Anne E. Mozel

Neurovascular coupling (NVC) uniquely describes cerebrovascular response to neural activation and has demonstrated impairments following concussion in adult patients. It is currently unclear how adolescent patients experience impaired NVC acutely following concussion during this dynamic phase of physiological development. The purpose of this study was to investigate NVC in acutely concussed adolescent patients relative to controls. We recruited patients presenting to a sports medicine practice within 28 days of a concussion or a musculoskeletal injury (controls). Transcranial Doppler ultrasound was used to measure changes in patients' posterior cerebral artery (PCA) velocity in response to two progressively challenging visual tasks: (1) reading and (2) visual search. Each task was presented in five 1-min trials (20 sec eyes closed/40 sec eyes open). Resting PCA velocity data were derived by averaging PCA velocity across a 2-min baseline period that preceded the visual tasks. Filtered task data were converted to time-series curves representing 40 consecutive 1-sec averages for each trial. Curves were then averaged across the five trials and time-aligned to stimulus onset (eyes open) to generate a single ensemble-averaged 40-sec curve representing NVC response for each participant for each task. Independent t tests were used to assess group differences (concussion vs. control) in resting PCA velocity. Separate linear mixed-effects models were used to evaluate group differences (concussion vs. control) in NVC response profiles for both visual tasks and group-by-task interaction. Twenty-one concussion patients (female = 8 [38.1%]; age = 14.4 ± 1.9 years) and 20 controls (female = 7 [35.0%]; age = 14.4 ± 1.9 years) were included in our analysis. Average resting PCA velocity did not significantly differ between concussion patients (36.6 ± 8.0 cm/sec) and controls (39.3 ± 8.5 cm/sec) ( t ₃₉ = 1.06; p = 0.30). There were no significant group differences in relative NVC response curves during the reading task ( F _1,1560 = 2.23; p = 0.14) or the visual search task ( F _1,1521 = 2.04; p = 0.15). In contrast, the differential response to task (e.g., increase from reading task to visual search task) was significantly greater in concussion patients than in controls ( p < 0.0001). The NVC response to the visual search task was 7.1% higher than the response to reading in concussion patients relative to being 5.5% higher in controls. Our data indicate that concussed patients present with a significantly greater response to more difficult tasks than do controls, suggesting that concussed adolescents require increased neural resource allocation as task difficulty increases. The study provides insight into the neurophysiological consequences of concussion in adolescent patients.

Context: Concussion research has primarily focused on sport-related mechanisms and excluded non–sport-related mechanisms. In adult populations, non–sport-related concussions (non-SRCs) demonstrated worse clinical outcomes compared with sport-related concussions (SRCs); however, investigations of non-SRCs in college-aged patients are limited. Objectives: To examine clinical outcomes in collegiate athletes with non-SRCs compared with SRCs and explore sex differences in outcomes among collegiate athletes with non-SRCs. Design: Prospective cohort study. Setting: Clinical setting. Patients or Other Participants: A total of 3500 athletes were included (n = 555 with non-SRCs, 42.5% female) from colleges or universities and service academies participating in the National Collegiate Athletic Association Department of Defense Concussion Assessment, Research and Education (CARE) Consortium. Main Outcome Measure(s): Dichotomous outcomes (yes or no) consisted of immediate reporting, mental status alterations, loss of consciousness, posttraumatic amnesia, retrograde amnesia, motor impairments, delayed symptom presentation, and required hospital transport. Continuous outcomes were symptom severity, days with concussion symptoms, and days lost to injury. Data were collected within 24 to 48 hours of injury and at return to play. Adjusted relative risks (ARRs) compared the likelihood of dichotomous outcomes by mechanism and by sex within patients with non-SRCs. Multivariate negative binomial regressions were used to assess group differences in continuous variables. Results: Athletes with non-SRCs were less likely to report immediately (ARR = 0.73, 95% CI = 0.65, 0.81) and more likely to report delayed symptom presentation (ARR = 1.17, 95% CI = 1.03, 1.32), loss of consciousness (ARR = 3.15, 95% CI = 2.32, 4.28), retrograde amnesia (ARR = 1.77, 95% CI = 1.22, 2.57), and motor impairment (ARR = 1.45, 95% CI = 1.14, 1.84). Athletes with non-SRCs described greater symptom severity, more symptomatic days, and more days lost to injury (P < .001) compared with those who had SRCs. Within the non-SRC group, female athletes indicated greater symptom severity, more symptomatic days, and more days lost to injury (P < .03) than male athletes. Conclusions: Athletes with non-SRCs had worse postinjury outcomes compared with those who had SRCs, and female athletes with non-SRCs had worse recovery metrics than male athletes. Our findings suggest that further investigation of individuals with non-SRCs is needed to improve concussion reporting and management.

Objectives The purpose of this study was to determine sex differences in recovery trajectories of assessments for sport-related concussion using Concussion Assessment, Research and Education (CARE) Consortium data. Methods National Collegiate Athletic Association athletes (N = 906; 61% female) from sex-comparable sports completed a pre-season baseline assessment and post-sport-related concussion assessments within 6 h of injury, 24–48 h, when they initiated their return to play progression, when they were cleared for unrestricted return to play, and 6 months post-injury. Assessments included the Standardized Assessment of Concussion, Balance Error Scoring System, Brief Symptom Inventory-18, Immediate Post-concussion Assessment and Cognitive Testing (ImPACT), Sport Concussion Assessment Tool-3 symptom evaluation, Clinical Reaction Time, King–Devick test, Vestibular Ocular Motor Screen, 12-item Short-Form Health Survey, Hospital Anxiety and Depression Scale, and Satisfaction with Life Scale. Results Only the Vestibular Ocular Motor Screen Total Symptom Score at the 24–48 h timepoint (p = 0.005) was statistically significantly different between sexes. Specifically, female athletes (mean = 60.2, 95% confidence interval [CI] 51.5–70.4) had higher Vestibular Ocular Motor Screen Total Symptom Scores than male athletes (mean = 36.9, 95% CI 27.6–49.3), but this difference resolved by the time of return-to-play initiation (female athletes, mean = 1.8, 95% CI 1.1–2.9; male athletes, mean = 4.1, 95% CI 1.5–10.9). Conclusions Sport-related concussion recovery trajectories for most assessments were similar for female and male National Collegiate Athletic Association athletes except for Vestibular Ocular Motor Screen symptoms within 48 h of sport-related concussion, which was greater in female athletes. Female athletes had a greater symptom burden across all timepoints, suggesting that cross-sectional observations may indicate sex differences despite similar recovery trajectories.

Objective:Concussion patients frequently report increased distractibility, with more than half endorsing “concentration difficulty”. Previous studies have demonstrated impairments in maintaining attention and voluntary attentional allocation in concussion patients. However, involuntary attentional allocation (distraction) is not well understood in the context of concussion. The goal of this study was to examine distraction in acute pediatric concussion patients, monitoring frontal lobe activity using functional near-infrared spectroscopy (fNIRS) - a noninvasive measure of local hemodynamic activity - to elucidate whether post-concussion distractibility is associated with the availability of attentional control resources.Participants and Methods:Participants included concussion patients (cases; n=19) presenting to specialty care within 28 days of injury (M=8.05, SD=5.55) and controls (n=16) presenting for reasons other than concussion. Participants were 13-17 years old (M=14.83, SD=1.10) and 57.1% female. Participants completed a computerized measure of behavioral distraction (the additional singleton paradigm) while frontal lobe activity was recorded using fNIRS 4-channel split sensor. On each trial, an array of shapes (five squares and one circle) was presented, and participants reported the orientation of a line segment inside a target shape (circle). The search array included a distractor (a square that differed in color) on 50% of trials. For each participant, the fNIR signal for epochs of each trial type (distractor present/absent) were averaged and subjected to a linear regression in which the data were fitted to a hemodynamic response function (HRF).Results:34 participants (19 cases, 15 controls) were included in our behavioral analysis. Reaction time (RT) was significantly slower on distractor present compared to distractor absent trials; F(1,32)=17.151, p<.001. There was no significant effect of group (case/control) on RT (F(1,32)=1.24, p=.273) or interaction between group and trial type (F(1,32)=1.05, p=.313). 29 participants (15 cases, 14 controls) were included in fNIRS analyses. The effect of group and distractor presence/absence on oxygenated hemoglobin (HbO2) was examined for each channel. A significant effect of distractor presence/absence was observed in channel 3; F(1,27)=8.510, p=.007. There were no significant effects of group or interactions between group and distractor presence/absence.Lastly, a capture index was calculated for each participant by subtracting average RT on distractor absent trials from distractor present trials and correlated with HbO2 (beta weights averaged across trial type) for each group at each channel. No significant correlations were observed. There was a trend towards a negative correlation for case participants, particularly in channel 1, which strengthened when an outlier was removed (r=-.407, p=.149).Conclusions:Reaction time and frontal lobe activity - which serves as a proxy for attentional control resources - were significantly higher when a distractor was present. Although there were no significant differences in behavioral distraction between groups, concussion patients trended towards higher levels of frontal lobe activity. Likewise, although not statistically significant, there was a trend towards a negative correlation for cases such that more attentional control resources (i.e., higher frontal lobe activity) was associated with less behavioral distraction (i.e., smaller capture index). This suggests that concussion patients may recruit more neural resources to produce comparable behavioral responses to healthy controls.