Types of Brain Injury
All brain injuries are unique. The brain can receive several different types of injuries depending on the type of force and amount of force that impacts the head. The type of injury the brain receives may affect just one functional area of the brain, various areas, or all areas of the brain.
Traumatic Brain Injury • Acquired Brain Injury • Levels of Brain Injury
Traumatic Brain Injury
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.
- 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 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.
- 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.
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,]).
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.
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
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.
Brain Injury Association of America, Causes of Brain Injury. www.biausa.org
Zasler, N. Brain Injury Source, Volume 3, Issue 3, Ask the Doctor
Levels of Brain Injury Brain Injury
Mild Traumatic Brain Injury (Glasgow Coma Scale score 13-15)
Mild traumatic brain injury occurs when:
- Loss of consciousness is very brief, usually a few seconds or minutes
- Loss of consciousness does not have to occur—the person may be dazed or confused
- Testing or scans of the brain may appear normal
- A mild traumatic brain injury is diagnosed only when there is a change in the mental status at the time of injury—the person is dazed, confused, or loses consciousness. The change in mental status indicates that the person’s brain functioning has been altered, this is called a concussion
Moderate Traumatic Brain Injury (Glasgow Coma Scale core 9-12)
Most brain injuries result from moderate and minor head injuries. Such injuries usually result from a non-penetrating blow to the head, and/or a violent shaking of the head. As luck would have it many individuals sustain such head injuries without any apparent consequences. However, for many others, such injuries result in lifelong disabling impairments.
A moderate traumatic brain injury occurs when:
- A loss of consciousness lasts from a few minutes to a few hours
- Confusion lasts from days to weeks
- Physical, cognitive, and/or behavioral impairments last for months or are permanent.
Persons with moderate traumatic brain injury generally can make a good recovery with treatment or successfully learn to compensate for their deficits.
Severe Brain Injury
Severe head injuries usually result from crushing blows or penetrating wounds to the head. Such injuries crush, rip and shear delicate brain tissue. This is the most life threatening, and the most intractable type of brain injury.
Typically, heroic measures are required in treatment of such injuries. Frequently, severe head trauma results in an open head injury, one in which the skull has been crushed or seriously fractured. Treatment of open head injuries usually requires prolonged hospitalization and extensive rehabilitation. Typically, rehabilitation is incomplete and for most part there is no return to pre-injury status. Closed head injuries can also result in severe brain injury.
TBI can cause a wide range of functional short- or long-term changes affecting thinking, sensation, language, or emotions.
TBI can also cause epilepsy and increase the risk for conditions such as Alzheimer’s disease, Parkinson’s disease, and other brain disorders that become more prevalent with age.1
Repeated mild TBIs occurring over an extended period of time (i.e., months, years) can result in cumulative neurological and cognitive deficits. Repeated mild TBIs occurring within a short period of time (i.e., hours, days, or weeks) can be catastrophic or fatal.
National Institute of Neurological Disorders and Stroke. Traumatic brain injury: hope through research. Bethesda (MD): National Institutes of Health; 2002 Feb. NIH Publication No.: 02-158.
Centers for Disease Control and Prevention (CDC), National Center for Injury Prevention and Control. Report to Congress on mild traumatic brain injury in the United States: steps to prevent a serious public health problem. Atlanta (GA): Centers for Disease Control and Prevention; 2003.
Brain Injury Association of America, Causes of Brain Injury. www.biausa.org