Traumatic brain injury (TBI), considered as an event and/or a disease, initiates a complex pathophysiologic central nervous system cascade with acute effects and secondary insults that may lead to chronic functional, neurocognitive, and neuropsychiatric deficits.
1 Traumatic brain injury is classified according to its degree of severity (mild, moderate, and severe). In the United States, there are more than 3.5 million emergency department visits for TBI and more than 280 000 patients are hospitalized annually with TBI, with most of these classified as mild TBI (mTBI). There are also many more individuals with mTBI who never seek medical attention. More than 300 000 armed service members sustained TBI during combat and training from 2000 to 2014.
2 Approximately half of patients with TBI in the United States incur at least some short-term disability.
3 Traumatic brain injury is associated with an increased risk of neurodegenerative disorders, such as Alzheimer disease, years or decades after injury.
4 In addition, repetitive mTBI is a risk factor for a neurodegenerative condition called chronic traumatic encephalopathy (CTE).
5-7 Chronic traumatic encephalopathy, which can be confirmed only by postmortem neuropathologic examination, is defined by the abnormal accumulation of hyperphosphorylated tau protein (P-tau) in neurons, astroglia, and cell processes distributed around small blood vessels at the depth of cortical sulci in an irregular pattern.
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