Epidemiology, Prevention, and Mechanisms of Brain Injury
Core concepts
Understand population-level patterns of traumatic brain injury (TBI): incidence peaks in young adults (motor vehicle crashes, sports) and older adults (falls), with males overrepresented except in older fall cohorts. Know that falls are the leading cause of TBI-related hospitalization in older adults; motor vehicle crashes and firearm injury dominate severe TBI and mortality. Distinguish intentional from unintentional injury - firearm-related TBI carries the highest case fatality. For stroke, know ischemic versus hemorrhagic proportions and modifiable risk factors. Understand prevention frameworks: primary (prevent the event - helmets, seatbelts, fall-proofing), secondary (early recognition and treatment), tertiary (rehabilitation to limit disability).
Traps
Questions test whether you can separate incidence from case fatality - the most common cause is not always the most lethal. Do not assume all TBI is sports-related; the epidemiologic burden is dominated by falls and MVCs. Remember that repeated mild injury (second impact, chronic traumatic encephalopathy risk) is a distinct mechanism from single severe injury. Chronic subdural hematoma in older adults is often linked to anticoagulation and minor trauma.
Rule of thumb
When asked "most common cause," match the population: older adults → falls; adolescents/young adults → MVCs; severe/fatal → firearms. When asked "most preventable," think primary prevention (helmets, restraints, fall modification).
Worked example
A 78-year-old on warfarin falls and develops progressive confusion over weeks. Think chronic subdural hematoma; the mechanism is bridging-vein tearing with anticoagulant amplification.