The mechanism of concussion involves a primary and secondary phase of tissue injury. A primary injury is immediate and irreversible, resulting from acceleration/deceleration mechanical damage. Secondary injuries result from non-mechanical damage derived from neuronal cell membrane disruption and axonal stretch. The membrane defects result from secondary injury and lead to ionic influx and accumulation of toxic substances such as glutamate within the nervous system. Individuals with mild concussion recover within a few days; however, 15% of patients with mild concussion suffer from long-term complications largely due to the secondary phase of injury.