(K-404) Effects of Fatigue on Concussed Individuals

Friday, October 13, 2023

9:30 AM – 10:30 AM PDT

Location: Exhibit Hall - Row K - Poster # 404

Presenting Author(s)

AH

Addie Harmon

Undergraduate Student
LeTourneau University
Wylie, Texas, United States

Co-Author(s)

RW

Riley Warlick

Graduate Student
East Carolina University, United States
BT

Brittany Trotter

PhD Student
East Carolina University, United States

Primary Investigator(s)

NM

Nicholas Murray

Professor
East Carolina University, United States

Introduction:: An estimated 1.6-3.8 million concussions occur in sports activity each year, however this number is still believed to be underestimated due to the number of concussions that are never officially diagnosed [1]. Concussions symptoms can be both cognitive and physical in nature and can persist for long periods of time [2]. Neurological impairment is a major concern post-concussion and can result in an elevated risk of repeat injury. Research has shown there is a higher risk of lower limb musculoskeletal injury after sustaining a concussion [3]. The specific aim of this study was to explore the role fatigue plays in exacerbating the risk of injury after concussion and how concussion ultimately leads to a loss of control.

Materials and Methods:: We recruited 24 participants, 17 healthy and 7 concussed. The inclusion criteria comprised being over the age of 18, having a diagnosed concussion in the last 13 months, as well as no known cardiovascular, renal, or metabolic dysfunction. The participants were fitted with a 32-channel g-Nautilus EEG cap and Polar heartrate monitor. They first completed a 60s go/no-go task in virtual reality (VR). The VR task was comprised of a moving corridor environment and round targets that were presented every 5s. There were two different target variations, one the participant was instructed to respond to and the other they were meant to ignore. This was followed by a volitional fatigue protocol, specifically, the Buffalo Concussion Treadmill Test. After completing the treadmill test, the subjects were refitted with the EEG cap and asked to repeat the initial VR task. Balance data was also collected using a force plate and used to calculate center of pressure, entropy, and mean velocity in both the X and Y directions. Eye tracking data was obtained during the VR task and used to calculate visual reaction time and entropy. EEG recordings were used to compare alpha and theta activity before and after fatigue.

Results, Conclusions, and Discussions::

A repeated measures ANOVA was used to compare metrics between healthy and concussed participants both before and after fatigue. There was no significant difference in visual reaction time and response accuracy between healthy and concussed participants. However, a significant difference was found in approximate entropy for eye movement (p < .05) demonstrating the presence of more random, less controlled reactions to the visual stimuli. Center of pressure in the X (p = 0.032) and Y (p=0.049) directions had numerically significant entropy differences and the sway patterns visually illustrated variation between groups and fatigue status. The concussed group showed a significant increase in alpha wave activity across the frontal regions of the brain post-fatigue (p < 0.01) while the healthy group had no change (p > 0.1). Theta wave activity heatmaps revealed a significant decrease (p < 0.01) in activity across the left central/ motor complex region in the concussed group following exercise. The healthy group experienced no significant change (p > 0.5) in theta activity following exercise across all regions.

Our results indicate that while performance outcomes did not significantly change between populations, concussed individuals required more brain activation to meet the same visual and motor demands as their non-concussed counterparts. The higher entropy in both eye movements and balance also shows a decrease in visuomotor control which also points to higher cognitive demand in concussed individuals.

Acknowledgements (Optional): : This material is based upon work supported by the National Science Foundation under Grant No. 1950507. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

References (Optional): :

[1] Daneshvar DH, Nowinski CJ, McKee AC, Cantu RC. The epidemiology of sport-related concussion. Clin Sports Med. 2011 Jan;30(1):1-17, vii. doi: 10.1016/j.csm.2010.08.006. PMID: 21074078; PMCID: PMC2987636.

[2] J. van der Naalt (2001) Prediction of Outcome in Mild to Moderate Head Injury: A Review, Journal of Clinical and Experimental Neuropsychology, 23:6, 837-851, DOI: 10.1076/jcen.23.6.837.1018

[3] Brooks MA, Peterson K, Biese K, Sanfilippo J, Heiderscheit BC, Bell DR. Concussion Increases Odds of Sustaining a Lower Extremity Musculoskeletal Injury After Return to Play Among Collegiate Athletes. The American Journal of Sports Medicine. 2016;44(3):742-747. doi:10.1177/0363546515622387