Utility of Pupillary Light Reflex Metrics as a Physiologic Biomarker for Adolescent Sport-Related Concussion

Investigating the Utility of the BrainEye Smartphone Eye Tracking Application and Platform in Concussion Management

BACKGROUND

Concussion is a common consequence of engaging in collision sports, with the often mild, transient nature of symptoms posing a considerable diagnostic and management challenge. This challenge is vastly magnified for athletes competing at grassroots/non-professional levels, who lack field side access to medical expertise in the assessment of a player's capacity to continue playing or need for further medical attention. The aim of this pilot study was to evaluate the utility of the BrainEye application and hardware (BrainEye platform) as a concussion screening tool, specifically determining (1) its sensitivity and specificity with respect to identifying an individual with a clinically diagnosed concussion, (2) the stability of the platform through test completion/failure rates, and (3) its usability through operator feedback and uptake/integration into concussion management protocols.

RESULTS

Using the BrainEye platform, 348 male professional Australian Rules footballers from 10 Australian Football League (AFL) clubs completed 4 simple ocular protocols (pupillary light reflex, PLR; smooth pursuit eye movements, SMP; near-point convergence, NPC; horizontal gaze nystagmus, HGN) at baseline, prior to the onset of the 2022 AFL season, and following the clinical diagnosis of concussion throughout the season during a game/training/practice (n = 11 players immediately following a concussive event, and on 14 occasions 2-7 days following a concussive event). Although club participation and protocol adherence rates were suboptimal, with clubs citing COVID-19 restrictions and cumbersome hardware set-up as primary reasons for non-participation/missing data, a BrainEye score that derived from an algorithm combining smooth pursuit and pupillary light reflex measures, achieved 100% sensitivity relative to clinical judgement, in identifying all instances of clinically diagnosed concussion, and 85% specificity.

CONCLUSIONS

Collectively, the results of this study suggest that by removing the requirement for add-on hardware and providing a smartphone-only option with direct feedback on performance to the user, the BrainEye application may provide a useful screening tool for sport-related concussion.

Assessing the Inter-Rater and Inter-Trial Reliability of the NeurOptics Pupillary Light Response-3000 Pupillometer

Background

An automated pupillometer is a handheld device used to stimulate the pupillary light response (PLR) and track the entirety of the response from constriction to dilation. Pupillometers provide objective data that clinicians can use to identify and assess brain injury. The validity of these devices has been previously established; however, the inter-rater and inter-trial reliability are unknown.

Purpose

The purpose of this study was to assess the inter-rater and inter-trial reliability of the NeurOptics PLR-3000 pupillometer device in measuring pupil size changes, constriction velocities, and dilation velocities. The authors hypothesized that inter-rater and inter-trial reliability would have intraclass correlation coefficients (ICC) greater than or equal to 0.70 for all PLR parameters.

Study

Design: Observational, reliability study Methods: Forty-eight healthy adults (age 18-40 years) without a history of neurological injury, optical surgery, or cognitive impairment participated. Two independent raters used the NeurOptics PLR-3000 to measure PLR parameters in the left and right eyes of each subject. Data for the average and individual trials of each PLR parameter were used to determine inter-rater and inter-trial reliability, respectively. Inter-rater and inter-trial reliability was evaluated using descriptive statistics, ICC, the standard error of measurement, Bland-Altman plots, and the minimal detectable change.

Results

Seven out of eight NeurOptics 3000-PLR parameters demonstrated moderate-to-excellent inter-rater (ICC range 0.72-0.96) and good-to-excellent inter-trial reliability (ICC range 0.76-0.98). The 75% recovery time parameter exhibited moderate inter-rater (ICC range 0.64-0.67) and poor-to-moderate inter-trial (ICC range 0.41-0.65) reliability.

Conclusion

The NeurOptics 3000-PLR demonstrated acceptable reliability in measuring initial and end pupil size, constriction and dilation velocity, and latency to change between different users and trials. However, the device exhibited unacceptable reliability when measuring the time to 75% pupil size recovery. The device can be used in detecting and monitoring brain injury but should be limited to reliable measures only.

Quantitative Pupillometry Predicts Return to Play and Tracks the Clinical Evolution of Mild Traumatic Brain Injury in US Military Academy Cadets: A Military Traumatic Brain Injury Initiative Study

BACKGROUND AND OBJECTIVES

The objective of this study was to determine the utility of the pupillary light reflex use as a biomarker of mild traumatic brain injury (mTBI).

METHODS

This prospective cohort study was conducted at The US Military Academy at West Point. Cadets underwent a standard battery of tests including Balance Error Scoring System, Sports Concussion Assessment Tool Fifth Edition Symptom Survey, Standard Assessment of Concussion, and measure of pupillary responses. Cadets who sustained an mTBI during training events or sports were evaluated with the same battery of tests and pupillometry within 48 hours of the injury (T1), at the initiation of a graded return to activity protocol (T2), and at unrestricted return to activity (T3).

RESULTS

Pupillary light reflex metrics were obtained in 1300 cadets at baseline. During the study period, 68 cadets sustained mTBIs. At T1 (<48 hours), cadets manifested significant postconcussion symptoms (Sports Concussion Assessment Tool Fifth Edition P < .001), and they had decreased cognitive performance (Standardized Assessment of Concussion P < .001) and higher balance error scores (Balance Error Scoring System P < .001) in comparison with their baseline assessment (T0). The clinical parameters showed normalization at time points T2 and T3. The pupillary responses demonstrated a pattern of significant change that returned to normal for several measures, including the difference between the constricted and initial pupillary diameter (T1 P < .001, T2 P < .05), dilation velocity (T1 P < .01, T2 P < .001), and percent of pupillary constriction (T1 P < .05). In addition, a combination of dilation velocity and maximum constriction velocity demonstrates moderate prediction ability regarding who can return to duty before or after 21 days (area under the curve = 0.71, 95% CI [0.56-0.86]).

CONCLUSION

This study's findings indicate that quantitative pupillometry has the potential to assist with injury identification and prediction of symptom severity and duration.

Smartphone-Based Pupillometry Using Machine Learning for the Diagnosis of Sports-Related Concussion

Background: Quantitative pupillometry has been proposed as an objective means to diagnose acute sports-related concussion (SRC). Objective: To assess the diagnostic accuracy of a smartphone-based quantitative pupillometer in the acute diagnosis of SRC. Methods: Division I college football players had baseline pupillometry including pupillary light reflex (PLR) parameters of maximum resting diameter, minimum diameter after light stimulus, percent change in pupil diameter, latency of pupil constriction onset, mean constriction velocity, maximum constriction velocity, and mean dilation velocity using a smartphone-based app. When an SRC occurred, athletes had the smartphone pupillometry repeated as part of their concussion testing. All combinations of the seven PLR parameters were tested in machine learning binary classification models to determine the optimal combination for differentiating between non-concussed and concussed athletes. Results: 93 football athletes underwent baseline pupillometry testing. Among these athletes, 11 suffered future SRC and had pupillometry recordings repeated at the time of diagnosis. In the machine learning pupillometry analysis that used the synthetic minority oversampling technique to account for the significant class imbalance in our dataset, the best-performing model was a random forest algorithm with the combination of latency, maximum diameter, minimum diameter, mean constriction velocity, and maximum constriction velocity PLR parameters as feature inputs. This model produced 91% overall accuracy, 98% sensitivity, 84.2% specificity, area under the curve (AUC) of 0.91, and an F1 score of 91.6% in differentiating between baseline and SRC recordings. In the machine learning analysis prior to oversampling of our imbalanced dataset, the best-performing model was k-nearest neighbors using latency, maximum diameter, maximum constriction velocity, and mean dilation velocity to produce 82% accuracy, 40% sensitivity, 87% specificity, AUC of 0.64, and F1 score of 24%. Conclusions: Smartphone pupillometry in combination with machine learning may provide fast and objective SRC diagnosis in football athletes.

Age-Related Variations in Clinical Profiles for Children with Sports- and Recreation-Related Concussions

OBJECTIVE

The purpose was to examine clinical profiles in concussed children aged 5-9 and 10-12 years and compare them with those of adolescents >12 years.

METHODS

This study included patients aged 5-18 years presenting to a specialty care concussion program with a sports- and recreation-related (SRR) concussion ≤28 days postinjury. Demographics, injury mechanisms, symptoms, and clinical features were assessed. Chi-squared tests, one-way ANOVA, and Kruskal-Wallis were used for comparisons across age groups.

RESULTS

A total of 3280 patients with SRR concussion were included: 5.0% were 5-9 years, 18.4% were 10-12 years, and 76.6% were 13-18 years. Younger age groups had more males than females (5-9 years: 70.7% vs. 29.3%) and more commonly sustained their injury during limited- (28.7%), and non-contact (7.9%) activities compared to other age groups (p < 0.01). Younger children presented less symptoms frequently (p ≤ 0.042), but higher symptom severity in somatic and emotional domains (p ≤ 0.016). Fewer 5-9-year-olds reported changes in school (25.6%), sleep (46.3%), and daily habits (40.9%) than adolescents (p < 0.001).

CONCLUSIONS

Among SRR-concussed children and adolescents, we found significant age-related variations in demographics, injury mechanism, symptoms, and clinical features. Recognizing these unique features in younger children may facilitate targeted management and treatment.

Clinical Utility of Ocular Assessments in Sport-Related Concussion: A Scoping Review

Background/objectives: Ocular tools and technologies may be used in the diagnosis of sport-related concussions (SRCs), but their clinical utility can vary. The following study aimed to review the literature pertaining to the reliability and diagnostic accuracy of such assessments. Methods: The preferred reporting items for systematic reviews and meta-analysis (PRISMA) extension for scoping reviews was adhered to. Reference standard reliability (RSR ≥ 0.75) and diagnostic accuracy (RSDA ≥ 0.80) were implemented to aid interpretation. Results: In total, 5223 articles were screened using the PCC acronym (Population, Concept, Context) with 74 included in the final analysis. Assessments included the King-Devick (KD) (n = 34), vestibular-ocular motor screening (VOMs) and/or near point of convergence (NPC) (n = 25), and various alternative tools and technologies (n = 20). The KD met RSR, but RSDA beyond amateur sport was limited. NPC met RSR but did not have RSDA to identify SRCs. The VOMs had conflicting RSR for total score and did not meet RSR in its individual tests. The VOMs total score did perform well in RSDA for SRCs. No alternative tool or technology met both RSR and RSDA. Conclusion: Ocular tools are useful, rapid screening tools but should remain within a multi-modal assessment for SRCs at this time.

Utility of iPhone-Based Pupillometry in Comparing Pupillary Dynamics Between Sport Concussed Subjects With Photosensitivity and Healthy Controls

BACKGROUND

To compare the pupillary dynamics using an iPhone-based pupillometry technique in subjects with sports concussion with photosensitivity and aged-matched controls.

METHODS

Fifty subjects with sports concussion were compared with 50 aged-matched healthy controls. Athletes with persistent concussive symptoms for 1 year or more after the initial injury were included. All the subjects underwent a Post-Concussion Symptom Scale (PCSS) administration followed by pupillary dynamics measurement using an iPhone-based application (Reflex-Pro PLR analyzer).

RESULTS

The mean age was 27 ± 4 years in the concussed group and 26 ± 5 years in the control group. In subjects with concussion, there was a significant decrease in the mean of the following parameters: average constriction speed (1.10 ± 0.15 vs 1.78 ± 0.12 mm/s; P < 0.001), maximum constriction speed (2.05 ± 0.26 vs 3.84 ± 0.28 mm/s; P < 0.001), average diameter (3.64 ± 0.12 vs 0.36 ± 0.05 mm; P < 0.001), maximum diameter (4.75 ± 0.17 vs 5.23 ± 0.16 mm; P < 0.001), and minimum diameter (2.75 ± 0.17 vs 3.64 ± 0.11 mm; P < 0.001). An increase in the following parameters was noted in concussion vs age-matched controls: dilation release amplitude (0.54 ± 0.96 vs 0.36 ± 0.05 mm; P < 0.001) and latency (0.25 ± 0.05 vs 0.21 ± 0.02 s; P < 0.001). Subjects with concussion with photosensitivity exhibited increased dilation release amplitudes ( P < 0.001).

CONCLUSIONS

Individuals with sport concussion had impairment in pupillary constriction velocities, latency, and diameter in more than 1 year after concussion. The increase in dilation release amplitude among subjects with concussion might serve as a biomarker in diagnosing the underlying symptom of photosensitivity. The iPhone-based pupillometry could serve as a convenient and diagnostic tool in diagnosing these symptoms.

Quantitative Pupillometry: Clinical Applications for the Internist

From the time of Galen, examination of the pupillary light reflex has been a standard of care across the continuum of health care. The growing body of evidence overwhelmingly supports the use of quantitative pupillometry over subjective examination with flashlight or penlight. At current time, pupillometers have become standard of care in many hospitals across 6 continents. This review paper provides an overview and rationale for pupillometer use and highlights literature supporting pupillometer-derived measures of the pupillary light reflex in both neurological and non-neurological patients across the health care continuum.

Normative Values for Pupillary Light Reflex Metrics Among Healthy Service Academy Cadets

INTRODUCTION

Assessments of the pupil's response to light have long been an integral part of neurologic examinations. More recently, the pupillary light reflex (PLR) has shown promise as a potential biomarker for the diagnosis of mild traumatic brain injury. However, to date, few large-scale normative data are available for comparison and reference, particularly, in military service members. The purpose of this study was to report normative values for eight PLR measurements among healthy service academy cadets based on sex, age, sleep, race, ethnicity, anisocoria, and concussion history.

METHODS

Freshmen entering a U.S. Service Academy completed a quantitative pupillometric assessment in conjunction with baseline concussion testing. PLR measurements were conducted using a Neuroptics PLR-3000 with a 121 µW light stimulus. The device measured maximum and minimum pupil diameter (mm), latency (time to maximum pupil constriction post-light stimulus [s]), peak and average constriction velocity (mm/s), average dilation velocity (mm/s), percentage pupil constriction, and T75 (time for pupil re-dilation from minimum pupil diameter to 75% maximum diameter [s]). During baseline testing, cadets also reported concussion history (yes and no) and hours slept the night before (<5.5 and ≥5.5). Normative values for each PLR measurement were calculated as mean ± SD, percentiles, and interquartile range. Mann-Whitney U tests were used to assess differences based on sex, concussion history, ethnicity, and hours slept for each PLR measurement. Kruskall-Wallis testing was used to assess differences based on age, race, and anisocoria. Alpha was set at .05 and nonparametric effect sizes (r) were calculated for statistically significant results. Effect sizes were interpreted as no effect (r < .1), small (r ≥.1-<.3), medium (r ≥.3-<.5), or large (r ≥ .5). All procedures were reviewed and approved by the local institutional review board and the U.S. Army Human Research Protection Office before the study was conducted. Each subject provided informed consent to participate in the study before data collection.

RESULTS

Of the 1,197 participants baselined, 514 cadets (131 female; 18.91 ± 0.96 years) consented and completed a valid baseline pupillometric assessment. Eighty participants reported at least one previous concussion and participants reported an average of 5.88 ± 1.63 h slept the previous night. Mann-Whitney U results suggest females had larger initial (z = -3.240; P = .001; r = .10) and end pupil diameter (z = -3.080; P = .002; r = .10), slower average dilation velocity (z = 3.254; P = .001; r = .11) and faster T75 values (z = -3.342; P = .001; r = .11). Age, sleep, and race stratified by sex, also displayed a significant impact on specific PLR metrics with effect sizes ranging from small to medium, while ethnicity, anisocoria, and concussion history did not display an impact on PLR metrics.

CONCLUSION

This study provides the largest population-specific normative values for eight PLR measurements. Initial and end pupil diameter, dilation velocity, and the T75 metrics differed by sex; however, these differences may not be clinically significant as small effect size was detected for all metrics. Sex, age, sleep, and race may impact specific PLR metrics and are worth consideration when performing PLR assessments for mild traumatic brain injury management.

Head Injury Treatment With Healthy and Advanced Dietary Supplements: A Pilot Randomized Controlled Trial of the Tolerability, Safety, and Efficacy of Branched Chain Amino Acids in the Treatment of Concussion in Adolescents and Young Adults

Concussion is a common injury in the adolescent and young adult populations. Although branched chain amino acid (BCAA) supplementation has shown improvements in neurocognitive and sleep function in pre-clinical animal models of mild-to-moderate traumatic brain injury (TBI), to date, no studies have been performed evaluating the efficacy of BCAAs in concussed adolescents and young adults. The goal of this pilot trial was to determine the efficacy, tolerability, and safety of varied doses of oral BCAA supplementation in a group of concussed adolescents and young adults. The study was conducted as a pilot, double-blind, randomized controlled trial of participants ages 11-34 presenting with concussion to outpatient clinics (sports medicine and primary care), urgent care, and emergency departments of a tertiary care pediatric children's hospital and an urban tertiary care adult hospital, between June 24, 2014 and December 5, 2020. Participants were randomized to one of five study arms (placebo and 15 g, 30 g, 45 g, and 54 g BCAA treatment daily) and followed for 21 days after enrollment. Outcome measures included daily computerized neurocognitive tests (processing speed, the a priori primary outcome; and attention, visual learning, and working memory), symptom score, physical and cognitive activity, sleep/wake alterations, treatment compliance, and adverse events. In total, 42 participants were randomized, 38 of whom provided analyzable data. We found no difference in our primary outcome of processing speed between the arms; however, there was a significant reduction in total symptom score (decrease of 4.4 points on a 0-54 scale for every 500 g of study drug consumed, p value for trend = 0.0036, [uncorrected]) and return to physical activity (increase of 0.503 points on a 0-5 scale for every 500 g of study drug consumed, p value for trend = 0.005 [uncorrected]). There were no serious adverse events. Eight of 38 participants reported a mild (not interfering with daily activity) or moderate (limitation of daily activity) adverse event; there were no differences in adverse events by arm, with only two reported mild adverse events (both gastrointestinal) in the highest (45 g and 54 g) BCAA arms. Although limited by slow enrollment, small sample size, and missing data, this study provides the first demonstration of efficacy, as well as safety and tolerability, of BCAAs in concussed adolescents and young adults; specifically, a dose-response effect in reducing concussion symptoms and a return to baseline physical activity in those treated with higher total doses of BCAAs. These findings provide important preliminary data to inform a larger trial of BCAA therapy to expedite concussion recovery.

Response Rate Patterns in Adolescents With Concussion Using Mobile Health and Remote Patient Monitoring: Observational Study

Background

A concussion is a common adolescent injury that can result in a constellation of symptoms, negatively affecting academic performance, neurobiological development, and quality of life. Mobile health (mHealth) technologies, such as apps for patients to report symptoms or wearables to measure physiological metrics like heart rate, have been shown to be promising in health maintenance. However, there is limited evidence about mHealth engagement in adolescents with a concussion during their recovery course.

Objective

This study aims to determine the response rate and response rate patterns in concussed adolescents reporting their daily symptoms through mHealth technology. It will also examine the effect of time-, demographic-, and injury-related characteristics on response rate patterns.

Methods

Participants aged between 11-18 years (median days since injury at enrollment: 11 days) were recruited from the concussion program of a tertiary care academic medical center and a suburban school's athletic teams. They were asked to report their daily symptoms using a mobile app. Participants were prompted to complete the Post-Concussion Symptom Inventory (PCSI) 3 times (ie, morning, afternoon, and evening) per day for 4 weeks following enrollment. The primary outcome was the response rate pattern over time (by day since initial app use and the day since injury). Time-, demographic-, and injury-related differences in reporting behaviors were compared using Mann Whitney U tests.

Results

A total of 56 participants were enrolled (mean age 15.3, SD 1.9 years; n=32, 57% female). The median response rate across all days of app use in the evening was 37.0% (IQR 27.2%-46.4%), which was significantly higher than the morning (21.2%, IQR 15.6%-30.5%) or afternoon (26.4%, IQR 21.1%-31.5%; P<.001). The median daily response was significantly different by sex (female: 53.8%, IQR 46.2%-64.2% vs male: 42.0%, IQR 28.6%-51.1%; P=.003), days since injury to app use (participants starting to use the app >7 days since injury: 54.1%, IQR 47.4%-62.2% vs starting to use the app ≤7 days since injury: 38.0%, IQR 26.0%-53.3%; P=.002), and concussion history (participants with a history of at least one prior concussion: 57.4%, IQR 44.5%-70.5% vs participants without concussion history: 42.3%, IQR 36.8%-53.5%; P=.03). There were no significant differences by age. Differences by injury mechanism (sports- and recreation-related injury: 39.6%, IQR 36.1%-50.4% vs non-sports- or recreation-related injury: 30.6%, IQR 20.0%-42.9%; P=.04) and initial symptom burden (PCSI scores greater than the median score of 47: 40.9%, IQR 35.2%-53.8% vs PCSI scores less than or equal to the median score: 31.9%, IQR 24.6%-40.6%; P=.04) were evident in the evening response rates; however, daily rates were not statistically different.

Conclusions

Evening may be the optimal time to prompt for daily concussion symptom assessment among concussed adolescents compared with morning or afternoon. Multiple demographic- and injury-related characteristics were associated with higher daily response rates, including for female participants, those with more than 1 week from injury to beginning mHealth monitoring, and those with a history of at least one previous concussion. Future studies may consider incentive strategies or adaptive digital concussion assessments to increase response rates in populations with low engagement.

Pupillary dynamics, accommodation and vergence in concussion

Concussion, which is usually associated with head injuries, has received considerable attention in recent years because of its possible long-term cognitive and visual consequences. The review summarised the mild traumatic brain injury literature. Pupillary dynamics, which are primarily mediated by the autonomic nervous system, play an important function in regulating the amount of light entering the eye, but they can be dramatically impacted after a concussion. This can result in aberrant pupillary responses, which may have ramifications for light sensitivity, a common post-concussion symptom. In concussed individuals, accommodation and vergence - the visual processes responsible for focusing on near and distant objects - might be interrupted, potentially leading to fuzzy vision, eyestrain, and difficulty with tasks that require precise visual coordination. Understanding the delicate interplay between these three components of vision in the setting of concussions is critical for creating more targeted diagnostic and rehabilitative techniques, ultimately enhancing the quality of life for those who have had head injuries.

Evaluation of Quantitative Pupillometry in Acute Postinjury Pediatric Concussion

BACKGROUND

Although millions of children sustain concussions each year, a rapid and objective test for concussion has remained elusive. The aim of this study was to investigate quantitative pupillometry in pediatric patients in the acute, postinjury setting.

METHODS

This was a prospective case-control study of concussed patients presenting to the emergency department within 72 hours of injury. Pupillary measurements were gathered using NeurOptics' PLR 3000; evaluation included a symptom checklist and neurocognitive assessment. Data were analyzed using descriptive statistics and regression models.

RESULTS

A total of 126 participants were enrolled. One significant difference in pupillometry between concussed and control participants was found: left minimum pupil diameter in 12- to 18 year-olds (P = 0.02). Models demonstrating odds of a concussion revealed significant associations for time to 75% recovery (T75) of the left pupil in five- to 11-year-olds and average dilation velocity of the left pupil in 12- to 18-year-olds (P = 0.03 and 0.02 respectively). Models predicting symptom improvement showed one significant association: percent change of the right pupil in five-to-11-year-olds (P = 0.02). Models predicting neurocognitive improvement in 12- to 18-year-olds demonstrated significant association in T75 in the left pupil for visual memory, visual motor processing speed, and reaction time (P = 0.002, P = 0.04, P = 0.04).

CONCLUSIONS

The limited statistically significant associations found in this study suggest that pupillometry may not be useful in pediatrics in the acute postinjury setting for either the diagnosis of concussion or to stratify risk for prolonged recovery.

The Role of Concussion History and Biological Sex on Pupillary Light Reflex Metrics in Adolescent Rugby Players: A Cross-Sectional Study

Background: Concussion examination is based primarily on clinical evaluation and symptomatic reporting. Pupillary light reflex (PLR) metrics may provide an objective physiological marker to inform concussion diagnosis and recovery, but few studies have assessed PLR, and normative data are lacking, particularly for adolescents. Aim: To capture PLR data in adolescent rugby players and examine the effects of concussion history and biological sex. Design: Cross-sectional. Methods: Male and female adolescent rugby union players aged 16 to 18 years were recruited at the start of the 2022-2023 playing season. PLR was recorded using a handheld pupillometer which provided seven different metrics relating to pupil diameter, constriction/dilation latency, and velocity. Data were analysed using a series of 2 × 2 ANOVAs to examine the main effects of independent variables: biological sex, concussion history, and their interactions, using adjusted p-values (p < 0.05). Results: 149 participants (75% male) were included. A total of 42% reported at least one previous concussion. Most metrics were unaffected by the independent variables. There were however significant main effects for concussion history (F = 4.11 (1); p = 0.05) and sex (F = 5.42 (1); p = 0.02) in end pupil diameters, and a main effect for sex in initial pupil diameters (F = 4.45 (1); p = 0.04). Although no significant interaction effects were found, on average, females with a concussion history presented with greater pupillary diameters and velocity metrics, with many pairwise comparisons showing large effects (SMD > 0.8). Conclusions: Pupillary diameters in adolescent athletes were significantly affected by concussion history and sex. The most extreme PLR metrics were recorded in females with a history of concussion (higher pupillary diameters and velocities). This highlights the importance of establishing baseline PLR metrics prior to interpretation of the PLR post-concussion. Long-standing PLR abnormalities post-concussion may reflect ongoing autonomic nervous system dysfunction. This warrants further investigation in longitudinal studies.

The Role of Automated Infrared Pupillometry in Traumatic Brain Injury: A Narrative Review

Pupillometry, an integral component of neurological examination, serves to evaluate both pupil size and reactivity. The conventional manual assessment exhibits inherent limitations, thereby necessitating the development of portable automated infrared pupillometers (PAIPs). Leveraging infrared technology, these devices provide an objective assessment, proving valuable in the context of brain injury for the detection of neuro-worsening and the facilitation of patient monitoring. In cases of mild brain trauma particularly, traditional methods face constraints. Conversely, in severe brain trauma scenarios, PAIPs contribute to neuro-prognostication and non-invasive neuromonitoring. Parameters derived from PAIPs exhibit correlations with changes in intracranial pressure. It is important to acknowledge, however, that PAIPs cannot replace invasive intracranial pressure monitoring while their widespread adoption awaits robust support from clinical studies. Ongoing research endeavors delve into the role of PAIPs in managing critical neuro-worsening in brain trauma patients, underscoring the non-invasive monitoring advantages while emphasizing the imperative for further clinical validation. Future advancements in this domain encompass sophisticated pupillary assessment tools and the integration of smartphone applications, emblematic of a continually evolving landscape.

The Variability of Recovery From Pediatric Concussion Using Multimodal Clinical Definitions

BACKGROUND

While concussions are common pediatric injuries, a lack of agreement on a standard definition of recovery creates multiple challenges for clinicians and researchers alike.

HYPOTHESIS

The percentage of concussed youth deemed recovered as part of a prospective cohort study will differ depending on the recovery definition.

STUDY DESIGN

Descriptive epidemiologic study of a prospectively enrolled observational cohort.

LEVEL OF EVIDENCE

Level 3.

METHODS

Participants aged 11 to 18 years were enrolled from the concussion program of a tertiary care academic center. Data were collected from initial and follow-up clinical visits ≤12 weeks from injury. A total of 10 recovery definitions were assessed: (1) cleared to full return to sports; (2) return to full school; (3) self-reported return to normal; (4) self-reported full return to school; (5) self-reported full return to exercise; (6) symptom return to preinjury state; (7) complete symptom resolution; (8) symptoms below standardized threshold; (9) no abnormal visio-vestibular examination (VVE) elements; and (10) ≤1 abnormal VVE assessments.

RESULTS

In total, 174 participants were enrolled. By week 4, 63.8% met at least 1 recovery definition versus 78.2% by week 8 versus 88.5% by week 12. For individual measures of recovery at week 4, percent recovered ranged from 5% by self-reported full return to exercise to 45% for ≤1 VVE abnormality (similar trends at 8 and 12 weeks).

CONCLUSION

There is wide variability in the proportion of youth considered recovered at various points following concussion depending on the definition of recovery, with higher proportions using physiologic examination-based measures and lower proportions using patient-reported measures.

CLINICAL RELEVANCE

These results further emphasize the need for a multimodal assessment of recovery by clinicians as a single and standardized definition of recovery that captures the broad impact of concussion on a given patient continues to be elusive.

Pupillometry as a new window to player fatigue? A glimpse inside the eyes of a Euro Cup Women's Basketball team

A rapidly emerging area of interest in high-pressure environments is that of pupillometry, where handheld quantitative infrared pupillometers (HQIPs) are able to track psycho-physiological fatigue in a fast, objective, valid, reliable, and non-invasive manner. However, the application of HQIPs in the context of athlete monitoring is yet to be determined. Therefore, the main aim of this pilot study was to examine the potential usefulness of a HQIP to monitor game-induced fatigue inside a professional female basketball setting by determining its (1) test-retest repeatability, (2) relationship with other biomarkers of game-induced fatigue, and (3) time-course from rested to fatigued states. A non-ophthalmologic practitioner performed a standardized Pupil Light Reflex (PLR) test using a medically graded HQIP among 9 professional female basketball players (2020-2021 Euro Cup) at baseline, 24-h pre-game (GD-1), 24-h post-game (GD+1) and 48-h post-game (GD+2). This was repeated over four subsequent games, equalling a total of 351 observations per eye. Two out of seven pupillometrics displayed good ICCs (0.95-0.99) (MinD and MaxD). Strong significant relationships were found between MaxD, MinD, and all registered biomarkers of game-induced fatigue (r = 0.69-0.82, p < 0.05), as well as between CV, MCV, and cognitive, lower-extremity muscle, and physiological fatigue markers (r = 0.74-0.76, p < 0.05). Three pupillometrics were able to detect a significant difference between rested and fatigued states. In particular, PC (right) (F = 5.173, η2 = 0.115 p = 0.028) and MCV (right) (F = 3.976, η2 = 0.090 p = 0.049) significantly decreased from baseline to GD+2, and LAT (left) (F = 4.023, η2 = 0.109 p = 0.009) significantly increased from GD-1 to GD+2. HQIPs have opened a new window of opportunity for monitoring game-induced fatigue in professional female basketball players. However, future research initiatives across larger and heterogenous samples, and longer investigation periods, are required to expand upon these preliminary findings.

The Ability of Vestibular and Oculomotor Screenings to Predict Recovery in Patients After Concussion: A Systematic Review of the Literature

OBJECTIVE

The objective of this systematic review was to investigate if a positive vestibular or oculomotor screening is predictive of recovery in patients after concussion.

DATA SOURCES

Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to search through PubMed, Ovid MEDLINE, SPORTDiscus, and the Cochrane Central Register of Controlled Trials (CENTRAL) and hand searches of included articles.

STUDY SELECTION

Two authors evaluated all articles for inclusion and assessed their quality using the Mixed Methods Assessment Tool.

DATA EXTRACTION

After quality assessment was completed, the authors extracted recovery time, vestibular or ocular assessment results, study population demographics, number of participants, inclusion and exclusion criteria, symptom scores, and any other outcomes of assessments reported in the included studies.

DATA SYNTHESIS

Data were critically analyzed by 2 of the authors and categorized into tables regarding the ability of researchers of each article to answer the research question. Many patients who have vision, vestibular, or oculomotor dysfunction appear to have longer recovery times than patients who do not.

CONCLUSIONS

Researchers routinely reported that vestibular and oculomotor screenings are prognostic of time to recovery. Specifically, a positive Vestibular Ocular Motor Screening test appears to consistently predict longer recovery.

Autonomic nervous system dysfunction in pediatric sport-related concussion: a systematic review

Objective

To identify, appraise and synthesize the evidence of autonomic nervous system (ANS) dysfunction following sport-related concussion in pediatric populations.

Methods

A literature search was conducted using MEDLINE (Ovid), SportDiscus (EBSCO), CINAHL (EBSCO), EMBASE (Ovid) and PsycINFO (Ovid). Studies were selected and appraised using the Joanna Briggs Institute (JBI) critical appraisal tools. Data was extracted from the included studies and qualitatively synthesized.

Results

Eleven studies were included in the synthesis. There was variability in the methods used to measure ANS function between studies, and sample populations and time to assessment following concussion varied considerably. There was also variability in the direction of change of ANS function between some studies.

Conclusion

This systematic review identifies that concussion is associated with dysregulation of ANS function in pediatric athletes. We identified some weaknesses in the extant literature which may be due to existing logistical and financial barriers to implementing valid ANS measurements in clinical and sports settings.

Pupillary Light Reflex and Multimodal Imaging in Patients With Central Serous Chorioretinopathy

Purpose

The purpose of this study was to investigate and compare the corresponding alterations of the pupillary response between acute and chronic central serous chorioretinopathy (CSC) and between different disease categories.

Methods

We recruited patients with unilateral acute and chronic CSC. An eye tracker was applied to determine the pupillary light reflex (PLR) and evaluate the following PLR metrics in healthy eyes: pupil diameter, diameter changes, including relative constriction amplitude (AMP%), and re-dilation ratio (D1%). Baseline optical coherence tomography (OCT), and fluorescein and indocyanine green angiography (FA/ICGA) were performed to analyze the relationship between pupillary response and retinal/choroidal architecture.

Results

In total, 52 patients were enrolled, including 25 with acute CSC and 27 with chronic CSC. Compared to the chronic CSC group, the acute CSC group displayed a significantly larger baseline pupil diameter (BPD; of 5.51 mm, P = 0.015), lower AMP% (34.40%, P = 0.004), and higher D1% (93.01%, P = 0.002), indicating sympathetic overactivity. On OCT, the total macular volume was positively correlated with the D1% (r = 0.48, P = 0.005) and negatively with AMP (r = -0.47, P = 0.007). On ICGA, the intense choroidal vascular hyperpermeability (CVH) group displayed a greater BPD than the nonintense CVH group. Additionally, 9 cases with later recurrent episodes following therapy showed a lower AMP% and higher D1% than the nonrecurrent group.

Conclusions

The PLR revealed sympathetic excitation in patients with acute CSC. The stronger D1% was significantly associated with greater total macular volume, and it may be a potential biomarker for predicting the later recurrence of CSC.

Validation of a Smartphone Pupillometry Application in Diagnosing Severe Traumatic Brain Injury

The pupillary light reflex (PLR) is an important biomarker for the detection and management of traumatic brain injury (TBI). We investigated the performance of PupilScreen, a smartphone-based pupillometry app, in classifying healthy control subjects and subjects with severe TBI in comparison to the current gold standard NeurOptics pupillometer (NPi-200 model with proprietary Neurological Pupil Index [NPi] TBI severity score). A total of 230 PLR video recordings taken using both the PupilScreen smartphone pupillometer and NeurOptics handheld device (NPi-200) pupillometer were collected from 33 subjects with severe TBI (sTBI) and 132 subjects who were healthy without self-reported neurological disease. Severe TBI status was determined by Glasgow Coma Scale (GCS) at the time of recording. The proprietary NPi score was collected from the NPi-200 pupillometer for each subject. Seven PLR curve morphological parameters were collected from the PupilScreen app for each subject. A comparison via t-test and via binary classification algorithm performance using NPi scores from the NPi-200 and PLR parameter data from the PupilScreen app was completed. This was used to determine how the frequently used NPi-200 proprietary NPi TBI severity score compares to the PupilScreen app in ability to distinguish between healthy and sTBI subjects. Binary classification models for this task were trained for the diagnosis of healthy or severe TBI using logistic regression, k-nearest neighbors, support vector machine, and random forest machine learning classification models. Overall classification accuracy, sensitivity, specificity, area under the curve, and F1 score values were calculated. Median GCS was 15 for the healthy cohort and 6 (interquartile range 2) for the severe TBI cohort. Smartphone app PLR parameters as well as NPi from the digital infrared pupillometer were significantly different between healthy and severe TBI cohorts; 33% of the study cohort had dark eye colors defined as brown eyes of varying shades. Across all classification models, the top performing PLR parameter combination for classifying subjects as healthy or sTBI for PupilScreen was maximum diameter, constriction velocity, maximum constriction velocity, and dilation velocity with accuracy, sensitivity, specificity, area under the curve (AUC), and F1 score of 87%, 85.9%, 88%, 0.869, and 0.85, respectively, in a random forest model. The proprietary NPi TBI severity score demonstrated greatest AUC value, F1 score, and sensitivity of 0.648, 0.567, and 50.9% respectively using a random forest classifier and greatest overall accuracy and specificity of 67.4% and 92.4% using a logistic regression model in the same classification task on the same dataset. The PupilScreen smartphone pupillometry app demonstrated binary healthy versus severe TBI classification ability greater than that of the NPi-200 proprietary NPi TBI severity score. These results may indicate the potential benefit of future study of this PupilScreen smartphone pupillometry application in comparison to the NPi-200 digital infrared pupillometer across the broader TBI spectrum, as well as in other neurological diseases.

Precision Concussion Management: Approaches to Quantifying Head Injury Severity and Recovery

Mitigating the substantial public health impact of concussion is a particularly difficult challenge. This is partly because concussion is a highly prevalent condition, and diagnosis is predominantly symptom-based. Much of contemporary concussion management relies on symptom interpretation and accurate reporting by patients. These types of reports may be influenced by a variety of factors for each individual, such as preexisting mental health conditions, headache disorders, and sleep conditions, among other factors. This can all be contributory to non-specific and potentially misleading clinical manifestations in the aftermath of a concussion. This review aimed to conduct an examination of the existing literature on emerging approaches for objectively evaluating potential concussion, as well as to highlight current gaps in understanding where further research is necessary. Objective assessments of visual and ocular motor concussion symptoms, specialized imaging techniques, and tissue-based concentrations of specific biomarkers have all shown promise for specifically characterizing diffuse brain injuries, and will be important to the future of concussion diagnosis and management. The consolidation of these approaches into a comprehensive examination progression will be the next horizon for increased precision in concussion diagnosis and treatment.

Neurophysiological Effects of Repeated Soccer Heading in Youth

Repeated head loading in sports is associated with negative long-term brain health, and there is growing evidence of short-term neurophysiological changes after repeated soccer heading. The objective of this study was to quantify the head kinematics and effects of repetitive soccer headers in adolescents using an instrumented mouthguard. Adolescent soccer players aged 13-18 years were randomly assigned to a kicking control, frontal heading, or oblique heading group. Participants completed neurophysiological assessments at three-time points: immediately prior to, immediately after, and approximately 24 h after completing 10 headers or kicks. The suite of assessments included the Post-Concussion Symptom Inventory, visio-vestibular exam, King-Devick test, modified Clinical Test of Sensory Interaction and Balance with force plate sway measurement, pupillary light reflex, and visual evoked potential. Data were collected for 19 participants (17 male). Frontal headers resulted in significantly higher peak resultant linear acceleration (17.4 ± 0.5 g) compared to oblique headers (12.1 ± 0.4 g, p < 0.001), and oblique headers resulted in significantly higher peak resultant angular acceleration (frontal: 1147 ± 45 rad/s2, oblique: 1410 ± 65 rad/s2, p < 0.001). There were no neurophysiological deficits for either heading group or significant differences from controls at either post-heading timepoint, and therefore, a bout of repeated headers did not result in changes in the neurophysiological measures evaluated in this study. The current study provided data regarding the direction of headers with the goal to reduce the risk of repetitive head loading for adolescent athletes.

Multisystem recovery after sport-related concussion in adolescent rugby players: a prospective study protocol

INTRODUCTION

Sport-related concussion is one of the most common injuries in adolescent rugby players with evidence of prolonged recovery in some concussed athletes. Concussion is a complex pathophysiological process that can affect a variety of subsystems with multifactorial presentation. Most research on adolescents recovery after concussion focuses on neurocognitive functioning and symptom outcomes over the short term. There is a need to explore concussion recovery over time across multiple subsystems in adolescent rugby players.

METHODS AND ANALYSIS

This prospective study will use sensorimotor and oculomotor outcomes in adolescent male and female rugby players aged 16-18 years. Players will be recruited from school or club rugby teams across the province of Ulster. Baseline assessment will be undertaken at the start of the playing season and will include questionnaires, Quantified Y Balance Test and Pupillary Light Reflex. Players who sustain a concussive event will be reassessed on all outcomes at 3 days, 7 days, 14 days, 23 days, 90 days, 180 days and 365 days postconcussion. For serial outcome data, we will examine response curves for each participant and make comparisons between known groups. We will use logistic regression to explore any association between demographic variables and recovery. The strength of the predictive model will be determined using R2, p values and ORs, with 95% CIs.

ETHICS AND DISSEMINATION

Ethical approval has been granted for this study from Ulster University Research Ethics Committee (REC/14/0060). This study will be published in an open-access research journal on completion.

TRIAL REGISTRATION NUMBER

ACTRN12622000931774p.

Vision as a piece of the head trauma puzzle

Approximately half of the brain's circuits are involved in vision and control of eye movements. Therefore, visual dysfunction is a common symptom of concussion, the mildest form of traumatic brain injury (TBI). Photosensitivity, vergence dysfunction, saccadic abnormalities, and distortions in visual perception have been reported as vision-related symptoms following concussion. Impaired visual function has also been reported in populations with a lifetime history of TBI. Consequently, vision-based tools have been developed to detect and diagnose concussion in the acute setting, and characterize visual and cognitive function in those with a lifetime history of TBI. Rapid automatized naming (RAN) tasks have provided widely accessible and quantitative measures of visual-cognitive function. Laboratory-based eye tracking approaches demonstrate promise in measuring visual function and validating results from RAN tasks in patients with concussion. Optical coherence tomography (OCT) has detected neurodegeneration in patients with Alzheimer's disease and multiple sclerosis and may provide critical insight into chronic conditions related to TBI, such as traumatic encephalopathy syndrome. Here, we review the literature and discuss the future directions of vision-based assessments of concussion and conditions related to TBI.

Altered Auditory and Visual Evoked Potentials following Single and Repeated Low-Velocity Head Rotations in 4-Week-Old Swine

Auditory and visually evoked potentials (EP) have the ability to monitor cognitive changes after concussion. In the literature, decreases in EP are commonly reported; however, a subset of studies shows increased cortical activity after injury. We studied auditory and visual EP in 4-week-old female Yorkshire piglets (N = 35) divided into anesthetized sham, and animals subject to single (sRNR) and repeated (rRNR) rapid non-impact head rotations (RNR) in the sagittal direction. Two-tone auditory oddball tasks and a simple white-light visual stimulus were evaluated in piglets pre-injury, and at days 1, 4- and 7 post injury using a 32-electrode net. Traditional EP indices (N1, P2 amplitudes and latencies) were extracted, and a piglet model was used to source-localize the data to estimate brain regions related to auditory and visual processing. In comparison to each group's pre-injury baselines, auditory Eps and brain activity (but not visual activity) were decreased in sham. In contrast, sRNR had increases in N1 and P2 amplitudes from both stimuli. The rRNR group had decreased visual N1 amplitudes but faster visual P2 latencies. Auditory and visual EPs have different change trajectories after sRNR and rRNR, suggesting that injury biomechanics are an important factor to delineate neurofunctional deficits after concussion.

Role of biomarkers and emerging technologies in defining and assessing neurobiological recovery after sport-related concussion: a systematic review

OBJECTIVE

Determine the role of fluid-based biomarkers, advanced neuroimaging, genetic testing and emerging technologies in defining and assessing neurobiological recovery after sport-related concussion (SRC).

DESIGN

Systematic review.

DATA SOURCES

Searches of seven databases from 1 January 2001 through 24 March 2022 using keywords and index terms relevant to concussion, sports and neurobiological recovery. Separate reviews were conducted for studies involving neuroimaging, fluid biomarkers, genetic testing and emerging technologies. A standardised method and data extraction tool was used to document the study design, population, methodology and results. Reviewers also rated the risk of bias and quality of each study.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies were included if they: (1) were published in English; (2) represented original research; (3) involved human research; (4) pertained only to SRC; (5) included data involving neuroimaging (including electrophysiological testing), fluid biomarkers or genetic testing or other advanced technologies used to assess neurobiological recovery after SRC; (6) had a minimum of one data collection point within 6 months post-SRC; and (7) contained a minimum sample size of 10 participants.

RESULTS

A total of 205 studies met inclusion criteria, including 81 neuroimaging, 50 fluid biomarkers, 5 genetic testing, 73 advanced technologies studies (4 studies overlapped two separate domains). Numerous studies have demonstrated the ability of neuroimaging and fluid-based biomarkers to detect the acute effects of concussion and to track neurobiological recovery after injury. Recent studies have also reported on the diagnostic and prognostic performance of emerging technologies in the assessment of SRC. In sum, the available evidence reinforces the theory that physiological recovery may persist beyond clinical recovery after SRC. The potential role of genetic testing remains unclear based on limited research.

CONCLUSIONS

Advanced neuroimaging, fluid-based biomarkers, genetic testing and emerging technologies are valuable research tools for the study of SRC, but there is not sufficient evidence to recommend their use in clinical practice.

PROSPERO REGISTRATION NUMBER

CRD42020164558.

Combat Sports as a Model for Measuring the Effects of Repeated Head Impacts on Autonomic Brain Function: A Brief Report of Pilot Data

Automated pupil light reflex (PLR) is a valid indicator of dysfunctional autonomic brain function following traumatic brain injury. PLR's use in identifying disturbed autonomic brain function following repeated head impacts without outwardly visible symptoms has not yet been examined. As a combat sport featuring repeated 'sub-concussive' head impacts, mixed martial arts (MMA) sparring may provide a model to understand such changes. The aim of this pilot study was to explore which, if any, PLR variables are affected by MMA sparring. A cohort of n = 7 MMA athletes (age = 24 ± 3 years; mass = 76.5 ± 9 kg; stature = 176.4 ± 8.5 cm) took part in their regular sparring sessions (eight rounds × 3 min: 1 min recovery). PLR of both eyes was measured immediately pre- and post-sparring using a Neuroptic NPi-200. Bayesian paired samples t-tests (BF₁₀ ≥ 3) revealed decreased maximum pupil size (BF₁₀ = 3), decreased minimum pupil size (BF₁₀ = 4) and reduced PLR latency (BF₁₀ = 3) post-sparring. Anisocoria was present prior to sparring and increased post-sparring, with both eyes having different minimum and maximum pupil sizes (BF₁₀ = 3-4) and constriction velocities post-sparring (BF₁₀ = 3). These pilot data suggest repeated head impacts may cause disturbances to autonomic brain function in the absence of outwardly visible symptoms. These results provide direction for cohort-controlled studies to formally investigate the potential changes observed.

Pupillary Light Response Deficits in 4-Week-Old Piglets and Adolescent Children after Low-Velocity Head Rotations and Sports-Related Concussions

Neurological disorders and traumatic brain injury (TBI) are among the leading causes of death and disability. The pupillary light reflex (PLR) is an emerging diagnostic tool for concussion in humans. We compared PLR obtained with a commercially available pupillometer in the 4 week old piglet model of the adolescent brain subject to rapid nonimpact head rotation (RNR), and in human adolescents with and without sports-related concussion (SRC). The 95% PLR reference ranges (RR, for maximum and minimum pupil diameter, latency, and average and peak constriction velocities) were established in healthy piglets (N = 13), and response reliability was validated in nine additional healthy piglets. PLR assessments were obtained in female piglets allocated to anesthetized sham (N = 10), single (sRNR, N = 13), and repeated (rRNR, N = 14) sagittal low-velocity RNR at pre-injury, as well as days 1, 4, and 7 post injury, and evaluated against RRs. In parallel, we established human PLR RRs in healthy adolescents (both sexes, N = 167) and compared healthy PLR to values obtained <28 days from a SRC (N = 177). In piglets, maximum and minimum diameter deficits were greater in rRNR than sRNR. Alterations peaked on day 1 post sRNR and rRNR, and remained altered at day 4 and 7. In SRC adolescents, the proportion of adolescents within the RR was significantly lower for maximum pupil diameter only (85.8%). We show that PLR deficits may persist in humans and piglets after low-velocity head rotations. Differences in timing of assessment after injury, developmental response to injury, and the number and magnitude of impacts may contribute to the differences observed between species. We conclude that PLR is a feasible, quantifiable involuntary physiological metric of neurological dysfunction in pigs, as well as humans. Healthy PLR porcine and human reference ranges established can be used for neurofunctional assessments after TBI or hypoxic exposures (e.g., stroke, apnea, or cardiac arrest).

Traumatic brain injury: Mechanisms, manifestations, and visual sequelae

Traumatic brain injury (TBI) results when external physical forces impact the head with sufficient intensity to cause damage to the brain. TBI can be mild, moderate, or severe and may have long-term consequences including visual difficulties, cognitive deficits, headache, pain, sleep disturbances, and post-traumatic epilepsy. Disruption of the normal functioning of the brain leads to a cascade of effects with molecular and anatomical changes, persistent neuronal hyperexcitation, neuroinflammation, and neuronal loss. Destructive processes that occur at the cellular and molecular level lead to inflammation, oxidative stress, calcium dysregulation, and apoptosis. Vascular damage, ischemia and loss of blood brain barrier integrity contribute to destruction of brain tissue. This review focuses on the cellular damage incited during TBI and the frequently life-altering lasting effects of this destruction on vision, cognition, balance, and sleep. The wide range of visual complaints associated with TBI are addressed and repair processes where there is potential for intervention and neuronal preservation are highlighted.

Vision-Based Eye Image Classification for Ophthalmic Measurement Systems

The accuracy and the overall performances of ophthalmic instrumentation, where specific analysis of eye images is involved, can be negatively influenced by invalid or incorrect frames acquired during everyday measurements of unaware or non-collaborative human patients and non-technical operators. Therefore, in this paper, we investigate and compare the adoption of several vision-based classification algorithms belonging to different fields, i.e., Machine Learning, Deep Learning, and Expert Systems, in order to improve the performance of an ophthalmic instrument designed for the Pupillary Light Reflex measurement. To test the implemented solutions, we collected and publicly released PopEYE as one of the first datasets consisting of 15 k eye images belonging to 22 different subjects acquired through the aforementioned specialized ophthalmic device. Finally, we discuss the experimental results in terms of classification accuracy of the eye status, as well as computational load analysis, since the proposed solution is designed to be implemented in embedded boards, which have limited hardware resources in computational power and memory size.

Quantitatively characterizing reflexive responses to pitch perturbations

Background

Reflexive pitch perturbation experiments are commonly used to investigate the neural mechanisms underlying vocal motor control. In these experiments, the fundamental frequency–the acoustic correlate of pitch–of a speech signal is shifted unexpectedly and played back to the speaker via headphones in near real-time. In response to the shift, speakers increase or decrease their fundamental frequency in the direction opposing the shift so that their perceived pitch is closer to what they intended. The goal of the current work is to develop a quantitative model of responses to reflexive perturbations that can be interpreted in terms of the physiological mechanisms underlying the response and that captures both group-mean data and individual subject responses.

Methods

A model framework was established that allowed the specification of several models based on Proportional-Integral-Derivative and State-Space/Directions Into Velocities of Articulators (DIVA) model classes. The performance of 19 models was compared in fitting experimental data from two published studies. The models were evaluated in terms of their ability to capture both population-level responses and individual differences in sensorimotor control processes.

Results

A three-parameter DIVA model performed best when fitting group-mean data from both studies; this model is equivalent to a single-rate state-space model and a first-order low pass filter model. The same model also provided stable estimates of parameters across samples from individual subject data and performed among the best models to differentiate between subjects. The three parameters correspond to gains in the auditory feedback controller’s response to a perceived error, the delay of this response, and the gain of the somatosensory feedback controller’s “resistance” to this correction. Excellent fits were also obtained from a four-parameter model with an additional auditory velocity error term; this model was better able to capture multi-component reflexive responses seen in some individual subjects.

Conclusion

Our results demonstrate the stereotyped nature of an individual’s responses to pitch perturbations. Further, we identified a model that captures population responses to pitch perturbations and characterizes individual differences in a stable manner with parameters that relate to underlying motor control capabilities. Future work will evaluate the model in characterizing responses from individuals with communication disorders.

Headache and Autonomic Dysfunction: a Review

PURPOSE OF REVIEW

We explore the anatomy of the central and peripheral autonomic pathways involved in primary headache as well as the mechanisms for secondary headache associated with disorders of the autonomic nervous system. The prevalence and clinical presentation of cranial and systemic autonomic symptoms in these conditions will be discussed, with a focus on recent studies.

RECENT FINDINGS

Several small studies have utilized the relationship between headache and the autonomic nervous system to identify potential biomarkers to aid in diagnosis of migraine and cluster headache. Headache in postural orthostatic tachycardia syndrome (POTS) has also been further characterized, particularly in its association with orthostatic headache and spontaneous intracranial hypotension (SIH). This review examines the pathophysiology of primary and secondary headache disorders in the context of the autonomic nervous system. Mechanisms of headache associated with systemic autonomic disorders are also reviewed.

Eye Tracking Metrics Differences among Uninjured Adolescents and Those with Acute or Persistent Post-Concussion Symptoms

SIGNIFICANCE

Eye tracking assessments that include pupil metrics can supplement current clinical assessments of vision and autonomic dysfunction in concussed adolescents.

PURPOSE

This study aimed to explore the utility of a 220-second eye tracking assessment in distinguishing eye position, saccadic movement, and pupillary dynamics among uninjured adolescents, those with acute post-concussion symptoms (≤28 days since concussion), or those with persistent post-concussion symptoms (>28 days since concussion).

METHODS

Two hundred fifty-six eye tracking metrics across a prospective observational cohort of 180 uninjured adolescents recruited from a private suburban high school and 224 concussed adolescents, with acute or persistent symptoms, recruited from a tertiary care subspecialty concussion care program, 13 to 17 years old, from August 2017 to June 2021 were compared. Kruskal-Wallis tests were used, and Bonferroni corrections were applied to account for multiple comparisons and constructed receiver operating characteristic curves. Principal components analysis and regression models were applied to determine whether eye tracking metrics can augment clinical and demographic information in differentiating uninjured controls from concussed adolescents.

RESULTS

Two metrics of eye position were worse in those with concussion than uninjured adolescents, and only one metric was significantly different between acute cases and persistent cases. Concussed adolescents had larger left and right mean, median, minimum, and maximum pupil size than uninjured controls. Concussed adolescents had greater differences in mean, median, and variance of left and right pupil size. Twelve metrics distinguished female concussed participants from uninjured; only four were associated with concussion status in males. A logistic regression model including clinical and demographics data and transformed eye tracking metrics performed better in predicting concussion status than clinical and demographics data alone.

CONCLUSIONS

Objective eye tracking technology is capable of quickly identifying vision and pupillary disturbances after concussion, augmenting traditional clinical concussion assessments. These metrics may add to existing clinical practice for monitoring recovery in a heterogeneous adolescent concussion population.

Mobile Smartphone-Based Digital Pupillometry Curves in the Diagnosis of Traumatic Brain Injury

Objective

The pupillary light reflex (PLR) and the pupillary diameter over time (the PLR curve) is an important biomarker of neurological disease, especially in the diagnosis of traumatic brain injury (TBI). We investigated whether PLR curves generated by a novel smartphone pupillometer application could be easily and accurately interpreted to aid in the diagnosis of TBI.

Methods

A total of 120 PLR curves from 42 healthy subjects and six patients with TBI were generated by PupilScreen. Eleven clinician raters, including one group of physicians and one group of neurocritical care nurses, classified 48 randomly selected normal and abnormal PLR curves without prior training or instruction. Rater accuracy, sensitivity, specificity, and interrater reliability were calculated.

Results

Clinician raters demonstrated 93% accuracy, 94% sensitivity, 92% specificity, 92% positive predictive value, and 93% negative predictive value in identifying normal and abnormal PLR curves. There was high within-group reliability (k = 0.85) and high interrater reliability (K = 0.75).

Conclusion

The PupilScreen smartphone application-based pupillometer produced PLR curves for clinical provider interpretation that led to accurate classification of normal and abnormal PLR data. Interrater reliability was greater than previous studies of manual pupillometry. This technology may be a good alternative to the use of subjective manual penlight pupillometry or digital pupillometry.

Brain trauma impacts retinal processing: photoreceptor pathway interactions in traumatic light sensitivity

BACKGROUND

Concussion-induced light sensitivity, or traumatic photalgia, is a lifelong debilitating problem for upwards of 50% of mild traumatic brain injury (mTBI) cases, though of unknown etiology. We employed spectral analysis of electroretinographic (ERG) responses to assess retinal changes in mTBI as a function of the degree of photalgia.

METHODS

The design was a case-control study of the changes in the ERG waveform as a function of level of light sensitivity in individuals who had suffered incidents of mild traumatic brain injury. The mTBI participants were categorized into non-, mild-, and severe-photalgic groups based on their spectral nociophysical settings. Light-adapted ERG responses were recorded from each eye for 200 ms on-off stimulation of three spectral colors (R:red, G:green, and B:blue) and their sum (W:white) at the highest pain-free intensity level for each participant. The requirement of controls for testing hypersensitive individuals at lower light levels was addressed by recording a full light intensity series in the control group.

RESULTS

Both the b-wave and the photopic negative response (PhNR) were significantly reduced in the non-photalgic mTBI group relative to controls. In the photalgic groups, the main b-wave peak shifted to the timing of the rod b-wave, with reduced amplitude at the timing of the cone response.

CONCLUSION

These results suggest the interpretation that the primary etiology of the painful light sensitivity in mTBI is release of the rod pathway from cone-mediated inhibition at high light levels, causing overactivation of the rod pathway.

Accommodative and pupillary dysfunctions in concussion/mild traumatic brain injury: A Review

BACKGROUND: Visual dysfunctions are common in individuals following concussion/mild traumatic brain injury (C/mTBI). Many deficits have been uncovered in their oculomotor system, such as in the pupil and accommodation. OBJECTIVE: To describe the static and dynamic abnormalities in the pupillary and accommodative systems in those with C/mTBI. This includes both diagnostic and therapeutic aspects, with emphasis on objectively-based test findings, as well as their basic and clinical ramifications. METHODS: PubMed, Google Scholar, and Semantic Scholar databases were searched from 1980–2020, using key words of accommodation, pupil, vision therapy, vision rehabilitation, and objective testing, for peer-reviewed papers, as well as related textbooks in the area, in those with C/mTBI. RESULTS: For both systems, most static and dynamic response parameters were abnormal: they were typically reduced, slowed, delayed, and/or more variable. Most of the abnormal accommodative parameters could be significantly improved with vision therapy. CONCLUSIONS: For both systems, most response parameters were abnormal, which could explain their visual symptoms and related problems. For accommodation, the improvements following vision therapy suggest the presence of considerable visual system plasticity, even in older adults with chronic brain injury.

Relationship between Visually Evoked Effects and Concussion in Youth

Increased sensitivity to light is common after concussion. Viewing a flickering light can also produce uncomfortable somatic sensations like nausea or headache. We examined effects evoked by viewing a patterned, flickering screen in a cohort of 81 uninjured youth athletes and 84 concussed youth. We used Multiple correspondence analysis and identified two primary dimensions of variation: the presence or absence of visually evoked effects and variation in the tendency to manifest effects that localized to the eyes (e.g., eye watering) versus more generalized neurological effects (e.g., headache). Based on these two primary dimensions, we grouped participants into three categories of evoked symptomatology: no effects, eye-predominant effects, and brain-predominant effects. A similar proportion of participants reported eye-predominant effects in the uninjured (33.3%) and concussed (32.1%) groups. By contrast, participants who experienced brain-predominant effects were almost entirely from the concussed group (1.2% of uninjured, 35.7% of concussed). The presence of brain-predominant effects was associated with a higher concussion symptom burden and reduced performance on visio-vestibular tasks. Our findings indicate that the experience of negative constitutional, somatic sensations in response to a dynamic visual stimulus is a salient marker of concussion and is indicative of more severe concussion symptomatology. We speculate that differences in visually evoked effects reflect varying levels of activation of the trigeminal nociceptive system.

Leadership Lessons in Concussion Management for Team Physicians

Over the last decade, with emphasis on concussion awareness and potential long-term deficits, concussions have become a public health concern. Although common, concussions are complex in nature and often require a collaborative treatment approach across multiple disciplines. In an athletic setting, the Team Physician plays a critical leadership role in the organization, management, and provision of care for concussed athletes. However, leadership strategies for the provision of concussion care utilized by the Team Physician have not been adequately described. This manuscript intends to describe advanced planning for concussion management and highlight best practices for the provision of care for the concussed athlete, to assist the Team Physician in coordinating optimal care. Specific emphasis will be placed on outlining a concussion management protocol aligned with evidence-based best practices.

Artificial Intelligence and Mapping a New Direction in Laboratory Medicine: A Review

BACKGROUND

Modern artificial intelligence (AI) and machine learning (ML) methods are now capable of completing tasks with performance characteristics that are comparable to those of expert human operators. As a result, many areas throughout healthcare are incorporating these technologies, including in vitro diagnostics and, more broadly, laboratory medicine. However, there are limited literature reviews of the landscape, likely future, and challenges of the application of AI/ML in laboratory medicine.

CONTENT

In this review, we begin with a brief introduction to AI and its subfield of ML. The ensuing sections describe ML systems that are currently in clinical laboratory practice or are being proposed for such use in recent literature, ML systems that use laboratory data outside the clinical laboratory, challenges to the adoption of ML, and future opportunities for ML in laboratory medicine.

SUMMARY

AI and ML have and will continue to influence the practice and scope of laboratory medicine dramatically. This has been made possible by advancements in modern computing and the widespread digitization of health information. These technologies are being rapidly developed and described, but in comparison, their implementation thus far has been modest. To spur the implementation of reliable and sophisticated ML-based technologies, we need to establish best practices further and improve our information system and communication infrastructure. The participation of the clinical laboratory community is essential to ensure that laboratory data are sufficiently available and incorporated conscientiously into robust, safe, and clinically effective ML-supported clinical diagnostics.

The Pupillary Light Reflex as a Biomarker of Concussion

The size of our pupils changes continuously in response to variations in ambient light levels, a process known as the pupillary light reflex (PLR). The PLR is not a simple reflex as its function is modulated by cognitive brain function and any long-term changes in brain function secondary to injury should cause a change in the parameters of the PLR. We performed a retrospective clinical review of the PLR of our patients using the BrightLamp Reflex iPhone app. The PLR variables of latency, maximum pupil diameter (MaxPD), minimum pupil diameter (MinPD), maximum constriction velocity (MCV), and the 75% recovery time (75% PRT) were associated with significant differences between subjects who had suffered a concussion and those that had not. There were also significant differences in PLR metrics over the life span and between genders and those subjects with and without symptoms. The differences in PLR metrics are modulated not only by concussion history but also by gender and whether or not the person has symptoms associated with a head injury. A concussive injury to the brain is associated with changes in the PLR that persist over the life span, representing biomarkers that might be used in clinical diagnosis, treatment, and decision making.

The Expanding Role of Quantitative Pupillometry in the Evaluation and Management of Traumatic Brain Injury

Traumatic brain injury is a rapidly increasing source of morbidity and mortality across the world. As such, the evaluation and management of traumatic brain injuries ranging from mild to severe are under active investigation. Over the last two decades, quantitative pupillometry has been increasingly found to be useful in both the immediate evaluation and ongoing management of traumatic brain injured patients. Given these findings and the portability and ease of use of modern pupillometers, further adoption and deployment of quantitative pupillometers into the preclinical and hospital settings of both resource rich and medically austere environments.

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.

Vergence, accommodation, and visual tracking in children and adolescents evaluated in a multidisciplinary concussion clinic

Many patients with concussion experience visual symptoms following injury that lead to a diagnosis of convergence insufficiency, accommodative insufficiency, or saccadic dysfunction. However, these diagnostic categories are based on aggregates of clinical tests developed from a non-concussed population and therefore may not accurately describe visual deficits in the concussed population. Thus, we sought to understand individual metrics of visual dysfunction in chronically symptomatic post-concussion patients. This retrospective cross-sectional study included patients examined at the multidisciplinary concussion clinic (MDCC) at Boston Children's Hospital over four years. Patients aged 5-21 years who had a complete assessment of eye alignment, vergence, accommodation, and visual tracking, and had visual acuity better than or equal to 20/30 in each eye were included. Patients with history of amblyopia, strabismus, or ocular pathology were excluded. Chart review yielded 116 patients who met inclusion criteria (median age 15 years, 64% female). The majority of patients (52%) experienced a single concussion and most were sports-related (50%). Clinical data show vergence, accommodation, or visual tracking deficits in 95% of patients. A receded near point of convergence (NPC, 70/116) and reduced accommodative amplitude (63/116) were the most common deficits. Both NPC and accommodative amplitude were significantly correlated with one another (r = -0.5) and with measures of visual tracking (r = -0.34). Patients with chronic post-concussion symptoms show deficits in individual metrics of vergence, accommodation and visual tracking. The high incidence of these deficits, specifically NPC and accommodative amplitude, highlights the need for a detailed sensorimotor evaluation to guide personalized treatment following concussion.

Daily Morning Blue Light Therapy for Post-mTBI Sleep Disruption: Effects on Brain Structure and Function

Background: Mild traumatic brain injuries (mTBIs) are associated with novel or worsened sleep disruption. Several studies indicate that daily morning blue light therapy (BLT) is effective for reducing post-mTBI daytime sleepiness and fatigue. Studies demonstrating changes in brain structure and function following BLT are limited. The present study's purpose is to identify the effect of daily morning BLT on brain structure and functional connectivity and the association between these changes and self-reported change in post-mTBI daytime sleepiness. Methods: A total of 62 individuals recovering from a mTBI were recruited from two US cities to participate in a double-blind placebo-controlled trial. Eligible individuals were randomly assigned to undergo 6 weeks of 30 min daily morning blue or placebo amber light therapy (ALT). Prior to and following treatment all individuals completed a comprehensive battery that included the Epworth Sleepiness Scale as a measure of self-reported daytime sleepiness. All individuals underwent a multimodal neuroimaging battery that included anatomical and resting-state functional magnetic resonance imaging. Atlas-based regional change in gray matter volume (GMV) and region-to-region functional connectivity from baseline to post-treatment were the primary endpoints for this study. Results: After adjusting for pre-treatment GMV, individuals receiving BLT had greater GMV than those receiving amber light in 15 regions of interest, including the right thalamus and bilateral prefrontal and orbitofrontal cortices. Improved daytime sleepiness was associated with greater GMV in 74 ROIs, covering many of the same general regions. Likewise, BLT was associated with increased functional connectivity between the thalamus and both prefrontal and orbitofrontal cortices. Improved daytime sleepiness was associated with increased functional connectivity between attention and cognitive control networks as well as decreased connectivity between visual, motor, and attention networks (all FDR corrected p < 0.05). Conclusions: Following daily morning BLT, moderate to large increases in both gray matter volume and functional connectivity were observed in areas and networks previously associated with both sleep regulation and daytime cognitive function, alertness, and attention. Additionally, these findings were associated with improvements in self-reported daytime sleepiness. Further work is needed to identify the personal characteristics that may selectively identify individuals recovering from a mTBI for whom BLT may be optimally beneficial.