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Table 1 Head trauma terminology

From: Identifying degenerative effects of repetitive head trauma with neuroimaging: a clinically-oriented review

Head trauma terminology Definitions and typical contexts
Traumatic Brain Injury (TBI) Symptomatic injury often requiring presence of either loss of consciousness (LOC) or posttraumatic amnesia (PTA)
Crudely delineated as “mild,” “moderate,” or “severe” based on duration of LOC or PTA or using Glasgow Coma Scale score
More commonly applied in studies of civilian populations in emergency department settings or military servicemembers and veterans than in sport-related head trauma settings
Concussion Symptomatic injury often considered interchangeable with “mild TBI”
In sport settings, concussion diagnoses frequently are made without documented LOC or PTA, but based on presence of other head trauma-associated symptoms like headache, dizziness, poor balance, nausea, or eye movement abnormalities, among others
Instances of “getting your bell rung,” “seeing stars,” or “clearing the cobwebs” typically qualify for a concussion diagnosis
Subconcussive Trauma Asymptomatic head impacts usually occurring in the context of collision sports
In collision sports like American football, athletes may sustain tens of thousands of asymptomatic, subconcussive head impacts in the course of an extended playing career
In military settings, servicemembers may experience subconcussive exposure in the form of repeated blast exposures or training activities (e.g., breacher or combat training) without associated acute clinical symptoms
Traumatic Encephalopathy Syndrome (TES) Research criteria proposed for classifying cognitive and neurobehavioral symptoms believed to be associated with repetitive head trauma and with onset typically years after last head trauma exposure
TES diagnostic criteria have high sensitivity but low specificity to underlying CTE neuropathology
In this review, “TES” refers to study populations defined by clinical symptomatology in the context of prior repetitive head trauma, without presumption of underlying CTE neuropathology
Chronic Traumatic Encephalopathy (CTE) Neuropathologic changes found in the brain per consensus diagnostic criteria (phosphorylated tau protein aggregates in neurons around blood vessels at the depths of cortical sulci)
CTE diagnosis is made independent of patient symptoms during life
In this review, “CTE” refers only to study populations with autopsy-confirmed evidence of CTE neuropathology
  1. Several terms lack consensus and there remains controversy regarding optimal characterization. These definitions were applied in the manuscript but may not directly overlap with use in other brain injury settings