Process of Brain Injury – DAI Injury Can Worsen
Process of Brain Injury – DAI Injury Can Worsen
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The Process of Brain Injury, from a deposition of the man I have most often quoted on this theme, Thomas Gennarelli, M.D.:
Q There is a phrase that I have used imperfectly for a long time, and I may have misattributed to you. “Brain injury is a process not an event.” Do you agree with that?
Q Are those your words?
A It depends on who you ask. If you look at your Web site, they’re your words.
Q Did I quote you? Was I quoting you when I used those words?
A I thought so, but I didn’t see an attribution, so I don’t know.
Dr. Gennarelli is the man who coined the term Diffuse Axonal Injury. It was from his detailed treatment of the Trauma, in Greenfield’s Neuropathology, that I first gained a detailed appreciation of the complexity of neurotrauma and the impact of biomechanical forces on the brain.
Dr. Gennarelli’s words: “Brain injury is a process, not an event,” have always clicked with me. Too much focus of medical diagnosis is on the event of concussion, not the process of brain injury which is ongoing.
The process of brain injury is not like our view of the sporting concussion. Our most vivid opportunity to observe the effects of concussion are in boxing matches. We can see the blow, we can see many different levels of disruption in how the brain works. We can even see the occasional LOC, or the near LOC event when a boxer is knocked down. If you are boxing fan, (which I am not) you have probably learned that recovery from concussion can be fairly quick. You know that when a boxer gets down, that for a period of time, likely to the end of the round, that boxer is in extreme peril. But if the boxer can avoid another concussion in the next minute or so, he has a chance to survive and may even recover sufficiently to win the fight.
From the fans perspective, it seems that the effects of concussion are short term, even as short as a couple of minutes. Yet what we are witnessing is not the end of the process of brain injury, it is only the end of “confusion.” The boxer is functioning on immediate memory. Despite the concussion, he has the capacity to do what a quarterback does, in calling the plays after a concussion. While his immediate memory is working, he is not confused, the brain cell may is fighting for its life.
An entire boxing match lasts 48 minutes, if it goes the distance. On a cellular level, most of the damage to the axon is just beginning at an hour and may continue to worsen for 48 to 72 more hours. Even though a boxer or athlete may seem capable of shaking off the effects of a concussion during the fight, the brain’s functioning will continue to deteriorate for days. What we observed about Conan in the first minutes after his concussion, is nothing like the difficulties he was having an hour later. An hour later, he didn’t recognize his own makeup tools. Click here for our discussion of Conan’s concussion. While the part of the brain that governs consciousness may be improving in the minute after a concussion, the brain cell itself may be just beginning the fight of it’s life.
The escalation of brain damage over time can be caused by brain swelling, by hemorrhage or bleeding within the brain, the “big stuff” we discussed on our severe brain injury pages. Click here for more on severe brain injury neuropathology. But the delayed effects of trauma are also occurring on the microscopic level.
The Process of Brain Injury Involves Cellular Damage
Dr. Gennarelli’s words again:
“In various combinations and various severities, the resultant cellular dysfunction (of brain injury) defines the nature and extent of the primary injury, the outcome of which may not become apparent for several days or even weeks after injury.” 
To diagnose mild traumatic brain injury, we must look at the process of brain injury, 24 hours after trauma. The neurological and cognitive functioning may have gotten worse, the next day, than it was during the time window of the ER visit. We can’t find the answer to whether the process of brain injury is ongoing, by putting the axons under a microscope. We do not biopsy of concussion survivors. We can see the process of brain injury after concussion, by testing the degree to which the brain has been working in the previous 24 hours. The easiest way to do that is by asking about memory for events since the accident. In sport cases, the IMPACT test is administered and other computerized neuropsychological tests. Athletes are also given tests of balance and coordination. Headaches are paid attention to. One of the most amorphous but consistently occurring symptoms “fogginess” in inquired into. I won’t try to define it. You will know it if you have it. See the Relation Between Fogginess and Neuropsychological Testing Following Concussion.
The reason the athletes, particularly football players, are given these serial followup tests, is that they want to be able to return to play. Until the athletes symptoms have cleared, they can’t return. The cycle of the football season puts a lot of emphasis on getting the athlete tested on Tuesday and Wednesday. In the NFL, if an athlete doesn’t practice on the midweek days, he probably isn’t going to play in the next game.
There is no such pressure to identify the process of brain injury in the rest of us when we suffer concussion. Since no radical medical intervention is available to reverse the process of brain injury after concussion, there is no perceived necessity to document the process of brain injury. Our protocol is have someone monitor you after discharge to make sure you don’t slip into a coma. Then take it easy for a few days and possibly followup with your doctor. And that much is only said to those who actually get the concussion identified.