Concussions in sport investigation of assessment measures and functional deficits /

by Thompson, James Wylie

iii One of the least understood, but most common injuries in sports is mild traumatic brain injury (MTBI), otherwise known as concussion. The severity of this injury is often dismissed and is euphemized as a bell-ringer or “ding”. This lack of recognition leads to a gross under-reporting of MTBI in both the general population and in the sporting arena. Mild brain injuries present as a difficult diagnosis for practitioners to manage. The impairments that result subsequent to a concussion are due to a variety of neuropathological processes triggered by damage caused when the brain matter collides with the rough, ridged edges of the skull or due to the rapid acceleration/deceleration and/or rotation of the brain. A lack of objective pathognomic signs of concussion means that a physician’s diagnosis often rests on an athlete’s honest report of subjective symptoms (e.g., headache, irritability, fatigue) that are also common in the nonconcussed population and known to vary day to day. As a result of the varying symptoms of concussions, currently employed tests used in concussion assessment and return to play decisions often give conflicting diagnoses and lack consistent results between testing methods. This has led to skepticism about the utility of these methods. At present, there are no evidence-based medical treatments for concussion that increase the speed or extent of recovery. Therefore, the best approach to concussion management emphasizes early recognition of symptoms, removal from sports and cognitively demanding activities, and prevention of additional concussive injuries. The underlying problem in concussion diagnosis is the application of current assessment methods; onedimensional testing protocols have the potential to miss diagnosing a concussion if the iv tests are not sensitive to an individual’s symptoms or pathology. More advanced testing paradigms are needed that use a combination of testing modalities that are complementary to each other. The aim of this research was to examine the pathological mechanisms of concussion from a multimodal perspective. The pathological mechanisms refer to the disorders in behavior and responses to stimuli that result following concussion. The multimodal perspective combined three testing methods (neuropsychological, postural and electroencephalographic) to ensure a global assessment; neuropsychological, postural under virtual reality conditions and electroencephalographic (EEG) measures. Four main conclusions are drawn from our results. First, neuropsychological symptoms resolve themselves more quickly than do postural or EEG changes. Second, there is a clear mismatch between subjects’ injury classifications when neuropsychological, postural and EEG testing paradigms are compared. Third, the use of a testing paradigm that combines the most sensitive tests from each modality appears to provide a more effective system for diagnostic and return to play measurements than does any one method alone. Lastly, applying low resolution electromagnetic tomographic assessment (LORETA) emerges as an effective tool for localizing cortical areas that have been negatively affected by the concussive injury. The findings are discussed in relation to neural plasticity underlying functional changes and with respect to their clinical implications.