**1. Introduction**

Advancement in knowledge regarding traumatic brain injury (TBI) is incessantly pursued, especially in terms of key terms definition establishment. The exertion of external force on the brain, whether directly or indirectly, which causes disturbance in its structural or functional aspect defines TBI [1–3]. While the former definition is generally accepted, significantly more heterogeneous definitions can be compiled for a term closely related to TBI named concussion.

Most definitions agreed to refer to the constellation of clinical symptoms measured by mainly neurologic and cognitive dysfunctions and not exclusively evident in mild TBI [4, 5]. However, other definitions associate concussion with sports [6, 7], and although there are fundamental overlapping parameters, several areas of multiplicity impede the development of a universally accepted definition. This issue may affect every aspect of TBI as it determines the case definition in any given research.
