Sports Concussion

Below are a number of commonly-asked questions, some of them describing what concussions are all about from a scientific standpoint and others dealing with more practical issues. hockey

People who are interested in the “nuts and bolts” of concussions will likely find the technical questions of interest; however, if you’re just interested in “what’s going on and what can I do” you need not read all the technical stuff to make sense of the practical information.


Some Technical Stuff

A concussion, also known as a mild traumatic brain injury or MTBI is a disruption of brain function caused by what are known as inertial forces.
As you might recall from your school science classes, inertia refers to the tendency of an object that isn’t moving to remain motionless and of an object that is moving to continue moving in the same direction and at the same speed. When something interferes with the speed or direction of movement of an object, how fast that object changes direction or speed is determined by its density. For example, if you hit the brakes on a truck full of gravel it’ll take longer to stop than it will if you hit the brakes on the same truck when it’s empty. The brain is made up of structures that have different densities so when its speed or direction of movement suddenly change some areas of the brain travel further than other areas, causing connecting fibers between those structures to be stretched.
These fibers carry messages between areas of the brain. They do this by moving certain chemicals into and out of the cell to create tiny electrical charges which carry messages to along the fiber and to the next cell. When these fibers are stretched chemical reactions occur within and around the cells that disrupt their ability move the chemicals into and out of the cell to create the signals. It is generally accepted that these chemical reactions are temporary and that the brain will, with time, recover its electrochemical balances. This is the primary mechanism of recovery in concussion. It is also known, however, that at times these fibers will break, and it is also suspected that such chemical imbalances may somehow damage the cells. These mechanisms are believed by some to explain why some symptoms persist over time. However, there are other competing explanations for why that happens.
This has been and continues to be a hotly debated question in the professional literature. However, when is all is said and done the real question is not whether concussions can cause brain injury, but rather how many concussions are needed or how severe must they be before damage occurs. Clearly not every little jar to the head causes a concussion. Equally clearly, it is clear that significant blow to the head can cause temporary and even permanent damage. In considering all of the existing literature we believe that it is also reasonable to conclude that having multiple significant concussions increases our chances of developing permanent symptoms if we have another concussion in the future and probably also increases our chances of developing other neurological problems, notably some forms of dementia, later in life. However, how many concussions one can have and how severe those concussions have to be before some sort of permanent damage occurs remains unknown.
The severity of a concussion cannot be determined by its persisting symptoms. Rather, it is determined by the symptoms that occur at the time of the concussion. Two specific symptoms are typically used to determine the severity of a concussion. The first is the person’s level of consciousness immediately following impact, which can range from the person being fully alert and oriented to seeming somewhat dazed, to being disoriented (meaning that they do not necessarily know where they are or what is going on around them) to being lethargic to being asleep but responsive to pain to being in a deep coma and unresponsive to any sort of stimulation. This is frequently quantified with a scale known as the Glasgow Coma Scale. The second symptom used to determine the severity of a concussion is the individual’s retrospective recall of it, which can range from having full recollection of what happened to having a partial or cloudy recollection of what happened to having actual gaps in memory both before and after the actual impact. There is no question that when the changes are extreme, as when an individual is in a coma and has memory lapses or gaps several days’ duration, a significant injury has occurred. However, the vast majority of concussions involve little or no memory loss at that time as well as little or no change in level of consciousness aside from perhaps being somewhat dazed or disoriented.
The severity of concussions is important because the more severe the concussion the more likely that the person will be left with persisting effects. However, everyone would agree with that statement, there is considerable disagreement as to how severe a concussion must be before they have any impact. Much of this argument revolves around the question of whether concussions have a linear effect (that is, every concussion has an impact and the more severe the greater the impact) or have a threshold effect (that is, up to a point they are harmless but past that point can have an impact).
Subconcussive injuries refer to situations where the head is jarred, but not at a level that is sufficient to cause any change in consciousness or memory. The most common example of this would be “heading” a ball when playing soccer. Some researchers have argued that subconcussive events, especially if they occur at a high frequency such as would happen with heading a soccer ball, can have a cumulative effect even if the individual never suffers any change in memory or level of consciousness. The most recent scientific reviews of the literature, however, have failed to demonstrate that subcutaneous concussive events do have a neuropsychological impact on the individual and it is in our opinion safe to conclude that even if subconcussive effects do create a risk it is extremely small.

Some Practical Stuff

A concussion is caused by an outside force suddenly changing the speed or direction of head movement. This can include forces that cause the head to suddenly begin moving (as when a boxer is hit in the jaw while standing still), to suddenly stop moving (as when a hockey player is thrown against the boards) or to suddenly change the direction of movement (as when a hockey player racing toward the goal is suddenly hit from the side by another player).
Concussions can be thought of as producing three types of symptoms which we term immediate symptoms, rapid onset symptoms, and persisting symptoms.  There are two immediate symptoms: Change in level of consciousness which can range from feeling dazed to a deep coma, and disruption of memory, which can range from a clouding of the memory to a complete absence of any memory of periods of time.  The rapid onset symptoms include a variety of physical symptoms including feelings of pressure in the head, headaches, drowsiness, blurred vision, nausea, vomiting, sensations of numbness in the body, fatigue, and/or sleep disturbance, cognitive symptoms including problems with attention, memory, reasoning and general mental efficiency, and emotional/behavioral symptoms including increased irritability, anxiety, depression, flattening of emotions or experiencing of more extreme emotions.  Persisting symptoms are discussed below.

Side-line tests, which are often given by a team physician, coach, or trainer, are useful in determining whether the individual, at that point in time, does have concussive symptoms. This, in turn, is useful in determining whether the individual should return to play or seek medical evaluation. Side-line testing has only limited usefulness with respect to predicting long-term outcome, and it is also questionable what meaning they have when administered hours or days after the suspected concussion, as such delayed testing can both miss subtle persisting symptoms and identify possible concussion symptoms that are at that point in time being produced by other factors such as sleep loss, anxiety, or pain.

Virtually all professional sports now forbid players from continuing to play after they have a concussion. Indeed, many professional sporting organizations such as the MLS, NHL and NFL have detailed protocols that must be followed, before the player can return to play. These typically involve demonstrating that the athlete can maintain vigorous physical activity without triggering concussion symptoms and that the athlete’s cognitive abilities are intact. Although such restrictions do not exist in school and amateur sports, we concur with this recommendation and strongly advise that anyone who suffers a concussion should be removed from play until the above sorts of criteria can be met. This typically involves a period of rest followed by gradual reactivation.
It has been observed clinically that activity, including both mental and physical activity can aggravate concussive symptoms or, if the symptoms largely resolved, trigger them again for brief periods of time.  This is led to most health practitioners recommending a period of physical and mental rest following a concussion.  However, how long that period should be has created conflicting views.  Some believe that complete rest for extended periods of time including weeks or even months is in order.  There is, however, no scientific evidence to support this recommendation and, indeed, there are indications that this is counterproductive.  Based on the existing literature, it is our view that it is advisable for the individual to reduce (although not necessarily severely restrict) activity until such time as the immediate symptoms have for the most part abated, and then engage in graduated mental and physical reactivation, tapering back when and if symptoms recur or intensify, and then increasing again once the symptoms subside.  It must be emphasized however that this recommendation is a general one and if symptoms are persisting it is important for the individual to be seen by a healthcare professional with expertise in dealing with concussion.
Symptoms can persist for a number of reasons.  One might be brain injury.  However, other physical injuries such as neck injuries leading to headaches or injuries to the inner ear balance system may also trigger such symptoms as can generalized pain problems and/or sleep disturbance.  In addition, emotional distress, anxiety, worry and depression can all lead to such symptoms as can changes in the individual’s life such as disruption of one’s work, school or social life.  At times the symptoms are, in the short term, triggered by the concussion but then maintained by some of these other factors.
In the past persisting symptoms were often believed to be due to a form of brain disorder called Postconcussion Syndrome. However, there are three major problems with this diagnosis. First, no one who has a concussion has all of these symptoms. In fact, there are not even clearly defined clusters or groups of these symptoms that tend to occur together. The question then becomes which symptoms or how many symptoms must be present for the diagnosis to be made. No one has found a scientifically satisfactory answer to this question, leading to wide variability across different health care providers in how this diagnosis is made. Second, none of these symptoms are specific to concussion, meaning that they only occur with concussion. Repeated studies have demonstrated that many people who haven’t had concussions but have had other physical disorders such as broken legs or emotional disruption such as anxiety, depression or even situational stress will report having many of these symptoms. Third, this disorder has not ever been definitively tied to any physically-demonstrated sort of brain damage and in fact there is no consistent relationship between the severity of Postconcussion Syndrome and the severity of brain injury. Because of this, in recent years the existence and utility of this diagnosis has been called into question.
Most symptoms of concussion will resolve within a fairly short period of time, meaning hours or, at most, few days or perhaps a week.  If symptoms do not abate in that timeframe or worsen it is strongly advised that health care attention be sought immediately.
There are a wide variety of health care professionals who describe themselves as specialists in sports medicine or concussion.  However, many of these specialists have no actual credentials to back up their claims.  The first step in determining if someone is indeed a qualified specialist is to determine whether he or she is registered or licensed in his or her profession by the state or province in which he practices.  The second step is to determine whether he or she has been trained in a recognized training program such as a residency program in medicine or psychology, or has simply “picked up” their skills from unsupervised practice or short training courses.  A third step is to determine whether he or she is certified by a recognized certification body.  In medicine that would mean certification by the American Board of Medical Specialities in the United States or in Canada being a Fellow of Royal College of Physicians and Surgeons of Canada.  In psychology that would mean being board-certified in Clinical Psychology or Clinical Neuropsychology by the American Board of Professional Psychology.  In other fields that might include being certified by the Canadian Athletic Therapists Association or by the American College of Sports Medicine.  All of these organizations have criteria individuals must meet to be certified as well as ongoing monitoring of continuing professional competency.  Note that many other certification bodies exist in all fields of health care, many of which in fact have little or no criteria for obtaining or retaining membership.  The key is to determine whether the certifying body is recognized by state or provincial licencing bodies or by larger health professional organizations such as the Canadian or American Medical Associations or Psychological Associations.  Note also that many qualified individuals do not have certification, so lack of certification does not necessarily mean that the individual isn’t qualified.  A final question you can consider is whether the individual is associated with recognized training institutions such as university medical schools or provides services to professional sporting organizations such as NHL, NFL or MLS teams.
Neuropsychological testing is useful in two ways.  First, it can be used once the individual has become symptom-free to determine whether there are any persisting cognitive problems that are not immediately apparent, but may have an impact as a person returns to various activities such as going back to school or work.  Second, neuropsychological testing can be very useful if symptoms persist in determining the nature of those symptoms and what can be done to treat them most effectively.
There is no one form of cognitive rehabilitation.  Instead the term refers to a variety of techniques that are of one of two sorts.  The first sort involves brain “exercises” and is based on the notion that the brain can be strengthened by cognitive exercises just as muscles can be strengthened by physical exercise.  The second sort focuses on teaching methods to compensate for weaknesses, such as developing systems of note-taking for memory problems.  Although there is considerable clinical experience and some research to support the utility of the compensatory methods, there is little research to support the “strengthening” methods.  Cognitive rehabilitation can be done on a face-to-face basis with a specialist in such treatment but is increasingly done using computerized programs, most of which rely on the “strengthening” model.  Although such methods seem to “make sense” and are often accompanied by testimonials from patients as to their value there is very little scientific evidence that demonstrates that they actually work.  When considering the claims of such programs, there are two points to keep in mind.  First, a good deal spontaneous recovery occurs over time even without treatment, so it’s very important to ask whether the treatment has demonstrated effects over and above what could be due to natural healing.  Second, it’s important to remember that testimonials are only to be published on websites or in other advertising materials if they are positive.  When was the last time you saw an ad quoting a customer as saying “well it didn’t work for me” or “I think I wasted my money.”
The answer to this often-asked question is short but disappointing:  We just don’t know.  Some sports programs and health professionals have set arbitrary cut-offs, after which they recommend against or even bar the athlete from returning to the sport.  The most common cut-off is three, leading to the “three strikes and you’re out” policy.  However there is no scientific basis to such rules.  Although advocates of cut-offs say they are erring on the side of caution, this argument ignores the reality that participating in sports is for many people a key part of their life and that sporting activities provide a variety of physical and psychological benefits to participants.  Because of this, giving up sports can have both physical and psychological costs.  We thus recommend against arbitrary cut-offs but do recommend that each time someone has a concussion they take some time, perhaps in consultation with a concussion specialist, to think about the pros and cons of continuing with versus leaving their sport.
Second impact syndrome (SIS) refers to a phenomena where an individual has a mild concussion and then, after suffering a second mild concussion experiences severe symptoms.  The symptoms, indeed, are so severe that they are believed to cause death in about 50% of cases and significant disability in the remaining 50% who survive.  Although this is a very frightening statistic, it must be taken with a grain of salt, as there are significant questions as to whether SIS even exists.  If it does, it is extremely rare.  For example, one study carefully searched out and examined every potential instance of SIS among people playing football in United States over a 13 year period.  In those 13 years, they found only 17 definite and 18 probable cases that fit the pattern for SIS.  Even if we accept that all of these were genuine cases of SIS, that’s less than three cases a year on average.  When one considers that every year 1.1 million high school students play football, and another 70,000 play football at the college/university level, not to mention the thousands of other people playing on amateur and professional teams, the risk of having SIS, even if it does exist, is literally close to one in a million.  When a condition is this rare, it is virtually impossible to prove that it even exists.  Further, cases of SIS have primarily been reported in adolescent males, where the second concussion occurs within days of the first concussion and before the individual has become symptom-free from the first concussion.  In short, despite the media hype surrounding SIS it is in our opinion not something to really worry about, especially if post-concussion protocols like those described above are followed.
Chronic Traumatic Encephalopathy (CTE) is a condition that is only been described fairly recently in the professional literature but has been given a great deal of media attention in the last few years.  Basically, the notion is individuals who have suffered repeated concussions, such as professional hockey or football players, can go on, later in life, to develop encephalopathy (a generalized deterioration of the brain) which in turn leads to profound cognitive, emotional and behavioral changes including violent behavior, suicidal behavior and so on.  As is true with SIS, there is a great deal of debate as to whether CTE exists at all.  The researchers have yet to demonstrate two critical points to establish this diagnosis:  (a) that the condition in fact exists and is not simply a variant of some other form of dementia; and (b) that this condition is caused by repeated concussions, as opposed to a variety of other factors that might account for such problems such as use of performance-enhancing or other drugs including alcohol, general tendencies towards aggressiveness and risk-taking which lead to them have concussions playing sports but also lead to them engaging in aggressive or dangerous behaviors outside of their sport and so on.  As with SIS, CTE is an extremely rare condition even if it does exist.  Indeed, there are fewer than 50 known cases reported to date, despite the wide media coverage of this condition and the literally millions of people who play sports at secondary, postsecondary, adult amateur and professional levels.
It is natural, given all the media attention to concussions, to be concerned about contact sports and the risk they pose for your child.  However, as the American Academy of Pediatricians has pointed out, the health risks created by physical inactivity are far greater than the risks arising from sports-related injuries.  Simply put, if your child is either going to play football or spend his or her time playing video games the risks of inactivity causes in terms of diabetes, childhood obesity, and a variety of other conditions are far more dangerous to your child than is football.  On the other hand, if your child can be persuaded to play a non-contact sports, that might be something you could encourage him or her to do.  In short, the bottom line is that your child is better off playing noncontact sports than contact sports but is better off playing contact sports than playing no sports at all, when the full spectrum of his or her current and future physical and mental health is considered.