Traumatic Brain Injuries – An Introduction for Veterans

This is the first article in a multi-part series covering brain injuries among members of the US Military. Brain injuries can be caused by congenital defects (occurring in the womb and present at birth), hereditary defects (caused by genetic mutations) or degenerative diseases such as Alzheimer’s disease or Parkinson’s disease. However, this article will focus on Traumatic and Non-Traumatic (aka Acquired) brain injuries.

Brain Injuries – Types, Causes, Symptoms & Prevalence Among Veterans

Traumatic brain injuries are caused by some external force that damages the brain. This is most commonly caused by blunt force trauma i.e. your head hitting something or something hitting your head. However, TBI can occur due to rapid deceleration or shaking of your head even if nothing contacts your head.

Acquired brain injuries are non-traumatic and are caused by things such as exposure to toxins, tumors or other health issues.

Traumatic brain injuries fall into three main categories:

  • Primary Brain Injuries are caused by a sudden event that damages the brain such as a fall, a gunshot wound or a car accident
  • Secondary Brain Injuries occur immediately following a primary brain injury and are the result of the brain (or parts of the brain) being deprived of oxygen. This category of brain injury can be caused by many reasons such as choking on vomit while unconscious, restricted airway due to body position or extensive blood loss following the initial injury
  • Tertiary Brain Injuries are the result of the changes that occur within the brain as a result of a primary brain injury. Typically, these changes include a wide array of cellular, tissue, blood vessel and chemical changes that can cause further damage. Secondary brain injuries such as swelling and bleeding are often far more serious than the primary brain injury that triggered them.


Types of Traumatic Brain Injury

  • Contusion is the bruising of brain tissue. Contusions are similar to bruises that might occur anywhere else on the body and involve the leakage of blood from blood vessels and localized swelling of the brain
  • Skull fractures result from blunt force trauma to the head resulting in breaks or cracks in the skull. Any force strong enough to cause a fracture to the skull is also likely to also result in contusion. Depressed skull fractures occur when the break displaces the bone inwards and can result in direct physical damage to the brain caused by the displaced skull fragment
  • Hemorrhages are bleeding within the brain and more commonly known as a stroke. They can be caused by trauma to the head but are normally the result of intravenous hypertension causing blood vessels within the brain to rupture and bleed
  • Hematomas are also referred to as blood clots. As distinct from hemorrhages which refer to ‘active’ bleeding, hematomas are the pooled blood that ‘clots’ following bleeding
  • Diffuse Axonal Injuries refers to widespread damage caused to the long nerve fibers within the brain known as axons. Axons allow different parts of the brain to ‘communicate’ with each other. If enough axons are damaged the brain loses its ability to perform many cognitive functions
  • Ischemia is a diffuse (brain-wide) injury that results from the brain being starved of oxygen. Ischemia can occur from choking, drowning or physical injury preventing a person from breathing.

The Severity of Brain Injuries among Veterans

During the 2020/2021 year there were over 450,000 cases of brain injuries diagnosed among US Military Veterans. The piechart below shows the severity of these cases:

Source: Military Health System (


How is Brain Injury Severity Classified

  • Mild TBI or Concussions are the most common form of TBI. Mild TBIs account for 75% of all traumatic brain injuries. Patients with concussion may feel dizzy or dazed and may experience some confusion and disorientation. Mild TBI patients may even experience a total lack of consciousness. However, to be classified as a mild TBI this lack of consciousness must not last longer than 30 minutes
  • Moderate TBIs are classified by a loss of consciousness of longer than 30 minutes but not longer than 24 hours. Moderate TBI patients may experience confusion and disorientation lasting for up to one week
  • Severe TBIs are classified by a loss of consciousness for 24 hours or longer.


Symptoms of Mild Traumatic Brain Injuries

In addition to the symptoms outlined above that are used to diagnose the severity of TBI other symptoms include:

  • Dizziness and balance problems
  • Confusion and disorientation
  • Headaches
  • Ringing in the ears (tinnitus) and sensitivity to sound (hyperacusis)
  • Problems with vision including sensitivity to light (photophobia)
  • Anxiety & stress
  • Fatigue and sleeping longer than usual


Symptoms of Moderate & Severe Traumatic Brain Injuries

In addition to the symptoms listed for mild TBI, moderate and Severe TBI symptoms can include:

  • Ongoing or repeated nausea
  • Dilated pupils
  • Slurred speech
  • An inability to wake from sleep
  • Headaches that get worse over time
  • Numbness of weakness in the limbs
  • Significant anxiety or agitation
  • Ataxia (loss of coordination)
  • Seizures or convulsions

If you are reading this and you or somebody you know is experiencing any of the symptoms listed above you should seek urgent medical attention as your condition could be life threatening!