Traumatic brain injury overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Traumatic brain injury (TBI) occurs when physical trauma causes brain damage. TBI can result from a closed head injury or a penetrating head injury and is one of two subsets of acquired brain injury (ABI). The other subset is non-traumatic brain injury, or injuries that do not involve external mechanical force (e.g. stroke, meningitis, anoxia). Parts of the brain that can be damaged include the cerebral hemispheres, cerebellum, and brain stem.
TBI can be mild, moderate, or severe, depending on the extent of the damage to the brain. TBI can cause a host of physical, cognitive, emotional, and social effects. Outcome can be anything from complete recovery to permanent disability or death.
Historical perspective
Classification
- Traumatic brain injury may be classified as either
- Focal vs. diffuse
- Open vs. closed
- Mild, moderate or severe
Pathophysiology
Unlike most forms of traumatic death, a large percentage of the people killed by brain trauma do not die right away but rather days to weeks after the event. Rather than improving after being hospitalized, some 40% of TBI patients deteriorate. Primary injury (the damage that occurs at the moment of trauma when tissues and blood vessels are stretched, compressed, and torn) is not adequate to explain this degeneration. Rather, the deterioration is caused by secondary injury, a complex set of biochemical cascades that occur in the minutes to days following the trauma and contribute a large amount to morbidity and mortality from TBI.
Causes
Transportation accidents involving automobiles, motorcycles, bicycles, and pedestrians cause half of all TBIs and the largest portion of TBI in people under age 75.[1] For those aged 75 and older, falls cause the majority of TBIs.[1] Approximately 20% of TBIs are due to violence, such as firearm assaults and child abuse, and about 3% are due to sports injuries.[1] Half of TBI incidents involve alcohol use.[1]
Differentiating Traumatic Brain Injury from other Diseases
Epidemiology and Demographics
Risk factors
Natural History, Complications and Prognosis
Natural history
Complications
The results of traumatic brain injury vary widely in type and duration. A head injured patient may experience physical effects of the trauma such as headaches, movement disorders (e.g. Parkinsonism), seizures, difficulty walking, sexual dysfunction, lethargy, or coma. Cognitive symptoms include changes in judgment or ability to reason or plan, memory problems, and loss of mathematical ability. Emotional problems include mood swings, poor impulse control, agitation, low frustration threshold, self-centeredness, clinical depression, and psychotic symptoms such as hallucinations and delusions.
Prognosis
Traumatic brain injury is a frequent cause of major long-term disability in individuals surviving head injuries sustained in war zones. This is becoming an issue of growing concern in modern warfare, in which rapid deployment of acute interventions is effective in saving the lives of combatants with significant head injuries. Traumatic brain injury has been identified as the "signature injury" among wounded soldiers of the current military engagement in Iraq.
Diagnosis
History and Symptoms
Physical Examination
Head injured people with signs of moderate or severe TBI should receive immediate emergency medical attention.
Laboratory Findings
X Ray
CT
MRI
Other Imaging Findings
Other Diagnostic Studies
Treatment
Medical Therapy
Surgery
Primary prevention
Rehabilitation
Cost-Effectiveness of Therapy
Future or Investigational Therapies
References
- ↑ 1.0 1.1 1.2 1.3 Traumatic Brain Injury: Hope Through Research. NINDS. Publication date February 2002. NIH Publication No. 02-2478. Prepared by: Office of Communications and Public Liaison, National Institute of Neurological Disorders and Stroke, National Institutes of Health