Dr. James Kelly: How Are Blast-Induced Concussions Graded?
Blast injury-induced concussions seem to be more complex than a single blow the the head concussion, like in sports. To date, there is no distinctive rating system for blast -induced concussions.
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Blast injury-related concussion, in the military's view, seems to be that it's a more complex injury than the single blow to the head, sports-related concussion that we understand better. There are grading scales used by certain military services. So, for instance, the Marines-- meaning the Navy medical personnel that care for the Marines-- grade concussions in a way that is very similar to a merging of the Colorado guideline and the American Academy of Neurology guideline with the three-grade scale. But the definition itself, that's Defense Department-wide, doesn't use a grading scale, and it's intended for all types of concussion-- blast-related or biomechanical injury in a crash or whatever-- so there isn't necessarily a distinctive concussion grading or assessment for a blast-related concussion that's different from any other type of concussion. The grades of concussion in the scales that have been merged and used, in one sense or another, in the Navy/Marines system would be--the mildest form is an alteration in mental status without there being a gap in memory; so no amnesia or unconsciousness. So it's a person who is fully awake the entire time but recognizes-- or other people recognize--that they're not tracking what's happening around them. So a confusional state is the neurological term for that particular threshold of Grade 1, if you will. Grade 2 would be something a little bit worse in the sense that there is either a gap in memory, which is one way of looking at it--so there's a post-traumatic amnesia-- or they have lingering symptoms related to the concussion that go on for a span of time, and that's somewhat arbitrary. The Academy of Neurology said 15 minutes, others had said more or less. Grade 3 would be witnessed loss of consciousness, and by that we truly mean paralytic coma-- and in either grading system, that's the same that way-- that there is actually a witnessed loss of consciousness, such that even the individual--the person with the injury-- wouldn't know that they were unconscious. They just have a gap in memory; a span of time they can't account for. So it requires--for a Grade 3, it truly requires that somebody else witness them truly being unconscious, even if it's just momentary.
Posted on BrainLine October 20, 2010.
James Kelly, MA, MD, FAAN, a neurologist, is one of America’s top experts on treating concussions. He currently serves as Executive Director of the Marcus Institute for Brain Health.
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