Mild Traumatic Brain Injury: Conflicting Diagnoses

    Concussions are a frighteningly common occurrence for many athletes.  Athletes in contact sports are at the highest risk, but just about every sport carries some risk of head injury.  The CDC estimates that between 1.6 and 3.8 million sports and recreation concussions occur each year. (1) Perhaps over a quarter of those who suffer Mild Traumatic Brain Injury (MTBI, the label for concussions now most common among non-athletic medical professionals) do not report their injuries, a statistic that my own personal observations would seem to confirm. (2) I have watched athletes suffer a concussion and stay on the field.  I have done it myself.  Why would many athletes engage in behavior that seems risky based on the potential consequences of playing with a concussion?  Part of the problem lies in the unreliability of the diagnosis.
    It is impossible to say exactly what a concussion is, because so many different grading systems are used to measure both their existence and severity.  The three most popular systems were developed by the American Academy of Neurobiology, the Colorado Medical Society, and Robert Cantu (a doctor  at Emerson Hospital in Massachusetts who specializes in neurosurgery and sports injuries.)  There are, however, 41 or more grading systems that exist, with no one really being able to tell which systems are better than others, due to the remarkable lack on agreement of even a baseline concussion.  While the three most used guidelines all agree that a concussion does not begin with loss of consciousness, the scales they take from there on out are vastly different.  A grade III concussion by the Cantu guidelines could be a grade II to the AAN, and a grade III to the AAN could be a grade II to Cantu.  Many of the differences are the result of the varying symptoms of a concussion.  Cantu focuses on post-traumatic amnesia and its duration, with loss-of-consciousness playing a role in the higher grades.  The CMA moves between various symptoms to explain gradation.  The AAN uses all post-concussive symptoms as a baseline, measuring their duration (with loss-of-consciousness being the distinguishing characteristic of a grade III.)  These many systems make it difficult for athletes to know when they have suffered a concussion, and when they've merely received a less serious knock to the head.  Different people can define the baseline of two of the grading systems (confusion) very differently.  Because of the disagreement on systematic diagnosis, its important for a potential concussion sufferer to be able to look for their own symptoms.
    According to a study done by a doctor at the University of Miami School of Medicine, “headache is the most common symptom of MTBI.” (3) The study also cites dizziness, loss of taste sensation, neck pain, and trouble sleeping as other physiological responses.  As might be expected with a brain injury, there are often psychological systems as well, including “irritability, lability, anxiety, and depression” as well as cognitive issues regarding “difficulties with concentration, attention, memory, word finding, information processing, and executive functioning.” (3) What causes these various symptoms (as well as the many not listed)?  The answer lies in the physiological response to head trauma.
    Mild Traumatic Brain Injury begins taking place when the brain impacts or is impacted by something.  The brain is surrounded by a fluid that acts as a cushion for it, but a large force may cause the brain and skull to collide.  Rotational movement is particularly dangerous, both in causing concussions and in the severity.  This rotation mostly impacts cell activity in the reticular activating system.  Some of the symptoms can potentially occur because of this trauma.  The RAS plays an important role in consciousness, and it must be working properly for a person to be conscious.  Extensive damage can lead to a coma, which is one of the most serious symptoms of a concussion.  Furthermore, the RAS plays a part in maintaining the circadian rhythm, so damage would likely alter sleep patterns.  Most of the other symptoms relate to the hyper-metabolism that results from brain trauma.  After injury, a number of neurotransmitters are released excessively, setting off a chain reaction that ends with an increased need for energy at the same time that blood flow is restricted.  This makes the brain very vulnerable in the time after a concussion, as the brain is already essentially running at breaking point.  Any additional damage carries the risk of catastrophic injury, which is why it is often noted that the first head impact after the concussion is the most dangerous (something my doctor told me.)
    While diagnosis may be problematic, it is generally accepted that a concussion can have very serious consequences and that an athlete who suffers one must be thoroughly examined and take a break from any potentially dangerous physical activity for some amount of time (dependent on the grade of the concussion.)  A study performed by Robert Cantu, concluded that “there is no universal agreement on concussion grading and return-to-play criteria after a concussion. There is, however, unanimous agreement that an athlete still suffering postconcussion symptoms at rest and exertion should not return to contact or collision sports.” (4) Nevertheless, athletes at nearly every level are allowed to play while still showing symptoms.  Ryan Church, outfielder for the New York Mets, suffered two concussions during the 2008 season before he was placed on the disabled list.  He played in a game before that despite complaints of dizziness and headaches.  When he was cleared to come back, he still felt slow and dizzy, and lasted only 10 more days before he had to go back on the disabled list.
    Why do mistakes like this occur on even the professional level?  Professional teams have hired athletes, and are trying to use them to get the most production out of them possible.  There is then potentially an incentive for teams to rush a player back from MTBI, while easily justifying it based on the variability of symptoms and diagnoses.  If a player has long term problems because of MTBI, the team has no liability.  As for college athletes and lower levels, people who play a sport generally do so because they like playing, so they want to return to action as soon as possible.  There can also be at all levels a strong internal pressure to not be seen as weak by teammates (a frame of mind that is speculated to be at the root of the NFL's problems with concussions.)  With the possible of athletes intentionally putting themselves at risk, prevention of MTBI and more serious complications with it are difficult.  When possible, teams should be using medical personnel not under team contract, to avoid conflicts of interest.  This is only really helpful at the professional level though.  To prevent injuries to younger athletes, more education is needed.  While diagnoses may be vague, there are still generally accepted signs of concussion, and the risks are not debated.  Athletes need to learn that returning from concussions early can cause massive brain damage, helping neither the team nor themselves, and a comprehensive athlete education plan that could be taught in schools is needed to help bring about that change in mindset.

References:

1)
http://docs.google.com/gview?a=v&q=cache:nltYiYyDHLgJ:www.cdc.gov/NCIPC/tbi/FactSheets/Concussion_in_Sports_factsheet.pdf+concussion+in+sports&hl=en&gl=us&pid=bl&srcid=ADGEESgmfbN22qYc3X_VJRqclzEVxZdzOTz0coaNFIV2yK7t7c5bkbn_eu1p_5NDa60J-fdh7ihkUyEsZQXlzA_ZQpor0IFLf_m4pCAXWq7y6h14PQgCgyHO9ptozZSAO6L0I7QvKM7P&sig=AFQjCNH-fMgTtWOhaqHA9oFXg4ia3Zga4wl accessed 7 November 2009

2) http://en.wikipedia.org/wiki/Concussion accessed 7 November 2009

3) http://archinte.highwire.org/cgi/content/full/158/15/1617 accessed 7 November 2009

4) http://www.nydailynews.com/sports/baseball/mets/2008/07/08/2008-07-08_ryan_church_cant_shake_concussions_heads.html accessed 7 November 2009