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

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.

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.

The effect of modified optic flow gain on quiet stance

Visual feedback provides critical information to support postural stability. Previous work has shown that magnifying visual feedback, such as by presenting individuals with biofeedback during balance tasks, can improve postural control. When studies manipulate the availability of optic flow directly, the conditions are often restricted to include an absence of visual feedback or sway referenced paradigms. Therefore, the aim of this study was to understand how manipulating the gain of optic flow contributes to quiet standing balance control among healthy adults. Optic flow was amplified or reduced relative to head motion using a virtual reality head-mounted display while participants stood quietly on either a firm or foam surface. Overall, when there was an increased reliance placed on the visual system by standing on foam, a tighter control of upright stance was observed as the gain of optic flow increased. Further, this study provided evidence that visual contributions to balance control may extend to higher frequencies of postural sway than previously theorized (greater than 0.1 Hz).

Test-Retest reliability and preliminary reliable change estimates for Sway Balance tests administered remotely in community-dwelling adults

OBJECTIVE

Impaired balance and postural stability can occur with advanced age, following traumatic brain injury, in association with neurological disorders and diseases, and as the result of acute or chronic orthopedic problems. The remote assessment of balance and postural stability could be of value in clinical practice and research. We examined the test-retest reliability and reliable change estimates for Sway Balance Mobile Application tests (Sway Medical, Tulsa OK, USA) administered remotely from the participant's home.

METHOD

Primarily young, healthy community-dwelling adults completed Sway Balance Mobile Application tests remotely on their personal mobile devices once per week for three consecutive weeks while being supervised with a video-based virtual connection. Sway Balance tests include five stances (i.e., feet together, tandem right foot forward, tandem left foot forward, single leg right foot, single leg left foot), which are averaged to compute a Sway Balance composite score from 0 to 100, with higher scores indicating better postural stability. We examined test-retest reliability (measured with intraclass correlation coefficients, ICCs) and preliminary reliable change estimates for 70%, 80%, and 90% confidence intervals.

RESULTS

Participants included 55 healthy adults (ages = 26.7 ± 9.9 years, interquartile range = 20-30, range = 18-58; 38 [69%] women). Test-retest reliability for the Sway Balance composite score across three weeks was.88. Test-retest reliability for individual stances ranged from 62 to 83 (all ps < 0.001). At the 80% confidence interval, preliminary reliable changes estimates were 9 points for the Sway Balance composite score.

CONCLUSIONS

For a remote administration, test-retest reliability was moderate-to-good for all Sway Balance stances, as well as for the Sway Balance composite score. Reliable change estimates may allow clinicians to determine whether an improvement or decline in performance is greater than the expected improvement or decline due to measurement error in young adults.

Patient perception of dizziness and imbalance does not correlate with gait measures in adolescent athletes post-concussion

BACKGROUND

Dizziness and gait impairments are commonly observed following a concussion, and both are associated with prolonged concussion recovery.

RESEARCH QUESTION

Is there a correlation between combined self-reported dizziness and balance impairment severity with objective gait impairments after concussion?

METHODS

Participants (n = 51; 15.4 ± 1.6 years; 51 % female; 7.3 ± 3.2 days post-injury) age 12-18 years self-reported ratings of dizziness and balance impairment using the Post-Concussion Symptom Inventory (PCSI) within 14 days of injury. Individual ratings of dizziness, balance impairment, and moving clumsily on the PCSI were combined to create a comprehensive dizziness and imbalance score. Participants also completed a smartphone-based gait evaluation under single-task and dual-task conditions. Correlation coefficients (Pearson r for normally distributed and Spearman rho for non-normally distributed variables) were calculated between self-reported symptoms and single and dual-task spatiotemporal gait parameters, specifically step velocity, step time, and step length.

RESULTS

Correlation coefficients indicated that there was low to no correlation between self-reported dizziness and imbalance impairment severity and smartphone-obtained gait parameters under single- or dual-task conditions, including step velocity (single-task: r=-0.22, p = 0.13; dual-task: r=-0.05, p = 0.72), step time (single-task: rho = 0.16, p = 0.27; dual-task: rho = 0.14, p = 0.33), and step length (single-task: r=-0.15, p = 0.30; dual-task: r = 0.03, p = 0.84).

SIGNIFICANCE

Self-reported dizziness and balance impairment severity within the first two weeks of concussion may not reflect objectively measured gait performance, given the lack of association between subjective symptom ratings and functional measures. Further, smartphone collected gait parameters may not provide the necessary sensitivity to detect an association with dizziness. The lack of significant correlation between self-reported symptoms and objective gait performance highlights the importance of using both objective and subjective measures to obtain a more complete picture of concussion deficits.