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Severity Classifications of Brain Injury

How is the severity of a brain injury classified?

Severity classification is done with several different tools including the widely used Glasgow Coma Scale (GCS).

The scale recognizes three levels of severity for traumatic brain injury: mild, moderate, and severe. An injured person’s eye responses, verbal responses, and motor responses are measured. The lowest score on the GCS is a three, meaning that a person does not open their eyes, makes no sounds, and makes no movements. A person with a score of three on the GCS is in a deep coma. The highest possible score is a 15.

It is very important to know that the GCS is helpful primarily in the assessment of severe brain injury. Dr. Bryan Jennett the author of the GCS Scale, states the following about the scale in the publication, Mild Head Injury, c.Oxford, 1989, page 24, It was not intended as a means of distinguishing among different types of milder injury. Many of these patients are oriented by the time they are assessed and therefore score at the top of the Glasgow scale. Yet some of these patients have had a period of altered consciousness, either witnessed or evidenced by their being amnesic for events immediately following injury. Impairment of consciousness is indicative of diffuse brain damage, but there can also be marked local damage without either alteration in consciousness or amnesia.”


including Mild Concussion

Brain injuries referred to by the medical community as “mild” most often occur as a result of blunt trauma or accelerating /

decelerating forces with one or more of the following conditions present during a surveillance period:

  • Transient confusion, disorientation, or impaired consciousness

  • Dysfunction of memory (amnesia) around the time of the injury

  • Seizure or convulsion

  • In children and infants: irritability, lethargy, or vomiting following injury

  • In older children and adults: headache, dizziness, irritability, fatigue, poor concentration

  • Loss of consciousness lasting 30 minutes or less

It is important to know that permanent and serious brain injury can occur in events that do not produce a loss of consciousness. The American Academy of Neurology describes concussion as a trauma-induced alteration in mental status that may or may not involve loss of consciousness.



Moderate Brain Injuries may include the following symptoms soon after the incident resulting in injury:

  • Loss of consciousness lasting longer than 30 minutes

  • Post-traumatic amnesia lasting longer than 24 hours

  • Penetrating cranio-cerebral injury



Severe Brain Injuries are the most life threatening and intractable type of brain injury and occur most often from crushing blows or penetrating wounds to the head.

Closed head injuries can also result in severe brain injury. These injuries crush, rip, and shear delicate brain tissue. Treatment requires prolonged hospitalization and extensive rehabilitation. Click here to go to our page about Types of Traumatic and Non-Traumatic Brain Injury.


Please note: The information on this website is not meant to replace the advice of a medical professional. You should consult your health care provider regarding specific medical concerns or treatment.

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