Defining Concussion and Mild Traumatic Brain Injury: a History of Confusion and Debate

As the understanding of the brain has evolved throughout history, so too has the understanding of brain injury and concussion. To this day, there is still debate over the definition of concussion, and what it entails. Some definitions, including that of the Merriam-Webster Dictionary, define a concussion as " (a) …a jarring injury of the brain, or (b) a hard blow or collision " [1], whereas the Center for Disease Control defines a concussion as a " complex pathophysiologic process affecting the brain, induced by traumatic biomechanical forces secondary to direct or indirect forces to the head " [2]. In the first definition, the concussion is the act of the physical blow; in the second definition the concussion is the state of having abnormal brain function after a blow to the head. These distinctions have evolved from various hypotheses about head injuries throughout history, and today they are often used interchangeably. In this essay I will outline the history of knowledge of head injury and concussion, in parallel with increased knowledge of neuroscience and the brain, followed by an analysis of current day texts and terms used in an attempt to better understand the history of the term and the modern day use of the word. Descriptions of head injuries date back to ancient times, as documented by the Egyptians, Greek, and Romans. Egyptian records have been found describing head injuries that were associated with disturbances in speech [3], which today we consider a symptom of concussion. Although there are many Roman recordings of head injury, they all appear to be lumped together [3], and there is no evident distinction of concussion from other types of head injuries. A translation of the Hippocratic corpus from ancient Greece says, " …In cerebral concussion, whatever the cause, the patient becomes speechless…falls down immediately, loses their speech, cannot see and hear… " [3]. However, it is unclear what exactly Hippocrates is describing as the concussion, whether it is the initial blow and the loss of consciousness that ensues, or the lingering symptoms of what we now call a concussion in the days following the injury. Perhaps he is combining both under one term. However, even though this clinical description of concussion existed, the term concussion had not yet been coined, and was inserted into this translation by modern day translators [3]. Hippocrates, the father of Western medicine, was the first scholar to state …