If you sustain a blow to the head from an car accident, a slip and fall accident or some kind of sports injury, the most likely traumatic brain injury you can suffer from is a concussion. A concussion may be one of the mildest brain injuries, but a concussion can still severely alter your daily life.

When it comes to grading concussions, there are three basic systems that are followed by doctors and hospitals. Each one is based from similar principles to the system before it as time changed. No matter which one is used for your concussion, concussion grading scales are important for diagnosis and treatment.

GradeCantuColorado Medical SocietyAmerican Academy of Neurology
Grade IGrade I concussions come with no loss of consciousness and less then 30 minutes of post-traumatic amnesia.A grade I concussion consists of just confusionA grade I concussion is associated with no loss of consciousness and confusion symptoms lasting less than 15 minutes.
Grade IIGrace II concussion patients lose consciousness for less than five minutes or have amnesia for between 30 minutes and 24 hours.A grade II concussion includes confusion and post-traumatic amnesiaGrade II concussions are the same only the confusion symptoms last longer than 15 minutes.
Grade IIIPeople with grade III concussions have a loss of consciousness lasting longer than five minutes or amnesia lasts for 24 hours.Grade III and IV concussions imply a loss of consciousness (grade III in seconds and grade IV in minutes).Grade III concussions are divided into subcategories of IIIa and IIIb: IIIa has loss of consciousness measured in seconds and loss of consciousness measured in minutes. Permanent brain injuries can occur with Grade II or Grade III concussions.

Cantu Guidelines

Robert Cantu published his original guidelines in 1986, and he used the following scenarios to classify concussions:

  • Grade I. Grade one concussions come with no loss of consciousness and less then 30 minutes of post-traumatic amnesia.
  • Grade II. Grace two concussion patients lose consciousness for less than five minutes or have amnesia for between 30 minutes and 24 hours.
  • Grade III. People with grade three concussions have a loss of consciousness lasting longer than five minutes or amnesia lasts for 24 hours.

In 2001, Cantu changed some of the guidelines to include other signs in addition to amnesia. After the changes, grade II concussions pertain to ones with loss of consciousness for less than a minute. Those with loss of consciousness for longer than a minute or with signs that last over a week were labeled as grade III.

Colorado Medical Society Guidelines

In response to the wrongful death of a high school student apparently caused by second-impact syndrome (suffering second concussion while still having effects from a first one), the Colorado Medical Society published another set of guidelines in 1991. According to the Colorado Medial Society:

  • A grade I concussion consists of just confusion,
  • A grade II concussion includes confusion and post-traumatic amnesia, and
  • Grade III and IV concussions imply a loss of consciousness (grade III in seconds and grade IV in minutes).

American Academy of Neurology Guidelines

The guidelines set by the American Academy of Neurology (AAN) are based on the guidelines set forth by the Colorado Medical Society. In the AANs guidelines:

  • A grade I concussion is associated with no loss of consciousness and confusion symptoms lasting less than 15 minutes.
  • Grade II concussions are the same only the confusion symptoms last longer than 15 minutes.
  • Grade III concussions are divided into subcategories of IIIa and IIIb: IIIa has loss of consciousness measured in seconds and loss of consciousness measured in minutes. Permanent brain injuries can occur with Grade II or Grade III concussions.

If you have experienced a traumatic brain injury due to an accident or by someone else’s negligence, talk to an attorney.


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