By far, the most common head injury in athletics is concussion, a transient disturbance of neurologic function caused by trauma. Fewer than 10 percent of concussions result in loss of consciousness.¹ Symptoms of concussion include dizziness, headache, difficulty in concentrating, disturbances of vision or equilibrium, post-traumatic amnesia (loss of memory for events occurring after the injury) and loss of consciousness.

It is estimated that, in high school football alone, as many as 250,000 concussions occur each year¹ and that up to 20 percent of players sustain a concussion.^2,3 Other sports in which players are also at risk for concussion or head injury include boxing, ice hockey, wrestling, gymnastics, lacrosse, soccer and basketball. Once a concussion has occurred, the player becomes as much as four to six times more likely to sustain a second concussion.^1,4,5 Although most of these head injuries are mild and resolve without sequelae, it is important to evaluate and treat them appropriately to avoid potentially life-threatening outcomes.

Guidelines

Management of concussion, including determination of when an athlete should return to play, remains a matter of controversy. Accurate assessment of signs and symptoms (e.g., loss of consciousness) and their duration is important in determining the severity of the injury. At least 16 different guidelines for the evaluation of concussion have been proposed.⁶ The plethora of guidelines reflects the lack of consensus, which results from the absence of evidence-based data.

In 1986, Cantu⁷ formulated a set of guidelines that became widely used; it was subsequently adopted by the American College of Sports Medicine (ACSM). In 1991, the Colorado Medical Society Guidelines⁸ were formulated in response to several deaths secondary to head injuries in Colorado high school football players. These guidelines are more restrictive than previous versions; they were subsequently adopted by the National Collegiate Athletic Association (NCAA). Most recently, the American Academy of Neurology (AAN) proposed another set of guidelines.⁹ Currently, no consensus exists within the sports-medicine community as to which set of guidelines is the most appropriate.

The most widely used guidelines^10,11 are compared in Table 1.^7–9,12 Each set attempts to categorize the severity of concussion. Grades are assigned (1, 2 and 3) but vary depending on which guidelines are used. Also, some guidelines propose the addition of a “ding” or “bellringer” category (these are slang terms to describe the mildest level of concussion). The variables used to classify the severity of the injury include the length and duration of concussion symptoms (Table 2), as well as the length and duration of post-traumatic amnesia or loss of consciousness.

Evaluation

Evaluation of an athlete with a head injury should begin with basic life support. Once it has been assured that airway, breathing and circulation are intact, it should be determined whether loss of consciousness has occurred. Momentary loss of consciousness may be difficult to ascertain. Careful observation by the sideline physician and the trainer, as well as questioning of the athlete and teammates on the field, should help to provide this information. Frequently, the injured athlete is confused and may not be the best source of information.

Initial Sideline Evaluation

When it has been determined that no loss of consciousness has occurred and that no injury to the cervical spine has been sustained, the athlete may be moved to the sideline. There, a neurologic examination should be performed. Cranial nerves, coordination and motor functioning should be assessed. Particular attention should be paid to cognitive functioning. Long- and short-term memory may be evaluated using standard techniques such as three-word memory and “serial sevens”; however, detailed questions about recent events may provide more accurate information.¹³

Questioning should include queries as to who the opponent is, what the score is, who the team played the previous week and who scored most recently. It is helpful if the athlete can be questioned by a coach about the specifics of assigned plays. This not only helps to determine the severity of any deficits, it can also demonstrate to the coach that, despite an ostensibly normal appearance, the athlete is unable to play safely.

The injured player should be reassessed frequently so that any deterioration or continuation of symptoms can be noted. Once it has been determined that the athlete should not return to play, the physician should remain committed to this decision. An athlete's attempt to return to play prematurely may not be the result of simple enthusiasm for the sport or disregard for medical advice; it may actually be due to an inability to remember medical instructions because of post-traumatic amnesia. Indeed, the athlete may not even recall sustaining the concussion. To prevent an athlete from returning to play prematurely, the physician or athletic trainer may choose to keep possession of an essential piece of the athlete's equipment, such as a helmet or shoe.¹²

Evaluation of the Athlete with Loss of Consciousness

Brief loss of consciousness presents a problem for the sideline physician. Debate continues about what constitutes “brief ” versus “prolonged” loss of consciousness and about the seriousness of a few seconds' loss of consciousness compared with more prolonged post-traumatic amnesia. The Colorado and AAN guidelines both recommend transporting persons who have sustained any loss of consciousness to a hospital for further evaluation. Depending on the experience and expertise of the sideline physician, it is probably best to err on the side of safety and transport the athlete to the hospital.

When loss of consciousness is prolonged, there is general agreement that the athlete should be transported, taking cervical spine precautions, to the nearest facility where neuroimaging can be performed.¹⁴ A computed tomographic (CT) scan is most often obtained because it is more readily available than magnetic resonance imaging (MRI) and is also less expensive. A CT scan will rule out head injuries that pose an immediate danger, such as acute epidural or subdural hemorrhage. Athletes with concussion have normal CT scans and MRIs.

Second-Impact Syndrome

All of the guidelines focus on the question of when it is safe for an athlete to return to play after an apparent concussion. Several serious risks are associated with premature return to play. The most serious is second-impact syndrome. This syndrome was first described in 1973.¹ Second-impact syndrome occurs in players who return to competition before the symptoms of a first concussion have completely resolved. A second blow to the head, even a minor one, can result in a loss of autoregulation of the brain's blood supply; this leads to a vascular engorgement and subsequent herniation of the brain that is usually fatal.³ Since 1992, 17 cases of second-impact syndrome have been reported.¹⁵ This translates to one or two cases per year resulting from injuries sustained in football alone.

Multiple Concussions

Although second-impact syndrome is the most serious potential consequence of premature return to play, other dangers also must be considered. There is evidence that repeated concussions can result in cumulative neurologic damage, even when the injuries are separated by months or years.^9,16 The most striking example of this is the “punch-drunk” syndrome that sometimes occurs in boxers. For this reason, it is important to obtain a thorough history of any previous concussions. If multiple concussions have occurred, sophisticated neuropsychologic testing may detect subtle cognitive deficits that could affect the athlete's decision to continue in this sport.

Postconcussion Syndrome

Returning to competition prematurely may also increase the likelihood that the athlete will develop postconcussion syndrome.¹⁷ This syndrome is characterized by fatigue, headaches, equilibrium disturbances or difficulty in concentrating that may persist for weeks to months after the initial injury. Anyone who continues to experience symptoms of concussion for more than a week or two after the injury should be considered a candidate for further evaluation, including imaging or neuropsychologic testing.

Return to Play

How, then, does a clinician decide when it is appropriate for an athlete who has had a concussion to return to play? Although many differences exist among the recognized guidelines, several areas of agreement can also be found. More than 90 percent of concussions are mild, and the various guidelines propose similar strategies for managing these injuries. First (and most importantly), they all agree that an athlete should not return to play while concussion symptoms are present.^7–9,12 Even if symptoms are absent at rest, the patient should be tested during exertion. It is not unusual for symptoms to return with exertion and, in these cases, athletes should still be restricted from play.

THE FIRST CONCUSSION

The type of concussion most frequently encountered by a clinician covering an athletic event is the mild form known in sports as the “ding” or “bellringer.” As mentioned above, the major guidelines propose similar approaches to the management of these injuries. If concussion symptoms clear away within 15 minutes and if no associated loss of consciousness or post-traumatic amnesia has occurred, the athlete may return to play that day. Some guidelines would permit an immediate return to play once the player is asymptomatic⁷; others recommend a 15- or 20-minute wait after symptoms have disappeared.^3,8,12

When an athlete experiences symptoms of concussion that last for more than 15 minutes or sustains a concussion associated with post-traumatic amnesia, the major guidelines agree that the athlete should be removed from the contest and should not return to play until asymptomatic for at least one week.^7–9,12 In practice, this means that an athlete who suffers a concussion during a Friday night contest and is subsequently restricted for one week may be able to play the following Friday evening. The athlete should undergo exertional testing, such as running drills and noncontact activity in practice, one to several days before returning to regular play. The guidelines also agree that an athlete who suffers any loss of consciousness should be removed from the game and should not be allowed to return to play for a minimum of one week.

SUBSEQUENT CONCUSSIONS

There is a lack of agreement about how to manage second or third concussions in the same athlete. In addition, no guidelines are offered for the management of serial concussions of different grades. For this reason, the clinician must understand the risks of returning an athlete to play and offer reasonable clinical judgment.

Education

It is of paramount importance that coaches, as well as players and their parents, understand the medical issues involved in concussion. Athletes are more likely to follow recommendations and present for medical evaluation if they know that premature return to play could result in death. It is also helpful when players understand that not every concussion results in automatic removal from athletic participation.

Final Comment

Physician coverage of athletic events is a service to the community and is required at many such events. It is important, especially in sports with a high risk of head injury, that the physician have an understanding of the assessment and management of concussion. The sideline physician should also be fully aware of the possible catastrophic sequelae of improperly managed concussion, such as second-impact syndrome. A working knowledge of other concerns, such as permanent neurologic damage secondary to cumulative trauma and postconcussion syndrome, is also necessary.

Return-to-play decisions are always difficult, especially in the face of pressure from uninformed coaches, athletes or parents. It is therefore vital that the sideline physician be familiar with the various guidelines for managing concussion and offer consistent, well thought-out treatment plans. The lack of consensus on this subject makes the clinician's role even more challenging. However, by focusing on the areas in which the different guidelines agree rather than those in which they differ, the clinician can feel prepared for most scenarios.