The physical injury to the brain is graded on a spectrum in categories termed mild, moderate, and severe. The severity of physical injury to the brain is a major factor in determining the ultimate outcome for the brain injured person. However, the level of injury to the brain is not always fully predictive in determining the level of future recovery.

The factors considered in grading brain injury generally include the following:

  • Glasgow Coma Scale score
  • Duration of loss of consciousness
  • Duration of post-traumatic amnesia

Glasgow Coma Scale (GCS)

The GCS is commonly used by emergency medical personnel in the initial assessment of the severity of physical insult to the brain. Typically, the GCS is assessed by paramedics in the field and again by triage personnel in the emergency department.

Glasgow Coma Scale
  • Eye Opening (E)

    3=To voice
    2=To pain

  • Verbal Response (V)

    5=Normal conversation
    4=Disoriented conversation
    3=Words, but not coherent
    2=No words…only sounds

  • Motor Response (M)

    5=Localizes to pain
    4=Withdraws to pain
    3=Decorticate posture

Total = E+V+M

Post-Traumatic Amnesia

Post-traumatic amnesia (PTA) can be generally defined as the period following injury during which the injured person is not fully conscious or aware of events occurring after the injuring event. Although the term PTA usually refers to the memory of events subsequent to the injury (anterograde amnesia), it is sometimes used to refer to events prior to the injury (retrograde amnesia). Memory problems may be due to either an actual memory disorder or to impaired ability to attend to or mentally acquire material.

Mild TBI

A widely accepted definition of mild traumatic brain injury is that developed and adopted by the American Congress of Rehabilitation Medicine in 1993. It is printed in the Journal of Head Trauma Rehabilitation as follows:

Definition of TBI

A patient with mild traumatic brain injury is a person who has had a traumatically induced physiological disruption of brain function, as manifested by at least one of the following:

  1. Any period of loss of consciousness;
  2. any loss of memory for events immediately before or after the accident;
  3. any alteration in mental state at the time of the accident (e.g., feeling dazed, disoriented, or confused); and
  4. focal neurological deficit(s) that may or may not be transient;

Mild TBI Micrographic

But where the severity of the injury does not exceed the following:

  • Loss of consciousness of approximately 30 minutes or less;
  • After 30 minutes, an initial Glasgow Coma Scale (GCS) of 13-15;
  • Posttraumatic amnesia (PTA) not greater than 24 hours.

Definition Comments

This definition includes: 1) the head being struck, 2) the head striking an object, and 3) the brain undergoing an acceleration/ deceleration movement (ie, whiplash) without direct external trauma to the head. It excludes stroke, anoxia, tumor, encephalitis, etc. Computed tomography, magnetic resonance imaging, electroencephalogram or routine neurological evaluations may be normal. Due to the lack of medical emergency, or the realities of certain medical systems, some patients may not have the above factors medically documented in the acute stage. In such cases, it is appropriate to consider symptomatology that, when linked to a traumatic head injury, can suggest the existence of a mild traumatic brain injury.


The above criteria define the event of a mild traumatic brain injury. Symptoms of brain injury may or may not persist, for varying lengths of time, after such a neurological event. It should be recognized that patients with mild traumatic brain injury can exhibit persistent emotional, cognitive, behavioral, and physical symptoms, alone or in combination, which may produce a functional disability. These symptoms generally fall into one of the following categories, and are additional evidence that a mild traumatic brain injury has occurred:

  1. physical symptoms of brain injury (eg, nausea, vomiting, dizziness, headache, blurred vision, sleep disturbance, quickness to fatigue, lethargy, or other sensory loss) that cannot be accounted for by peripheral injury or other causes;
  2. cognitive deficits (eg, involving attention, concentration, perception, memory, speech/language, or executive functions) that cannot be completely accounted for by emotional state or other causes; and
  3. behavioral change(s) and/or alterations in degree of emotional responsivity (eg, irritability, quickness to anger, disinhibition, or emotional lability) that cannot be accounted for by a psychological reaction to physical or emotional stress or other causes.

Symptomatology Comments

Some patients may not become aware of, or admit, the extent of their symptoms until they attempt to return to normal functioning. In such cases, the evidence for mild traumatic brain injury must be reconstructed. Mild traumatic brain injury may also be overlooked in the face of more dramatic physical injury (eg, orthopedic or spinal cord injury). The constellation of symptoms has previously been referred to as minor head injury, post-concussive syndrome, traumatic head syndrome, traumatic cephalgia, post-brain injury syndrome and posttraumatic syndrome.

Journal of Head Trauma Rehabilitation (1993:8(3):86-87).

It is important to note that any alteration in consciousness is sufficient to support the diagnosis of mild TBI; a complete loss of consciousness is not required. Moreover, brain injury of any severity can occur upon rapid acceleration/deceleration movement (i.e., whiplash) without direct trauma to the head. Such movement can produce axonal shearing, sometimes called diffuse axonal injury, in the brain. Axonal shearing is often present even when not apparent on CT or MRI imaging studies.

Moderate TBI

Moderate brain injuries are generally defined as those in which a GCS of 9 to 12 has been recorded; the duration of low of consciousness was 30 minutes to one week; the duration of PTA was greater than 24 hours but not more than one (1) week. Moderate brain injuries often produce positive findings such as contusions or bleeding on CT or MRI imaging studies.

Severe TBI

Severe brain injuries are generally defined as those in which a GCS score of 8 or below was recorded, the duration of loss of consciousness was greater than one (1) week; the duration of PTA exceeded one (1) week. Severe brain injuries can be expected in most instances to produce positive findings on imaging studies. Such findings may include not only contusions or bleeding but may also manifest in herniations of brain tissue or shifts in location of one or more portions of the brain.

Outcome After TBI

Various studies regarding the long-term consequences after brain injury provide different statistics and measures. Generally, it can be said that 85-95% of persons who have suffered a mild TBI will make a complete recovery. Some heath care professionals believe that this percentage is overstated because most people who make a full recovery are adequately assessed and evaluated, while some people who have not fully recovered fall through the cracks in the health care system and are not provided with adequate follow up evaluation or care. The percentage of persons who have suffered a moderate brain injury who subsequently make a full recovery can be estimated at about 60%. Severe brain injury survivors generally make a full recovery in about 15-20% of the cases.

Traumatic Brain Injury Recovery

Recovery from brain injury is usually evaluated at established markers. Typically, assessments in the progress of recovery are made at the one week, one month, three month, six month, one year and two year marks. Most brain injury professionals agree that if a person has not made a complete recovery after two years, it is unlikely that full recovery with complete cessation of all sequelae will occur. However, additional progress to minimize or negate the consequences of brain injury can continue with additional progress even years after injury. It should be further noted that the farther along the initial two-year continuum an injury survivor progresses without full resolution, the less the chance that full resolution occurs. This means that a person who has not made a full recovery at the one (1) year mark has less chance to make a full recovery than a like person only six (6) months post injury. This suggests that it is important that early evaluations be conducted and treatment interventions established so that the brain injury survivor can maximize his/her chances for complete recovery.

Outcome of the brain injury is sometimes measured using the Glasgow Outcome Scale. This scale is not fully specific in the criteria for measuring ongoing disability, but it does provide for major classification categories including death, persistent vegetative state, severe disability, moderate disability, and good recovery. It should be noted that good recovery does not necessarily mean complete recovery.

Outcome is sometimes measured in the recovery phase by use of the Rancho Los Amigos Scale-Revised. This scale can be used to asses the effectiveness of treatment. The scale is divided into nine (9) classifications as set forth below:

Level I – No Response: Total Assistance

  • Complete absence of observable change in behavior when presented visual, auditory, tactile, proprioceptive, vestibular or painful stimuli.

Level II – Generalized Response: Total Assistance

  • Demonstrates generalized reflex response to painful stimuli.
  • Responds to repeated auditory stimuli with increased or decreased activity.
  • Responds to external stimuli with physiological changes generalized, gross body movement and/or not purposeful vocalization.
  • Responses noted above may be same regardless of type and location of stimulation.
  • Responses may be significantly delayed.

Level III – Localized Response: Total Assistance

  • Demonstrates withdrawal or vocalization to painful stimuli.
  • Turns toward or away from auditory stimuli.
  • Blinks when strong light crosses visual field.
  • Follows moving object passed within visual field.
  • Responds to discomfort by pulling tubes or restraints.
  • Responds inconsistently to simple commands.
  • Responses directly related to type of stimulus.
  • May respond to some persons (especially family and friends) but not to others.

Level IV – Confused/Agitated: Maximal Assistance

  • Alert and in heightened state of activity.
  • Purposeful attempts to remove restraints or tubes or crawl out of bed.
  • May perform motor activities such as sitting, reaching and walking but without any apparent purpose or upon another’s request.
  • Very brief and usually non-purposeful moments of sustained alternatives and divided attention.
  • Absent short-term memory.
  • May cry out or scream out of proportion to stimulus even after its removal.
  • May exhibit aggressive or flight behavior.
  • Mood may swing from euphoric to hostile with no apparent relationship to environmental events.
  • Unable to cooperate with treatment efforts.
  • Verbalizations are frequently incoherent and/or inappropriate to activity or environment.

Level V – Confused, Inappropriate Non-Agitated: Maximal Assistance

  • Alert, not agitated but may wander randomly or with a vague intention of going home.
  • May become agitated in response to external stimulation, and/or lack of environmental structure.
  • Not oriented to person, place or time.
  • Frequent brief periods, non-purposeful sustained attention.
  • Severely impaired recent memory, with confusion of past and present in reaction to ongoing activity.
  • Absent goal directed, problem solving, self-monitoring behavior.
  • Often demonstrates inappropriate use of objects without external direction.
  • May be able to perform previously learned tasks when structured and cues provided.
  • Unable to learn new information.
  • Able to respond appropriately to simple commands fairly consistently with external structures and cues.
  • Responses to simple commands without external structure are random and non-purposeful in relation to command.
  • Able to converse on a social, automatic level for brief periods of time when provided external structure and cues.
  • Verbalizations about present events become inappropriate and confabulatory when external structure and cues are not provided.

Level VI – Confused, Appropriate: Moderate Assistance

  • Inconsistently oriented to person, time and place.
  • Able to attend to highly familiar tasks in non-distracting environment for 30 minutes with moderate redirection.
  • Remote memory has more depth and detail than recent memory.
  • Vague recognition of some staff.
  • Able to use assistive memory aide with maximum assistance.
  • Emerging awareness of appropriate response to self, family and basic needs.
  • Moderate assist to problem solve barriers to task completion.
  • Supervised for old learning (e.g. self care).
  • Shows carry over for relearned familiar tasks (e.g. self care).
  • Maximum assistance for new learning with little or nor carry over.
  • Unaware of impairments, disabilities and safety risks.
  • Consistently follows simple directions.
  • Verbal expressions are appropriate in highly familiar and structured situations.

Level VII – Automatic, Appropriate: Minimal Assistance for Daily Living Skills

  • Consistently oriented to person and place, within highly familiar environments. Moderate assistance for orientation to time.
  • Able to attend to highly familiar tasks in a non-distraction environment for at least 30 minutes with minimal assist to complete tasks.
  • Minimal supervision for new learning.
  • Demonstrates carry over of new learning.
  • Initiates and carries out steps to complete familiar personal and household routine but has shallow recall of what he/she has been doing.
  • Able to monitor accuracy and completeness of each step in routine personal and household ADLs and modify plan with minimal assistance.
  • Superficial awareness of his/her condition but unaware of specific impairments and disabilities and the limits they place on his/her ability to safely, accurately and completely carry out his/her household, community, work and leisure ADLs.
  • Minimal supervision for safety in routine home and community activities.
  • Unrealistic planning for the future.
  • Unable to think about consequences of a decision or action.
  • Overestimates abilities.
  • Unaware of others’ needs and feelings.
  • Oppositional/uncooperative.
  • Unable to recognize inappropriate social interaction behavior.

Level VIII – Purposeful, Appropriate: Stand-By Assistance

  • Consistently oriented to person, place and time.
  • Independently attends to and completes familiar tasks for 1 hour in distracting environments.
  • Able to recall and integrate past and recent events.
  • Uses assistive memory devices to recall daily schedule, “to do” lists and record critical information for later use with stand-by assistance.
  • Initiates and carries out steps to complete familiar personal, household, community, work and leisure routines with stand-by assistance and can modify the plan when needed with minimal assistance.
  • Requires no assistance once new tasks/activities are learned.
  • Aware of and acknowledges impairments and disabilities when they interfere with task completion but requires stand-by assistance to take appropriate corrective action.
  • Thinks about consequences of a decision or action with minimal assistance.
  • Overestimates or underestimates abilities.
  • Acknowledges others’ needs and feelings and responds appropriately with minimal assistance.
  • Depressed.
  • Irritable.
  • Low frustration tolerance/easily angered.
  • Argumentative.
  • Self-centered.
  • Uncharacteristically dependent/independent.
  • Able to recognize and acknowledge inappropriate social interaction behavior while it is occurring and takes corrective action with minimal assistance.

Level IX – Purposeful, Appropriate: Stand-By Assistance on Request

  • Independently shifts back and forth between tasks and completes them accurately for at least two consecutive hours.
  • Uses assistive memory devices to recall daily schedule, “to do” lists and record critical information for later use with assistance when requested.
  • Initiates and carries out steps to complete familiar personal, household, work and leisure tasks independently and unfamiliar personal, household, work and leisure tasks with assistance when requested.
  • Aware of and acknowledges impairments and disabilities when they interfere with task completion and takes appropriate corrective action but requires stand-by assist to anticipate a problem before it occurs and take action to avoid it.
  • Able to think about consequences of decisions or actions with assistance when requested.
  • Accurately estimates abilities but requires stand-by assistance to adjust to task demands.
  • Acknowledges others’ needs and feelings and responds appropriately with stand-by assistance.
  • Depression may continue.
  • May be easily irritable.
  • May have low frustration tolerance.
  • Able to self monitor appropriateness of social interaction with stand-by assistance. Level X – Purposeful, Appropriate: Modified Independent
  • Able to handle multiple tasks simultaneously in all environments but may require periodic breaks.
  • Able to independently procure, create and maintain own assistive memory devices.
  • Independently initiates and carries out steps to complete familiar and unfamiliar personal, household, community, work and leisure tasks but may require more than usual amount of time and/or compensatory strategies to complete them.
  • Anticipates impact of impairments and disabilities on ability to complete daily living tasks and takes action to avoid problems before they occur but may require more than usual amount of time and/or compensatory strategies.
  • Able to independently think about consequences of decisions or actions but may require more than usual amount of time and/or comepensatory strategies to select the appropriate decision or action.
  • Accurately estimates abilities and independently adjusts to task demands.
  • Able to recognize the needs and feelings of others and automatically respond in appropriate manner.
  • Periodic periods of depression may occur.
  • Irritability and low frustration tolerance when sick, fatigued and/or under emotional stress.
  • Social interaction behavior is consistently appropriate.

Original Scale co-authored by Chris Hagen, Ph.D., Danese Malkmus, M.A., Patricia Durham, M.A. Communication Disorders Service, Rancho Los Amigos Hospital, 1972. Revised 11/15/74 by Danese Malkmus, M.A., and Kathryn Stenderup, O.T.R. Revised scale 1997 by Chris Hagen.