Chronic Traumatic Encephalopathy

Traumatic head injuries severe enough to affect the brain and generate clinically evident damage have been described for millennia and continue to represent a major medical, social, and economic concern. Traumatic brain injury (TBI) can be caused by human activities, inventions, or tools (e.g., falls, motor vehicle accidents, contact sports, weapons, etc.). The causes of TBI have undergone changes, having been replaced or modified along the course of human history (e.g., the introduction of new form of transportation, new machines, new weapons, new tools, etc.), and therefore investigators are constantly challenged to engage in scientific efforts to identify specific pathophysiologic mechanisms and more effective treatments, for each type of TBI that appears at each given period of history. TBI, either as a single event (single TBI (sTBI)) or as multiple events (repetitive TBI (rTBI)), can cause short- or long-term pathologic effects on the central nervous system (CNS). These neuropathologic effects can create a wide spectrum of clinical outcomes associated with differing levels of severity that correspond to variable levels of success for both pharmacologic and rehabilitation treatments. In this chapter, we summarize the main features of chronic traumatic encephalopathy (CTE), which is the macroscopic and neurohistological features observed in the brains of persons with a history of TBI, especially rTBI.