Author ORCID Identifier

https://orcid.org/0000-0003-4551-7540

Year of Publication

2020

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Health Sciences

Department

Rehabilitation Sciences

First Advisor

Dr. Matthew C. Hoch

Second Advisor

Dr. Anne D. Olson

Abstract

Sports-related concussions (SRC), or mild traumatic brain injuries that occur as a result of sports or athletic participation, are said to affect approximately 300,000 young adults and 1.4 million youth athletes in the United States on an annual basis. SRC create a significant burden on the health care system by generating an estimated $60 billion dollars in direct and indirect costs in 2000. In addition to the financial burden these injuries create, they additionally impose both short- and long-term effects for those effected and their overall health. Among the many effects of concussions are physical signs as symptoms such as headache, dizziness, emotional/behavioral changes and coordination issues. Traditional diagnosis strategies rely on the individual’s self-report of experienced symptoms. In addition to symptoms, it is well documented that systems within the body are affected by these injuries and manifest in various functional deficits. Among these systems and deficits are those to the vestibular system, which is the system largely responsible for maintaining upright postural stability or balance and the stabilization of gaze during head movements, both crucial in athletic participation. These functions are mediated by the vestibulospinal reflex (VSR) and the vestibulo-ocular reflex (VOR). Advances in technology have made it possible to measure function of these reflexes and identify potential deficits to the system. These advances provide clinicians objective methods of measuring function and may improve current clinical practice and concussion management strategies including better return to play criteria. The primary purpose of this dissertation was to investigate how measures of vestibular function are related to time to medical clearance in athletes with a recent SRC. This dissertation also sought to establish normative estimates for VOR function and explore the relationship between VSR and VOR measures of function. Further, the relationship between objective measures of VSR and VOR function and self-reported symptoms and function was investigated. To achieve this purpose, several aims were investigated. The first aim sought to establish normative values for the DVAT and GST in collegiate athletes and explore the effect of sport, sex, and concussion history on VOR assessments. The second aim explored potential relationships between the Concussion Balance Test (COBALT), Dynamic Visual Acuity Test (DVAT), Gaze Stabilization Test (GST), and self-reported vestibular symptoms in collegiate athletes with and without a history of concussion. The final aim sought to explore potential predictors of prolonged recovery in a sample of adolescent and young adult athletes who have reported to a concussion clinic after sustaining an SRC. This exploratory investigation identified predictors, relative to vestibular function and other factors that influenced the time to recovery. Identified predictors of recovery included the number of days from the injury to the initial visit to the clinic, the number of visits from initial visit to medical clearance, the number of days to a successful COBALT completion. The results of this dissertation begin to provide more information regarding vestibular function as it relates to SRC as well as identifying factors that may be modifiable to improve outcomes. First, through the establishment of normative estimates of vestibular function, it was discovered that there are differences in normative vestibular function based on sports participation. Thus, it may be suggested that vestibular function may be improved based on the requirements and nature of the sport and can be improved with practice. Additionally, the standards for returning to play based on vestibular function should be unique to the activity an athlete is return. Additionally, understanding the relationships between measures of vestibular function may help in the identification of the most efficacious multi-faceted assessment strategy. Finally, identifying predictors of prolonged recovery relative to the vestibular function can aid in improving outcomes. Thus, further justifying the need for more comprehensive assessments.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2020.203

Available for download on Thursday, May 20, 2021

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