Minimal Detectable Change for the ImPACT Subtests at Baseline.

OBJECTIVE: To establish the minimal detectable change (MDC) of the subtests that comprise the composite scores from remotely administered Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) baselines. METHOD: Remote ImPACT baseline data from 172 (male = 45, female = 127) National Collegiate Athletic Association Division I student-athletes from the 2020 and 2021 athletic preseasons were used to calculate the MDC at the 95%, 90%, and 80% confidence intervals (CIs) for all subtest scores used to generate the four core composite scores and the impulse control composite. RESULTS: The MDCs for the verbal memory subtests at the 95% CI were 10.31 for word memory percent correct, 4.68 for symbol match total correct hidden, and 18.25 for three letters percentage correct. Visual memory subtest MDCs were 19.03 for design memory total percent correct and 4.90 for XO total correct memory. Visual motor speed subtest MDCs were 18.89 for XO total correct interference and 5.40 for three letters average counted correctly. Reaction time (RT) MDCs were 0.12 for XO average correct, 0.95 for symbol match average correct RT, and 0.28 for color match average correct. Impulse control MDCs were 5.97 for XO total incorrect and 1.15 for color match total commissions. One-way repeated measures MANOVA, repeated measures ANOVAs, and Wilcoxon signed-ranks test all suggested no significant difference between any subtests across two remote ImPACT baselines. CONCLUSIONS: The ImPACT subtest scores did not significantly change between athletic seasons. Our study suggests the subtests be evaluated in conjunction with the composite scores to provide additional metrics for clinical interpretation.

Virtual Reality Application for Vestibular/Ocular Motor Screening: Current Clinical Protocol Versus a Novel Prototype.

BACKGROUND: Virtual reality (VR) has been explored to improve baseline and postinjury assessments in sport-related concussion (SRC). Some experience symptoms related to VR, unrelated to concussion. This may deter use of vestibular/ocular motor screening (VOMS) using VR. Baseline VR VOMS symptomatology differentiates baseline from overall symptomatology. HYPOTHESIS: There will be no difference between current clinical manual VOMS (MAN), a clinical prototype (PRO), and VR for symptom provocation change score (SPCS) and near point of convergence (NPC) average score in a healthy population and sex differences among the 3 modes of administration. STUDY DESIGN: Cohort study. LEVEL OF EVIDENCE: Level 3. METHODS: A total of 688 National Collegiate Athletic Association Division I student-athletes completed VOMS using 3 methods (MAN, N = 111; female athletes, N = 47; male athletes, N = 64; average age, 21 years; PRO, N = 365; female athletes, N = 154; male athletes, N = 211; average age, 21 years; VR, N = 212; female athletes, N = 78; male athletes, N = 134; average age = 20 years) over a 3-year period (2019-2021) during annual baseline testing. Exclusion criteria were as follows: self-reported motion sickness in the past 6 months, existing or previous neurological insult, attention deficit hyperactivity disorder, learning disabilities, or noncorrected vision impairment. Administration of MAN followed the current clinical protocols, PRO used a novel prototype, and VR used an HTC Vive Pro Eye head mounted display. Symptom provocation was compared using Mann-Whitney U tests across each VOMS subtest with total SPCS and NPC average by each method. RESULTS: MAN had significantly (P < 0.01) more baseline SPCS (MAN = 0.466 ± 1.165, PRO = 0.163 ± 0.644, VR = 0.161 ± 0.933) and significantly (P < 0.01) and more SPCS (MAN = 0.396 ± 1.081, PRO = 0.128 ± 0.427, VR = 0.48 ± 0.845) when compared with PRO and VR. NPC average measurements for VR (average, 2.99 ± 0.684 cm) were significantly greater than MAN (average, 2.91 ± 3.35 cm; P < 0.01; Cohen's d = 0.03) and PRO (average, 2.21 ± 1.81 cm; P < 0.01; Cohen's d = 0.57). For sex differences, female athletes reported greater SPCS with PRO (female athletes, 0.29 ± 0.87; male athletes, 0.06 ± 0.29; P < 0.01) but not in VR or MAN. CONCLUSION: Using a VR system to administer the VOMS may not elicit additional symptoms, resulting in fewer false positives and is somewhat stable between sexes. CLINICAL RELEVANCE: VOMS may allow for standardization among administrators and reduce possible false positives.

Preliminary Examination of Guardian Cap Head Impact Kinematics Using Instrumented Mouthguards.

CONTEXT: Guardian Caps (GCs) are currently the most popular external helmet-add on designed to reduce the head impact magnitude experienced by American football players. GCs have been endorsed by influential professional organizations, however few studies evaluating the efficacy of GCs are publicly available. OBJECTIVE: The objective of this study is to present preliminary on-field head kinematics data for NCAA Division I American football players using instrumented mouthguards through closely matched pre-season workouts both with and without GCs. DESIGN: Case Series. SETTING: The study took place during the 2022 American football pre-season. PATIENTS OR OTHER PARTICIPANTS: 25 Male NCAA Division I student-athletes participating in American football completed some portion of the 6 workouts included in this study. Of the 25 total participants, 7 completed all 6 workouts using their instrumented mouthguards. MAIN OUTCOME MEASURE(S): The peak linear acceleration (PLA), peak angular acceleration (PAA) and total impacts were collected using instrumented mouthguards (iMG) during 3 pre-season workouts using traditional helmets (TRAD), and 3 with Guardian Caps used in additional to a traditional helmet (GC). The TRAD and GC values for PLA, PAA and total impacts were analyzed using ANOVAs. RESULTS: There was no significant difference between the collapsed mean values for the entire sample between TRAD and GC for PLA (TRAD=16.3±2.0, GC=17.2±3.3Gs; p=0.20), PAA (TRAD=992.1±209.2, GC=1029.4±261.1rad/s2; p=0.51 and the total amount of impacts (TRAD=9.3±4.7, GC=9.7±5.7; p=0.72). Similarly, no difference was observed between TRAD and GC for PLA (TRAD=16.1±1.2, GC=17.2±2.79Gs; p=0.32), PAA (TRAD=951.2±95.4, GC=1038.0±166.8rad/s2; p=0.29 and total impacts (TRAD=9.6±4.2, GC=9.7±5.04s; p=0.32) between sessions for the7 repeated players. CONCLUSIONS: These data suggest no difference in head kinematics data (PLA, PAA and total impacts) when GCs are worn. This study suggests GCs may not be effective in reducing the magnitude of head impacts experienced by NCAA Division I American football players.

Preliminary Examination of Guardian Cap Head Impact Data Using Instrumented Mouthguards.

Purpose The objective of this study is to present preliminary on-field head kinematics data for NCAA Division I American football players through closely matched pre-season workouts both with and without Guardian Caps (GCs). Methods 42 NCAA Division I American football players wore instrumented mouthguards (iMMs) for 6 closely matched workouts, 3 in traditional helmets (PRE) and 3 with GCs (POST) affixed to the exterior of their helmets. This includes 7 players who had consistent data through all workouts. Results There was no significant difference between the collapsed mean values for the entire sample between PRE and POST for peak linear acceleration (PLA) (PRE=16.3, POST=17.2Gs; p=0.20), Peak Angular Acceleration (PAA) (PRE=992.1, POST=1029.4rad/s2; p=0.51 and the total amount of impacts (PRE=9.3, POST=9.7; p=0.72). Similarly, no difference was observed between PRE and POST for PLA (PRE=16.1, POST=17.2Gs; p=0.32), PAA (PRE=951.2, POST=1038.0rad/s2; p=0.29 and total impacts (PRE=9.6, POST=9.7; p=0.32) between sessions for the 7 repeated players. Conclusion These data suggest no difference in head kinematics data (PLA, PAA and total impacts) when GCs are worn. This study suggests GCs are not effective in reducing the magnitude of head impacts experienced by NCAA Division I American football players.

Older adults with a history of falling exhibit altered cortical oscillatory mechanisms during continuous postural maintenance.

Background and Aim: The significant risk of falling in older adults 65 years or older presents a substantial problem for these individuals, their caretakers, and the health-care system at large. As the proportion of older adults in the United States is only expected to grow over the next few decades, a better understanding of physiological and cortical changes that make an older adult more susceptible to a fall is crucial. Prior studies have displayed differences in postural dynamics and stability in older adults with a fall history (FH) and those who are non-fallers (NF), suggesting surplus alterations that occur in some older adults (i.e., FH group) in addition to the natural aging process. Methods: The present study measured postural dynamics while the FH, NF, and young adult (YA) groups performed continuous postural maintenance. In addition, electroencephalography activity was recorded while participants performed upright postural stance to examine any group differences in cortical areas involved in postural control. Results: As expected, older participants (FH and NF) exhibited worse postural stability, as evidenced by increased excursion, compared to the YA group. Further, while NF and YA show increased alpha activity in occipital areas during the most demanding postural task (eyes closed), the FH group did not show any differences in occipital alpha power between postural tasks. Conclusions: As alpha activity reflects suppression of bottom-up processing and thus diversion of cognitive resources toward postural centers during more demanding postural maintenance, deficits in this regulatory function in the FH group are a possible impaired cortical mechanism putting these individuals at greater fall risk. Relevance for Patients: Impaired inhibitory function in older adults may impact postural control and increase their risk of falling. Interventions that aim at addressing cortical processing deficits may improve postural stability and facilitate independent living in this population.

Minimal detectable change for the ImPACT test administered remotely.

CONTEXT: The Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) is one of the most widely used computerized neurocognitive assessment batteries in athletics, serving as both a baseline and post-injury assessment. It has become increasingly popular to administer the ImPACT baseline test in an un-supervised remote environment, however, it is unknown if the lack of supervision affects the test-retest reliability. OBJECTIVE: To establish the minimal detectable change (MDC) of composite scores from the ImPACT test when administered to National Collegiate Athletic Association (NCAA) Division I student-athletes in an un-supervised remote environment before two consecutive athletic seasons. DESIGN: Cross-Sectional. SETTING: Participants were provided with a unique link and detailed written instructions on how to complete the ImPACT test at home. PATIENTS OR OTHER PARTICIPANTS: NCAA Division I student-athletes. MAIN OUTCOME MEASURE(S): Remote ImPACT baseline test results from the 2020-2021 and 2021-2022 athletic seasons were analyzed. The MDC was calculated at the 95%, 90%, and 80% confidence intervals for each of the ImPACT composite scores, as well as the average and standard deviation. RESULTS: The MDC at the 95% confidence interval was found to be 18.6 for the verbal memory composite score, 24.44 for visual memory, 8.76 for visual motor, 0.14 for reaction time, and 6.13 for impulse control. One-way repeated measures MANOVA, repeated measures ANOVA, and Wilcoxon signed-ranks test all suggest no significant difference between the composite scores and impulse control between time points. CONCLUSIONS: The ImPACT test composite scores and impulse control did not significantly change between the two remote testing time points when administered approximately a year between testing. Our study suggests the MDC serve as a clinician's guide for evaluating changes in ImPACT baseline scores and in making clinical judgments on sports-related concussion when the test is administered at home.

A novel smartphone application is reliable for repeat administration and comparable to the Tekscan Strideway for spatiotemporal gait.

Smartphone applications are increasingly being used to measure gait due to their portability and cost-effectiveness. Important reliability metrics are not available for most of these devices. The purpose of this article was to evaluate the test-retest reliability and concurrent validity of spatiotemporal gait using the novel Gait Analyzer smartphone application compared to the Tekscan Strideway. Healthy participants (n=23) completed 12 trials of 10-meter walking, at two separate time points, using Gait Analyzer and while walking across the Tekscan Strideway. The results suggest excellent test-retest reliability for the Gait Analyzer and good test-retest reliability for the Tekscan Strideway for both velocity and cadence. At both time points, these devices were moderately to strongly correlated to one another for both velocity and cadence. These data suggest that the Gait Analyzer and Tekscan Strideway are reliable over time and can comparably calculate velocity and cadence.

Test-Retest Reliability of Remote ImPACT Administration.

OBJECTIVE: To evaluate the performance and test-retest reliability obtained when administering a computerized baseline neurocognitive exam to NCAA Division I student-athletes in a controlled laboratory setting versus an uncontrolled remote location. METHOD: A sample of 129 (female = 100) Division I student-athletes completed Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) pre-season assessments for two distinct and respective sports seasons in a controlled laboratory environment and an uncontrolled remote environment. Depending on the environment, participants were given verbal (controlled) or written (uncontrolled) guidelines for taking the test. RESULTS: Multivariate repeated-measures ANOVA's determined that there were no within-subject differences between testing environments on ImPACT composite scores and cognitive efficiency index (CEI). The Chi-square test did not find any significant differences in impulse control or the number of invalid test scores, as determined by ImPACT, between environments. Intraclass correlations found the ImPACT subtest scores to range in test-retest reliability across testing environments, demonstrating moderate (verbal memory composite, r = 0.46; visual memory composite, r = 0.64; reaction time, r = 0.61; impulse control, r = 0.52; and CEI, r = 0.61) and good (visual motor composite, r = 0.77) test-retest reliability. CONCLUSIONS: Results indicate that ImPACT is reliable between controlled and uncontrolled testing environments. This further suggests that ImPACT can be administered in a remote environment, pending specific adherence to testing instructions, or in the event of social distancing or isolation policies.

Sport-related concussion adopt a more conservative approach to straight path walking and turning during tandem gait.

BACKGROUND: It is currently unknown what specific neuronal deficits influence postural instability following SRC; however, the modulation of postural control relies heavily on the appropriate integration of sensory information from the visual, vestibular, and somatosensory system. It is possible symptom provocation of vestibular or ocular function is related to unsteady gait patterns during tandem gait. AIM: The purpose of this study was to evaluate the differences in temporal and center of pressure (CoP) metrics during discrete events of instrumented tandem gait (iTG) among those with sport-related concussion (SRC) compared to healthy controls. Secondarily, this study attempted to evaluate the relationship between iTG CoP metrics and the Vestibular/Ocular Motor Screening (VOMS) Exam. MATERIALS AND METHODS: 30 collegiate athletes with SRC and 30 healthy controls completed three single task (ST) iTG trials on an instrumented walkway and the VOMS. All individuals with SRC were assessed within 24-48 h post-injury while all controls were measured during pre-participation physicals. CoP metrics in the anteroposterior (AP) and mediolateral (ML) directions and time to completion were evaluated during the first, turn and second pass of iTG between groups. VOMS score was correlated to the CoP metrics across the discrete events. RESULTS: Athletes with SRC took longer to complete tandem gait (P<0.001) along with the first pass, second pass but not the turn when compared to the control group. SRC had slower velocity in the AP direction during both the first (P<0.001) and second pass (P<0.001) with increased postural sway in the ML direction during the first pass (P=0.014). During the turn, athletes with SRC had postural sway in the ML direction (P=0.008). Finally, VOMS score was weakly negatively related to CoP velocity in the AP direction during first (r=-0.39) and second (r=-0.36) pass while being weakly positively related to postural sway during the turn (r=-0.30). CONCLUSIONS: Athletes with SRC adopted a more conservative walking pattern and the presence of vestibular and/or ocular symptoms influence the ability to perform heel-to-toe walking. RELEVANCE FOR PATIENTS: Individuals with SRC will walk slower during heel-to-toe walking and move more in the ML direction with great movement in the ML direction while en pointe turning. This may increase given the total amount of vestibular or vision symptoms following the SRC.

Impaired visual working memory and reduced connectivity in undergraduates with a history of mild traumatic brain injury.

Mild traumatic brain injury (mTBI), or concussion, accounts for 85% of all TBIs. Yet survivors anticipate full cognitive recovery within several months of injury, if not sooner, dependent upon the specific outcome/measure. Recovery is variable and deficits in executive function, e.g., working memory (WM) can persist years post-mTBI. We tested whether cognitive deficits persist in otherwise healthy undergraduates, as a conservative indicator for mTBI survivors at large. We collected WM performance (change detection, n-back tasks) using various stimuli (shapes, locations, letters; aurally presented numbers and letters), and wide-ranging cognitive assessments (e.g., RBANS). We replicated the observation of a general visual WM deficit, with preserved auditory WM. Surprisingly, visual WM deficits were equivalent in participants with a history of mTBI (mean 4.3 years post-injury) and in undergraduates with recent sports-related mTBI (mean 17 days post-injury). In seeking the underlying mechanism of these behavioral deficits, we collected resting state fMRI (rsfMRI) and EEG (rsEEG). RsfMRI revealed significantly reduced connectivity within WM-relevant networks (default mode, central executive, dorsal attention, salience), whereas rsEEG identified no differences (modularity, global efficiency, local efficiency). In summary, otherwise healthy current undergraduates with a history of mTBI present behavioral deficits with evidence of persistent disconnection long after full recovery is expected.

Effects of attention deficit hyperactivity disorder and learning disability on vestibular and ocular baseline concussion assessment in pediatric athletes.

Vestibular and ocular motor assessment has gained popularity as a tool for sport-related concussion among healthcare professionals. With awareness of premorbid risk factors, such as attentional problems, it is imperative to understand their effects at baseline. The purpose of this study was to examine the effects of attention deficit/hyperactivity disorder (ADHD) and diagnosed learning disability (LD) on vestibular and oculomotor baseline concussion assessment in pediatrics. Pediatric athletes between the ages of 8 and 14 years with ADHD/LD (n = 30) and match controls without ADHD/LD (n = 30) completed baseline concussion testing, consisting of symptom provocation on the Vestibular/Ocular Motor Screening (VOMS) and oculomotor performance on near point of convergence (NPC) and King-Devick (K-D) tools. Those diagnosed with ADHD/LD performed worse on baseline saccades (p range = .02-.10), convergence (p = .04), vestibular ocular reflex (VOR) (p = .03) and visual motion sensitivity (VMS) (p = .04) of the VOMS. Base rate analyses revealed that 26% of athletes in the ADHD/LD group had ≥1 and 13.3% had ≥2 VOMS domains over clinical cutoff levels, compared to 3.3% (≥1 domain) and 0 (≥2 domains) of controls. Individuals with ADHD/LD also performed worse on K-D assessment (p = .005). However, no differences were reported on NPC distance (p = .19). These findings suggest worse baseline concussion assessment scores on vestibular/ocular motor assessment domains in pediatric athletes diagnosed with ADHD/LD. Additional research is needed on assessment outcomes to determine if special consideration to those diagnosed with ADHD/LD is warranted.

Impairments in Dynamic Postural Control across Concussion Clinical Milestones.

The aim of this study was to assess gait initiation (GI) performance longitudinally across clinical concussion recovery milestones through return to participation (RTP). We recruited 54 collegiate student-athletes, 27 with concussions and 27 matched controls (15 female and 12 male per group). Participants performed five trials of GI at baseline and again at five post-concussion clinical milestones: 1) Acute, the day clinical tests achieved baseline values on the 2) Balance Error Scoring System (BESS), 3) Immediate Post-Concussion Assessment and Cognitive Test ImPACT, 4) Asymptomatic, and 5) RTP Day. GI performance on six outcome measures (anterior/posterior and medial/lateral center of pressure displacements and velocities during the anticipatory postural adjustment [APA] phase and initial step length and velocity) with repeated-measures mixed model and pair-wise post hoc. A reliable change index (RCI) was calculated, and post-concussion participant's performance was compared to the RCI at milestones. There were significant interactions for APA posterior and lateral displacement, APA posterior velocity, step length, and step velocity. The post-hoc tests identified significant deficits across clinical milestones and at RTP for APA posterior and lateral displacement, step length, and step velocity. There were no post-hoc differences for any outcome measure in the control group. At RTP, 85.2-88.9% of concussion participants had at least one outcome measure which exceeded the 80% or 95% RCI. The primary finding of this study was persistent impairments in dynamic postural control, suggesting ongoing neurophysiological impairment despite clinical recovery. These results suggest that collegiate student-athletes may be RTP before neurophysiological recovery and potentially exposing themselves to elevated risk of recurrent concussion or subsequent musculoskeletal injury.

Repetitive head impacts affect mediolateral postural sway entropy in the absence of vision following a competitive athletic season: preliminary findings.

BACKGROUND: Repetitive head impacts (RHIs) have received more notice over the past decade. More sensitive measures, such as postural control, have been used to evaluate if there are biomechanical changes after RHI exposure. Similar to the clinical findings, most of the studies have failed to find any significant changes across an athletic season. However, these studies included those with a concussion history and only assessed postural control in the eyes open (EO) condition, rather than in both the EO and eyes closed (EC) conditions. AIM: The purpose of this study was to investigate postural control changes during quiet stance following a season of RHI in Division I football athletes who did not have a prior diagnosed signet ring cell compared to a group of non-RHI athletes with no history of a diagnosed sport-related concussion. MATERIALS AND METHODS: Eighteen male Division I athletes were recruited and met the inclusion criteria: Nine football athletes (RHI group) and nine baseball athletes (CON group). All athletes performed three 30 s trials while standing with feet together on a force platform during EC and EO conditions. Center of pressure data was analyzed with sample entropy (SampEn) in the anteroposterior (AP) and mediolateral (ML) directions. SampEn data were analyzed with a three-level linear mixed effects model or the multilevel model, with the three levels being condition, time, and group. RESULTS: The analysis reported no significant effect for SampEn AP, but reported a significant three-way interaction (Group by Task by Time) for SampEn ML. Specifically, SampEn ML was significantly higher for EC than EO for both groups. CONCLUSIONS: There are postural control changes from pre- to post-season, with the main contributor being EC postural control. Thus, there could be a change in the sensory reweighting dynamics due to RHI and the effect of sport. RELEVANCE FOR PATIENTS: RHI may be better assessed in the clinical setting with EC, rather than with EO. Furthermore, clinicians should include tasks that deprive sensory inputs to examine the effects of RHI.

Effects of exercise on symptoms, vestibular/ocular motor screening and postural stability in a college-aged sample.

AIM: To examine the effects of maximal exercise on symptoms, vestibular/ocular motor screening (VOMS) and postural stability. METHODOLOGY: A total of 17 college-aged individuals completed a symptom scale, VOMS and the modified Clinical Test for Sensory Interaction and Balance (m-CTSIB), followed by a graded maximal exercise treadmill test. Assessments were repeated post exercise, 20 and 40 min post-exercise. RESULTS: Significant increases in total symptoms, symptom severity scores and m-CTSIB scores from baseline to immediate post exercise were reported. Following 20-min recovery, improvements were noted on symptoms, visual motion sensitivity on VOMS and m-CTSIB. CONCLUSION: Symptoms and postural stability are influenced by exercise and following 20 min of rest, returned to baseline, indicating that a period of 20 min following a suspected concussion may be needed to negate exercise effects.

Smooth Pursuit and Saccades after Sport-Related Concussion.

Smooth pursuit eye movements (SPEMs) and saccadic eye movements are both commonly impaired following sport-related concussion (SRC). Typical oculomotor assessments measure individual eye movements in a series of restrictive tests designed to isolate features such as response times. These measures lack ecological validity for athletes because athletes are adept at simple tasks designed for the general population. Yet, because eye movement metrics are sensitive and well-characterized neuroanatomically, it would be valuable to test whether athletes exhibit abnormal eye movements with more challenging tasks. To address this gap in knowledge, we collected eye-tracking data during a sport-like task to gain insight on gaze behavior during active self-motion. SPEMs and saccadic eye movements were recorded during a sport-like visual task within 24-48 h following SRC. Thirty-six Division I student-athletes were divided into SRC and control (CON) groups. All participants completed two blocks of the Wii Fit© soccer heading game (WF) while wearing a monocular infrared eye tracker. Eye movement classification systems quantified saccadic amplitude (SA), velocity (SV), and count (SC); as well as SPEM velocity (SPV) and amplitude (SPA). Separate Mann-Whitney U tests evaluated SPA and SC and found no significant effects (SPA, p = 0.11; SC, p = 0.10). A multi-variate analysis of variance (MANOVA) for remaining variables revealed SPV was significantly greater in CON (p < 0.05), but the SRC group had greater SA and SV (p < 0.05). These findings suggest that during a sport-like task, to maintain foveation SRC subjects used larger amplitude, faster saccades, but exhibited slower SPEMs. Measuring oculomotor function during ecologically valid, sport-like tasks may serve as a concussion biomarker and provide insights into eye movement control after SRC.

Deep brain stimulation enhances movement complexity during gait in individuals with Parkinson's disease.

Deep brain stimulation (DBS) is associated with substantial improvements in motor symptoms of PD. Emerging evidence has suggested that nonlinear measures of complexity may provide greater insight into the efficacy of anti-PD treatments. This study investigated sample entropy and complexity index values in individuals with PD when DBS was OFF compared to ON. Five individuals with PD using DBS performed a four-minute treadmill walking task while 3D kinematics were collected over two periods of 30 s. Participants were tested in the DBS-ON and DBS-OFF conditions. Sample entropy (SE) and complexity index (CI) values were calculated for ankle, knee and hip joint angles. Paired samples t-tests were used to compare mean SE and CI values between the DBS-OFF and DBS-ON conditions, respectively. No differences in SE or CI were observed between the DBS-ON and DBS-OFF conditions at the ankle. At the knee, the DBS-ON was associated with greater SE and CI values than the DBS-OFF condition. At the hip, DBS-ON was associated with greater SE and CI values than the DBS-OFF condition. DBS enhances complexity of movement at the hip and knee joints while complexity at the ankle joint is not significantly altered. Greater complexity of knee and hip joint motion may represent increased adaptability and a greater number of available strategies to complete the gait task.

The effect of acute pain on executive function.

BACKGROUND AND AIM: Executive functions are high-level cognitive processes that allow a person to success-fully engage in an independent and self-fulfilling life. Previous literature indicates that chronic pain can affect executive function, but there are limited studies that investigate the effect of acute pain on executive function. The purpose of this study was to determine if acute pain affects executive function in recreationally active indi-viduals who sustained a musculoskeletal injury. METHODS: Twenty-four recreationally active participants who presented with acute pain following a muscu-loskeletal injury underwent a neuropsychological battery within 72 hours of injury. Follow up testing occurred within two weeks from the initial testing session when participants were pain free. Pain intensity was measured using the Visual Analog Scale (VAS). The neuropsychological battery consisted of the following tests: Digit Span (DS), Rey Auditory Verbal Learning Test (RAVLT), and Trail Making Test B (TMT-B). The DS was bro-ken into two separate scores, the RAVLT four scores, and TMT-B one score. Seven paired samples t-tests were conducted using an adjusted alpha level of 0.007. RESULTS: Participants had significantly improved scores when pain free in DS forwards (p < 0.007) and TMT-B (p < 0.007). No significant difference was observed for the DS backward (p = 0.023), RAVLT A1 (p = 0.563), RAVLT sum A1 to A5 (p = 0.953), RAVLT A6 (p = 1.0), RAVLT recognition list A (p = 0.009). These results suggest that immediate recall and complex attention may be diminished in individ-uals who experience acute pain due to a musculoskeletal injury. CONCLUSIONS: Results from this study suggest acute pain from musculoskeletal injuries may disrupt executive function. RELEVANCE FOR PATIENTS: Patients should be aware that there may be cognitive changes after a musculoskeletal injury. Knowing which cognitive domains may be impaired during acute pain could impact clinical practice and further benefit patients suffering from pain and its associated symptoms.

Clinical Assessments of Balance in Adults with Concussion: An Update.

Postural instability is a cardinal indicator of concussion. Assessments of the postural control system range from clinical to laboratory tests that assess the balance of the individual. In a previous article regarding clinical assessment of balance in adults with concussion, we reviewed the importance of balance as a component in concussion evaluations. The purpose of this review article is to update the information previously published in 2014. Since 2014, research has provided evidence for the incorporation of dynamic methods for evaluating balance postconcussion with particular emphasis on sensory system integration and dual tasking. Therefore, this review will examine the current state of knowledge on how concussion injuries affect postural control, advancements in evaluating balance postconcussion, such as novel eye-tracking techniques, and current recommendations for best practices for balance assessment.

Repetitive Head Impacts in Football Do Not Impair Dynamic Postural Control.

PURPOSE: The purpose of this study was to assess the effect of repetitive head impacts experienced by football players compared to noncontact athletes on dynamic postural control during both single-task (ST) and dual-task (DT) conditions. METHODS: Thirty-four football players wearing accelerometer instrumented helmets and 13 cheerleaders performed a dynamic postural control battery, consisting of ST and DT gait initiation, gait, and gait termination, both prior to and following the football season. A 2 (group) × 2 (time) repeated measures ANOVA compared performance across 32 dynamic postural outcomes. A linear regression was performed on postural control change scores with common head impact kinematics serving as the independent variables. RESULTS: The football players experienced a mean of 538.1 ± 409.1 head impacts in the season with a mean linear acceleration of 27.8g ± 3.2g. There were no significant interactions for any of the ST or DT dynamic postural control tasks. There was a significant relationship between head impact kinematics and the lateral center of pressure displacement during the anticipatory postural adjustment phase (r = 0.26, P = 0.010) and transitional phase (r = 0.511, P = 0.042) during ST gait initiation. For both measures, the number of impacts exceeding 98g was the only significant predictor of decreased center of pressure displacement. CONCLUSIONS: A single competitive football season did not adversely affect dynamic postural control when comparing football players to cheerleaders who do not experience repetitive head impacts. Furthermore, there were limited relationships with head impact kinematics suggesting that a single season of football does not adversely affect most outcome measures of instrumented dynamic postural control. These findings are consistent with most studies which fail to identify clinical differences related to repetitive head impacts.

Repetitive head impacts do not affect postural control following a competitive athletic season.

Evidence suggests that Repetitive Head Impacts (RHI) directly influence the brain over the course of a single contact collision season yet do not significantly impact a player's performance on the standard clinical concussion assessment battery. The purpose of this study was to investigate changes in static postural control after a season of RHI in Division I football athletes using more sensitive measures of postural control as compared to a non-head contact sports. Fourteen Division I football players (CON) (age=20.4±1.12years) and fourteen non-contact athletes (NON) (2 male, 11 female; age=19.85±1.21years) completed a single trial of two minutes of eyes open quiet upright stance on a force platform (1000Hz) prior to athletic participation (PRE) and at the end of the athletic season (POST). All CON athletes wore helmets outfitted with Head Impact Telemetry (HIT) sensors and total number of RHI and linear accelerations forces of each RHI were recorded. Center of pressure root mean square (RMS), peak excursion velocity (PEV), and sample entropy (SampEn) in the anteroposterior (AP) and mediolateral (ML) directions were calculated. CON group experienced 649.5±496.8 mean number of impacts, 27.1±3.0 mean linear accelerations, with ≈1% of total player impacts exceeded 98g over the course of the season. There were no significant interactions for group x time RMS in the AP (p=0.434) and ML (p=0.114) directions, PEV in the AP (p=0.262) and ML (p=0.977) directions, and SampEn in the AP (p=0.499) and ML (p=0.984) directions. In addition, no significant interactions for group were observed for RMS in the AP (p=0.105) and ML (p=0.272) directions, PEV in the AP (p=0.081) and ML (p=0.143) directions, and SampEn in the AP (p=0.583) and ML (p=0.129) directions. These results suggest that over the course of a single competitive season, RHI do not negatively impact postural control even when measured with sensitive non-linear metrics.