Patients, health care providers, and members of the media have been known to use the term “severe concussion” when discussing mild traumatic brain injuries. Whenever I hear someone use this term, I ask them to tell me what criteria they are using to classify a concussion as “severe.” No one has ever been able to provide an answer. The reason is simple – there are no criteria.

First, a basic primer. Concussions are also known as mild traumatic brain injuries. There are several different systems for defining mild traumatic brain injuries and once certain neurological indicators are exceeded (e.g., Glasgow Coma Scale score, loss of consciousness length, and post-traumatic amnesia length) then the brain injury is classified as either moderate or severe. This is a very important distinction because brain injury is not a unitary construct. That is, moderate to severe brain injuries have many different features which set them apart from mild traumatic brain injuries.

Referring to a mild traumatic brain injury as “severe” is misleading because it leads people to believe that the brain injury is more significant than it actually is. This does not mean that mild traumatic brain injuries should be treated lightly or that they are not heterogenous. Indeed, some cases involve no loss of consciousness whereas others lose consciousness for 25-minutes. Some cases have no signs of brain damage on neuroimaging whereas other cases do have neuroimaging findings that reflect brain damage. Regardless, all of these brain injuries are still all classified as mild. As can be seen by reviewing the mild traumatic brain injury definitional criteria, the American Academy of Neurology (AAN) developed a system for classifying different grades of concussion. Notice that the AAN used the terms grade 1, grade 2, and grade 3. They did not use the word “severe” and neither did any other system.

This topic is so important because the choice of words matters greatly when information is conveyed to patients about this topic. An important step in early concussion management is to provide the patient with factual information but to also help the patient understand that the injury was mild and that the symptoms will likely resolve with time. This is principle behind the mild TBI treatment guide which has been empirically shown to decrease the incidence of persistent symptoms after concussion. Conveying to patients that they have suffered severe brain damage when they have actually suffered mild brain damage runs counter to such treatment efforts and will likely increase the chance that patients develops persistent symptoms. In sum, MTBIFacts.com advises against using the term “severe concussion” and instead advises using peer-reviewed, consensus based criteria if any gradations are to be used at all.