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Do the Physical Characteristics of a Virtual Reality Device Contraindicate Its Use for Balance Assessment?

Jason P. Mihalik, Luv Kohli, and Mary C. Whitton

Context:

Virtual reality environments may allow researchers to investigate functional balance performance without risks associated with testing in the real world.

Objective:

To investigate the effects of the mass of a head-mounted display (HMD) on balance performance.

Design:

Counterbalanced pretest-posttest.

Setting:

Virtual reality laboratory.

Participants:

20 healthy college students.

Intervention(s):

Balance Error Scoring System (BESS) with a tracker-only headband and again with tracker plus HMD was performed.

Main Outcome Measures:

BESS error scores, elliptical sway area, and center of pressure travel distance were recorded.

Results:

No effect of the HMD mass on balance performance was observed. A significant stance by surface interaction was present but was negated when the HMD conditions were included in the model.

Conclusions:

The mass of a HMD has not been proven to adversely affect balance performance. These data suggest the HMD mass is not a contraindication to the use of immersive virtual environments in future concussion research involving balance.

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Effects of a Single-Task Versus a Dual-Task Paradigm on Cognition and Balance in Healthy Subjects

Luke M. Ross, Johna K. Register-Mihalik, Jason P. Mihalik, Karen L. McCulloch, William E. Prentice, Edgar W. Shields, and Kevin M. Guskiewicz

Context:

Recent evidence has revealed deficiencies in the ability to divide attention after concussion.

Objective:

To examine the effects of a single vs a dual task on cognition and balance in healthy subjects and to examine reliability of 2 dual-task paradigms while examining the overall feasibility of the tasks.

Design:

Pretest–posttest experimental design.

Setting:

Sports medicine research laboratory.

Patients:

30 healthy, recreationally active college students.

Intervention:

Subjects performed balance and cognitive tasks under the single- and dual-task conditions during 2 test sessions 14 d apart.

Main Outcome Measures:

The procedural reaction-time (PRT) test of the Automated Neuropsychological Assessment Metrics (eyes-closed tasks) and an adapted Procedural Auditory Task (PAT; eyes-open tasks) were used to assess cognition. The NeuroCom Sensory Organization Test (SOT) and the Balance Error Scoring System (BESS) were used to assess balance performance. Five 2-way, within-subject ANOVAs and a paired-samples t test were used to analyze the data. ICCs were used to assess reliability across 2 test sessions.

Results:

On the SOT, performance significantly improved between test sessions (F 1,29 = 35.695, P < .001) and from the single to the dual task (F 1,29 = 9.604, P = .004). On the PRT, performance significantly improved between test sessions (F 1,29 = 57.252, P < .001) and from the single to the dual task (F 1,29 = 7.673, P = .010). No differences were seen on the BESS and the PAT. Reliability across test sessions ranged from moderate to poor for outcome measure.

Conclusions:

The BESS appears to be a more reliable and functional tool in dual-task conditions as a result of its increased reliability and clinical applicability. In addition, the BESS is more readily available to clinicians than the SOT.

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Progressive Visual Occlusion and Postural Control Responses in Individuals With and Without Chronic Ankle Instability

Lilly H. VanDeMark, Christina B. Vander Vegt, Cassie B. Ford, Jason P. Mihalik, and Erik A. Wikstrom

Context: Prophylactic and rehabilitative balance training is needed to maximize postural control and develop appropriate sensory organization strategies. Partially occluding vision during functional exercise may promote appropriate sensory organization strategies, but little is known about the influence of partially occluded vision on postural control in those with and without a history of musculoskeletal injury. Objective: To determine the effect of increasing levels of visual occlusion on postural control in a heterogeneous sample of those with and without chronic ankle instability (CAI). The secondary objective was to explore postural control responses to increasing levels of visual occlusion among those with unilateral and bilateral CAI relative to uninjured controls. Design: Cross-sectional. Setting: Sports medicine research laboratory. Patients or Other Participants: Twenty-five participants with unilateral CAI, 10 with bilateral CAI, and 16 participants with no history of lower extremity injury. Main Outcome Measures: All participants completed four 3-minute postural control assessments in double-limb stance under the following 4 visual conditions: (1) eyes open, (2) low occlusion, (3) high occlusion, and (4) eyes closed. Low- and high-occlusion conditions were produced using stroboscopic eyewear. Postural control outcomes included time-to-boundary minima means in the anteroposterior (TTB-AP) and mediolateral directions (TTB-ML). Repeated-measures analysis of variances tested the effects of visual condition on TTB-AP and TTB-ML. Results: Postural control under the eyes-open condition was significantly better (ie, higher) than the limited visual occlusion and eyes-closed conditions (P < .001) for TTB-AP and TTB-ML. For TTB-AP only, partially occluded vision resulted in better postural control than the eyes-closed condition (P ≤ .003). Conclusions: Partial and complete visual occlusion impaired postural control during dual-limb stance in a heterogeneous sample of those with and without CAI. Stroboscopic eyewear appears to induce postural control impairments to the same extent as complete visual occlusion in the mediolateral direction.

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Effects of College Athlete Life Stressors on Baseline Concussion Measures

J.D. DeFreese, Michael J. Baum, Julianne D. Schmidt, Benjamin M. Goerger, Nikki Barczak, Kevin M. Guskiewicz, and Jason P. Mihalik

Context: Concussion baseline testing helps injury evaluation by allowing postinjury comparisons to preinjury measures. To facilitate best practice, common neurocognitive, balance, and symptom report metrics used in concussion baseline testing merit examination relative to participant life stressors. Objective: The purpose of this study was to determine if life stressors are associated with college athlete neurocognitive function, postural control, and symptom scores at preseason baseline assessment. Design: All study variables were collected in a single laboratory session where athletes completed valid and reliable psychometrics as well as a computerized neurocognitive and balance assessments. Setting: Sports medicine research center on an American university campus. Participants: A convenience sample of 123 college student-athletes: 47 females (age = 18.9 [4.3] y) and 76 males (age = 19.4 [1.6] y). Main Outcome Measures: Participants were categorized into low, moderate, or high life stressors groups using scores from the Social Readjustment Rating Scale-Revised. Dependent variables included outcomes from the CNS Vitals Signs test, the Sensory Organization Test, and the graded symptom checklist indexing neurocognition, balance, and symptom severity, respectfully. Results: One-way analysis of variance revealed that the moderate life stressors group performed significantly worse than the low life stressors group on the baseline verbal memory domain of the CNS Vital Signs (F 2,119 = 3.28; P = .04) only. Conclusion: In the current college athlete sample, few baseline concussion assessment variables were found to be significantly associated with life stressors. Considering the clinical significance of these variables, psychological life stressors may not be a confounding factor in concussion evaluation.