Normative Scores for the NIH Toolbox Dynamic Visual Acuity Test from 3 to 85 Years

Advances in dynamic visual acuity test research

The dynamic visual acuity test (DVAT) is a functional evaluation tool for the impairment and compensation of the vestibular system, which could reflect the Vestibulo-ocular reflex (VOR) function. We present an overview of DVAT research, displaying recent advances in test methods, application, and influencing factors; and discussing the clinical value of DVAT to provide a reference for clinical application. There are two primary types of DVAT: dynamic-object DVAT and static-object DVAT. For the latter, in addition to the traditional bedside DVAT, there are numerous other approaches, including Computerized DVAT (cDVAT), DVAT on a treadmill, DVAT on a rotary, head thrust DVA (htDVA) and functional head impulse testing (fHIT), gaze shift dynamic visual acuity with walking (gsDVA), translational dynamic visual acuity test (tDVAT), pediatric DVAT. The results of DAVT are affected by subject [occupation, static visual acuity (SVA), age, eyeglass lenses], testing methods, caffeine, and alcohol. DVAT has numerous clinical applications, such as screening for vestibular impairment, assessing vestibular rehabilitation, predicting fall risk, and evaluating ophthalmology-related disorders, vestibular disorders, and central system disorders.

Team Approach to Delayed Pediatric Vestibular Diagnosis: A Case Study

BACKGROUND AND PURPOSE

This report highlights the challenges of diagnosing pediatric vestibular neuritis following dental treatment and addressing fear avoidance behaviors.

CASE DESCRIPTION

An 11-year-old boy came to physical therapy with vestibular dysfunction following dental treatment that was unable to be diagnosed by emergency department staff. The participant received multispecialty treatment for 6 weeks.

MEASUREMENTS

Computerized Dynamic Posturography, Limits of Stability, Dizziness Handicap Inventory, Functional Gait Assessment, Dynamic Visual Acuity, and Modified Clinical Test of Sensory Interaction on Balance.

OUTCOMES

Most notable improvements were seen in Limits of Stability and Computerized Dynamic Posturography. The participant made a full return to school and sport.

CONCLUSIONS

The difficulty of pediatric vestibular neuritis diagnosis led to fear avoidance behaviors that were addressed by a collaborative specialty approach.

WHAT THIS ADDS TO EVIDENCE

This is the first documented case of pediatric vestibular neuritis as a complication of a dental procedure with intervention focused on fear avoidance behaviors.

Rehabilitation to Improve Gaze and Postural Stability in People With Multiple Sclerosis: A Randomized Clinical Trial

BACKGROUND

People with multiple sclerosis (PwMS) frequently experience dizziness and imbalance that may be caused by central vestibular system dysfunction. Vestibular rehabilitation may offer an approach for improving dysfunction in these people.

OBJECTIVE

To test the efficacy of a gaze and postural stability (GPS) retraining intervention compared to a strength and endurance (SAE) intervention in PwMS.

METHODS

About 41 PwMS, with complaints of dizziness or history of falls, were randomized to either the GPS or SAE groups. Following randomization participants completed 6-weeks of 3×/week progressive training, delivered one-on-one by a provider. Following intervention, testing was performed at the primary (6-weeks) and secondary time point (10-weeks). A restricted maximum likelihood estimation mixed effects model was used to examine changes in the primary outcome of the Dizziness Handicap Inventory (DHI) between the 2 groups at the primary and secondary time point. Similar models were used to explore secondary outcomes between groups at both timepoints.

RESULTS

Thirty-five people completed the study (17 GPS; 18 SAE). The change in the DHI at the primary time point was not statistically different between the GPS and SAE groups (mean difference = 2.33 [95% CI -9.18, 12.85]). However, both groups demonstrated significant improvement from baseline to 6-weeks (GPS -8.73; SAE -7.31). Similar results were observed for secondary outcomes and at the secondary timepoint.

CONCLUSIONS

In this sample of PwMS with complaints of dizziness or imbalance, 6-weeks of GPS training did not result in significantly greater improvements in dizziness handicap or balance compared to 6-weeks of SAE training.

Vestibular Rehabilitation for Peripheral Vestibular Hypofunction: An Updated Clinical Practice Guideline From the Academy of Neurologic Physical Therapy of the American Physical Therapy Association

Background:

Uncompensated vestibular hypofunction can result in symptoms of dizziness, imbalance, and/or oscillopsia, gaze and gait instability, and impaired navigation and spatial orientation; thus, may negatively impact an individual's quality of life, ability to perform activities of daily living, drive, and work. It is estimated that one-third of adults in the United States have vestibular dysfunction and the incidence increases with age. There is strong evidence supporting vestibular physical therapy for reducing symptoms, improving gaze and postural stability, and improving function in individuals with vestibular hypofunction. The purpose of this revised clinical practice guideline is to improve quality of care and outcomes for individuals with acute, subacute, and chronic unilateral and bilateral vestibular hypofunction by providing evidence-based recommendations regarding appropriate exercises.

Methods:

These guidelines are a revision of the 2016 guidelines and involved a systematic review of the literature published since 2015 through June 2020 across 6 databases. Article types included meta-analyses, systematic reviews, randomized controlled trials, cohort studies, case-control series, and case series for human subjects, published in English. Sixty-seven articles were identified as relevant to this clinical practice guideline and critically appraised for level of evidence.

Results:

Based on strong evidence, clinicians should offer vestibular rehabilitation to adults with unilateral and bilateral vestibular hypofunction who present with impairments, activity limitations, and participation restrictions related to the vestibular deficit. Based on strong evidence and a preponderance of harm over benefit, clinicians should not include voluntary saccadic or smooth-pursuit eye movements in isolation (ie, without head movement) to promote gaze stability. Based on moderate to strong evidence, clinicians may offer specific exercise techniques to target identified activity limitations and participation restrictions, including virtual reality or augmented sensory feedback. Based on strong evidence and in consideration of patient preference, clinicians should offer supervised vestibular rehabilitation. Based on moderate to weak evidence, clinicians may prescribe weekly clinic visits plus a home exercise program of gaze stabilization exercises consisting of a minimum of: (1) 3 times per day for a total of at least 12 minutes daily for individuals with acute/subacute unilateral vestibular hypofunction; (2) 3 to 5 times per day for a total of at least 20 minutes daily for 4 to 6 weeks for individuals with chronic unilateral vestibular hypofunction; (3) 3 to 5 times per day for a total of 20 to 40 minutes daily for approximately 5 to 7 weeks for individuals with bilateral vestibular hypofunction. Based on moderate evidence, clinicians may prescribe static and dynamic balance exercises for a minimum of 20 minutes daily for at least 4 to 6 weeks for individuals with chronic unilateral vestibular hypofunction and, based on expert opinion, for a minimum of 6 to 9 weeks for individuals with bilateral vestibular hypofunction. Based on moderate evidence, clinicians may use achievement of primary goals, resolution of symptoms, normalized balance and vestibular function, or plateau in progress as reasons for stopping therapy. Based on moderate to strong evidence, clinicians may evaluate factors, including time from onset of symptoms, comorbidities, cognitive function, and use of medication that could modify rehabilitation outcomes.

Discussion:

Recent evidence supports the original recommendations from the 2016 guidelines. There is strong evidence that vestibular physical therapy provides a clear and substantial benefit to individuals with unilateral and bilateral vestibular hypofunction.

Limitations:

The focus of the guideline was on peripheral vestibular hypofunction; thus, the recommendations of the guideline may not apply to individuals with central vestibular disorders. One criterion for study inclusion was that vestibular hypofunction was determined based on objective vestibular function tests. This guideline may not apply to individuals who report symptoms of dizziness, imbalance, and/or oscillopsia without a diagnosis of vestibular hypofunction.

Disclaimer:

These recommendations are intended as a guide to optimize rehabilitation outcomes for individuals undergoing vestibular physical therapy. The contents of this guideline were developed with support from the American Physical Therapy Association and the Academy of Neurologic Physical Therapy using a rigorous review process. The authors declared no conflict of interest and maintained editorial independence.

Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A369).

Characterizing gaze and postural stability deficits in people with multiple sclerosis

BACKGROUND

People with Multiple Sclerosis (PwMS) experience a wide range of symptoms that can alter function and limit activity and community participation. Symptoms including sensory changes, weakness, fatigue and others have been well documented. However, symptoms related to changes in vestibular related function, including gaze and postural stability have not been fully explored. While some recent studies have begun to provide insight into these deficits in PwMS and have explored the use of rehabilitation paradigms for their management, much remains unknown about the full extent of these deficits. Therefore, this study aimed to characterize the presence of gaze and postural stability deficits in measures across the World Health Organization International Classification of Functioning, Disability, and Health (WHO ICF) and to examine how deficits in domains of body structure and function and activity contribute to participation level limitations.

METHODS

Baseline data from 41 PwMS (mean(SD) age = 53.9(11.2), 78% female) enrolled as part of a randomized clinical trial were used in this analysis. Measures of gaze and postural stability from the ICF domains of body structure and function (Vestibular ocular reflex [VOR] gain and postural sway area), activity (computerized dynamic visual acuity [cDVA] and MiniBEST test), and participation (Dizziness handicap inventory [DHI] and Activities Balance Confidence [ABC] scale) along with demographic data were used to characterize the sample. To explore relationships between ICF domains for gaze and postural stability, univariate correlations were performed between measures from each domain using Pearson's correlations. Separate multivariate regression models examined how measures from the body structure and function and activity domains contributed to the variance in the participation level outcomes. Variance explained by the models was quantified using R-squared statistic and contribution of the independent variables were quantified using the beta coefficient (p < 0.05).

RESULTS

Correlation analysis demonstrated significant relationships in the postural stability measures across domains. Specifically, between postural sway area on a firm surface and MiniBEST test score (r = -.48;p < 0.01) and MiniBEST test score and ABC score (r = 0.5;p < 0.01). Significant correlations were also found between the gaze stability measures of horizontal and vertical VOR gain (r = .68;p < 0.001), horizontal VOR gain and dynamic visual acuity (r = .38;p = 0.02), and vertical VOR gain and dynamic visual acuity (r = .54;p < 0.001). Regression models assessing postural stability, found that only the MiniBEST score significantly contributed to the variance in ABC score (p = 0.01) and the full model explained 34% of the variance in ABC score. Regression modeling of gaze stability outcomes did not produce any variable that significantly contributed to the variance in DHI score and the full model explained 18% of the variance in DHI score.

CONCLUSIONS

PwMS in this sample demonstrated deficits in gaze and postural stability across the domains of the WHO ICF compared to past samples of PwMS and healthy cohorts. Correlation between measures in the different domains were present, but no strong relationship between measures of body structure and function, activity and participation level outcomes were observed. This lack of relationship across the domains is likely contributed to the relatively small sample size, the high level of variability observed in the outcomes, and the diverse presentation often seen in PwMS.

Head movement kinematics are altered during gaze stability exercises in vestibular schwannoma patients

Gaze stability is the ability of the eyes to fixate a stable point when the head is moving in space. Because gaze stability is impaired in peripheral vestibular loss patients, gaze stabilization exercises are often prescribed to facilitate compensation. However, both the assessment and prescription of these exercises are subjective. Accordingly, here we quantified head motion kinematics in patients with vestibular loss while they performed the standard of care gaze stability exercises, both before and after surgical deafferentation. We also correlate the head kinematic data with standard clinical outcome measures. Using inertial measurement units, we quantified head movements in patients as they transitioned through these two vestibular states characterized by different levels of peripheral damage. Comparison with age-matched healthy control subjects revealed that the same kinematic measurements were significantly abnormal in patients both pre- and post-surgery. Regardless of direction, patients took a longer time to move their heads during the exercises. Interestingly, these changes in kinematics suggest a strategy that existed preoperatively and remained symmetric after surgery although the patients then had complete unilateral vestibular loss. Further, we found that this kinematic assessment was a good predictor of clinical outcomes, and that pre-surgery clinical measures could predict post-surgery head kinematics. Thus, together, our results provide the first experimental evidence that patients show significant changes in head kinematics during gaze stability exercises, even prior to surgery. This suggests that early changes in head kinematic strategy due to significant but incomplete vestibular loss are already maladaptive as compared to controls.

Diagnosing vestibular hypofunction: an update

Unilateral or bilateral vestibular hypofunction presents most commonly with symptoms of dizziness or postural imbalance and affects a large population. However, it is often missed because no quantitative testing of vestibular function is performed, or misdiagnosed due to a lack of standardization of vestibular testing. Therefore, this article reviews the current status of the most frequently used vestibular tests for canal and otolith function. This information can also be used to reach a consensus about the systematic diagnosis of vestibular hypofunction.

Bilateral vestibulopathy and age: experimental considerations for testing dynamic visual acuity on a treadmill

INTRODUCTION

Bilateral vestibulopathy (BVP) can affect visual acuity in dynamic conditions, like walking. This can be assessed by testing Dynamic Visual Acuity (DVA) on a treadmill at different walking speeds. Apart from BVP, age itself might influence DVA and the ability to complete the test. The objective of this study was to investigate whether DVA tested while walking, and the drop-out rate (the inability to complete all walking speeds of the test) are significantly influenced by age in BVP-patients and healthy subjects.

METHODS

Forty-four BVP-patients (20 male, mean age 59 years) and 63 healthy subjects (27 male, mean age 46 years) performed the DVA test on a treadmill at 0 (static condition), 2, 4 and 6 km/h (dynamic conditions). The dynamic visual acuity loss was calculated as the difference between visual acuity in the static condition and visual acuity in each walking condition. The dependency of the drop-out rate and dynamic visual acuity loss on BVP and age was investigated at all walking speeds, as well as the dependency of dynamic visual acuity loss on speed.

RESULTS

Age and BVP significantly increased the drop-out rate (p ≤ 0.038). A significantly higher dynamic visual acuity loss was found at all speeds in BVP-patients compared to healthy subjects (p < 0.001). Age showed no effect on dynamic visual acuity loss in both groups. In BVP-patients, increasing walking speeds resulted in higher dynamic visual acuity loss (p ≤ 0.036).

CONCLUSION

DVA tested while walking on a treadmill, is one of the few "close to reality" functional outcome measures of vestibular function in the vertical plane. It is able to demonstrate significant loss of DVA in bilateral vestibulopathy patients. However, since bilateral vestibulopathy and age significantly increase the drop-out rate at faster walking speeds, it is recommended to use age-matched controls. Furthermore, it could be considered to use an individual "preferred" walking speed and to limit maximum walking speed in older subjects when testing DVA on a treadmill.

Improvement After Vestibular Rehabilitation Not Explained by Improved Passive VOR Gain

Gaze stability exercises are a critical component of vestibular rehabilitation for individuals with vestibular hypofunction and many studies reveal the rehabilitation improves functional performance. However, few studies have examined the vestibular physiologic mechanisms (semicircular canal; otolith) responsible for such recovery after patients with vestibular hypofunction complete gaze and gait stability exercises. The purpose of this study was to compare behavioral outcome measures (i.e., visual acuity during head rotation) with physiological measures (i.e., gain of the vestibulo-ocular reflex) of gaze stability following a progressive vestibular rehabilitation program in patients following unilateral vestibular deafferentation surgery (UVD). We recruited n = 43 patients (n = 18 female, mean 52 ± 13 years, range 23-80 years) after unilateral deafferentation from vestibular schwannoma; n = 38 (25 female, mean 46.9 ± 15.9 years, range 22-77 years) age-matched healthy controls for dynamic visual acuity testing, and another n = 28 (14 female, age 45 ± 17, range 20-77 years) healthy controls for video head impulse testing. Data presented is from n = 19 patients (14 female, mean 48.9 ± 14.7 years) with UVD who completed a baseline assessment ~6 weeks after surgery, 5 weeks of vestibular physical therapy and a final measurement. As a group, subjective and fall risk measures improved with a meaningful clinical relevance. Dynamic visual acuity (DVA) during active head rotation improved [mean ipsilesional 38.57% ± 26.32 (n = 15/19)]; mean contralesional 39.96% ± 22.62 (n = 12/19), though not uniformly. However, as a group passive yaw VOR gain (mean ipsilesional pre 0.44 ± 0.18 vs. post 0.44 ± 0.15; mean contralesional pre 0.81 ± 0.19 vs. post 0.85 ± 0.09) did not show any change (p ≥ 0.4) after rehabilitation. The velocity of the overt compensatory saccades during ipsilesional head impulses were reduced after rehabilitation; no other metric of oculomotor function changed (p ≥ 0.4). Preserved utricular function was correlated with improved yaw DVA and preserved saccular function was correlated with improved pitch DVA. Our results suggest that 5 weeks of vestibular rehabilitation using gaze and gait stability exercises improves both subjective and behavioral performance despite absent change in VOR gain in a majority of patients, and that residual otolith function appears correlated with such change.

Balance, gait and dizziness in adult cochlear implant users: A cross sectional study

Objective: Cochlear implantation is associated with vestibular impairment due to the close proximity of the structures. The aim of the study was to quantify dizziness/vertigo, gaze instability, balance and gait problems in a sample of adult cochlear implant (CI) users.Methods: An observational, cross sectional study evaluated subjective dizziness (Vestibular Rehabilitation Benefit Questionnaire (VRBQ)), balance confidence (Activities Specific Balance Questionnaire (ABC)), gait (Functional Gait Assessment (FGA) and 10m walk test), balance (Equitest Sensory Organisation Test (SOT)), and computerised dynamic visual acuity (DVA). The Dix Hallpike test was performed to test for benign paroxysmal positional vertigo (BPPV).Results: Twenty participants (n=10F), 2.8(±2.7) years post implantation, with mean age 59.3(±15.8) years were assessed. Subjective dizziness (VRBQ) was low (15.0% (±15.5)) and balance confidence was high (ABC: 82.1%±14.9). FGA scores (25.1 ± 4.4) and gait speed (1.8 (±0.3) m/sec) were below normal. Dx Hallpike was positive in 3. Gaze instability was found in 50% (DVA loss, 0.29 (± 0.16) LogMAR), while 79% demonstrated balance impairment (mean SOT score, 57.8%±14.5), with 42% falling on SOT condition 5.Discussion: Evidence of vestibular dysfunction was identified in these adult CI users.Conclusion: Access to vestibular function assessment and rehabilitation is required in adult CI users.

Gaze stability in the elite athlete: A normative observational study

BACKGROUND

The ability to clearly perceive an object while the head is in motion is important in athletics, as it relates to performance and potentially to injury prevention. Normative data for healthy adults on measures of gaze stability have been established. However, data for elite athletes is scarce.

OBJECTIVE

To describe performance of elite athletes on computerized gaze stability testing and establish normative data for reference.

METHODS

Data were acquired via retrospective chart review. 134 male professional baseball players completed computerized Visual Acuity, Visual Perception Time and Gaze Stability Tests as part of a multi-modal baseline testing session.

RESULTS

Performance of all athletes was superior to general population norms reported in the literature. There were no significant differences between the optimal and suboptimal consistency groups or between English-speaking and non- or limited-English speaking players.

CONCLUSIONS

Similar to prior studies with smaller samples that have examined GST in athletes, we found high levels of GST performance in professional baseball players relative to normative data for the general population. Normative data for elite athletes was established using this healthy sample. This study underscores the importance of understanding the unique abilities of elite athletes when providing therapy after injury.

The Gaze Stabilization Test Following Concussion

BACKGROUND

Concussion can cause vestibular dysfunction and oculomotor abnormalities which can lead to dizziness and protracted recovery time. There are few clinically useful, functional measures of the vestibulo-ocular reflex (VOR) post-concussion.

PURPOSE

The purpose of this study was to examine the gaze stabilization test (GST) in those referred for vestibular physical therapy following concussion, to determine the association between GST and other measures of recovery following concussion, and to examine the effect of demographic variables on GST performance.

RESEARCH DESIGN

Retrospective chart review.

STUDY SAMPLE

One hundred fifty-eight individuals who sustained a concussion and were referred to vestibular physical therapy.

DATA COLLECTION AND ANALYSIS

Horizontal and vertical GST scores (HGST and VGST), neurocognitive testing results, and demographic data were extracted retrospectively from the patient health record. Correlations between GST velocity and neurocognitive test results and between GST and patient-reported outcomes were examined. Differences in GST performance among patient subgroups were examined using one-way analysis of variance.

RESULTS

Subjects included individuals aged 12 to 43 years (mean = 20, standard deviation [SD] = 7), with most having sport-related concussion (67%). The mean time from injury to GST was 215 days (SD = 241) and the mean time from physical therapy evaluation to GST was 48 days (SD = 54). HGST and VGST had a weak positive correlation to the Activities-Specific Balance Confidence Scale (r = 0.20, r = 0.21) and weak negative correlation to the Dizziness Handicap Inventory (r = -0.18, r = -0.22). HGST had a weak positive correlation to the visual motor processing speed domain of the immediate post-concussion assessment and cognitive test (r = 0.20). Male patients achieved significantly higher velocities than female patients on HGST and VGST (p = 0.02, p = 0.01).

CONCLUSIONS

The present study details the use of GST in patients with concussion and demonstrates an association with common outcome measures in vestibular rehabilitation. Results indicate that patients who achieved higher velocities on GST perceived lower handicap due to dizziness and had higher confidence in their balance. GST may be a relevant test of VOR in this population, as it is a more functional test of the VOR required for sports. Future work is needed to further evaluate the role of GST in concussion management.

A speed-based approach to vestibular rehabilitation for peripheral vestibular hypofunction: A retrospective chart review

BACKGROUND:

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSIONS:

Exergaming in a Moving Virtual World to Train Vestibular Functions and Gait; a Proof-of-Concept-Study With Older Adults

Background: The use of Exergames designed to improve physical and cognitive functioning is relatively new in rehabilitation. Exergaming allows the training of skills, the handling of tools, and procedures; however, often, the potential of these aspects are not assessed before they are adopted in clinical settings. This study aimed at exploring the effects of exergaming on vestibular functions and gait in healthy community dwelling older adults using a proof-of-concept study design registered under ClinicalTrials.gov NCT03160352. Methods: A pre-test-post-test one-group study design comprising 10 older adults (mean age of 73.5 ± 7.6 years, four males) investigated the feasibility of eight exergaming training sessions (for 160 min) and the effects on dynamic visual acuity (DVA), functional gait assessment (FGA), and extended timed get-up-and-go (ETGUG). The simulator sickness questionnaire (SSQ) and the game scores were evaluated for the feasibility of the intervention. Wilcoxon test and Cohen's d (d) were chosen to test for differences and for effect size estimation. Results: Exergaming led to a significantly improved DVA (z = -2.50, p = 0.01, d = 1.35) with improvements in 9 out of 10 participants. In addition, the FGA significantly improved with a large effect size (z = -2.25, p = 0.02, d = 1.17). Specifically, component tasks such as walking with horizontal head turns (p = 0.03), gait with a narrow base of support (p = 0.03), ambulating backward (p = 0.05) significantly improved. The ETGUG component task Gait initiation significantly improved (p = 0.04). No change was found in gait speed and SSQ. The game scores of the participants improved continuously during the course of the intervention for every game. Discussion: This proof-of-concept study suggests that the use of exergaming that requires active stepping movements and that contains moving game projection is feasible and facilitates gaze stability during head movements in healthy community dwelling older adults. Aspects of functional gait and gait initiation also improved. Future research aimed at testing this exergaming intervention in patients suffering from vestibular impairments is warranted.

Augmenting cognitive training in older adults (The ACT Study): Design and Methods of a Phase III tDCS and cognitive training trial

BACKGROUND

Adults over age 65 represent the fastest growing population in the US. Decline in cognitive abilities is a hallmark of advanced age and is associated with loss of independence and dementia risk. There is a pressing need to develop effective interventions for slowing or reversing the cognitive aging process. While certain forms of cognitive training have shown promise in this area, effects only sometimes transfer to neuropsychological tests within or outside the trained domain. This paper describes a NIA-funded Phase III adaptive multisite randomized clinical trial, examining whether transcranial direct current stimulation (tDCS) of frontal cortices enhances neurocognitive outcomes achieved from cognitive training in older adults experiencing age-related cognitive decline: the Augmenting Cognitive Training in Older Adults study (ACT).

METHODS

ACT will enroll 360 participants aged 65 to 89 with age-related cognitive decline, but not dementia. Participants will undergo cognitive training intervention or education training-control combined with tDCS or sham tDCS control. Cognitive training employs a suite of eight adaptive training tasks focused on attention/speed of processing and working memory from Posit Science BrainHQ. Training control involves exposure to educational nature/history videos and related content questions of the same interval/duration as the cognitive training. Participants are assessed at baseline, after training (12weeks), and 12-month follow-up on our primary outcome measure, NIH Toolbox Fluid Cognition Composite Score, as well as a comprehensive neurocognitive, functional, clinical and multimodal neuroimaging battery.

SIGNIFICANCE

The findings from this study have the potential to significantly enhance efforts to ameliorate cognitive aging and slow dementia.

Evidence of dynamic visual acuity impairment in asymptomatic mixed martial arts fighters

AIM

The purpose of this study was to determine the amount of visual acuity loss with head movement in actively training mixed martial arts (MMA) fighters.

METHODS

Vestibulo-ocular reflex function of 22 asymptomatic, male MMA fighters (age = 29.2 ± 5.1) was assessed by taking the difference between static visual acuity and the dynamic visual acuity test, in both yaw and pitch planes.

RESULTS

The mean static visual acuity testing logMAR was -0.173 (standard deviation [SD] = 0.114). Mean dynamic visual acuity test values decreased with head movement to 0.196 logMAR (SD = 0.103) in yaw; p < 0.001, and to 0.283 logMAR (SD = 0.133) in pitch; p < 0.001.

CONCLUSION

MMA fighters had a decay, beyond normal ranges, in visual acuity during head movement. These decreases may suggest vestibulo-ocular reflex impairment and were unrelated to self-reported concussion history. These results should be cautiously interpreted since there was not a control group.

Reliability and Normative Data for the Dynamic Visual Acuity Test for Vestibular Screening

HYPOTHESIS

The purpose of this study was to determine reliability of computerized dynamic visual acuity (DVA) testing and to determine reference values for younger and older adults.

BACKGROUND

A primary function of the vestibular system is to maintain gaze stability during head motion. The DVA test quantifies gaze stabilization with the head moving versus stationary. Commercially available computerized systems allow clinicians to incorporate DVA into their assessment; however, information regarding reliability and normative values of these systems is sparse.

METHODS

Forty-six healthy adults, grouped by age, with normal vestibular function were recruited. Each participant completed computerized DVA testing including static visual acuity, minimum perception time, and DVA using the NeuroCom inVision System. Testing was performed by two examiners in the same session and then repeated at a follow-up session 3 to 14 days later. Intraclass correlation coefficients (ICCs) were used to determine inter-rater and test-retest reliability.

RESULTS

ICCs for inter-rater reliability ranged from 0.323 to 0.937 and from 0.434 to 0.909 for horizontal and vertical head movements, respectively. ICCs for test-retest reliability ranged from 0.154 to 0.856 and from 0.377 to 0.9062 for horizontal and vertical head movements, respectively. Overall, raw scores (left/right DVA and up/down DVA) were more reliable than DVA loss scores.

CONCLUSION

Reliability of a commercially available DVA system has poor-to-fair reliability for DVA loss scores. The use of a convergence paradigm and not incorporating the forced choice paradigm may contribute to poor reliability.

Acute peripheral vestibular deficit increases redundancy in random number generation

Unilateral peripheral vestibular deficit leads to broad cognitive difficulties and biases in spatial orientation. More specifically, vestibular patients typically show a spatial bias toward their affected ear in the subjective visual vertical, head and trunk orientation, fall tendency, and walking trajectory. By means of a random number generation task, we set out to investigate how an acute peripheral vestibular deficit affects the mental representation of numbers in space. Furthermore, the random number generation task allowed us to test if patients with peripheral vestibular deficit show evidence of impaired executive functions while keeping the head straight and while performing active head turns. Previous research using galvanic vestibular stimulation in healthy people has shown no effects on number space, but revealed increased redundancy of the generated numbers. Other studies reported a spatial bias in number representation during active and passive head turns. In this experiment, we tested 43 patients with acute vestibular neuritis (18 patients with left-sided and 25 with right-sided vestibular deficit) and 28 age-matched healthy controls. We found no bias in number space in patients with peripheral vestibular deficit but showed increased redundancy in patients during active head turns. Patients showed worse performance in generating sequences of random numbers, which indicates a deficit in the updating component of executive functions. We argue that RNG is a promising candidate for a time- and cost-effective assessment of executive functions in patients suffering from a peripheral vestibular deficit.

Postural Stability During Standing Balance and Sit-to-Stand in Master Athlete Runners Compared With Nonathletic Old and Young Adults

The aim of this study was to compare postural sway during a series of static balancing tasks and during five chair rises between healthy young (mean [SEM], age 26 [1] years), healthy old (age 67 [1] years) and master athlete runners (age 67 [1] years; competing and training for the previous 51 [5] years) using the Microsoft Kinect One. The healthy old had more sway than the healthy young in all balance tasks. The master athletes had similar sway to young athletes during two-leg balancing and one-leg standing with eyes open. When balancing on one leg with eyes closed, both the healthy old and the master athletes had around 17-fold more sway than the young athletes. The healthy old and master athletes also had less anterio-posterior movement during chair rising compared with young athletes. These results suggest that masters runners are not spared from the age-associated decline in postural stability and may benefit from specific balance training.