Levels of Severity of 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 (Glasgow Coma Scale core 3-8)

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.

Vegetative State (Glasgow Coma Scale less Than 3):

Sleep wake cycles
Aruosal, but no interaction with environment
No localized response to pain

Persistent Vegetative State:

Vegetative state lasting longer than one month

Brain Death:

No brain function
Specific criteria needed for making this diagnosis

Resources and Information can be found at the following:

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

The Frontal Lobe is located just behind the skull of the forehead, and it governs our ability to reason, make judgments, organize information and control some motor/muscle functions

​​Frontal Lobe Functions 
Attention and concentration
Speaking (expressive language) 
Motor planning and initiation
Awareness of abilities and limitations
Mental flexibility
Inhibition of behavior
Problem solving
Planning and anticipation

Complications after Brain Injury

Reference: Mayo Clinic Staff 

Several complications can occur immediately or soon after a traumatic brain injury. Severe injuries increase the risk of a greater number of complications and more-severe complications.

Altered consciousness

Moderate to severe traumatic brain injury can result in prolonged or permanent changes in a person's state of consciousness, awareness or responsiveness. Different states of consciousness include:

Coma. A person in a coma is unconscious, unaware of anything and unable to respond to any stimulus. This results from widespread damage to all parts of the brain. After a few days to a few weeks, a person may emerge from a coma or enter a vegetative state.

Vegetative state. Widespread damage to the brain can result in a vegetative state. Although the person is unaware of his or her surroundings, he or she may open his or her eyes, make sounds, respond to reflexes, or move.

It's possible that a vegetative state can become permanent, but often individuals progress to a minimally conscious state.

Minimally conscious state. A minimally conscious state is a condition of severely altered consciousness but with some evidence of self-awareness or awareness of one's environment. It is often a transitional state from a coma or vegetative condition to greater recovery.

Locked-in syndrome. A person in a locked-in state is aware of his or her surroundings and awake, but he or she isn't able to speak or move. The person may be able to communicate with eye movement or blinking.

This state results from damage limited to the lower brain and brainstem. This rarely occurs after trauma and is more commonly due to a stroke in that area of the brain.

Brain death. When there is no measurable activity in the brain and the brainstem, this is called brain death. In a person who has been declared brain dead, removal of breathing devices will result in cessation of breathing and eventual heart failure. Brain death is considered irreversible.


Some people with traumatic brain injury will have seizures within the first week. Some serious injuries may result in recurring seizures, called post-traumatic epilepsy.

Fluid buildup

Cerebrospinal fluid may build up in the spaces in the brain (cerebral ventricles) of some people who have had traumatic brain injuries, causing increased pressure and swelling in the brain.


Skull fractures or penetrating wounds can tear the layers of protective tissues (meninges) that surround the brain. This can enable bacteria to enter the brain and cause infections. An infection of the meninges (meningitis) could spread to the rest of the nervous system if not treated.

Blood vessel damage

Several small or large blood vessels in the brain may be damaged in a traumatic brain injury. This damage could lead to a stroke, blood clots or other problems.

Nerve damage

Injuries to the base of the skull can damage nerves that emerge directly from the brain (cranial nerves). Cranial nerve damage may result in:

Paralysis of facial muscles
Damage to the nerves responsible for eye movements, which can cause double vision
Damage to the nerves that provide sense of smell
Loss of vision
Loss of facial sensation
Swallowing problems

Intellectual problems

Many people who have had a significant brain injury will experience changes in their thinking (cognitive) skills. Traumatic brain injury can result in problems with many skills, including:

Cognitive problems

Speed of mental processing
Attention or concentration

Executive functioning problems

Beginning or completing tasks

Communication problems

Language and communications problems are common following traumatic brain injuries. These problems can cause frustration, conflict and misunderstanding for people with a traumatic brain injury, as well as family members, friends and care providers.

Communication problems may include:

Cognitive problems

Difficulty understanding speech or writing
Difficulty speaking or writing
Inability to organize thoughts and ideas
Trouble following conversations

Social problems

Trouble with turn taking or topic selection
Problems with changes in tone, pitch or emphasis to express emotions, attitudes or subtle differences in meaning
Difficulty deciphering nonverbal signals
Trouble reading cues from listeners
Trouble starting or stopping conversations
Inability to use the muscles needed to form words (dysarthria)

Behavioral changes

People who've experienced brain injury often experience changes in behaviors. These may include:

Difficulty with self-control
Lack of awareness of abilities
Risky behavior
Inaccurate self-image
Difficulty in social situations
Verbal or physical outbursts

Emotional changes

Emotional changes may include:

Mood swings
Lack of empathy for others
Changes in self-esteem

Sensory problems

Problems involving senses may include:

Persistent ringing in the ears
Difficulty recognizing objects
Impaired hand-eye coordination
Blind spots or double vision
A bitter taste, a bad smell or difficulty smelling
Skin tingling, pain or itching
Trouble with balance or dizziness

Degenerative brain diseases

A traumatic brain injury may increase the risk of diseases that result in the gradual degeneration of brain cells and gradual loss of brain functions, though this risk cannot yet be determined with any certainty for an individual. These include:

Alzheimer's disease, which primarily causes the progressive loss of memory and other thinking skills
Parkinson's disease, a progressive condition that causes movement problems, such as tremors, rigidity and slow movements
Dementia pugilistica — most often associated with repetitive blows to the head in career boxing — which causes symptoms of dementia and movement problems

For more information: ​http://www.mayoclinic.org/diseases-conditions/traumatic-brain-injury/basics/complications/CON-20029302

The Parietal Lobe is near the back and top of the head. It’s involved with visual attention, sensation (touch and pressure) and integration of senses

Parietal Lobe Functions 
Sense of touch 
Spatial perception
Differentiation (identification) of size, shapes, and colors
Visual perception



The Occipital Lobe is located at the back of the skull. This part of the brain controls vision as well as vision processing.

Occipital Lobe Functions 
Vision Processing

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The Temporal Lobes are located on each side of the head above the ears. They control hearing and are related to smell, taste and short-term memory (especially visual and verbal).

Temporal Lobe Functions 
Understanding language (receptive language)


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  ​Brain Injury: I can explain it to you, but I cannot understand it for you

What are the Symptoms of TBI? (may include...) 

Headaches / Irritability / Sadness / Memory Loss / Emotional (more or less) / Mood Changes / Nervousness    

Vomiting / Balance Problems / Dizziness / Fatigue or Drowsiness / Sleep (more or less) / Trouble Sleeping

Sensitivity to Light / Numbness / Tingling / Sensitivity to Noise / Dazed or Stunned / Difficulty Remembering Conversations / Difficulty Concentrating  / Difficulty Making Decisions / Slow Response to Questions / Ringing in the Ears / Mentally Foggy / Feeling Slowed Down