Description

Traumatic brain injury (TBI) is caused by externally inflicted trauma that may result in significant impairment of an individual's physical, cognitive, and psychosocial functioning:

• The management of acute TBI is outside the scope of this chapter.

Epidemiology

• Predominant age: Highest incidence in the very young (0–4), in persons 15–24 years of age, and those >75
• Predominant sex: Male > Female (2:1)

• 1.2–1.7 million Americans sustain a TBI per year.
• 50,000 deaths per year
• 80,000–90,000 sustain long-term disabilities.

Prevalence
5.3 million Americans have TBI-related disabilities.

Risk Factors

• High risk: Male, age 15–34
• Moderate risk <5 years and >60 years
• Lower socioeconomic status (head injury)

General Prevention

Improved safety standards and programs designed to minimize injury from vehicular-related events (motor vehicle, motorcycle, bicycle, pedestrian), falls, violence, sports, and recreation provide best prevention against TBI (1)[C].

Pathophysiology

• Cortical contusions due to coup-contrecoup injuries. Although axonal rupture from shear and tensile forces can occur at the time of severe head injury, milder degrees of axonal damage may play a role in mild TBI.
• Disruption of axonal neurofilament organization impairs axonal transport, leading to axonal swelling, Wallerian degeneration, and transection.
• Release of excitatory neurotransmitters acetylcholine, glutamate, and aspartate, and generation of free radicals may contribute to secondary injury.

Etiology

• Falls and motor vehicle accidents (MVAs) are most common causes
• Violence-related TBI increasing (10% of all cases)
• Sports and recreation injuries (especially in teenagers and young adults)

Commonly Associated Conditions

• Psychosis
• Suicide attempts
• Substance abuse
• Attention deficit disorder