Traumatic brain injury (TBI) is any injury to the brain caused by trauma to the head. Motor vehicle accidents are the major cause of TBI in people under age 75. These include accidents involving automobiles, motorcycles, bicycles, and pedestrians. About twenty percent of TBIs are due to violence, such as gunshots and child abuse, and three percent are due to sports injuries. Half of all traumatic brain injuries occur in patients between 15-34 years of age. Men are more likely to suffer a head-injury than women.
A blow or jolt to the head can cause a type of mild brain injury called a concussion. Some symptoms of a concussion are:
- Persistent low-grade headaches
- Having more trouble than usual remembering things, concentrating, or making decisions
- Feeling tired all the time
- Feeling sad, anxious, or listless
- Becoming easily irritated for little or no reason
It's estimated that there are over 3.3 million people in the United States with a TBI-related disability. An April 2008 Rand study found 19% of United States military personnel returning from Iraq and Afghanistan reported possible traumatic brain injuries. A researchers called the prevalence of TBI "a major health crisis". A Dutch study found that 40% of people with brain injuries are able to return to their jobs after one or two years.
Diffuse Axonal Injury
Neurons (cells in the brain and central nervous system) communicate with each other via long fibers called axons. Diffuse axonal injury results from microscopic tearing of these axons caused by stretching and twisting the brain. Torn axons release chemicals that are toxic to nearby neurons, creating additional damage. Diffuse axonal injury can be caused by car accidents (e.g., whiplash), concussions, or abusive or violent events (such as violently shaking a baby). The symptoms of diffuse axonal injury depend on the severity and location of tearing, and can include temporary or permanent cognitive (thinking) impairment, fever, muscle rigidity, high blood pressure, coma, or death. Treatment of diffuse axonal injury is designed to prevent additional damage from occurring and can include medications and/or neurosurgery.