Citations

Background: Many neurological and cognitive disorders have early oculomotor hallmarks. The Oculo-Cognitive Addition Test (OCAT) is a quick, objective screening tool that measures eye movement and time-based biomarkers of cognitive processing during simple mental addition tasks in under two minutes. Normative values for age, sex, education level, and apolipoprotein E Type 4 (APOE ε4) carrier status must be established so cognitively normal populations are not misdiagnosed. Methods: A total of 382 participants completed OCAT, with 350 participants making up the normative cohort from which raw gaze data were processed to derive fixations, saccades, blinks, pupillary dynamics, and time-based features. Separate multiple linear regression models were fitted for each feature with age, sex, education, and APOE ε4 carrier status as predictors to establish demographic-adjusted normative equations. Results: Processing time, fixation time, fixation size and fixation area and their variability increased progressively from the first to the third number within each addition sequence, consistent with increasing cognitive workload. Demographic-adjusted multiple linear regression models generated normative equations for individual OCAT features based on age, sex, education, and APOE ε4 carrier status. These models were used to derive individualized expected values, 95% reference intervals, and z-scores. Conclusions: These demographic-adjusted normative equations enable individualized interpretation of OCAT performance and are necessary steps towards clinical implementation.

Background/Objectives: Hearing loss is frequently misunderstood by communication partners and healthcare providers of patients with hearing loss alike, leading to gaps in counseling, medical adherence, and empathy. Hearing loss simulation is a technique that can clarify patient experience by illustrating how hearing loss affects daily listening and speech discrimination. The current research explores the influences of a web-based hearing loss simulator on how hearing loss is understood by communication partners, audiologists, and medical providers/students. Methods: Using a convergent parallel mixed-methods design, 72 participants (communication partners, audiologists, and medical providers/residents) completed a guided trial with the hearing simulator, either one-on-one or in group settings, and subsequently completed a questionnaire regarding their experiences. The simulation trial included demonstrations of hearing loss and amplification across four listening environments: speech in quiet, in noise, at a distance, as well as listening to instrumental music. Results: Communication partners reported that they gained a better understanding of their partner’s hearing loss, with all expressing increased feelings of empathy towards their partner and individuals with hearing loss. When compared to audiologists, communication partners were significantly more surprised by the impact of hearing loss on speech understanding. Medical providers and students emphasized the value of the simulator as a counseling tool and highly recommended that other providers use the simulator with their patients. Conclusions: Simulating hearing loss can be beneficial for counseling purposes and medical training. These findings suggest that hearing loss simulation can enhance empathy and communication across clinical and educational contexts.

Background/Objectives: Dizziness is a symptom of many disorders across a wide range of etiologies. If dizzy patients are seen for vestibular evaluation with an audiologist and no vestibular reason for the patient’s dizziness is found, the medical referral pathway can become convoluted. This can leave patients feeling discouraged and unable to manage their symptoms. Clinically symptomatic chronic respiratory alkalosis (CSCRA) is an acid–base disorder that typically presents with dizziness but is unfamiliar to practitioners in vestibular and balance care settings. Methods: In a retrospective chart review deemed exempt by the Mayo Clinic Institutional Review Board, 74 patients at Mayo Clinic Arizona were included. All had consultations with both Audiology and Aerospace Medicine to assess their dizzy symptoms. Results: After completing vestibular testing, arterial blood gas (ABG) testing, and a functional test developed at Mayo Clinic Arizona called the Capnic Challenge test, 40% of patients were found to have CSCRA contributing to their dizzy symptoms. Many of these patients also had common comorbidities of CSCRA, like postural orthostatic tachycardia syndrome (POTS), migraines, and sleep apnea. Fewer than one-fourth of these patients had measurable vestibulopathies causing their dizziness. Half of the patients referred by the vestibular audiologist to Aerospace Medicine had a diagnosis of CSCRA. Conclusions: Assessment for CSCRA should be considered as a next step for patients presenting with dizziness without a vestibular component. Being aware of the prevalence of CSCRA and its comorbidities may help balance providers offer quality interprofessional referrals and improve patient quality of life.

Background/Objectives: Mild cognitive impairment (MCI) affects multiple functional and cognitive domains, rendering it challenging to diagnose. Brief mental status exams are insensitive while detailed neuropsychological testing is time-consuming and presents accessibility issues. By contrast, the Oculo-Cognitive Addition Test (OCAT) is a rapid, objective tool that measures oculometric features during mental addition tasks under one minute. This study aims to develop artificial intelligence (AI)-derived predictive models using OCAT eye movement and time-based features for the early detection of those at risk for MCI, requiring more thorough assessment. Methods: The OCAT with integrated eye tracking was completed by 250 patients at the Mayo Clinic Arizona Department of Neurology. Raw gaze data analysis yielded time-related and eye movement features. Random Forest and univariate decision trees were the feature selection methods used to identify predictors of Dementia Rating Scale (DRS) outcomes. Logistic regression (LR) and K-nearest neighbors (KNN) supervised models were trained to classify PMCI using three feature sets: time-only, eye-only, and combined. Results: LR models achieved the highest performance using the combined time and eye movement features, with an accuracy of 0.97, recall of 0.91, and an AUPRC of 0.95. The eye-only and time-only LR models also performed well (accuracy = 0.93), though with slightly lower F1-scores (0.87 and 0.86, respectively). Overall, models leveraging both time and eye movement features consistently outperformed those using individual feature sets. Conclusions: Machine learning models trained on OCAT-derived features can reliably predict DRS outcomes (PASS/FAIL), offering a promising approach for early MCI identification. With further refinement, OCAT has the potential to serve as a practical and scalable cognitive screening tool, suitable for use in clinics, at the bedside, or in remote and resource-limited settings.

Abstract Introduction In military settings, ear-worn communication systems and hearing protection have equal importance, but opposite purposes. It is crucial to provide clear communication signal free of noise that may also be hazardous to hearing. Electrical auditory stimulation is a mode of transmitting high fidelity speech information with an amplitude modulated electromagnetic signal that is sent transcutaneously through electrodes. No traditional ear-worn transducer is needed, offering various locations for receiving auditory information on the head and body. The purpose of the current study is to evaluate the speech intelligibility at different locations on the head and body in quiet and noise. Materials and Methods Fifty participants total took part in this study with Mayo Clinic IRB approval and informed consent. All completed a pure-tone air conduction hearing test verifying normal hearing. In the first experiment, 20 participants completed electrical word recognition testing in quiet at 3 unique locations using 16-item Modified Rhyme Test (MRT) recordings transmitted through a Tonndorf Audimax Model 500 Audiometer in a repeated measures counter-balanced design. In the second experiment, 30 participants completed testing in quiet as well as in background noise at 3 mastoid-anchored locations, using 68-70 dBA of pink noise presented in the sound field through an immersive Spatial Reality sound system. One-way repeated-measures ANOVA was used for comparing the transformed percent MRT scores between 3 locations on the head, followed by the pairwise comparison of the post-hoc analysis using the t-test. For the second experiment, 2-way repeated-measures ANOVA was used to detect the main effects (location and condition) and interaction, followed by multiple comparisons using paired t-tests. Results The percent correct score on the modified MRT tests at the mastoid location during electrical hearing stimulation was statistically significantly greater than at the neck location. Three placements that all had at least one mastoid electrode placement (bilateral mastoid, wrist, and neck) produced very similar MRT scores in a quiet environment. The 2-way repeated measures ANOVA performed on the transformed MRT percent scores showed a significant main effect because of the condition (quiet vs. noise) but did not reveal any significant effect of location. MRT percent correct scores in the noisy condition at all 3 locations were statistically significantly lower than in the quiet condition. All average percent correct scores were greater than 80% in noise. Conclusions Non-acoustic transcutaneous electrical stimulation of the cochlea was shown to perform well in both quiet and noisy environments opening opportunities for future implementations that will help safeguard hearing by decreasing the risk of acoustic damage although maintaining excellent word recognition. Clinical Trial Registration Identifier: NCT05112809.

Background/Objectives: Galvanic vestibular stimulation (GVS) integrated into virtual reality (VR) environments enhances immersion and mitigates cybersickness. It is well known that GVS can affect standing balance. Most studies have investigated the effects of GVS in VR in seated conditions. The purpose of this study was to evaluate the impact of joint GVS and VR with moving visual stimulus on standing balance. Methods: Using a repeated measures counter-balanced design, motion sickness, postural sway, and velocity utilizing the center of pressure (COP) along the mediolateral (ML) and anteroposterior (AP) axes were obtained in 18 subjects during optokinetic (OPK) stimulus (black and white vertical bars moving from left to the right) in VR across three interventions: GVS in the same direction of visual stimulus—left to right ear (Positive GVS), GVS in the opposite direction of visual stimulus—right to left ear (Negative GVS), and without GVS (Null GVS). Motion sickness symptom scoring was obtained using the Pensacola Diagnostic Index. Results: The PDI score was increased significantly in the Negative GVS. The root mean square and sway range of COP along ML was greater during the Positive GVS and Negative GVS than the Null GVS, while, along AP, it was only greater during Negative GVS. During Positive GVS, mean positive and negative peak velocities, only in ML, were increased and decreased, respectively. During Negative GVS, only negative peak velocities in both ML and AP directions were decreased. Conclusions: This research highlights the importance of testing combined VR and GVS to assess standing balance while mitigating cybersickness.

Introduction The sharpened Romberg test (SRT) is a physical maneuver that has been used to identify ataxia in individuals in resource-limited settings. Previous research has suggested that performance on balance testing may be affected by hypocapnia. In this study, we sought to determine whether acute hyperventilation-induced hypocapnia affects performance on the SRT at 501 meters above sea level. Methods We recruited 22 healthy subjects. Each subject performed a baseline SRT. Subjects were then asked to hyperventilate to the point of hypocapnia, confirmed by measurement with a capnometer. Subjects were then asked to re-perform SRT. The primary endpoint was time to loss of balance, measured as time-to-stepout. Results Time-to-stepout (TTS) on SRT at baseline had a mean ± standard deviation of 101 ± 117 s. In the hypocapnic condition, TTS was reduced to 48 ± 68 s. TTS normalized to 121 ± 132 s after recovery to normal capnic levels. Time-to-stepout was found to be significantly shorter in the hypocapnic measurement compared to the baseline measurement ( P = .0128). Statistical analysis was conducted using one-tailed, paired sample T-tests using a P-value of < .05. Conclusions Our study found a statistically and clinically significant reduction in performance on a balance test (SRT) when exposed to acute hyperventilation-induced hypocapnia compared to a eucapnic control. Our results suggest that acute hypocapnia may contribute to neurological dysfunction independently of hypobaric hypoxia.