The relevance of assessing cerebral metabolic recovery for a safe return to play following concussion

Concussion, a peculiar type of mild traumatic brain injury (mTBI) frequently encountered in sports medicine, is characterized by complex molecular alterations of various important functions of neuronal cells, including mitochondrial-related energy supply, ionic homeostasis, neurotransmitters, N-acetylaspartate (NAA) homeostasis, and even gene expression. Most of these molecular and metabolic derangements are of limited duration (spontaneous recovery of metabolism and cell functions), representing the bases of the metabolic brain vulnerability occurring after mTBI. In this chapter, we describe results of experimental studies evidencing the connections among mTBI, energy metabolism, mitochondrial dysfunctions, and NAA, as well as we summarize results of clinical studies demonstrating that the monitoring of brain metabolism (NAA and creatine) by proton magnetic resonance spectroscopy (1HMRS) is a useful tool to increase the safety of return to play of athletes after a concussion. The application of 1H-MRS in concussed athletes shows that clinical symptoms clear much faster than normalization of brain metabolism. 1H-MRS allows to measure objective parameters of biochemical relevance and is suitable to determine the end of the period of brain vulnerability. This information cannot otherwise be obtained with clinical tests of current use and is important to minimize the risks related to an early return on the field of concussed athletes.