Severity of TBI

Mild, Moderate, and Severe TBI

Traumatic brain injury severity is commonly described as mild, moderate, or severe. Injury severity is traditionally based on duration of loss of consciousness and/or coma rating scale or score, post-traumatic amnesia (PTA), and brain imaging results. Mild, moderate, and severe TBI may be characterized as follows:

  • Mild TBI
    • Brief loss of consciousness, usually a few seconds or minutes
    • PTA for less than 1 hour of the TBI
    • Normal brain imaging results
  • Moderate TBI
    • Loss of consciousness for 1 – 24 hours
    • PTA for 1 – 24 hours of the TBI
    • Abnormal brain imaging results
  • Severe TBI
    • Loss of consciousness or coma for more than 24 hours
    • PTA for more than 24 hours of the TBI
    • Abnormal brain imaging results

Severe TBI may be further sub-categorized as follows:

  1. Coma- a state of unconsciousness from which the individual cannot be awakened
  2. Vegetative State- a state in which an individual is not in a coma (i.e. awake) but is not aware of the environment
  3. Persistent Vegetative State- a vegetative state that has lasted for more than a month
  4. Minimally Responsive State- a state in which a person with a severe TBI is no longer in a coma or vegetative state and inconsistently interacts with/responds to the environment.


EXAMPLES of common cognitive-communicative, physical, and psychosocial/emotional consequences after mild, moderate, and severe TBI follow:

Mild TBI

  • Cognitive-Communicative
    • Decreased attention and concentration
    • Decreased speed of processing
    • Memory problems
    • Getting lost or confused
    • Decreased awareness and insight regarding difficulties
  • Psychosocial/Emotional
    • Irritability
    • Depression and anxiety
    • Emotional mood swings
  • Physical
    • Headache
    • Fatigue
    • Sleep disturbance
    • Visual disturbance
    • Dizziness
    • Nausea
    • Balance problems

Moderate and Severe TBI

  • Cognitive-Communicative
    • Decreased attention and concentration
    • Distractibility
    • Memory problems
    • Decreased speed of processing
    • Increased confusion
    • Perseveration
    • Impulsiveness
    • Decreased interaction skills
    • Decreased executive function abilities (for example, planning, organization, problem solving)
    • Decreased awareness of, and insight regarding, difficulties
  • Psychosocial/Emotional
    • Dependent behaviors
    • Apathy
    • Decreased lack of motivation
    • Irritability
    • Acting out
    • Depression
    • Denial of difficulties
  • Physical
    • Difficulty speaking and being understood
    • Physical paralysis/weakness/spasticity
    • Difficulties with sense of touch, temperature, movement, position
    • Chronic pain
    • Decreased bowel and bladder control
    • Sleep disorders
    • Loss of stamina
    • Appetite changes
    • Partial or total loss of vision
    • Weakness of eye muscles and/or double vision (diplopia)
    • Blurred vision
    • Problems judging distance
    • Involuntary eye movements (nystagmus)
    • Intolerance of light (photophobia)
    • Decreased or loss of hearing
    • Ringing in the ears (tinnitus)
    • Increased sensitivity to sounds
    • Loss or diminished sense of smell (anosmia)
    • Loss or reduced sense of taste