Association of Multidomain Assessment Outcomes With Referral for Vestibular Therapy After Concussion.

CONTEXT: Multiple aspects of a multidomain assessment have been validated for identifying concussion; however, researchers have yet to determine which components are related to referral for vestibular therapy. OBJECTIVE: To identify which variables from a multidomain assessment were associated with receiving a referral for vestibular therapy after a concussion. DESIGN: Retrospective chart review, level of evidence 3. PATIENTS OR OTHER PARTICIPANTS: Participants (n = 331; age = 16.9 ± 7.2 years; 39.3% female) were diagnosed with a concussion per international consensus criteria by a clinical neuropsychologist after presenting to a concussion specialty clinic. MAIN OUTCOME MEASURE(S): Medical chart data were extracted from the first clinical visit regarding preinjury medical history, computerized neurocognition, Post-Concussion Symptom Scale, Concussion Clinical Profiles Screen, and Vestibular Ocular Motor Screening within 16.2 ± 46.7 days of injury. We built 5 backwards logistic regression models to associate the outcomes from each of the 5 assessments with referral for vestibular therapy. A final logistic regression model was generated using variables retained in the previous 5 models as potential predictors of referral for vestibular therapy. RESULTS: The 5 models built from individual components of the multidomain assessment predicted referral for vestibular therapy (R2 = 0.01-0.28) with 1 to 6 statistically significant variables. The final multivariate model (R2 = 0.40) retained 9 significant variables, represented by each of the 5 multidomain assessments except neurocognition. Variables that had the strongest association with vestibular therapy referral were motor vehicle accident mechanism of injury (odds ratio [OR] = 15.45), migraine history (OR = 3.25), increased headache when concentrating (OR = 1.81), and horizontal vestibular ocular reflex (OR = 1.63). CONCLUSIONS: We demonstrated the utility of a multidomain assessment and identified outcomes associated with a referral for vestibular therapy after a concussion.

False-Positive Rates and Associated Risk Factors on the Vestibular-Ocular Motor Screening and Modified Balance Error Scoring System in US Military Personnel.

CONTEXT: In 2018, the US military developed the Military Acute Concussion Evaluation-2 (MACE-2) to inform the acute evaluation of mild traumatic brain injury (mTBI). However, researchers have yet to investigate false-positive rates for components of the MACE-2, including the Vestibular-Ocular Motor Screening (VOMS) and modified Balance Error Scoring System (mBESS), in military personnel. OBJECTIVE: To examine factors associated with false-positive results on the VOMS and mBESS in US Army Special Operations Command (USASOC) personnel. DESIGN: Cross-sectional study. SETTING: Military medical clinic. PATIENTS OR OTHER PARTICIPANTS: A total of 416 healthy USASOC personnel completed the medical history, VOMS, and mBESS evaluations. MAIN OUTCOME MEASURE(S): False-positive rates for the VOMS (≥2 on VOMS symptom items, >5 cm for near point of convergence [NPC] distance) and mBESS (total score >4) were determined using χ2 analyses and independent-samples t tests. Multivariable logistic regressions (LRs) with adjusted odds ratios (aORs) were performed to identify risk factors for false-positive results on the VOMS and mBESS. The VOMS item false-positive rates ranged from 10.6% (smooth pursuits) to 17.5% (NPC). The mBESS total score false-positive rate was 36.5%. RESULTS: The multivariable LR model supported 3 significant predictors of VOMS false-positives, age (aOR = 1.07; 95% CI = 1.02, 1.12; P = .007), migraine history (aOR = 2.49; 95% CI = 1.29, 4.81; P = .007), and motion sickness history (aOR = 2.46; 95% CI = 1.34, 4.50; P = .004). Only a history of motion sickness was a significant predictor of mBESS false-positive findings (aOR = 2.34; 95% CI = 1.34, 4.05; P = .002). CONCLUSIONS: False-positive rates across VOMS items were low and associated with age and a history of mTBI, migraine, or motion sickness. False-positive results for the mBESS total score were higher (36.5%) and associated only with a history of motion sickness. These risk factors for false-positive findings should be considered when administering and interpreting VOMS and mBESS components of the MACE-2 in this population.

Temporal Differences in Concussion Symptom Factors in Adolescents following Sports-Related Concussion.

OBJECTIVE: To evaluate temporal differences in concussion symptoms up to 30 days following a sports-related concussion. STUDY DESIGN: Adolescent and young adult athletes (n = 782) were separated based on time since injury at presentation as Early (0-7 days; n = 321, age: 15.4 ± 1.9 years, 51.7% female), Middle (8-14 days; n = 281, age: 15.8 ± 2.2 years, 54.8% female), and Late (15-30 days; n = 180, age: 15.6 ± 1.8 years, 52.8% female). All participants completed the 22-item Post-Concussion Symptom Scale at first visit. A confirmatory factor analysis was completed separately for each time since injury cohort using a 4-component model reported previously. RESULTS: The confirmatory factor analysis model fit was acceptable for Early, Middle, and Late (using cognitive-migraine-fatigue, affective, sleep, and somatic factors). Both affective (change = 0.30; P = .01; Cohen d = 0.30) and sleep (change = 0.51; P ≤ .001; Cohen d = 0.47) factors were significantly greater in the Late group compared with the Early, but not Middle, groups. The previously reported 4-factor symptom model, including cognitive-migraine-fatigue, affective, somatic, and sleep factors, was appropriate for adolescents up to 30 days' postinjury. However, adolescents who presented between 15 and 30 days' postinjury reported greater affective and sleep symptoms than those who presented within 1 week. CONCLUSIONS: Clinicians should consider these temporal differences when evaluating concussion symptoms in adolescents, as greater affective and sleep symptoms can be predictive of prolonged recovery/persistent complications.

A Randomized Controlled Trial of Precision Vestibular Rehabilitation in Adolescents following Concussion: Preliminary Findings.

OBJECTIVE: To compare the effectiveness of a 4-week precision vestibular rehabilitation intervention compared with a behavioral management control intervention for adolescents with vestibular symptoms/impairment within 21 days of a concussion. STUDY DESIGN: This study used double-blind, randomized controlled trial design involving adolescent (12-18 years) patients with a diagnosed sport/recreation-related concussion with vestibular symptoms/impairment from a concussion-specialty clinic between October 2018 and February 2020. Eligible participants were randomized in a 1:1 to either a 4-week vestibular intervention group (VESTIB) or a behavioral management control group (CONTROL). CONTROLS (n = 25) were prescribed behavioral management strategies (eg, physical activity, sleep, hydration, nutrition, stress management) and instructed to perform stretching/physical activity (eg, walking, stationary cycle) 30 minutes/day. VESTIB (n = 25) were prescribed precision vestibular rehabilitation exercises and instructed to perform at-home exercises for 30 minutes/day. Primary outcomes were improvement in Vestibular/Ocular Motor Screening vestibular items (ie, horizontal/vertical vestibular-ocular reflex, visual motion sensitivity) at 4 weeks postenrollment. RESULTS: We screened 310 and enrolled a total of 55 (18%) adolescent patients who were randomized to one of the interventions. Fifty of fifty-five (91%) participants completed all aspects of the study protocol. Participants in VESTIB improved significantly across the intervention period in horizontal (mean difference-1.628; 95% CI [-3.20, -0.06]; P = .04) and vertical (mean difference-2.24; 95% CI [-4.01, -0.48]; P = .01) vestibular-ocular reflex, but not visual motion sensitivity (mean difference-2.03; 95% CI [-4.26, 0.19]) of the Vestibular/Ocular Motor Screening score compared with CONTROLS. CONCLUSIONS: Overall, the vestibular intervention group experienced greater clinical improvements in vestibular symptoms/impairment than controls across the 4-week intervention. TRIAL REGISTRATION: ClinicalTrials.gov: NCT03555370.

Network Analysis of Sport-Related Concussion Research During the Past Decade (2010-2019).

CONTEXT: Research into sport-related concussion (SRC) has grown substantially over the past decade, yet no authors to date have synthesized developments over this critical time period. OBJECTIVE: To apply a network-analysis approach in evaluating trends in the SRC literature using a comprehensive search of original, peer-reviewed research articles involving human participants published between January 1, 2010, and December 15, 2019. DESIGN: Narrative review. MAIN OUTCOME MEASURE(S): Bibliometric maps were derived from a comprehensive search of all published, peer-reviewed SRC articles in the Web of Science database. A clustering algorithm was used to evaluate associations among journals, organizations or institutions, authors, and key words. The online search yielded 6130 articles, 528 journals, 7598 authors, 1966 organizations, and 3293 key words. RESULTS: The analysis supported 5 thematic clusters of journals: (1) biomechanics/sports medicine (n = 15), (2) pediatrics/rehabilitation (n = 15), (3) neurotrauma/neurology/neurosurgery (n = 11), (4) general sports medicine (n = 11), and (5) neuropsychology (n = 7). The analysis identified 4 organizational clusters of hub institutions: (1) University of North Carolina (n = 19), (2) University of Toronto (n = 19), (3) University of Michigan (n = 11), and (4) University of Pittsburgh (n = 10). Network analysis revealed 8 clusters for SRC key words, each with a central topic area: (1) epidemiology (n = 14), (2) rehabilitation (n = 12), (3) biomechanics (n = 11), (4) imaging (n = 10), (5) assessment (n = 9), (6) mental health/chronic traumatic encephalopathy (n = 9), (7) neurocognition (n = 8), and (8) symptoms/impairments (n = 5). CONCLUSIONS: The findings suggest that during the past decade SRC research has (1) been published primarily in sports medicine, pediatric, and neuro-focused journals, (2) involved a select group of researchers from several key institutions, and (3) concentrated on new topical areas, including treatment or rehabilitation and mental health.

Utility of 1 Measurement Versus Multiple Measurements of Near Point of Convergence After Concussion.

CONTEXT: Increased near point of convergence (NPC) distance is a common finding after concussion and is associated with physical symptoms and worsened neurocognitive performance. Vestibular/Ocular Motor Screening measures NPC distance across 3 trials and uses the average measurement to inform clinical care. However, whether 3 trials are necessary, are consistent, or add clinical utility is unknown. OBJECTIVE: To investigate the consistency across 3 trials of NPC and establish the classification accuracy (ie, clinical utility) of 1 or 2 trials compared with the standardized average of 3 trials. DESIGN: Retrospective cohort study. SETTING: Sports medicine clinic and research laboratory. PATIENTS OR OTHER PARTICIPANTS: Consecutively enrolled patients aged 10 to 22 years with diagnosed concussions (74% sport related; n = 380). MAIN OUTCOME MEASURE(S): The previously reported clinical cutoff value of ≥5 cm across 3 trials was used. Pearson correlation and intraclass correlation coefficients were used to evaluate agreement between trials and average scores. Reliable change indices (RCIs) using 95% confidence intervals were also calculated. RESULTS: The Pearson correlation (r = .98) and intraclass correlation (0.98) coefficients revealed excellent agreement between the first measurement and average NPC distance across 3 measurements. The RCI across all trials was 2 cm. When the first NPC measurement was ≤3 cm or ≥7 cm, agreement existed within the RCI between the first measurement and the average of 3 measurements in 99.6% of cases. When we averaged the first and second measurements, 379/380 (99.7%) participants had the same classification (ie, <5 cm = normal, ≥5 cm = abnormal) as the average NPC distance across 3 measurements. CONCLUSIONS: Our findings suggest limited utility of multiple or average NPC distance measurements when the initial NPC distance is outside of RCI clinical cutoffs (ie, ≤3 cm or ≥7 cm). Given the high consistency between the first measurement and average NPC distance across 3 trials, only 1 measurement of NPC distance is warranted unless the first measurement is between 3 and 7 cm.

Bilateral Strength Asymmetries and Unilateral Strength Imbalance: Predicting Ankle Injury When Considered With Higher Body Mass in US Special Forcesa.

CONTEXT: Ankle injury is one of the most common conditions in athletics and military activities. Strength asymmetry (SA) and imbalance may represent a risk factor for injury, but past investigations have produced ambiguous conclusions. Perhaps one explanation for this ambiguity is the fact that these authors used univariate models to predict injury. OBJECTIVE: To evaluate the predictive utility of SA and imbalance calculations for ankle injury in univariate and multivariate prediction models. DESIGN: Prospective cohort study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 140 male US Air Force Special Forces. MAIN OUTCOME MEASURE(S): Baseline testing consisted of body composition, isometric strength, and aerobic and anaerobic capacity. A clinician conducted medical chart reviews 365 days posttesting to document the incidence of ankle injury. Strength asymmetries were calculated based on the equations most prevalent in the literature along with known physiological predictors of injury in the military: age, height, weight, body composition, and aerobic capacity. Simple logistic regression was conducted using each predictor, and backward stepwise logistic regression was conducted with each equation method and the physiological predictors entered initially into the model. RESULTS: Strength asymmetry or imbalance or both, as a univariate predictor, was not able to predict ankle injury 365 days posttesting. Body mass (P = .01) and body mass index (P = .01) significantly predicted ankle injury. Strength asymmetry or imbalance or both significantly predicted ankle injury when considered with body mass (P = .002-.008). CONCLUSIONS: As a univariate predictor, SA did not predict ankle injury. However, SA contributed significantly to predicting ankle injury in a multivariate model using body mass. Interpreting SA and imbalance in the presence of other physiological variables can help elucidate the risk of ankle injury.

Using Machine Learning to Predict Lower-Extremity Injury in US Special Forces.

INTRODUCTION: Musculoskeletal injury rates in military personnel remain unacceptably high. Application of machine learning algorithms could be useful in multivariate models to predict injury in this population. The purpose of this study was to investigate if interaction between individual predictors, using a decision tree model, could be used to develop a population-specific algorithm of lower-extremity injury (LEI) risk. METHODS: One hundred forty Air Force Special Forces Operators (27.4 ± 5.0 yr, 177.6 ± 5.8 cm, 83.8 ± 8.4 kg) volunteered for this prospective cohort study. Baseline testing included body composition, isokinetic strength, flexibility, aerobic/anaerobic capacity, anaerobic power, and landing biomechanics. To evaluate unilateral landing patterns, subjects jumped off two-feet from a distance (40% of their height) over a hurdle and landing single-legged on a force plate. Medical chart reviews were conducted 365 d postbaseline. χ automatic interaction detection (CHAID) was used, which compares predictor variables to LEI and assigns a population-specific "cut-point" for the most relevant predictors. RESULTS: Twenty-seven percent of operators (n = 38) suffered LEI. A maximum knee flexion angle difference of 25.1% had the highest association with injury in this population (P = 0.006). Operators with >25.1% differences in max knee flexion angle (n = 13) suffered LEI at a 69.2% rate. Seven of the 13 Operators with >25.1% difference in max knee flexion angle weighed >81.8 kg, and 100% of those operators suffered LEI (P = 0.047; n = 7). Only 33% of operators with >25.1% difference in max knee flexion angle that weighed <81.8 kg suffered LEI. CONCLUSIONS: This study demonstrated increased risk of LEI over a 365-d period in Operators with greater differences in single-leg landing strategies and higher body mass. The CHAID approach can be a powerful tool to analyze population-specific risk factors for injury, along with how those factors may interact to enhance risk.

Shared Neuromuscular Performance Traits in Military Personnel with Prior Concussion.

Concussions are common in military personnel and may result in increased risk of musculoskeletal injury. One plausible explanation for this risk could be that neuromotor deficiencies enhance injury risk after a concussion through altered muscular activation/contraction timing. PURPOSE: To compare military personnel with at least one concussion during the past 1 month to 2 yr (CONCUSSED) to military branch-matched, age-matched, and Special Operations Forces group-matched controls (CONTROL) on physiological, musculoskeletal, and biomechanical performance. METHODS: A total of 48 (24 CONCUSSED, 24 CONTROL) male Air Force and Naval Special Warfare Operators age 19 to 34 yr participated in the study. Participants self-reported demographics/injury history and completed the following assessments: 1) physiological-body composition, anaerobic power and capacity, aerobic capacity and lactate threshold; 2) musculoskeletal-lower extremity isokinetic strength testing, including time to peak torque; and 3) biomechanical-single-leg jump and landing task, including landing kinematics of the hip, knee and ankle. A machine learning decision tree algorithm (C5.0) and one-way ANOVA were used to compare the two groups on these outcomes. RESULTS: Despite nonsignificant differences using ANOVA, the C5.0 algorithm revealed CONCUSSED demonstrated quicker time to peak knee flexion angle during the single-leg landing task (≤0.170 s; CONCUSSED: n = 22 vs CONTROL: n = 14), longer time to peak torque in knee extension isokinetic strength testing (>500 ms; CONCUSSED: n = 18 vs CONTROL: n = 4) and larger knee flexion angle at initial contact (>7.7°; CONCUSSED: n = 18 vs CONTROL: n = 2). CONCLUSION: The findings supported the hypothesis that CONCUSSED military personnel would demonstrate altered neuromuscular control in landing strategies and muscular activation. Future research should assess prospectively neuromuscular changes after a concussion and determine if these changes increase risk of subsequent musculoskeletal injuries.