Characterization of neurochemical and physiological changes after brain injury using magnetic resonance spectroscopy
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Liu, Zexuan
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Abstract
Diagnosis and prognosis of brain injury in contact sports, including American football, are challenging. As part of a larger prospective controlled clinical trial, the goal of this thesis was to use magnetic resonance spectroscopy (MRS) to investigate alterations in brain neurochemistry in a cohort of high school athletes over a season of American football as a function of head impact exposure, concussion diagnosis, and application of a jugular vein compression (JVC) collar. Single-voxel MRS data were acquired in 215 male participants in the primary motor cortex (M1) and rostral anterior cingulate cortex (ACC) pre- and post-season. Metabolites of interest included total N-acetylaspartate + N-acetylaspartyl glutamate (tNAA), total glycerophosphocholine + phosphocholine (tCho), myo-inositol (myoI), and glutamine + glutamate (Glx), all relative to total creatine + phosphocreatine (tCr). Group-wise differences in metabolites were determined using Friedman’s or Mann Whitney U tests. Relationships between changes in metabolites/tCr over the season and head impacts with mean g-force thresholds between >20 g and >150 g, in 10 g intervals, were analyzed using linear regressions, accounting for effects of concussion and JVC collar.
Key results included a significant decrease in tCho/tCr and increase in Glx/tCr in the ACC, and significant decrease in myoI/tCr in M1 were observed from pre- to post-season. The relationship between changes in tCho/tCr in both M1 and ACC and head impacts with mean g-force thresholds between >80 g and >140 g differed significantly between participants with and without a diagnosed concussion. Post-hoc analyses revealed increased tCho/tCr was positively associated with impacts for thresholds >100 g and >110 g in M1 in participants with a diagnosed concussion. In the collar group, changes in myoI/tCr in the ACC were significantly and negatively associated with head impacts with mean g-force thresholds of >110, and >120 g.
This is the largest longitudinal study to-date examining the relationship between metabolite alterations measured with MRS and head impact exposure in a cohort of high school football athletes. The associations between changes in tCho/tCr and head impacts at high magnitudes in participants with a diagnosed concussion suggest tCho may be a key indicator for concussion-related brain alterations after repeated head impacts in competitive sports.
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2023-05-02
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