What is a Traumatic Brain Injury - TBI?

The Center for Disease Control defines a traumatic brain injury (TBI) as a disruption in the normal function of the brain that can be caused by a bump, blow, or jolt to the head, or penetrating head injury (also known as an open head injury).

​It is important to note that certain types of traumatic brain injury may increase the risk of developing Alzheimer's or another form of Dementia years after the injury takes place.

Concussion (Traumatic Brain Injury - TBI)
Even a concussion can cause substantial difficulties or impairments that can last a lifetime. Whiplash can result in the same difficulties as head injury. Such impairments can be helped by rehabilitation, however many individuals are released from treatment without referrals to brain injury rehabilitation, or guidance of any sort.

• A concussion can be caused by direct blows to the head, gunshot wounds, violent shaking of the head, or force from a whiplash type injury.
• Both closed and open head injuries can produce a concussion. A concussion is the most common type of traumatic brain injury.
• A concussion is caused when the brain receives trauma from an impact or a sudden momentum or movement change. The blood vessels in the brain may stretch and cranial nerves may be damaged.
• A person may or may not experience a brief loss of consciousness.
• A person may remain conscious, but feel dazed.
• A concussion may or may not show up on a diagnostic imaging test, such as a CAT Scan.
• Skull fracture, brain bleeding, or swelling may or may not be present. Therefore, concussion is sometimes defined by exclusion and is considered a complex neurobehavioral syndrome.
• A concussion can cause diffuse axonal type injury resulting in temporary or permanent damage.
• A blood clot in the brain can occur occasionally and be fatal.
• It may take a few months to a few years for a concussion to heal.

Contusion (Traumatic Brain Injury - TBI)

• A contusion can be the result of a direct impact to the head.
• A contusion is a bruise (bleeding) on the brain.
• Large contusions may need to be surgically removed.

Coup-Contrecoup (Traumatic Brain Injury - TBI)

• Coup-Contrecoup Injury describes contusions that are both at the site of the impact and on the complete opposite side of the brain.
• This occurs when the force impacting the head is not only great enough to cause a contusion at the site of impact, but also is able to move the brain and cause it to slam into the opposite side of the skull, which causes the additional contusion.

Diffuse Axonal (Traumatic Brain Injury - TBI)

• A Diffuse Axonal Injury can be caused by shaking or strong rotation of the head, as with Shaken Baby Syndrome, or by rotational forces, such as with a car accident.
• Injury occurs because the unmoving brain lags behind the movement of the skull, causing brain structures to tear.
• There is extensive tearing of nerve tissue throughout the brain. This can cause brain chemicals to be released, causing additional injury.
• The tearing of the nerve tissue disrupts the brain’s regular communication and chemical processes.
• This disturbance in the brain can produce temporary or permanent widespread brain damage, coma, or death.
• A person with a diffuse axonal injury could present a variety of functional impairments depending on where the shearing (tears) occurred in the brain.

Penetration /  Open (Traumatic Brain Injury - TBI)
Penetrating injury to the brain occurs from the impact of a bullet, knife or other sharp object that forces hair, skin, bones and fragments from the object into the brain.

• Objects traveling at a low rate of speed through the skull and brain can ricochet within the skull, which widens the area of damage.
• A “through-and-through” injury occurs if an object enters the skull, goes through the brain, and exits the skull. Through-and-through traumatic brain injuries include the effects of penetration injuries, plus additional shearing, stretching and rupture of brain tissue. (Brumback R. (1996). Oklahoma Notes: Neurology and Clinical Neuroscience. (2nd Ed.). New York: Springer.)
• The devastating traumatic brain injuries caused by bullet wounds result in a 91% firearm-related death rate overall. (Center for Disease Control. [Online August 22, 2002: http://www.cdc.gov/ncipc/didop/tbi.htm#rate,]).
• Firearms are the single largest cause of death from traumatic brain injury. (Center for Disease Control. [Online August 22, 2002: http://www.cdc.gov/ncipc/didop/tbi.htm#rate,]).

Types and Levels of Brain Injuries

Acquired Brain Injury
Acquired Brain Injury, (ABI), results from damage to the brain caused by strokes, tumors, anoxia, hypoxia, toxins, degenerative diseases, near drowning and/or other conditions not necessarily caused by an external force.

Anoxia

Anoxic Brain Injury occurs when the brain does not receive any oxygen. Cells in the brain need oxygen to survive and function.

Types of Anoxic Brain Injury
>> Anoxic Anoxia- Brain injury from no oxygen supplied to the brain
>> Anemic Anoxia- Brain injury from blood that does not carry enough oxygen
>> Toxic Anoxia- Brain injury from toxins or metabolites that block oxygen in the blood from being used Zasler, N. Brain Injury Source, Volume 3, Issue 3, Ask the Doctor

Hypoxic
A Hypoxic Brain Injury results when the brain receives some, but not enough oxygen.

Types of Hypoxic Brain Injury
Hypoxic Ischemic Brain Injury, also called Stagnant Hypoxia or Ischemic Insult- Brain injury occurs because of a lack of blood flow to the brain because of a critical reduction in blood flow or blood pressure.

Mild Cognitive Impairment (MCI)

Mild cognitive impairment (MCI) is an intermediate stage between the expected cognitive decline of normal aging and the more-serious decline of dementia. It can involve problems with memory, language, thinking and judgment that are greater than normal age-related changes.

If you have mild cognitive impairment, you may be aware that your memory or mental function has "slipped." Your family and close friends also may notice a change. But generally these changes aren't severe enough to significantly interfere with your day-to-day life and usual activities.

Mild cognitive impairment may increase your risk of later progressing to dementia, caused by Alzheimer's disease or other neurological conditions. But some people with mild cognitive impairment never get worse, and a few eventually get better.

CAUSES:

Current evidence indicates that MCI often, but not always, arises from a lesser degree of the same types of brain changes seen in Alzheimer's disease or other forms of dementia. Some of these changes have been identified in autopsy studies of people with MCI. These changes include:

• Abnormal clumps of beta-amyloid protein (plaques) and microscopic protein clumps of tau characteristic of Alzheimer's disease (tangles)
  
• Lewy bodies, which are microscopic clumps of another protein associated with Parkinson's disease, dementia with Lewy bodies and some cases of Alzheimer's disease
  
• Small strokes or reduced blood flow through brain blood vessels
  

Brain-imaging studies show that the following changes may be associated with MCI:

• Shrinkage of the hippocampus, a brain region important for memory
• Enlargement of the brain's fluid-filled spaces (ventricles)
  
• Reduced use of glucose, the sugar that's the primary source of energy for cells, in key brain regions