Measurement Properties of the Activities-Specific Balance Confidence Scale in Adults From the General Population With Concussion: A Report From the Toronto Concussion Study.

OBJECTIVE: The aim of this study was to establish the internal consistency and construct validity of the Activities-specific Balance Confidence (ABC) Scale and ABC-6 in adults from the general population with concussion. DESIGN: Prospective analysis. SETTING: Outpatient concussion care clinic. PARTICIPANTS: Adults from the general population with concussion referred to a concussion care clinic within 7 days of injury (N=511). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Balance confidence was assessed with the Activities-specific Balance Confidence (ABC) Scale and the ABC-6. Concussion symptoms were characterized using the Sport Concussion Assessment Tool version 5 (SCAT5) symptom checklist. Instrumented measures of balance and gait included center of pressure velocity and double support time, respectively. Balance was also assessed using the mBESS. RESULTS: The ABC and ABC-6 were strongly correlated (ρ=0.980, P<.001). Cronbach α for ABC and ABC-6 was 0.966 and 0.940, respectively. Factor analysis verified the existence of 2 components of the ABC, 1 including all items of the ABC-6 as well as 3 additional items. ABC and ABC-6 were moderately significantly correlated with SCAT5 symptom number, severity, and symptom domain (ρ=-0.350 to -0.604). However, correlations between ABC and ABC-6 with instrumented measures of balance and gait were not statistically significant, except for double support time during dual-task gait with ABC-6 (ρ=-0.218). CONCLUSIONS: In community-dwelling adults with concussion, the ABC and ABC-6 have good internal consistency. Convergent validity is stronger for symptom endorsement measures within SCAT5 domains, which has a similar construct (subjectivity) to balance confidence. Both the ABC and ABC-6 are valid measures of balance self-efficacy in adults from the general population with concussion. The ABC-6 may be a useful tool for characterizing the effect of concussion on perceptions of the ability to perform functional tasks that challenge balance and mobility.

Optimizing early education provided at the Hull-Ellis Concussion and Research Clinic: A multiple methods evaluation from the Toronto Concussion Study.

OBJECTIVES: The purpose of this study was to determine factors and characteristics associated with changes in knowledge among adults receiving education within the first 8 weeks post-concussion. The study also aimed to understand desired preferences (i.e. content, format) for education post-concussion from the perspective of patients and physicians. METHODS: Patient-participants (17-85 years) were prospectively recruited within one week of a concussion. Participants received education over visits from Weeks 1 to 8 post-injury. Primary outcome measures were participant responses on a concussion knowledge questionnaire at Weeks 1 (n = 334) and 8 (n = 195), and feedback regarding education through interviews. Other variables collected included preexisting medical history, physician assessed recovery and symptoms. RESULTS: There was a significant increase in average knowledge on the concussion knowledge questionnaire across time (71% vs 75% correct; p = 0.004). Participants with higher levels of education, female sex and preexisting diagnoses of depression or anxiety had more correct responses at Week 1. Healthcare providers had varying comfort levels addressing mood-related symptoms. CONCLUSIONS: There is a need to tailor education provided to concussion patients based on preinjury characteristics, i.e., mood disorders and demographic factors. Healthcare providers may need additional training in addressing mood symptoms and should modify the approach to fit patients' unique needs.

Revisiting the ICHD-3 criteria for headache attributed to mild traumatic injury to the head: Insights from the Toronto Concussion Study Analysis of Acute Headaches Following Concussion.

BACKGROUND: There is limited prospective data on the prevalence, timing of onset, and characteristics of acute headache following concussion/mild traumatic brain injury. METHODS: Adults diagnosed with concussion (arising from injuries not related to work or motor vehicle accidents) were recruited from emergency departments and seen within one week post injury wherein they completed questionnaires assessing demographic variables, pre-injury headache history, post-injury headache history, and the Sport Concussion Assessment Tool (SCAT-3) symptom checklist, the Sleep and Concussion Questionnaire (SCQ) and mood/anxiety on the Brief Symptom Inventory (BSI). RESULTS: A total of 302 participants (59% female) were enrolled (mean age 33.6 years) and almost all (92%) endorsed post-traumatic headache (PTH) with 94% endorsing headache onset within 24 hours of injury. Headache location was not correlated with site of injury. Most participants (84%) experienced daily headache. Headache quality was pressure/squeezing in 69% and throbbing/pulsing type in 22%. Associated symptoms included: photophobia (74%), phonophobia (72%) and nausea (55%). SCAT-3 symptom scores, Brief Symptom Inventory and Sleep and Concussion Questionnaire scores were significantly higher in those endorsing acute PTH. No significant differences were found in week 1 acute PTH by sex, history of migraine, pre-injury headache frequency, anxiety, or depression, nor presence/absence of post-traumatic amnesia and self-reported loss of consciousness. CONCLUSIONS: This study highlights the very high incidence of acute PTH following concussion, the timing of onset and characteristics of acute PTH, the associated psychological and sleep disturbances and notes that the current ICHD-3 criteria for headaches attributed to mild traumatic injury to the head are reasonable, the interval between injury and headache onset should not be extended beyond seven days and could, potentially, be shorted to allow for greater diagnostic precision.

The Toronto Concussion Study: Sense of smell is not associated with concussion severity or recovery.

OBJECTIVE: To examine sense of smell as a biomarker for both severity and duration of post-concussion symptoms. METHODS: Participants were recruited prospectively from an outpatient concussion clinic. Sense of smell was assessed using the University of Pennsylvania Smell Identification Test (UPSIT) within 7 days, and 4, 8 - or 16-weeks post-injury. UPSIT normative data were used as normal controls. The main outcomes were: symptom severity on the Sport Concussion Assessment Tool 3 (SCAT3) symptom inventory and time to physician-declared recovery. RESULTS: A total of 167 participants (mean age 32.9 [SD, 12.2] years, 59% female [n = 99]) were classified at 1 week post injury as follows: severe hyposmia in 5 (3%), moderate hyposmia in 10 (6%), mild hyposmia in 48 (29%), and normosmia in 104 (62%) individuals. A convenience sample of 81 individuals with concussion were tested at follow-up. Acute impairment of sense of smell following concussion was not associated with symptom severity on the SCAT3 or time to recovery. Sense of smell was stable from baseline to follow-up in this population. CONCLUSION: This study provides evidence that routine testing of sense of smell in individuals with concussion is not warranted as a biomarker for severity of concussion and concussion recovery.

Normative Data for the Fear Avoidance Behavior After Traumatic Brain Injury Questionnaire in a Clinical Sample of Adults With Mild TBI.

OBJECTIVE: Fear avoidance behavior after a concussion or mild traumatic brain injury (mTBI) is associated with a number of adverse outcomes, such as higher symptom burden, emotional distress, and disability. The Fear Avoidance Behavior after Traumatic Brain Injury Questionnaire (FAB-TBI) is a recently developed and validated self-report measure of fear avoidance after mTBI. The objective of this study was to derive clinical normative data for the FAB-TBI. To determine whether demographic stratification was necessary and to further support clinical interpretation, we also explored associations between fear avoidance behavior and demographic and injury variables. SETTING: Five concussion clinics in Canada. PARTICIPANTS: Adults who sustained an mTBI (N = 563). DESIGN: Cross-sectional. MAIN MEASURES: Participants completed the Fear Avoidance Behavior after Traumatic Brain Injury Questionnaire (FAB-TBI) and measures of postconcussion symptom burden (Rivermead Postconcussion Symptoms Questionnaire, Sport Concussion Assessment Tool-5) at clinic intake. RESULTS: Generalized linear modeling revealed that females reported more fear avoidance than males (95% CI = 0.66 to 2.75), indicating that FAB-TBI normative data should be stratified by sex. Differences between recruitment sites on FAB-TBI scores were reduced but not eliminated by controlling for potential confounds. Loss of consciousness (95% CI =0.61 to 2.76) and higher postconcussion symptom burden (95% CI = 0.79 to 1.03) were also associated with higher FAB-TBI scores, but time since injury was not (95% = CI -0.4 to 0.03). Tables to convert FAB-TBI raw scores to Rasch scores to percentiles are presented. CONCLUSION: These findings support clinical interpretation of the FAB-TBI and further study of fear avoidance after mTBI.

The Toronto concussion study: a cross-sectional analysis of balance deficits following acute concussion in community-dwelling adults.

Objective: To characterize balance deficits in community-dwelling adults following acute concussion.Design: Cross-sectional observational study.Methods: Individuals with acute concussion (n=100) and healthy controls (n=20) completed the BESS (Balance Error Scoring System) and quiet standing trials on forceplates with the eyes open, closed, or during a cognitive dual task. BESS score and centre-of-pressure root mean square and high-frequency power (0.4-3Hz) were used to characterize group differences. In a secondary analysis, participants were subdivided based on self-reported symptoms of balance problems and dizziness using the SCAT-3 (Sport Concussion Assessment Tool - Third Edition) Symptom Checklist.Results: In comparing individuals with concussion and controls, BESS score (16.0 ± 6.0 vs 12.6 ± 3.8; F(1,116) = 5.814, p = .017) and anteroposterior [F(1.78, 204.2) = 11.93, p < .001] and mediolateral [F(1, 114) = 10.05, p = .002] high-frequency power revealed significant group differences. Dividing individuals based on self-reported symptoms revealed significant differences in mediolateral high frequency power, such that participants reporting balance and dizziness problems as well as those participants not reporting balance or dizziness symptoms following concussion were less stable than controls.Conclusions: Deficits in clinical and posturographic measures of balance occur in community-dwelling adults with concussion. These measures do not align with self-reported balance symptoms. Future research and clinical practice aimed at careful selection of optimized balance assessment is recommended.

The Toronto Concussion Study: a longitudinal analysis of balance deficits following concussion in community-dwelling adults.

OBJECTIVE: To characterize recovery of balance deficits in community-dwelling adults with concussion. HYPOTHESIS: Balance measures will improve 2 weeks after injury and persist over 12 weeks. DESIGN: Prospective longitudinal observational study. METHODS: Assessments included the Balance Error Scoring System (BESS) and quiet standing during eyes open, eyes closed, and a cognitive dual task. Recovery was determined using a Hierarchical Growth Curve Model (HGCM) at Week1 (n = 61), Week2 (n = 58), Week4 (n = 53), Week8 (n = 51), and Week12 (n = 39) post-injury. Within-individual follow-up analysis was conducted using the coefficient of variation (quiet standing measures) and a reliable change index (BESS) on 28 individuals with concussion assessed at all 5 time points. RESULTS: Self-reported symptom score recovered between Week 4-8. Anteroposterior COP velocity (eyes closed) was the only variable to show statistically significant (p < .05) recovery in the HGCM. The within-individual analysis identified fewer than 43% (12/28) of participants recovered by Week 12, relative to their own Week 1 assessment. CONCLUSIONS: While recovery of balance deficits was observed in 1 variable over 12 weeks, less than half of the participants included in all assessments demonstrated improvement in balance outcomes. Future research and clinical practice should focus on the unique characteristics of community-dwelling adults with concussion to optimize recovery in this cohort.

Self-reported Balance Disturbance and Performance-Based Balance Impairment After Concussion in the General Population.

OBJECTIVE: To characterize the prevalence of, and relationship between, self-reported balance disturbance and performance-based balance impairment in the general population with concussion. SETTING: Rehabilitation hospital outpatient concussion clinic. PARTICIPANTS: One hundred six individuals with concussion (49 males, mean age = 32.4; SD = 11.5 years), mean (SD) = 5 (1.8) days postinjury. DESIGN: Cross-sectional observational study. MAIN MEASURES: SCAT3 Symptoms Subscale, Balance Error Scoring System, modified Balance Error Scoring System, and center-of-pressure root-mean-square amplitude and velocity in eyes open and closed conditions. RESULTS: The majority of participants reported balance or dizziness symptoms (54% and 63%, respectively) and demonstrated balance impairment on the Balance Error Scoring System and modified Balance Error Scoring System (66% and 58%, respectively). The prevalence of balance impairment across center-of-pressure measures varied from 32% to 48%. There was no effect of balance or dizziness symptom severity on any of the balance measures (F2,103 = 1.02; P = .44) and (F2,103 = 1.45; P = .10), respectively. There was poor agreement between self-report of balance/dizziness symptoms and identified balance impairment across all balance measures (all κ ≤ 0.26 and κ ≤ 0.20, respectively). CONCLUSIONS: There was no clear relationship between the subjective experience of balance disturbance and objective measures of balance impairment in the general population. These results have implications for clinical evaluation of postconcussive deficits and determination of recovery.

The Toronto Concussion Study: a prospective investigation of characteristics in a cohort of adults from the general population seeking care following acute concussion, 2016-2020.

Purpose: There is limited research regarding the characteristics of those from the general population who seek care following acute concussion. Methods: To address this gap, a large cohort of 473 adults diagnosed with an acute concussion (female participants = 287; male participants = 186) was followed using objective measures prospectively over 16 weeks beginning at a mean of 5.1 days post-injury. Results: Falls were the most common mechanism of injury (MOI) (n = 137, 29.0%), followed by sports-related recreation (n = 119, 25.2%). Male participants were more likely to be injured playing recreational sports or in a violence-related incident; female participants were more likely to be injured by falling. Post-traumatic amnesia (PTA) was reported by 80 participants (16.9 %), and loss of consciousness (LOC) was reported by 110 (23.3%). In total, 54 participants (11.4%) reported both PTA and LOC. Male participants had significantly higher rates of PTA and LOC after their injury compared to their female counterparts. Higher initial symptom burden was associated with a longer duration of recovery for both male and female participants. Female participants had more symptoms and higher severity of symptoms at presentation compared to male participants. Female participants were identified to have a longer recovery duration, with a mean survival time of 6.50 weeks compared to 5.45 weeks in male participants (p < 0.0001). A relatively high proportion of female and male participants in this study reported premorbid diagnoses of depression and anxiety compared to general population characteristics. Conclusion: Although premorbid diagnoses of depression and/or anxiety were associated with higher symptom burden at the initial visit, the duration of symptoms was not directly associated with a pre-injury history of psychological/psychiatric disturbance. This cohort of adults, from the general population, seeking care for their acute concussion attained clinical and functional recovery over a period of 4-12 weeks.

Characterizing the profiles of patients with acute concussion versus prolonged post-concussion symptoms in Ontario.

Identifying vulnerability factors for developing persisting concussion symptoms is imperative for determining which patients may require specialized treatment. Using cross-sectional questionnaire data from an Ontario-wide observational concussion study, we compared patients with acute concussion (≤ 14 days) and prolonged post-concussion symptoms (PPCS) (≥ 90 days) on four factors of interest: sex, history of mental health disorders, history of headaches/migraines, and past concussions. Differences in profile between the two groups were also explored. 110 patients with acute concussion and 96 patients with PPCS were included in our study. The groups did not differ on the four factors of interest. Interestingly, both groups had greater proportions of females (acute concussion: 61.1% F; PPCS: 66.3% F). Patient profiles, however, differed wherein patients with PPCS were significantly older, more symptomatic, more likely to have been injured in a transportation-related incident, and more likely to live outside a Metropolitan city. These novel risk factors for persisting concussion symptoms require replication and highlight the need to re-evaluate previously identified risk factors as more and more concussions occur in non-athletes and different risk factors may be at play.

Characterizing Sleep and Wakefulness in the Acute Phase of Concussion in the General Population: A Naturalistic Cohort from the Toronto Concussion Study.

Growing literature links concussion to changes in sleep and wakefulness in humans and in rodent models. Sleep has been linked with synaptic reorganization under other conditions; however, the characterization and role of sleep after acute concussion remains poorly understood. While much research has focused on insomnia among patients with chronic or persistent concussion symptoms, there is limited understanding of sleep and acute concussion, its potential role in recovery, and associated risk factors for the development of chronic sleep disturbance. Studies to date are limited by small sample sizes of primarily athlete or military populations. Additional studies among the general population are critical to inform best practice guidelines. We examined the sleep and daytime wakefulness of 472 adults from a naturalistic general population cohort (mean age, 33.3 years, females = 60.8%) within seven days of diagnosed concussion, using a validated, condition-specific measure, the Sleep and Concussion Questionnaire. Participants identified immediate changes in sleep characterized by hypersomnia and difficulty maintaining daytime wakefulness; 35% considered these changes as moderate to severe and 79% required monitoring or follow-up. Females experienced significantly greater severity of changes in sleep compared with males. Positive correlations between severity of sleep and pain and headache were identified. Differences by sex are an important consideration for early intervention and long-term monitoring. Because sleep was compromised by pain, pain management is also an integral part of early intervention. Our findings suggest that assessment of sleep beginning in the acute stage is a critical component of concussion management in the general population.

The Toronto Concussion Study: Reference Data for Balance and Gait Measures in Community-Dwelling Adults With Concussion.

OBJECTIVE: Concussion can cause deficits in balance and gait. Much of what is known about how concussion affects balance and gait has been derived from studies involving youth, high school, and university athletes. However, investigation into the effects of concussion on balance and gait in community-dwelling young, middle-age, and older aged adults is limited. This study aimed to present descriptive reference values for common balance and gait measures in community-dwelling adults between the ages of 20 and 69 years with concussion. METHODS: In this observational study, 318 participants were enrolled from a concussion care clinic at a rehabilitation hospital in an urban center and were assessed within 7 days of injury. Balance measures included the Balance Error Scoring System (BESS), modified BESS, and center-of-pressure root mean square during quiet standing. Gait measures included velocity (absolute and height adjusted), cadence, and step length during self-paced gait. Data were binned by decade-long age range. RESULTS: Mean (SD) per-decade scores for the BESS ranged from 14.8 (5.1) to 21.8 (5.6) errors and 4.0 (3.0) to 9.4 (4.6) errors for the modified BESS. Mean values for center-of-pressure root mean square in the anteroposterior direction ranged from 0.42 (0.18) to 0.52 (0.26) with the eyes open, and from 0.49 (0.19) to 0.62 (0.39) with eyes closed. Mean absolute gait velocity ranged from 98.5 (9.1) to 119.3 (21.3) cm/s. The range of step length values was 58.2 (6.8) to 66.3 (7.3) cm and cadence ranged from 102.1 (9.8) to 108.6 (10.8) steps/min across age groups. CONCLUSION: These data provide insight into the impact of concussion on balance and mobility in community-dwelling adults across the lifespan. IMPACT: Community-dwelling adults can experience concussion across the lifespan. Availability of reference values for commonly used balance and gait measures can help to inform clinical strategies and progression of recovery of balance and mobility after injury.

Can Sport Concussion Assessment Tool (SCAT) Symptom Scores Be Converted to Rivermead Post-concussion Symptoms Questionnaire (RPQ) Scores and Vice Versa? Findings From the Toronto Concussion Study.

Background: The Rivermead Post-Concussion Symptoms Questionnaire (RPQ) and the Sports Concussion Assessment Tool (SCAT) are widely used self-report tools assessing the type, number, and severity of concussion symptoms. There are overlapping symptoms and domains, though they are scored differently. The SCAT consists of 22 questions with a 7-point Likert scale for a total possible score 132. The RPQ has 16 questions and a 5-point Likert scale for a total of 64 possible points. Being able to convert between the two scores would facilitate comparison of results in the concussion literature. Objectives: To develop equations to convert scores on the SCAT to the RPQ and vice versa. Methods: Adults (17-85 years) diagnosed with a concussion at a referring emergency department were seen in the Hull-Ellis Concussion and Research Clinic, a rapid access concussion clinic at Toronto Rehab-University Health Network (UHN) Toronto Canada, within 7 days of injury. The RPQ and SCAT symptom checklists as well as demographic questionnaires were administered to all participants at Weeks 1, 2, 3, 4, 5, 6, 7, 8, 12, 16. Results: 215 participants had 1,168 matched RPQ and SCAT assessments. Total scores of the RPQ and the SCAT had a rho = 0.91 (p < 0.001); correlations were lower for sub-scores of specific symptom domains (range 0.74-0.87, p < 0.001 for all domain comparisons). An equation was derived to calculate SCAT scores using the number and severity of symptoms on the RPQ. Estimated scores were within 3 points of the observed total score on the SCAT. A second equation was derived to calculate the RPQ from the proportion weighted total score of the SCAT. This equation estimated corresponding scores within 3 points of the observed score on the RPQ. Conclusions: The RPQ and SCAT symptom checklists total scores are highly correlated and can be used to estimate the total score on the corresponding assessment. The symptom subdomains are also strongly correlated between the 2 scales however not as strongly correlated as the total score. The equations will enable researchers and clinicians to quickly convert between the scales and to directly compare concussion research findings.

A Promising Subject-Level Classification Model for Acute Concussion Based on Cerebrovascular Reactivity Metrics.

Concussion imaging research has primarily focused on neuronal disruption with lesser emphasis directed toward vascular dysfunction. However, blood flow metrics may be more sensitive than measures of neuronal integrity. Vascular dysfunction can be assessed by measuring cerebrovascular reactivity (CVR)-the change in cerebral blood flow per unit change in vasodilatory stimulus. CVR metrics, including speed and magnitude of flow responses to a standardized well-controlled vasoactive stimulus, are potentially useful for assessing individual subjects following concussion given that blood flow dysregulation is known to occur with traumatic brain injury. We assessed changes in CVR metrics to a standardized vasodilatory stimulus during the acute phase of concussion. Using a case control design, 20 concussed participants and 20 healthy controls (HCs) underwent CVR assessment measuring blood oxygen-level dependent (BOLD) magnetic resonance imaging using precise changes in end-tidal partial pressure of CO2 (PETCO2). Metrics were calculated for the whole brain, gray matter (GM), and white matter (WM) using sex-stratification. A leave-one-out receiver operating characteristic (ROC) analysis classified concussed from HCs based on CVR metrics. CVR magnitude was greater and speed of response faster in concussed participants relative to HCs, with WM showing higher classification accuracy compared with GM. ROC analysis for WM-CVR metrics revealed an area under the curve of 0.94 in males and 0.90 in females for speed and magnitude of response respectively. These greater than normal responses to a vasodilatory stimulus warrant further investigation to compare the predictive ability of CVR metrics against structural injury metrics for diagnosis and prognosis in acute concussion.