.Conclusions: Virtual SVV™ data from our healthy subjects were consistent with previously published normative SVV data. Virtual SVV™ data from our 43 health subjects only had weak correlation with c-VEMP, AC-elicited and BC-elicited oVEMPs. These data serve as a baseline for a future study of patients with unilateral utricular dysfunction.Significance: The Virtual SVV™ can be an attractive substitute for traditional SVV in clinical settings.

Assessment of Subjective Visual Vertical (SVV) Using the "Bucket Test" and the Virtual SVV System.

OBJECTIVE: The purpose of this study was to describe the variability and test-retest reliability of a commercially available subjective visual vertical (SVV) system known as Virtual SVV (Interacoustics). In addition, the study aimed to compare the reliability of the Virtual system with a previously established bucket test of SVV. STUDY DESIGN: Fifteen participants with normal hearing, normal middle ear function, and normal utricular function were included in the study. Each participant underwent static SVV testing using both the Virtual system and the bucket test. Subjects completed 2 testing sessions to determine test-retest reliability. For each test, data were collected with the head at 0°, tilted 45° to the right, and tilted 45° to the left. SETTING: This study was conducted in a balance function laboratory embedded in a large, tertiary care otology clinic. RESULTS: The mean SVV values obtained with the Virtual system were within 1°-2° from 0 with the head positioned at 0°, which is in agreement with many other studies of SVV with the head at 0° (Akin & Murnane, 2009; Halmagyi & Curthoys, 1999; Zwergal, Rettinger, Frenzel, Dieterich, & Strupp, 2009). Using the intraclass correlation coefficient, test-retest reliability of the Virtual system was excellent in the 45° left position and fair to good in the 45° right and 0° position. Test-retest reliability of the bucket test was poor in all head positions. CONCLUSIONS: The Virtual system is a more reliable measure of static SVV than the bucket test. Therefore, the Virtual system could be utilized as a screening device for utricular dysfunction in busy clinical settings.