Ocular motor assessment in concussion: Current status and future directions

Clinician-Prioritized Measures to Use in a Remote Concussion Assessment: Delphi Study

BACKGROUND

There is little guidance available, and no uniform assessment battery is used in either in-person or remote evaluations of people who are experiencing persistent physical symptoms post concussion. Selecting the most appropriate measures for both in-person and remote physical assessments is challenging because of the lack of expert consensus and guidance.

OBJECTIVE

This study used expert consensus processes to identify clinical measures currently used to assess 5 physical domains affected by concussion (neurological examination, cervical spine, vestibular, oculomotor, or effort) and determine the feasibility of applying the identified measures virtually.

METHODS

The Delphi approach was used. In the first round, experienced clinicians were surveyed regarding using measures in concussion assessment. In the second round, clinicians reviewed information regarding the psychometric properties of all measures identified in the first round by at least 15% (9/58) of participants. In the second round, experts rank-ordered the measures from most relevant to least relevant based on their clinical experience and documented psychometric properties. A working group of 4 expert clinicians then determined the feasibility of virtually administering the final set of measures.

RESULTS

In total, 59 clinicians completed survey round 1 listing all measures they used to assess the physical domains affected by a concussion. The frequency counts of the 146 different measures identified were determined. Further, 33 clinicians completed the second-round survey and rank-ordered 22 measures that met the 15% cutoff criterion retained from round 1. Measures ranked first were coordination, range of motion, vestibular ocular motor screening, and smooth pursuits. These measures were feasible to administer virtually by the working group members; however, modifications for remote administration were recommended, such as adjusting the measurement method.

CONCLUSIONS

Clinicians ranked assessment of coordination (finger-to-nose test and rapid alternating movement test), cervical spine range of motion, vestibular ocular motor screening, and smooth pursuits as the most relevant measures under their respective domains. Based on expert opinion, these clinical measures are considered feasible to administer for concussion physical examinations in the remote context, with modifications; however, the psychometric properties have yet to be explored.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR2-10.2196/40446.

MICK (Mobile Integrated Cognitive Kit) App for Concussion Assessment in a Youth Ice Hockey League

BACKGROUND

Visual symptoms are common after concussion. Rapid automatized naming (RAN) tasks are simple performance measures that demonstrate worse time scores in the setting of acute or more remote injury.

METHODS

We evaluated the capacity for the Mobile Universal Lexicon Evaluation System (MULES) and Staggered Uneven Number (SUN) testing to be feasibly administered during preseason testing in a cohort of youth ice hockey athletes using a novel computerized app, the Mobile Integrated Cognitive Kit (MICK). Participants from a youth hockey league underwent preseason testing.

RESULTS

Among 60 participants, the median age was 13 years (range 6-17). The median best time for the MULES was 49.8 seconds (range = 34.2-141.0) and the median best time for the SUN was 70.1 (range = 36.6-200.0). As is characteristic of timed performance measures, there were learning effects between the first and second trials for both the MULES (median improvement = 10.6 seconds, range = -32.3 to 92.0, P < 0.001, Wilcoxon signed-rank test) and SUN (median improvement = 2.4 seconds, range= -8.0 to 15.1, P = 0.001, Wilcoxon signed-rank test). Age was a predictor of best baseline times, with longer (worse) times for younger participants for MULES (P < 0.001, rs = -0.67) and SUN (P < 0.001, rs = -0.54 Spearman rank correlation). Degrees of learning effect did not vary with age (P > 0.05, rs = -0.2).

CONCLUSIONS

Vision-based RAN tasks, such as the MULES and SUN, can be feasibly administered using the MICK app during preseason baseline testing in youth sports teams. The results suggest that more frequent baseline tests are necessary for preadolescent athletes because of the relation of RAN task performance to age.

What are the Protocols and Resources for Sport-Related Concussion Among Top National Collegiate Athletic Association Football Programs? A Cross-Sectional Survey of A5 Schools

OBJECTIVE

This study summarizes findings from a cross-sectional survey conducted among National Collegiate Athletic Association (NCAA) Division 1 football programs, focusing on sport-related concussion (SRC) protocols for the 2018 season.

DESIGN

Cross-sectional survey study.

SETTING

65 football programs within the Autonomy Five (A5) NCAA conferences.

PARTICIPANTS

Athletic trainers and team physicians who attended a football safety meeting at the NCAA offices June 17 to 18, 2019, representing their respective institutions.

INTERVENTION

Electronic surveys were distributed on June 14, 2019, before the football safety meeting.

MAIN OUTCOME MEASURES

Results for 16 unique questions involving SRC protocols and resources were summarized and evaluated.

RESULTS

The survey garnered responses from 46 of 65 programs (response rate = 71%). For baseline testing, 98% measured baseline postural stability and balance, 87% used baseline neurocognitive testing, while only 61% assessed baseline vestibular and/or ocular function. Regarding concussion prevention, 51% did not recommend additional measures, while 4% and 24% recommended cervical compression collars and omega-3 supplementation, respectively. In postconcussion treatment, 26% initiated aerobic exercise 1 day postconcussion if symptoms were stable, 24% waited at least 48 hours, 4% waited for the athlete to return to baseline, 11% waited until the athlete became asymptomatic, and 35% determined procedures on a case-by-case basis.

CONCLUSIONS

Most institutions assessed postural stability/balance and neurocognitive functioning at baseline and introduced light aerobic exercise within 48 h postconcussion. There was variation in baseline assessment methods and concussion prevention recommendations. These survey findings deepen our understanding of diverse SRC protocols in NCAA football programs.

Assessment of Oculomotor Functions as a Biomarker in Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI), or concussion, is a major public health problem, and ambiguity still exists regarding its diagnosis. While functional magnetic resonance imaging (fMRI) has been identified as a helpful screening tool for concussion, its limited accessibility in clinical or field settings necessitates a more efficient alternative. Oculomotor function deficit is an often-reported pathology in mTBI. Due to the neuroanatomical overlap between eye-movement circuitry and mTBI pathophysiology, visual deficits are expected. In this study, we investigate the possibility of using an oculomotor assessment tool for finding biomarkers in concussion. We used fMRI with tasks evaluating oculomotor functions: smooth pursuit (SP), saccades, anti-saccades, and optokinetic nystagmus (OKN). Before the scanning, the testing with a system of virtual reality goggles with integrated eye- and head-tracking was used where subjects performed the same tasks as those used in fMRI. Twenty-nine concussed symptomatic adults (CSA) within 1-month postconcussion and 29 age- and sex-matched healthy controls (HCS) were tested to examine blood oxygen level-dependent (BOLD) fMRI alterations associated with performances in oculomotor function after mTBI and evaluate the efficacy of the oculomotor assessment in detecting oculomotor and gaze deficits following mTBI. Comparing CSA with HCS, significant differences were observed in anti-saccades and OKN performance. CSA group exhibited elevated %BOLD signal change on each task compared with HCS: in the superior frontal gyrus during the smooth pursuit, inferior frontal gyrus during the saccades, putamen and dorsolateral prefrontal cortex (DLPFC) during the anti-saccades, and lingual gyrus and IFG during the OKN. Key findings include the following: (1) oculomotor deficits in concussed subjects compared with controls, (2) abnormal activation patterns in areas related to the regulation and control of oculomotor movements, suggesting concussion-induced disruptions, and (3) the potential of oculomotor assessment as a promising approach for mTBI biomarkers, with anti-saccades and OKN identified as the most sensitive tasks.

Altered Oculomotor and Vestibulo-ocular Function in Children and Adolescents Postconcussion

OBJECTIVE

To document (1) oculomotor (OM) and vestibulo-ocular (VO) function in children with concussion who were symptomatic at the time of assessment and to compare it with that in children with concussion who were clinically recovered (asymptomatic) and in children with no concussive injury, and (2) the extent to which OM and VO function relates to postconcussion symptom severity in injured children.

SETTING

Participants were recruited from a concussion clinic or the community.

PARTICIPANTS

A total of 108 youth with concussion (72 symptomatic; 36 recovered) and 79 healthy youth (aged 9-18 years). Youth with concussion were included if aged 9 to 18 years, had no previous concussion within the last 12 months, less than 90 days since injury, and no known existing visual disorders or learning disabilities.

STUDY DESIGN

A prospective cross-sectional study.

MAIN MEASURES

All participants were tested for OM and VO function with a commercial virtual reality (VR) eye-tracking system (Neuroflex ® , Montreal,Québec, Canada). Participants in the concussion group who completed the postconcussion symptoms were scored with the Post-Concussion Symptom Inventory.

RESULTS

There was a significant group effect for vergence during smooth pursuit ( F2,176 = 10.90; P < .05), mean latency during saccades ( F2,171 = 5.99; P = .003), and mean response delay during antisaccades ( F2,177 = 9.07; P < .05), where children with symptomatic concussion showed poorer performance than clinically recovered and healthy children. Similar results were found in VO for average vestibular ocular reflex gain in the horizontal leftward ( F2,168 = 7; P = .001) and rightward directions ( F2,163 = 13.08; P < .05) and vertical upward ( F2,147 = 7.60; P = .001) and downward directions ( F2,144 = 13.70; P < .05). Mean saccade error was positively correlated to total Post-Concussion Symptom Inventory scores in younger clinically recovered children.

CONCLUSION

VR eye tracking may be an effective tool for identifying OM and VO deficits in the subacute phase (<90 days) postconcussion.

iVOMS: Instrumented Vestibular / Ocular motor screen in healthy controls and mild traumatic brain injury

Objective Vestibular/ocular deficits occur with mild traumatic brain injury (mTBI). The vestibular/ocular motor screening (VOMS) tool is used to assess individuals post-mTBI, which primarily relies upon subjective self-reported symptoms. Instrumenting the VOMS (iVOMS) with technology may allow for more objective assessment post-mTBI, which reflects actual task performance. This study aimed to validate the iVOMS analytically and clinically in mTBI and controls. Methods Seventy-nine people with sub-acute mTBI (<12 weeks post-injury) and forty-four healthy control participants performed the VOMS whilst wearing a mobile eye-tracking on a one-off visit. People with mTBI were included if they were within 12 weeks of a physician diagnosis. Participants were excluded if they had any musculoskeletal, neurological or sensory deficits which could explain dysfunction. A series of custom-made eye tracking algorithms were used to assess recorded eye-movements. Results The iVOMS was analytically valid compared to the reference (ICC2,1 0.85-0.99) in mTBI and controls. The iVOMS outcomes were clinically valid as there were significant differences between groups for convergence, vertical saccades, smooth pursuit, vestibular ocular reflex and visual motion sensitivity outcomes. However, there was no significant relationship between iVOMS outcomes and self-reported symptoms. Conclusion The iVOMS is analytically and clinically valid in mTBI and controls, but further work is required to examine the sensitivity of iVOMS outcomes across the mTBI spectrum. Findings also highlighted that symptom and physiological issue resolution post-mTBI may not coincide and relationships need further examination.

Exploring oculomotor functions in a pilot study with healthy controls: Insights from eye-tracking and fMRI

Eye-tracking techniques have gained widespread application in various fields including research on the visual system, neurosciences, psychology, and human-computer interaction, with emerging clinical implications. In this preliminary phase of our study, we introduce a pilot test of innovative virtual reality technology designed for tracking head and eye movements among healthy individuals. This tool was developed to assess the presence of mild traumatic brain injury (mTBI), given the frequent association of oculomotor function deficits with such injuries. Alongside eye-tracking, we also integrated fMRI due to the complementary nature of these techniques, offering insights into both neural activation patterns and behavioural responses, thereby providing a comprehensive understanding of oculomotor function. We used fMRI with tasks evaluating oculomotor functions: Smooth Pursuit (SP), Saccades, Anti-Saccades, and Optokinetic Nystagmus (OKN). Prior to the scanning, the testing with a system of VR goggles with integrated eye and head tracking was used where subjects performed the same tasks as those used in fMRI. 31 healthy adult controls (HCs) were tested with the purpose of identifying brain regions associated with these tasks and collecting preliminary norms for later comparison with concussed subjects. HCs' fMRI results showed following peak activation regions: SP-cuneus, superior parietal lobule, paracentral lobule, inferior parietal lobule (IPL), cerebellartonsil (CT); Saccades-middle frontal gyrus (MFG), postcentral gyrus, medial frontal gyrus; Anti-saccades-precuneus, IPL, MFG; OKN-middle temporal gyrus, ACC, postcentral gyrus, MFG, CT. These results demonstrated brain regions associated with the performance on oculomotor tasks in healthy controls and most of the highlighted areas are corresponding with those affected in concussion. This suggests that the involvement of brain areas susceptible to mTBI in implementing oculomotor evaluation, taken together with commonly reported oculomotor difficulties post-concussion, may lead to finding objective biomarkers using eye-tracking tasks.

Evaluating Post-concussion Clinical Management of University-Aged Performing Artists: A Systematic Review

INTRODUCTION

Contemporary concussion literature has yet to establish appropriate clinical management guidelines to address the unique needs of performing arts populations, especially at the collegiate level. Therefore, the purpose of this investigation was to collate current evidence regarding post-concussion return to performance management among university-aged performing artists to generate broad clinical implications.

METHODS

The research team was comprised of two faculty members in the performing arts, one concussion researcher, and athletic trainer, two university librarians, and one physical therapy graduate student with expertise in post-concussion management among performing arts patients. Two librarians searched the literature using PubMed, Cochrane, SPORTdiscus, and Education Research Complete. Studies were eligible for preliminary inclusion if they were written in English, conducted in the United States, as well as published in a peer-reviewed journal. There were no restrictions on publication date due to the limited literature on this topic. The most recent search was conducted in July 2023.

RESULTS

Of the 18 studies identified during the search process, only 2 met the inclusion criteria. Broadly, this investigation identified common mechanisms of injury among stage crew/technicians and dancers who are of university-age. Furthermore, both studies identified several patients who opted to return to performing arts on their own volition. However, there were no studies that solely focused on the collegiate performing arts population and their return to performance procedures.

CONCLUSIONS

Overall, these findings highlight a momentous gap in concussion literature regarding how to guide clinicians and academic teams when returning collegiate performing artists back to their performance environment(s). Thus, additional research is strongly warranted to understand the lived experiences of performing artists with concussion, as well as how to address specific coursework-related demands to support their recovery.

Association of Auditory Interference and Ocular-Motor Response with Subconcussive Head Impacts in Adolescent Football Players

The aim of this study was to examine whether neuro-ophthalmological function, as assessed by the King-Devick test (KDT), alters during a high school football season and to explore the role of auditory interference on the sensitivity of KDT. During the 2021 and 2022 high school football seasons, football players' neuro-ophthalmological function was assessed at five time points (preseason, three in-season, postseason), whereas control athletes were assessed at preseason and postseason. Two-hundred ten football players and 80 control athletes participated in the study. The year 1 cohort (n = 94 football, n = 10 control) was tested with a conventional KDT, whereas the year 2 cohort (n = 116 football, n = 70 control) was tested with KDT while listening to loud traffic sounds to induce auditory interference. There were improvements in KDT during a season among football players, regardless of conventional KDT (preseason 53.4 ± 9.3 vs. postseason 46.4 ± 8.5 sec; β = -1.7, SE = 0.12, p < 0.01) or KDT with auditory interference (preseason 52.3 ± 11.5 vs. postseason 45.1 ± 9.5 sec; β = -1.7, SE = 0.11, p < 0.001). The degree of improvement was similar between the tests, with no significant group-by-time interaction (β = -0.08, SE = 0.17, p = 0.65). The control athletes also improved KDT performance at a similar degree as the football cohorts in both KDT conditions. Our data suggest that KDT performance improves during a season, regardless of auditory interference or head impact exposure. KDT performance was not impacted by a noisy environment, supporting its sideline utility for screening more severe forms of injury.

A Proposed Mechanism for Visual Vertigo: Post-Concussion Patients Have Higher Gain From Visual Input Into Subcortical Gaze Stabilization

Purpose

Post-concussion syndrome (PCS) is commonly associated with dizziness and visual motion sensitivity. This case-control study set out to explore altered motion processing in PCS by measuring gaze stabilization as a reflection of the capacity of the brain to integrate motion, and it aimed to uncover mechanisms of injury where invasive subcortical recordings are not feasible.

Methods

A total of 554 eye movements were analyzed in 10 PCS patients and nine healthy controls across 171 trials. Optokinetic and vestibulo-ocular reflexes were recorded using a head-mounted eye tracker while participants were exposed to visual, vestibular, and visuo-vestibular motion stimulations in the roll plane. Torsional and vergence eye movements were analyzed in terms of slow-phase velocities, gain, nystagmus frequency, and sensory-specific contributions toward gaze stabilization.

Results

Participants expressed eye-movement responses consistent with expected gaze stabilization; slow phases were fastest for visuo-vestibular trials and slowest for visual stimulations (P < 0.001) and increased with stimulus acceleration (P < 0.001). Concussed patients demonstrated increased gain from visual input to gaze stabilization (P = 0.005), faster slow phases (P = 0.013), earlier nystagmus beats (P = 0.003), and higher relative visual influence over the gaze-stabilizing response (P = 0.001), presenting robust effect sizes despite the limited population size.

Conclusions

The enhanced neural responsiveness to visual motion in PCS, combined with semi-intact visuo-vestibular integration, presented a subcortical hierarchy for altered gaze stabilization. Drawing on comparable animal trials, findings suggest that concussed patients may suffer from diffuse injuries to inhibiting pathways for optokinetic information, likely early in the visuo-vestibular hierarchy of sensorimotor integration. These findings offer context for common but elusive symptoms, presenting a neurological explanation for motion sensitivity and visual vertigo in PCS.

Changes in Eye Tracking Features Across Periods of Overpressure Exposure

INTRODUCTION

Repetitive exposure to blast overpressure waves can be a part of routine military and law enforcement training. However, our understanding of the effects of that repetitive exposure on human neurophysiology remains limited. To link an individual's cumulative exposure with their neurophysiological effects, overpressure dosimetry needs to be concurrently collected with relevant physiological signals. Eye tracking has shown promise for providing insight into neurophysiological change because of neural injury, but video-based technology limits usage to a laboratory or clinic. In the present work, we show capability for using electrooculography-based eye tracking to enable physiological assessment in the field during activities involved repetitive blast exposures.

MATERIALS AND METHODS

Overpressure dosimetry was accomplished by using a body-worn measurement system that captures continuous sound pressure levels as well as pressure waveforms of blast event in the range of 135-185 dB peak (0.1-36 kPa). Electrooculography eye tracking was performed using a commercial Shimmer Sensing system, which captured horizontal eye movements of both the left and right eyes, as well as vertical eye movements of the right eye, from which blinks can also be extracted. Data were collected during breaching activities that included repetitive use of explosives. Participants in the study were U.S. Army Special Operators and Federal Bureau of Investigations special agents. Approval for research was received by the Massachucetts Institute of Technology Committee on the Use of Humans as Experimental Subjects, the Air Force Human Research Protections Office, and the Federal Bureau of Investigations Institutional Review Board.

RESULTS

The energy from overpressure events was accumulated and summarized into an 8-hour equivalent of sound pressure level (i.e., LZeq8hr). The total exposure in a single day, i.e., the LZeq8hr, ranged from 110 to 160 dB. Oculomotor features, such as blink and saccade rate, as well as variance in blink waveforms, show changes across the period of overpressure exposure. However, the features that showed significant change across the population were not necessarily the ones that showed significant correlation with the levels of overpressure exposure. A regression model built to predict overpressure levels from oculomotor features alone showed a significant association (R = 0.51, P < .01). Investigation of the model indicates that changes in the saccade rate and blink waveforms are driving the relationship.

CONCLUSIONS

This study successfully demonstrated that eye tracking can be performed during training activities, such as explosive breaching, and that the modality may provide insight into neurophysiological change across periods of overpressure exposure. The results presented herein show that electrooculography-based eye tracking may be a useful method of assessing individualized physiological effects of overpressure exposure in the field. Future work is focused on time-dependent modeling to assess continuous changes in eye movements as this will enable building dose-response curves.

Concussion Rehabilitation and the Application of Ten Movement Training Principles

Concussion awareness continues to grow in all aspects of healthcare, including the areas of prevention, acute care, and ongoing rehabilitation. Most of the concussion research to date has focussed on the challenges around screening and diagnosing what can be a complex mix of brain impairments that overlay with additional pre-existing comorbidities. While we expect further progress in concussion diagnosis, progress also continues to be made around proactive rehabilitation, with the emergence of interventions that can enhance the recovery process, maximise function and independence with a return to study, work, and play. Traditionally, optimal multimodal assessments of concussion have treated the physical, cognitive, and psychological domains of brain injury separately, which supports diagnosis, and informs appropriate follow-up care. Due to the complex nature of brain injury, multimodal assessments direct care toward professionals from many different disciplines including medicine, physiotherapy, psychology, neuropsychology, ophthalmology, and exercise physiology. In addition, these professionals may work in different fields such as sports, neurorehabilitation, vestibular, musculoskeletal, community, vocational, and general practice clinical settings. Rehabilitation interventions for concussions employed in practice are also likely to use a blend of theoretical principles from motor control, cognitive, and psychological sciences. This scale of diversity can make information dissemination, collaboration, and innovation challenging. The Ten Movement Training Principles (MTPs) have been proposed as a usable and relevant concept to guide and support clinical reasoning in neurorehabilitation. When applied to concussion rehabilitation, these same 10 principles provide a comprehensive overview of key rehabilitation strategies for current and future practice. Future collaborations can use these training principles to support clinical and research innovations including the rapid rise of technologies in this growing field of rehabilitation practice.

Quotidian Profile of Vergence Angle in Ambulatory Subjects Monitored With Wearable Eye Tracking Glasses

Purpose

Wearable eye trackers record gaze position as ambulatory subjects navigate their environment. Tobii Pro Glasses 3 were tested to assess their accuracy and precision in the measurement of vergence angle.

Methods

Four subjects wore the eye tracking glasses, with their head stabilized, while fixating at a series of distances corresponding to vergence demands of: 0.25, 0.50, 1, 2, 4, 8, 16, and 32°. After these laboratory trials were completed, 10 subjects wore the glasses for a prolonged period while carrying out their customary daily pursuits. A vergence profile was compiled for each subject and compared with interpupillary distance.

Results

In the laboratory, the eye tracking glasses were comparable in accuracy to remote video eye trackers, outputting a mean vergence value within 1° of demand at all angles except 32°. In ambulatory subjects, the glasses were less accurate, due to tracking interruptions and measurement errors, partly mitigated by the application of data filters. Nonetheless, a useful record of vergence behavior was obtained in every subject. Vergence profiles often had a bimodal distribution, reflecting a preponderance of activities at near (mobile phone and computer) or far (driving and walking). As expected, vergence angle correlated with interpupillary distance.

Conclusions

Wearable eye tracking glasses make it possible to compile a nearly continuous record of vergence angle over hours, which can be correlated with the corresponding visual scene viewed by ambulatory subjects.

Translational Relevance

This technology provides new insight into the diversity of human ocular motor behavior and may become useful for the diagnosis of disorders that affect vergence function such as: convergence insufficiency, Parkinson disease, and strabismus.

Functional Connectivity in the Mouse Brainstem Represents Signs of Recovery from Concussion

Mild traumatic brain injury (mTBI) is one of the most frequent neurological disorders. Diagnostic criteria for mTBI are based on cognitive or neurological symptoms without fully understanding the neuropathological basis for explaining behaviors. From the neuropathological perspective of mTBI, recent neuroimaging studies have focused on structural or functional differences in motor-related cortical regions but did not compare topological network properties between the post-concussion days in the brainstem. We investigated temporal changes in functional connectivity and evaluated network properties of functional networks in the mouse brainstem. We observed a significantly decreased functional connectivity and global and local network properties on post-concussion day 7, which normalized on post-concussion day 14. Functional connectivity and local network properties on post-concussion day 2 were also significantly decreased compared with those on post-concussion day 14, but there were no significant group differences in global network properties between days 2 and 14. We also observed that the local efficiency and clustering coefficient of the brainstem network were significantly correlated with anxiety-like behaviors on post-concussion days 7 and 14. This study suggests that functional connectivity in the mouse brainstem provides vital recovery signs from concussion through functional reorganization.

Pre- and post-season visio-vestibular function in healthy adolescent athletes

OBJECTIVE

To evaluate pre - to post-season differences in individual subtests of the Visio-Vestibular Examination (VVE) in healthy middle and high school athletes.

METHODS

This prospective cohort study recruited participants from a private suburban United States secondary school. Participants completed a demographic questionnaire prior to the start of their season. A proxy for head impact exposure was estimated by incorporating previously published head impact frequencies by team and sport. The VVE was completed pre - and post-season and consisted of 9 subtests: smooth pursuit, horizontal/vertical saccades and gaze stability, binocular convergence, left/right monocular accommodation, and complex tandem gait. Generalized estimating equations were employed to assess the relative risk of an abnormal VVE outcome based on testing session (pre - vs. post-season).

RESULTS

Participants included middle and high school athletes (n = 115; female = 59 (51.3%); median age at first assessment = 14.9 years, [IQR = 13.6, 16.0]) during 2017/18 - 2019/20 school years. During pre-season testing, accommodation (10.0%) and complex tandem gait (9.2%) had the largest proportion of abnormal outcomes, while smooth pursuits (10.6%) and convergence (9.5%) had the largest proportion of abnormal outcomes post-season. When assessing the effect of testing session on the relative risk of any abnormal VVE subtest, there were no significant findings (P ≥ 0.25). Additionally, there were no significant effects of testing session when adjusting for estimated head impact exposure for any VVE subtest (P ≥ 0.25).

CONCLUSIONS

Visio-vestibular function as measured by the VVE does not change from pre - to post-season in otherwise healthy adolescent athletes. Our findings suggest that the VVE may be stable and robust to typical neurodevelopment occurring in this dynamic age group and help inform post-injury interpretation of visio-vestibular impairments.

Monitoring the acute and subacute recovery of cognitive ocular motor changes after a sports-related concussion

Identifying when recovery from a sports-related concussion (SRC) has occurred remains a challenge in clinical practice. This study investigated the utility of ocular motor (OM) assessment to monitor recovery post-SRC between sexes and compared to common clinical measures. From 139 preseason baseline assessments (i.e. before they sustained an SRC), 18 (12 males, 6 females) consequent SRCs were sustained and the longitudinal follow-ups were collected at 2, 6, and 13 days post-SRC. Participants completed visually guided, antisaccade (AS), and memory-guided saccade tasks requiring a saccade toward, away from, and to a remembered target, respectively. Changes in latency (processing speed), visual–spatial accuracy, and errors were measured. Clinical measures included The Sports Concussion Assessment Tool, King-Devick test, Stroop task, and Digit span. AS latency was significantly longer at 2 days and returned to baseline by 13-days post-SRC in females only (P &lt; 0.001). Symptom numbers recovered from 2 to 6 days and 13 days (P &lt; 0.05). Persistently poorer AS visual–spatial accuracy was identified at 2, 6 and 13 days post-SRC (P &lt; 0.05) in both males and females but with differing trajectories. Clinical measures demonstrated consistent improvement reminiscent of practice effects. OM saccade assessment may have improved utility in tracking recovery compared to conventional measures and between sexes.

Comparison of Prescribed Physical Therapy to a Home Exercise Program for Pediatric Sports-Related Concussion Patients

The purpose of this retrospective chart review was to compare sports-related concussion (SRC) recovery time in protracted recovery (≥28 days) patients who were prescribed physical therapy (PPT) with those who were only provided a home exercise program (HEP). We hypothesized PPT would be associated with shorter recovery times relative to HEP. Associations were evaluated with multivariable zero-truncated negative binomial regressions. Among the 48 (30.2%) PPT and 111 (69.8%) HEP patients, the majority were female (57.9%), the mean age was 15.3 ± 1.4 (PPT) and 14.2 ± 2.8 (HEP), and time to clinic was a median 6.0 (IQR = 3.0–27.0; PPT) and 7.0 (IQR = 3.0–23.0; HEP) days. After adjusting for demographic (age, sex) and clinical measures (concussion history, convergence, VOMS, PCSS score, and days to clinic), PPT unexpectedly was associated with 1.21 (95% CI: 1.05, 1.41) additional recovery days compared with HEP. One reason for this could be related to patients adhering to the number of a priori prescribed PT sessions which may or may not have aligned with the patient’s symptom resolution. Future research should explore this hypothesis while aiming to evaluate the effect of PPT versus HEP using a randomized design. If confirmed, these findings are encouraging for patients who could not otherwise access or afford specialty rehabilitation.

Evaluation of the Visual System by the Primary Care Provider Following Concussion

Concussion is a common injury in childhood and has the potential for substantial impact on quality of life. Visual issues have been increasingly recognized as a common problem after concussion. Many children initially seek care for concussion with their pediatrician, making it even more important for pediatricians to recognize, evaluate, and refer children with visual issues after concussion. This clinical report is intended to support the recommendations in the companion policy statement on vision and concussion and provides definitions of some of the physiologic aspects of the visual system as they relate to concussion. A description of clinically feasible testing methodologies is provided in more detail to aid the clinician in assessing the visual system in a focused fashion after concussion. This guidance helps direct clinical management, including support for return to school, sports, and other activities, as well as potential referral for subspecialty care for the subset of those with persistent symptoms.

Rapid Automatized Picture Naming in an Outpatient Concussion Center: Quantitative Eye Movements during the Mobile Universal Lexicon Evaluation System (MULES) Test

Number and picture rapid automatized naming (RAN) tests are useful sideline diagnostic tools. The main outcome measure of these RAN tests is the completion time, which is prolonged with a concussion, yet yields no information about eye movement behavior. We investigated eye movements during a digitized Mobile Universal Lexicon Evaluation System (MULES) test of rapid picture naming. A total of 23 participants with a history of concussion and 50 control participants performed MULES testing with simultaneous eye tracking. The test times were longer in participants with a concussion (32.4 s [95% CI 30.4, 35.8] vs. 26.9 s [95% CI 25.9, 28.0], t=6.1). The participants with a concussion made more saccades per picture than the controls (3.6 [95% CI 3.3, 4.1] vs. 2.7 [95% CI 2.5, 3.0]), and this increase was correlated with longer MULES times (r = 0.46, p = 0.026). The inter-saccadic intervals (ISI) did not differ between the groups, nor did they correlate with the test times. Following a concussion, eye movement behavior differs during number versus picture RAN performance. Prior studies have shown that ISI prolongation is the key finding for a number-based RAN test, whereas this study shows a primary finding of an increased saccade number per picture with a picture-based RAN test. Number-based and picture-based RAN tests may be complimentary in concussion detection, as they may detect different injury effects or compensatory strategies.

Exploring Vestibular/Ocular and Cognitive Dysfunction as Prognostic Factors for Protracted Recovery in Sports-Related Concussion Patients Aged 8 to 12 Years

OBJECTIVE

To explore the prognostic ability of the vestibular/ocular motor screening (VOMS), King-Devick (K-D) Test, and C3 Logix Trails A and B to identify protracted recovery from sports-related concussion (SRC) in patients aged 8 to 12 years.

DESIGN

Retrospective cohort analysis.

SETTING

Specialty pediatric sports concussion clinic.

PARTICIPANTS

A total of 114 youth athletes aged 8 to 12 years who were diagnosed with an SRC within 7 days of injury.

INDEPENDENT VARIABLES

A positive screen on the VOMS, K-D, and C3 Logix Trails A and Trails B. Combined positive screens on multiple tests (ie, 2, 3, or all 4 positive screens of 4 possible).

MAIN OUTCOME MEASURES

Recovery time in days and protracted recovery (recovery time ≥30-days) were the primary outcomes of interest.

RESULTS

A positive VOMS screen was associated with 1.31 greater days to SRC recovery ( P = 0.02) than a negative VOMS screen. The K-D and C3 Logix tests were not significantly associated with recovery time, nor were any combinations of tests ( P > 0.05). The VOMS demonstrated moderate prognostic ability to predict normal recovery (negative predictive value = 80.78% [95% CI = 63.73-90.95]). Overall predictive accuracy of normal versus protracted recovery was strongest when a participant screened positive on all 4 tests (Accuracy = 76.32% [95% CI = 67.45-83.78]).

CONCLUSIONS

The VOMS was associated with overall recovery time and proved to be a useful test to identify those who would experience a normal recovery time. Combining the 4 tests improved the prognostic accuracy of the protocol in predicting protracted versus normal recovery. These findings suggest that combining multiple, varied assessments of cognition and vestibular/ocular functions may better explain factors contributing to protracted recovery.

Blink duration is increased in concussed youth athletes: a validity study using eye tracking in male youth and adult athletes of selected contact sports

OBJECTIVE

Diagnosing a sports-related concussion (SRC) remains challenging, and research into diagnostic tools is limited. This study investigated whether selected eye tracking variables would be a valid tool to diagnose and monitor SRC in adult and youth participants in selected contact sports, such as Rugby Union (rugby) and football (soccer).

METHODS

This prospective cohort study, with 70 concussed and 92 non-concussed adult and youth athletes, assessed the validity of five previously selected eye tracking variables for SRC diagnostics and management. The performance between concussed and age-matched control (non-concussed) athletes, as well as between three successive testing sessions in the concussed athletes were compared. Self-paced saccade count in adult group; blink duration in the memory-guided saccade and sinusoidal smooth pursuit tasks, proportion of antisaccade errors, and gain of diagonal smooth pursuit in the youth group were assessed.

RESULTS

The youth concussed group had higher blink duration in the fast memory-guided saccades task (p = 0.001, η2 = 0.17) and a tendency for higher blink duration in the sinusoidal smooth pursuit task (p = 0.016, η2 = 0.06) compared to the youth control group. In both tasks the blink duration in the concussed youth group decreased from session 1 to session 2 by 24% and 18%, accordingly, although statistical significance was not reached. The concussed adult group demonstrated a lower number of self-paced saccades compared to controls (p = 0.05, η2 = 0.09), which gradually increased, with the largest difference between session 1 and session 3 (p = 0.02).

CONCLUSIONS

Blink duration in youth athletes holds promise as a valid metric for concussion diagnostics and monitoring. It is recommended to focus future studies on comparing eye tracking performance within the same concussed athletes over time rather than comparing them to healthy controls.

An investigation into the measurement properties of the King-Devick Eye Tracking system

Objectives

Eye tracking has been gaining increasing attention as a possible assessment and monitoring tool for concussion. The King-Devick test (K-DT) was expanded to include an infrared video-oculography-based eye tracker (K-D ET). Therefore, the aim was to provide evidence on the reliability of the K-D ET system under an exercise condition.

Methods

Participants (N = 61; 26 male, 35 female; age range 19-25) were allocated to an exercise or sedentary group. Both groups completed a baseline K-D ET measurement and then either two 10-min exercise or sedentary interventions with repeated K-D ET measurements between interventions.

Results

The test-retest reliability of the K-D ET ranged from good to excellent for the different variables measured. The mean ± SD of the differences for the total number of saccades was 1.04 ± 4.01 and there was an observable difference (p = 0.005) in the trial number. There were no observable differences for the intervention (p = 0.768), gender (p = 0.121) and trial (p = 0.777) for average saccade’s velocity. The mean ± SD of the difference of the total fixations before and after intervention across both trials was 1.04 ± 3.63 and there was an observable difference in the trial number (p = 0.025). The mean ± SD of the differences for the Inter-Saccadic Interval and the fixation polyarea before and after intervention across both trials were 1.86 ± 22.99 msec and 0.51 ± 59.11 mm2 and no observable differences for the intervention, gender and trial.

Conclusion

The results provide evidence on the reliability of the K-D ET, and the eye-tracking components and demonstrate the relationship between completion time and other variables of the K-D ET system. This is vital as the use of the K-DT may be increasing and the combination of the K-DT and eye tracking as one single package highlights the need to specifically measure the reliability of this combined unit.

Clinical testing of mild traumatic brain injury using computerised eye-tracking tests

Traumatic brain injury (TBI) refers to the alteration of typical brain function that occurs following a blow to the head. Even a mild case of traumatic brain injury (mTBI) can lead to long-term impairment, so accurate and timely detection is vital. Visual symptoms are common following mTBI, so while it may seem to fall outside their typical scope of practice, optometrists are ideally qualified to assess the visual impacts and help with the diagnosis of mTBI. Given that mTBI is challenging to objectively diagnose and has no universally accepted diagnostic criteria, clinicians can lack confidence in diagnosing mTBI, and be hesitant in becoming involved in the management of such patients. The development of easily quantifiable techniques using eye tracking as an objective diagnostic tool provides practitioners with an easier pathway into the field, assigning numerical values to parameters which are difficult to assess using conventional optometric tests. As this evolving technology becomes increasingly integrated into optometric clinical settings, the potential for it to identify deficits accurately and reliably in patients following mTBI, and to monitor both their recovery and the effectiveness of potential treatments will increase. This paper provides an overview of clinical tests, relevant to optometrists, that can uncover oculomotor, attentional, and exteroceptive deficits following a mTBI, so that an optometrist with an interest in eye tracking can play a role in the detection and monitoring of mTBI symptoms.

King-Devick Test Performance and Cognitive Dysfunction after Concussion: A Pilot Eye Movement Study

(1) Background: The King-Devick (KD) rapid number naming test is sensitive for concussion diagnosis, with increased test time from baseline as the outcome measure. Eye tracking during KD performance in concussed individuals shows an association between inter-saccadic interval (ISI) (the time between saccades) prolongation and prolonged testing time. This pilot study retrospectively assesses the relation between ISI prolongation during KD testing and cognitive performance in persistently-symptomatic individuals post-concussion. (2) Results: Fourteen participants (median age 34 years; 6 women) with prior neuropsychological assessment and KD testing with eye tracking were included. KD test times (72.6 ± 20.7 s) and median ISI (379.1 ± 199.1 msec) were prolonged compared to published normative values. Greater ISI prolongation was associated with lower scores for processing speed (WAIS-IV Coding, r = 0.72, p = 0.0017), attention/working memory (Trails Making A, r = −0.65, p = 0.006) (Digit Span Forward, r = 0.57, p = −0.017) (Digit Span Backward, r= −0.55, p = 0.021) (Digit Span Total, r = −0.74, p = 0.001), and executive function (Stroop Color Word Interference, r = −0.8, p = 0.0003). (3) Conclusions: This pilot study provides preliminary evidence suggesting that cognitive dysfunction may be associated with prolonged ISI and KD test times in concussion.

Saccade and Fixation Eye Movements During Walking in People With Mild Traumatic Brain Injury

Background: Clinical and laboratory assessment of people with mild traumatic brain injury (mTBI) indicate impairments in eye movements. These tests are typically done in a static, seated position. Recently, the use of mobile eye-tracking systems has been proposed to quantify subtle deficits in eye movements and visual sampling during different tasks. However, the impact of mTBI on eye movements during functional tasks such as walking remains unknown.

Objective: Evaluate differences in eye-tracking measures collected during gait between healthy controls (HC) and patients in the sub-acute stages of mTBI recovery and to determine if there are associations between eye-tracking measures and gait speed.

Methods: Thirty-seven HC participants and 67individuals with mTBI were instructed to walk back and forth over 10-m, at a comfortable self-selected speed. A single 1-min trial was performed. Eye-tracking measures were recorded using a mobile eye-tracking system (head-mounted infra-red Tobbii Pro Glasses 2, 100 Hz, Tobii Technology Inc. VA, United States). Eye-tracking measures included saccadic (frequency, mean and peak velocity, duration and distance) and fixation measurements (frequency and duration). Gait was assessed using six inertial sensors (both feet, sternum, right wrist, lumbar vertebrae and the forehead) and gait velocity was selected as the primary outcome. General linear model was used to compare the groups and association between gait and eye-tracking outcomes were explored using partial correlations.

Results: Individuals with mTBI showed significantly reduced saccade frequency (p = 0.016), duration (p = 0.028) and peak velocity (p = 0.032) compared to the HC group. No significant differences between groups were observed for the saccade distance, fixation measures and gait velocity (p > 0.05). A positive correlation was observed between saccade duration and gait velocity only for participants with mTBI (p = 0.025).

Conclusion: Findings suggest impaired saccadic eye movement, but not fixations, during walking in individuals with mTBI. These findings have implications in real-world function including return to sport for athletes and return to duty for military service members. Future research should investigate whether or not saccade outcomes are influenced by the time after the trauma and rehabilitation.

Cognitive ocular motor deficits and white matter damage chronically after sports-related concussion

A history of concussion has been linked to long-term cognitive deficits; however, the neural underpinnings of these abnormalities are poorly understood. This study recruited 26 asymptomatic male Australian footballers with a remote history of concussion (i.e. at least six months since last concussion), and 23 non-collision sport athlete controls with no history of concussion. Participants completed three ocular motor tasks (prosaccade, antisaccade and a cognitively complex switch task) to assess processing speed, inhibitory control and cognitive flexibility, respectively. Diffusion tensor imaging data were acquired using a 3 T MRI scanner, and analysed using tract-based spatial statistics, to investigate white matter abnormalities and how they relate to ocular motor performance. Australian footballers had significantly slower adjusted antisaccade latencies compared to controls (P = 0.035). A significant switch cost (i.e. switch trial error > repeat trial error) was also found on the switch task, with Australian footballers performing increased magnitude of errors on prosaccade switch trials relative to prosaccade repeat trials (P = 0.023). Diffusion tensor imaging analysis found decreased fractional anisotropy, a marker of white matter damage, in major white matter tracts (i.e. corpus callosum, corticospinal tract) in Australian footballers relative to controls. Notably, a larger prosaccade switch cost was significantly related to reduced fractional anisotropy in anterior white matter regions found to connect to the prefrontal cortex (i.e. a key cortical ocular motor centre involved in executive functioning and task switching). Taken together, Australian footballers with a history of concussion have ocular motor deficits indicative of poorer cognitive processing speed and cognitive flexibility, which are related to reduce white matter integrity in regions projecting to important cognitive ocular motor structures. These findings provide novel insights into the neural mechanisms that may underly chronic cognitive impairments in individuals with a history of concussion.

Eye tracking to assess concussions: an intra-rater reliability study with healthy youth and adult athletes of selected contact and collision team sports

Eye movements that are dependent on cognition hold promise in assessing sports-related concussions but research on reliability of eye tracking measurements in athletic cohorts is very limited. This observational test-retest study aimed to establish whether eye tracking technology is a reliable tool for assessing sports-related concussions in youth and adult athletes partaking in contact and collision team sports. Forty-three youth (15.4 ± 2.2 years) and 27 adult (22.2 ± 2.9 years) Rugby Union and soccer players completed the study. Eye movements were recorded using SMIRED250mobile while participants completed a test battery twice, with a 1-week interval that included self-paced saccade (SPS), fixation stability, memory-guided sequence (MGS), smooth pursuit (SP), and antisaccades (AS) tasks. Intra-class correlation coefficient (ICC), measurement error (SEM) and smallest real difference (SRD) were calculated for 47 variables. Seventeen variables achieved an ICC > 0.50. In the adults, saccade count in SPS had good reliability (ICC = 0.86, SRD = 146.6 saccades). In the youth, the average blink duration in MGS had excellent reliability (ICC = 0.99, SRD = 59.4 ms); directional errors in AS tasks and gain of diagonal SP had good reliability (ICC = 0.78 and 0.77, SRD = 25.3 and 395.1%, respectively). Four metrics were found in this study to be reliable candidates for further biomarker validity research in contact and collision sport cohorts. Many variables failed to present a sufficient level of robustness for a practical diagnostic tool; possibly, because athletic cohorts have higher homogeneity, along with latent adverse effects of undetected concussions and repetitive head impacts. Since reliability of a measure can influence type II error, effect sizes, and confidence intervals, it is strongly advocated to conduct dedicated reliability evaluations prior to any validity studies.

Visual effects of concussion: A review

A concussion occurs when a direct or indirect force is transmitted to the brain, causing a change in brain function. Given that approximately half the brain circuits are involved in vision and the control of eye movements, a concussion frequently results in visual symptoms. Ophthalmic abnormalities are helpful in the assessment of acute concussion, identified by rapid automized naming tasks and eye movement assessments. In particular, convergence, eye-tracking and the vestibular-ocular motor screening tool may be used. For patients suffering from post-concussion syndrome more than 3 months from the original injury, abnormalities may be found in convergence, accommodation and smooth pursuit. Orthoptic exercises are useful rehabilitation tools to allow patients to return to school, work and recreation. This article provides a brief overview of concussion as it relates to vision and ophthalmic practice.

Traumatic brain injury and sight loss in military and veteran populations- a review

War and combat exposure pose great risks to the vision system. More recently, vision related deficiencies and impairments have become common with the increased use of powerful explosive devices and the subsequent rise in incidence of traumatic brain injury (TBI). Studies have looked at the effects of injury severity, aetiology of injury and the stage at which visual problems become apparent. There was little discrepancy found between the frequencies or types of visual dysfunctions across blast and non-blast related groups, however complete sight loss appeared to occur only in those who had a blast-related injury. Generally, the more severe the injury, the greater the likelihood of specific visual disturbances occurring, and a study found total sight loss to only occur in cases with greater severity. Diagnosis of mild TBI (mTBI) is challenging. Being able to identify a potential TBI via visual symptoms may offer a new avenue for diagnosis.

Brain function associated with reaction time after sport-related concussion

Concussion is associated with significant functional disturbances in the first week post-injury. Computerized neurocognitive testing tools have become widely adopted in concussion management, to identify specific domains of impairment and obtain more objective measures of recovery. Reaction time (RT) slowing is a common sequela of concussion, however, the functional brain networks that underlie RT performance remain under-studied in both healthy and concussed athletic cohorts. This study used blood-oxygenation-level-dependent function magnetic resonance imaging (BOLD fMRI) to evaluate resting brain function of 45 university-level athletes with concussion in the first week post-injury, along with a control cohort of 102 athletes without recent concussion. We evaluated the main effects of concussion and RT on functional connectivity, along with concussion × RT interactions, using multivariate analysis techniques. Concussion was associated with reduced connectivity throughout the brain, whereas RT slowing was associated with elevated connectivity in parietal and temporal regions, for both control and concussed groups. For the concussed group, RT slowing was also associated with disrupted connectivity between fronto-insular and default mode networks. For concussed athletes, the brain networks associated with slower post-injury RT also showed similar but non-significant associations with longitudinal changes in RT performance relative to pre-injury baseline. These study findings provide new insights into the effects of concussion on neurocognitive function and suggest the presence of functional brain networks that are specific to concussion-related RT slowing.

Using Dynamics of Eye Movements, Speech Articulation and Brain Activity to Predict and Track mTBI Screening Outcomes

Repeated subconcussive blows to the head during sports or other contact activities may have a cumulative and long lasting effect on cognitive functioning. Unobtrusive measurement and tracking of cognitive functioning is needed to enable preventative interventions for people at elevated risk of concussive injury. The focus of the present study is to investigate the potential for using passive measurements of fine motor movements (smooth pursuit eye tracking and read speech) and resting state brain activity (measured using fMRI) to complement existing diagnostic tools, such as the Immediate Post-concussion Assessment and Cognitive Testing (ImPACT), that are used for this purpose. Thirty-one high school American football and soccer athletes were tracked through the course of a sports season. Hypotheses were that (1) measures of complexity of fine motor coordination and of resting state brain activity are predictive of cognitive functioning measured by the ImPACT test, and (2) within-subject changes in these measures over the course of a sports season are predictive of changes in ImPACT scores. The first principal component of the six ImPACT composite scores was used as a latent factor that represents cognitive functioning. This latent factor was positively correlated with four of the ImPACT composites: verbal memory, visual memory, visual motor speed and reaction speed. Strong correlations, ranging between r = 0.26 and r = 0.49, were found between this latent factor and complexity features derived from each sensor modality. Based on a regression model, the complexity features were combined across sensor modalities and used to predict the latent factor on out-of-sample subjects. The predictions correlated with the true latent factor with r = 0.71. Within-subject changes over time were predicted with r = 0.34. These results indicate the potential to predict cognitive performance from passive monitoring of fine motor movements and brain activity, offering initial support for future application in detection of performance deficits associated with subconcussive events.

Discriminative Validity of Vestibular Ocular Motor Screening in Identifying Concussion Among Collegiate Athletes: A National Collegiate Athletic Association-Department of Defense Concussion Assessment, Research, and Education Consortium Study

BACKGROUND

Vestibular and ocular motor screening tools, such as the Vestibular/Ocular Motor Screening (VOMS), are recognized as important components of a multifaceted evaluation of sport-related concussion. Previous research has supported the predictive utility of the VOMS in identifying concussion, but researchers have yet to examine the predictive utility of the VOMS among collegiate athletes in the first few days after injury.

PURPOSE

To determine the discriminative validity of individual VOMS item scores and an overall VOMS score for identifying collegiate athletes with an acute sport-related concussion (≤72 hours) from healthy controls matched by age, sex, and concussion history.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Participants (N = 570) aged 17 to 25 years were included from 8 institutions of the National Collegiate Athletic Association-Department of Defense CARE Consortium (Concussion Assessment, Research, and Education): 285 athletes who were concussed (per current consensus guidelines) and 285 healthy controls matched by age, sex, and concussion history. Participants completed the VOMS within 3 days of injury (concussion) or during preseason (ie, baseline; control). Symptoms are totaled for each VOMS item for an item score (maximum, 40) and totaled across items for an overall score (maximum, 280), and distance (centimeters) for near point of convergence (NPC) is averaged across 3 trials. Receiver operating characteristic analysis of the area under the curve (AUC) was performed on cutoff scores using Youden index (J) for each VOMS item, overall VOMS score, and NPC distance average. A logistic regression was conducted to identify which VOMS scores identified concussed status.

RESULTS

A symptom score ≥1 on each VOMS item and horizontal vestibular/ocular reflex ≥2 significantly discriminated concussion from control (AUC, 0.89-0.90). NPC distance did not significantly identify concussion from control (AUC, 0.51). The VOMS overall score had the highest accuracy (AUC, 0.91) for identifying sport-related concussion from control. Among the individual items, vertical saccades ≥1 and horizontal vestibular/ocular reflex ≥2 best discriminated concussion from control.

CONCLUSION

The findings indicate that individual VOMS items and overall VOMS scores are useful in identifying concussion in collegiate athletes within 3 days of injury. Clinicians can use the cutoffs from this study to help identify concussion in collegiate athletes.

Long-Term Effects of Repetitive Mild Traumatic Injury on the Visual System in Wild-Type and TDP-43 Transgenic Mice

Little is known about the impairments and pathological changes in the visual system in mild brain trauma, especially repetitive mild traumatic brain injury (mTBI). The goal of this study was to examine and compare the effects of repeated head impacts on the neurodegeneration, axonal integrity, and glial activity in the optic tract (OT), as well as on neuronal preservation, glial responses, and synaptic organization in the lateral geniculate nucleus (LGN) and superior colliculus (SC), in wild-type mice and transgenic animals with overexpression of human TDP-43 mutant protein (TDP-43^G348C) at 6 months after repeated closed head traumas. Animals were also assessed in the Barnes maze (BM) task. Neurodegeneration, axonal injury, and gliosis were detected in the OT of the injured animals of both genotypes. In the traumatized mice, myelination of surviving axons was mostly preserved, and the expression of neurofilament light chain was unaffected. Repetitive mTBI did not induce changes in the LGN and the SC, nor did it affect the performance of the BM task in the traumatized wild-type and TDP-43 transgenic mice. Differences in neuropathological and behavioral assessments between the injured wild-type and TDP-43^G348C mice were not revealed. Results of the current study suggest that repetitive mTBI was associated with chronic damage and inflammation in the OT in wild-type and TDP-43^G348C mice, which were not accompanied with behavioral problems and were not affected by the TDP-43 genotype, while the LGN and the SC remained preserved in the used experimental conditions.

OculoMotor Assessment Tool Test Procedure and Normative Data

SIGNIFICANCE

This study establishes normative data and a testing procedure for the oculomotor assessment tool. The oculomotor assessment tool standardizes visual targets for the Vestibular/OculoMotor Screening assessment and provides additional metrics that may aid in the differentiation between those with normal and those with abnormal oculomotor function potentially caused by a concussion.

PURPOSE

This study aimed to assess the oculomotor endurance of healthy participants with no self-reported history of concussions using the oculomotor assessment tool.

METHODS

Healthy participants (n = 376, average age of 20.4 years, range of 11 to 34 years, with no self-reported history of concussions) were recruited to perform the following three tasks for 60 seconds each: (1) horizontal saccades, (2) vertical saccades, and (3) vergence jumps. The participants were instructed to alternate visual fixation between two targets for each of the tasks as fast as they could without overshooting or undershooting the visual target. The differences in the number of eye movements between the initial and latter 30 seconds of the 1-minute test were analyzed.

RESULTS

A statistical difference (P < .001) was observed in the number of eye movements for all three tasks (horizontal saccades [70 ± 15 for initial 30 seconds, 63 ± 13 for latter 30 seconds], vertical saccades [68 ± 14, 63 ± 13], and vergence jumps [43 ± 11, 39 ± 10]) between the initial and latter 30 seconds. No significant differences were identified in the number of eye movements or the change in eye movements between the initial and latter 30 seconds based on sex.

CONCLUSIONS

These results establish a normative database for various eye movements. These data could potentially be used to compare different patient populations who have binocular endurance dysfunctions potentially due to traumatic brain injury, such as patients with concussion(s).

Disparity vergence differences between typically occurring and concussion-related convergence insufficiency pediatric patients

This study sought to test the hypothesis that significant differences would be observed in clinical measures, symptoms, and objective assessments of vergence eye movements between children with typically developing convergence insufficiency (TYP-CI) and children with persistent post-concussion symptoms with convergence insufficiency (PPCS-CI). Data from age-matched binocularly normal controls (BNC) were used for comparison. Data from three groups of children 11 to 17 years of age are presented: BNC (N = 11), TYP-CI (N = 10), and PPCS-CI (N = 15). Clinical measures of vergence, accommodation, and symptom severity were collected. Symmetrical 4° disparity vergence eye movements were quantified with an eye tracker integrated into a head-mounted display (Oculus DK2). Peak velocity and final response amplitude of convergence and divergence eye movement responses were assessed. The mean near point of convergence (break) was more receded (worse), the amplitude of accommodation more deficient, and convergent and divergent peak velocities slower in the PPCS-CI group compared with the TYP-CI and BNC groups. These results suggest that PPCS-CI may be a different clinical entity than TYP-CI. Hence, more research is warranted to determine whether the therapeutic interventions that are effective for TYP-CI can also be used for PPCS-CI populations.

Rehabilitation of visual disorders

While there is a long history of rehabilitation for motor deficits following cerebral lesions, less is known about our ability to improve visual deficits. Vision therapy, prisms, occluders, and filters have been advocated for patients with mild traumatic brain injury, on the premise that some of their symptoms may reflect abnormal visual or ocular motor function, but the evidence for their efficacy is modest. For hemianopia, attempts to restore vision have had unimpressive results, though it appears possible to generate blindsight through training. Strategic approaches that train more efficient use of visual search in hemianopia have shown consistent benefit in visual function, while prism aids may help some patients. There are many varieties of alexia. Strategic adaptation of saccades can improve hemianopic alexia, but there has been less work and mixed results for pure alexia, neglect dyslexia, attentional dyslexia, and the central dyslexias. A number of approaches have been tried in prosopagnosia, with recent studies of small groups suggesting that face perception of prosopagnosic subjects can be enhanced through perceptual learning.

One size fits none: neurobiologic-specific modifications for the assessment, diagnosis, and treatment of sport-related concussion (SRC)

PRIMARY OBJECTIVE

- To discuss how the underlying neuroanatomy and neurobiology of five sport-related concussion (SRC) clinical profiles impacts assessment and treatment.

RESEARCH DESIGN

- Narrative review.

METHODS AND PROCEDURES

- Based on the current literature and clinical experience, arguments against the traditional SRC protocol and for a clinical profiles-based SRC protocol are made.

MAIN OUTCOMES AND RESULTS

- While the clinical profiles-based SRC protocol is widely used and accepted, there has been little published regarding the link to the underlying neuropathology. Our narrative review describes the five SRC clinical profiles: vestibular, ocular, mood, post-traumatic migraine, and cognitive/fatigue. For these profiles, the underlying neuroanatomy and neurobiology is outlined, as well as how that anatomy and biology impact the profiles' etiology, assessment, and treatment. The cervical and sleep modifiers are also briefly covered.

CONCLUSIONS

- Utilizing this model, clinicians are able to provide an individualized assessment, conceptualization, and treatment plan for SRC, leading to improved outcomes and clinical experiences for athletes.

Using Oculomotor Features to Predict Changes in Optic Nerve Sheath Diameter and ImPACT Scores From Contact-Sport Athletes

There is mounting evidence linking the cumulative effects of repetitive head impacts to neuro-degenerative conditions. Robust clinical assessment tools to identify mild traumatic brain injuries are needed to assist with timely diagnosis for return-to-field decisions and appropriately guide rehabilitation. The focus of the present study is to investigate the potential for oculomotor features to complement existing diagnostic tools, such as measurements of Optic Nerve Sheath Diameter (ONSD) and Immediate Post-concussion Assessment and Cognitive Testing (ImPACT). Thirty-one high school American football and soccer athletes were tracked through the course of a sports season. Given the high risk of repetitive head impacts associated with both soccer and football, our hypotheses were that (1) ONSD and ImPACT scores would worsen through the season and (2) oculomotor features would effectively capture both neurophysiological changes reflected by ONSD and neuro-functional status assessed via ImPACT. Oculomotor features were used as input to Linear Mixed-Effects Regression models to predict ONSD and ImPACT scores as outcomes. Prediction accuracy was evaluated to identify explicit relationships between eye movements, ONSD, and ImPACT scores. Significant Pearson correlations were observed between predicted and actual outcomes for ONSD (Raw = 0.70; Normalized = 0.45) and for ImPACT (Raw = 0.86; Normalized = 0.71), demonstrating the capability of oculomotor features to capture neurological changes detected by both ONSD and ImPACT. The most predictive features were found to relate to motor control and visual-motor processing. In future work, oculomotor models, linking neural structures to oculomotor function, can be built to gain extended mechanistic insights into neurophysiological changes observed through seasons of participation in contact sports.

Approaches for Monitoring Warfighter Blast-related Exposures in Training to Develop Effective Safety Standards

INTRODUCTION

Traumatic brain injuries are of concern to the sports and military communities because of the age of the participants and costly burden to society. To markedly reduce the impact of traumatic brain injury and its sequela (TBI-S), it is necessary to determine the initial vulnerability of individuals as well as identify new technologies that indicate early signs of TBI-S.

MATERIALS AND METHODS

Currently, diverse methods have been used by the authors and others in laboratory settings to reveal early signs of persistent TBI-S including simulation modeling of the effect of rapid deceleration on the deviatoric strain (shear force) imposed on specific brain regions, auditory evoked potential (AEP) measurements to determine injury to the auditory cortex optokinetic nystagmus (OKN) measures sensitive to vestibular trauma, and optical coherence tomography (OCT) measures that reveal changes in central visual function obtained noninvasively by examination of the retina.

RESULTS

Simulation studies provided technical information on maximal deviatoric strain at the base of the sulci and interface of gray and white matter consistent with results from neuropathology and from magnetic resonance imaging. The AEP and OKN reveal measurable injury to similar regions below the Sylvian fissure including auditory cortex and midbrain, and the OCT reveals changes to the retina consistent with forceful deceleration effects.

CONCLUSIONS

The studies and results are consistent with prior work demonstrating that noninvasive tests may be sensitive to the presence of TBI-S, potentially in the training field as advances in the portability of test instruments are underway. When combined with baseline data gathered from individuals in quantitative form, key variances can emerge. Therefore, it is hypothesized that AEP, OKN, and OCT, taken together, may yield faster objective and quantitative neurophysiological measures serving as a "signature" of neural injury and more indicative of potentially persistent TBI-S-recommending larger scale longitudinal studies.

Fixation stability as a biomarker for differentiating mild traumatic brain injury from age matched controls in pediatrics

OBJECTIVES

Traumatic brain injury (TBI) is an increasingly significant health concern worldwide, compounded by the difficultly in detection and diagnosis. Fortunately, a growing body of research has identified oculomotor behavior, specifically fixations, saccades and smooth pursuit eye movements as a promising endophenotype for neurotrauma. To date, limited research exists using fixation stability in a comparative study to indicate the presence of a mild TBI (mTBI), especially in the pediatric population.

METHODS

The present study examined data from 91 individuals clinically diagnosed with mTBI and a further 140 age- and gender-matched controls. They all completed the RightEye fixation stability test using a remote eye tracker. Participants were compared on five fixation metrics: Bivariate Contour Ellipse Area (BCEA), Convergence Point, Depth, Disassociated Phoria, and Targeting Displacement.

RESULTS

Results were analyzed using one-way univariate ANOVAs, ROC analysis, and stepwise logistic regression. BCEA results revealed significant differences between groups with the mTBI group showing a larger gaze spread, indicative of less ability to keep the eyes close to the target without deviating.

CONCLUSIONS

Fixation stability is detrimentally impacted by mTBI in pediatric patients, and the oculomotor test can be used to differentiate between those with and without an mTBI.

Shortened telomeres and serum protein biomarker abnormalities in collision sport athletes regardless of concussion history and sex

Mild brain injuries are frequent in athletes engaging in collision sports and have been linked to a range of long-term neurological abnormalities. There is a need to identify how these potential abnormalities manifest using objective measures; determine whether changes are due to concussive and/or sub-concussive injuries; and examine how biological sex affects outcomes. This study investigated cognitive, cellular, and molecular biomarkers in male and female amateur Australian footballers (i.e. Australia’s most participated collision sport). 95 Australian footballers (69 males, 26 females), both with and without a history of concussion, as well as 49 control athletes (28 males, 21 females) with no history of brain trauma or participation in collision sports were recruited to the study. Ocular motor assessment was used to examine cognitive function. Telomere length, a biomarker of cellular senescence and neurological health, was examined in saliva. Serum levels of tau, phosphorylated tau, neurofilament light chain, and 4-hydroxynonenal were used as markers to assess axonal injury and oxidative stress. Australian footballers had reduced telomere length (p = 0.031) and increased serum protein levels of 4-hydroxynonenal (p = 0.001), tau (p = 0.007), and phosphorylated tau (p = 0.036). These findings were independent of concussion history and sex. No significant ocular motor differences were found. Taken together, these findings suggest that engagement in collision sports, regardless of sex or a history of concussion, is associated with shortened telomeres, axonal injury, and oxidative stress. These saliva- and serum-based biomarkers may be useful to monitor neurological injury in collision sport athletes.

Concussion Management for the Orthopaedic Surgeon

Orthopaedic surgeons functioning as team physicians are in a unique position to recognize subtle changes in an athlete's behavior and may be the first responders to concussions at sporting events. The rate of sports-related concussions has increased over the past few decades, necessitating that orthopaedic team physicians gain a greater understanding of the diagnosis and management of this condition. During the sideline evaluation, life-threatening injuries must be ruled out before concussion evaluation may take place. In most cases, patients experience a resolution of symptoms within a week; however, a smaller subset of patients experience persistent symptoms. Physicians covering sporting events must remain current regarding recommendations for treating sports-related concussions and must document their management plan to minimize potential harm to an athlete.

Neurovascular Coupling in Special Operations Forces Combat Soldiers

The purpose of this study was to investigate how concussion history affects neurovascular coupling in Special Operations Forces (SOF) combat Soldiers. We studied 100 SOF combat Soldiers [age = 33.5 ± 4.3 years; height = 180.4 ± 6.0 cm; 55 (55.0%) with self-reported concussion history]. We employed transcranial Doppler (TCD) ultrasound to assess neurovascular coupling (NVC) via changes in posterior cerebral artery (PCA) velocity in response to a reading and a visual search task. Baseline TCD data were collected for 2 min. NVC was quantified by the percent change in overall PCA response curves. We employed linear mixed effect models using a linear spline with one knot to assess group differences in percent change observed in the PCA velocity response curves between SOF combat Soldiers with and without a concussion history. Baseline PCA velocity did not significantly differ (t₉₈ = 1.28, p = 0.20) between those with and without concussion history. Relative PCA velocity response curves did not differ between those with and without a concussion history during the reading task (F_1,98 = 0.80, p = 0.37) or the visual search task (F_1,98 = 0.52, p = 0.47). When assessing only SOF combat Soldiers with a concussion history, differential response to task was significantly greater in those with 3 or more concussions (F_1,4341 = 27.24, p < 0.0001) relative to those with 1-2 concussions. Despite no main effect of concussion history on neurovascular coupling response in SOF combat Soldiers, we observed a dose-response based on lifetime concussion incidence. While long-term neurophysiological effects associated with head impact and blast-related injury are currently unknown, assessing NVC response may provide further insight into cerebrovascular function and overall physiological health.

The Effects of Mild Traumatic Brain Injury on Cognitive-Motor Integration for Skilled Performance

Adults exposed to blast and blunt impact often experience mild traumatic brain injury, affecting neural functions related to sensory, cognitive, and motor function. In this perspective article, we will review the effects of impact and blast exposure on functional performance that requires the integration of these sensory, cognitive, and motor control systems. We describe cognitive-motor integration and how it relates to successfully navigating skilled activities crucial for work, duty, sport, and even daily life. We review our research on the behavioral effects of traumatic impact and blast exposure on cognitive-motor integration in both younger and older adults, and the neural networks that are involved in these types of skills. Overall, we have observed impairments in rule-based skilled performance as a function of both physical impact and blast exposure. The extent of these impairments depended on the age at injury and the sex of the individual. It appears, however, that cognitive-motor integration deficits can be mitigated by the level of skill expertise of the affected individual, suggesting that such experience imparts resiliency in the brain networks that underly the control of complex visuomotor performance. Finally, we discuss the next steps needed to comprehensively understand the impact of trauma and blast exposure on functional movement control.

Clinical Detection and Recovery of Vestibular and Oculomotor Impairments Among Amateur Athletes Following Sport-Related Concussion: A Prospective, Matched-Cohort Study

OBJECTIVE

To (1) quantify the diagnostic accuracy of the vestibular/oculomotor screening (VOMS), and (2) determine the recovery of vestibular and oculomotor impairments exhibited by concussed athletes compared with nonconcussed athletes using the VOMS.

SETTING

Clinical assessment laboratory.

PARTICIPANTS

Amateur athletes who were diagnosed with sport-related concussion by emergency department physicians, and non-concussed, control athletes.

DESIGN

Prospective, longitudinal study.

MAIN MEASURES

Participants were assessed 1 week following sport-related concussion, upon clearance to return-to-sporting activity, and 2 weeks following return-to-sporting activity by a study investigator who administered the VOMS. We calculated test sensitivity, specificity, and positive and negative predictive values to estimate the diagnostic accuracy of the VOMS. We performed a mixed-design analysis of variance to assess differences in VOMS symptom scores reported by concussed athletes compared with control athletes.

RESULTS

Fifty concussion participants and 50 control participants completed the study. The VOMS demonstrated sensitivity and specificity of 96% and 46%, respectively, and produced positive and negative predictive values of 64% and 92%, respectively. The concussion group exhibited a significantly greater symptom provocation change score from baseline than the control group for all test domains of the VOMS only in the first week following concussion.

CONCLUSION

The VOMS may be most useful as a clinical screening tool to rule out, rather than confirm, the presence of sport-related concussion. The VOMS may be appropriate to inform the recovery of vestibular and oculomotor impairments exhibited by concussed individuals over time.

Concussion Office Based Rehabilitation Assessment: A Novel Clinical Tool for Concussion Assessment and Management

The Concussion Office Based Rehabilitation Assessment (COBRA) is a novel tool constructed to ensure a comprehensive assessment of patients who may have sustained a concussion. The SCAT-5 (Sport Concussion Assessment Tool) has long been the gold standard for concussion assessment, however, it was designed as a sideline tool and its utility can be seen to decrease after a few days post-concussion. It also does not prompt evaluation of all the phenotypes of concussion. As such, the COBRA was created to assess the majority of potential manifestations of concussion in the office setting a day or two after an injury has been sustained. The COBRA utilizes the eight phenotypes of concussion as a guide to assess each of the potential biopsychosocial features that can be associated with these injuries and can be used to guide evidence-based treatments. Through early identification of concussion phenotypes, the clinician may start optimal treatment and hopefully prevent prolonged recovery and persisting symptoms.

A Decade of mTBI Experience: What Have We Learned? A Summary of Proceedings From a NATO Lecture Series on Military mTBI

Mild traumatic brain injury (mTBI, also known as a concussion) as a consequence of battlefield blast exposure or blunt force trauma has been of increasing concern to militaries during recent conflicts. This concern is due to the frequency of exposure to improvised explosive devices for forces engaged in operations both in Iraq and Afghanistan coupled with the recognition that mTBI may go unreported or undetected. Blasts can lead to mTBI through a variety of mechanisms. Debate continues as to whether exposure to a primary blast wave alone is sufficient to create brain injury in humans, and if so, exactly how this occurs with an intact skull. Resources dedicated to research in this area have also varied substantially among contributing NATO countries. Most of the research has been conducted in the US, focused on addressing uncertainties in management practices. Development of objective diagnostic tests should be a top priority to facilitate both diagnosis and prognosis, thereby improving management. It is expected that blast exposure and blunt force trauma to the head will continue to be a potential source of injury during future conflicts. An improved understanding of the effects of blast exposure will better enable military medical providers to manage mTBI cases and develop optimal protective measures. Without the immediate pressures that come with a high operational tempo, the time is right to look back at lessons learned, make full use of available data, and modify mitigation strategies with both available evidence and new evidence as it comes to light. Toward that end, leveraging our cooperation with the civilian medical community is critical because the military experience over the past 10 years has led to a renewed interest in many similar issues pertaining to mTBI in the civilian world. Such cross-fertilization of knowledge will undoubtedly benefit all. This paper highlights similarities and differences in approach to mTBI patient care in NATO and partner countries and provides a summary of and lessons learned from a NATO lecture series on the topic of mTBI, demonstrating utility of having patients present their experiences to a medical audience, linking practical clinical care to policy approaches.

Neuroimaging and Psychometric Assessment of Mild Cognitive Impairment After Traumatic Brain Injury

Traumatic brain injury (TBI) can be serious partly due to the challenges of assessing and treating its neurocognitive and affective sequelae. The effects of a single TBI may persist for years and can limit patients’ activities due to somatic complaints (headaches, vertigo, sleep disturbances, nausea, light or sound sensitivity), affective sequelae (post-traumatic depressive symptoms, anxiety, irritability, emotional instability) and mild cognitive impairment (MCI, including social cognition disturbances, attention deficits, information processing speed decreases, memory degradation and executive dysfunction). Despite a growing amount of research, study comparison and knowledge synthesis in this field are problematic due to TBI heterogeneity and factors like injury mechanism, age at or time since injury. The relative lack of standardization in neuropsychological assessment strategies for quantifying sequelae adds to these challenges, and the proper administration of neuropsychological testing relative to the relationship between TBI, MCI and neuroimaging has not been reviewed satisfactorily. Social cognition impairments after TBI (e.g., disturbed emotion recognition, theory of mind impairment, altered self-awareness) and their neuroimaging correlates have not been explored thoroughly. This review consolidates recent findings on the cognitive and affective consequences of TBI in relation to neuropsychological testing strategies, to neurobiological and neuroimaging correlates, and to patient age at and assessment time after injury. All cognitive domains recognized by the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) are reviewed, including social cognition, complex attention, learning and memory, executive function, language and perceptual-motor function. Affect and effort are additionally discussed owing to their relationships to cognition and to their potentially confounding effects. Our findings highlight non-negligible cognitive and affective impairments following TBI, their gravity often increasing with injury severity. Future research should study (A) language, executive and perceptual-motor function (whose evolution post-TBI remains under-explored), (B) the effects of age at and time since injury, and (C) cognitive impairment severity as a function of injury severity. Such efforts should aim to develop and standardize batteries for cognitive subdomains—rather than only domains—with high ecological validity. Additionally, they should utilize multivariate techniques like factor analysis and related methods to clarify which cognitive subdomains or components are indeed measured by standardized tests.

A preliminary analysis of biomechanics and saccadic responses for concussion

Background

Concussion is an injury that occurs in non-sporting and sporting environments. To determine improved clinical methods for identifying this injury, it is important to develop and understand how the impact event results in quantifiable differences in brain functioning—functioning that has been quantified in the past using saccadic measures. The purpose of this research was to examine the relationships between oculomotor deficits, specifically antisaccade responses, and the biomechanics of impact for a concussion.

Methods

Participants underwent a diffusion tensor imaging protocol as well as saccadic testing to determine differences in brain functioning in comparison to controls. The injury event was then reconstructed in laboratory using physical and finite element models to determine the biomechanics of the impact and brain tissue strain. Relationships between the biomechanical variables and antisaccade responses were then examined.

Results

The diffusion tensor imaging analyses found that there was a decrease in radial diffusivity and axial diffusivity found in the cerebral peduncle (p < 0.05) and cingulum hippocampus (p < 0.05), respectively. There was an increase in the axial diffusivity for the corona radiata (p < 0.05). The saccadic testing found an increase in mean latency for the concussed group (p < 0.05). The results indicated no significant relationship between mean latency, duration, amplitude and peak velocity antisaccade measures and the biomechanical variables. This may have been influenced not only by a lack of sensitivity in biomechanical variable to antisaccade responses, but also to these responses being affected by factors other than injury such as attentiveness and wakefulness.

Conclusion

While the sample of this research was small, this research suggests that to improve the understanding of the relationship between impact biomechanics and concussion, methods that can quantify the damage to brain structures through imaging, such as diffusion tensor imaging, may be more appropriate.