Special Feature

Sports Concussions: Grading Severity and Advising on Return to Play

By Andrew D. Perron, MD, FACEP, and Clifford R. Peck, MD

Concussion, or mild traumatic brain injury (MTBI), is a common occurrence in contact and collision sports. The medical literature estimates between 200,000 and 300,000 concussions occur per year in the United States. However, the true incidence is almost certainly higher, since many concussions likely go unnoticed by coaches, trainers, families, and players. Further, the concussion may be recognized only by the individual player, who potentially is motivated to not report the injury out of fear that he or she may be removed from play. For the clinician, the area of sports concussions and MTBI can be confusing due to the relative paucity of scientific evidence to support the clinical decision-making process in the emergency department (ED) and beyond. Good scientific research in this area has been hampered by an inconsistent definition of concussion, widely divergent injury mechanisms, poor means of measuring cognitive deficits, and inconsistent return to play guidelines.

Separating Myth from Fact

A common myth surrounding concussion is that diagnosis requires a transient loss of consciousness (LOC) or amnesia.1 This is unsettling when recent studies argue that greater than 75% of concussions do not involve LOC.2 Experts in the field have broadened the definition to include any posttraumatic alteration in mental status that may or may not involve LOC. Some have even called for the term MTBI to be used in place of concussion, as the definition of concussion has become so muddied in the medical literature.

Concussion can occur in any sport, but those with high-velocity collisions between players (e.g., football, hockey, and boxing) have a higher incidence. Many concussion studies have focused on high school, college, and professional football players, which carries an estimated annual incidence of concussion of 10%. A recent study has confirmed what many experts in the field have postulated in the past: namely, that concussion begets concussion. This study prospectively followed a cohort of NCAA football players and reports a strong association between previous concussions and the likelihood of subsequent concussion. For example, a collegiate football player with a history of three or more concussions (lifetime) was three times more likely to have a subsequent concussion, as compared to players without previous concussion.2 With experts in the field unsure about the cumulative effect of repetitive concussion and the possibility of "the second impact syndrome" (where the individual not yet recovered from and initial mild traumatic brain injury sustains a blow to the head that results in swift, uncontrollable increase in intracranial pressure due to diffuse brain swelling, resulting in death or a permanent vegetative state), researchers have focused on strategies to diagnosis and limit exposure to concussion.3,4

Although confusion and amnesia are the cardinal features of concussion, they can present in many ways. Athletes may lose consciousness, appear ataxic, or show memory deficits, but more commonly they will exhibit subtle changes such as a vacant stare, slowed speech, or emotional lability. The process for evaluating the athlete for concussion should be systematic. Any worrisome signs or symptoms should be identified immediately, and evidence of increased intracranial pressure should be treated immediately.5 In 1997, McCrea et al established a Standardized Assessment of Concussion (SAC) in a group of varsity high school football players. Trainers on the sideline administered a series of questions that tested orientation, immediate memory, concentration, and delayed recall. Compared to baseline values recorded in a control group, the total score (out of 30) obtained by concussive players immediately following injury was significantly lower than that of the total nonconcussive sample.6

Grading Concussion Severity

Over the years, multiple attempts have been made to develop criteria to grade concussion in terms of severity and then offer return to play (RTP) guidelines. Currently, there are 23 separate concussion-grading schemes, which has largely served to confuse coaches, trainers, and physicians. The American Academy of Neurology AAN) published recommendations in 1997 after a thorough literature search and input from a multi-disciplinary panel.7 Acccording to the AAN recommendations, a Grade 1 concussion involves transient confusion, but no LOC. The concussion symptoms or mental status abnormalities resolve in fewer than 15 minutes. Grade 1 concussion is the most common, yet the most difficult to recognize. Grade 2 concussion does not involve LOC, but symptoms or mental status abnormalities last more than 15 minutes. Any persistent Grade 2 symptoms (greater than one hour) warrant medical observation. Grade 3 concussion involves LOC, either brief (seconds) or prolonged (minutes). Athletes with Grade 3 concussion should be evaluated by a physician.

The AAN also offers recommendations for return to play, but stresses that these are options. No coach, trainer, or physician will be faulted for more conservative measures. After a Grade 1 concussion, the player should be assessed immediately and at five-minute intervals for mental status abnormalities and post-concussive symptoms both at rest and with exertion. The athlete may return to play (RTP) if mental status abnormalities and post-concussive symptoms clear within 15 minutes. If the player experiences a second Grade 1 concussion that day, he should be removed from play and may RTP if asymptomatic for one week both at rest and with exertion. After a Grade 2 concussion, the athlete should be removed from play and disallowed from returning to the contest. He should be re-examined frequently for signs of intracranial pathology. The athlete may RTP if asymptomatic for one week both at rest and with exertion. Following a second Grade 2 concussion that season, the athlete may RTP if asymptomatic for two weeks both at rest and with exertion.

Grade 3 concussion with continued LOC warrants immediate medical attention. In this case, the athlete should be transported by ambulance to the nearest ED for neurological evaluation and possible neuroimaging. If findings are normal at the time of the initial evaluation, the patient may be sent home with family and explicit instructions for care. After a brief LOC (seconds) Grade 3 concussion, the athlete should be removed from play and may RTP if asymptomatic for one week both at rest and with exertion. After prolonged LOC (minutes) Grade 3 concussion, the athlete should be removed from play and may RTP if asymptomatic for two weeks both at rest and with exertion. Following a second Grade 3 concussion, the athlete should be withheld from play for a minimum of one month. Termination of the season should be considered.

The injured athlete with prolonged LOC or deteriorating symptoms should be transported by ambulance for ED evaluation. These patients should undergo appropriate trauma evaluation, including the ABCs (airway, breathing, circulation) of life support and cervical spine immobilization, if appropriate. After complete physical evaluation with particular attention to the neurological examination, the emergency physician must decide whether the patient requires neuroimaging or specialty consultation. Not all patients who suffer a concussion require computed tomography (CT) of the head.5 However, since data from prospective clinical trials do not exist, the emergency physician must decide on a patient-to-patient basis. Support for head CT includes LOC of more than five minutes, persistent amnesia, focal neurological signs, and concern for a depressed skull fracture.


There is no single way to manage the concussed athlete, but trends are evident in the literature. The concussed athlete should be removed from play and immediately examined. If prolonged LOC or deteriorating status is evident, the athlete should be examined immediately by a physician. The post-concussed athlete should not RTP until completely asymptomatic at rest and with exertion. Multiple concussions may have a cumulative effect on the athlete and warrant further medical evaluation. Every sport carries a risk of injury. The goal is to foster solid competition while ensuring safety to its participants. In this respect, it is the physician’s role to provide objective assessment of the injured athlete and guidance about the advisability of safe return to competition.8,9  

Dr. Perron, Dr. Peck is an emergency medicine resident at Maine Medical Center, Portland.


1. McCrory P. The eighth wonder of the world: The mythology of concussion management. Br J Sports Med 1999; 33:136-137.

2. Guskiewicz KM, et al. Cumulative effects associated with recurrent concussion in collegiate football players. JAMA 2003;290:2549-2555.

3. McCrory P, et al. Second impact syndrome. Neurology 1998;50:677-683.

4. Rabadi MH, et al. The cumulative effect of repetitive concussion in sports. Clin J Sports Med 2001;11:194-198.

5. Porier MP, et al. Sports related concussions. Pediatr Emerg Care 2000;4:278-283.

6. McCrea M, et al. Standardized assessment of concussion in football players. Neurology 1997;48:586-588.

7. AAN Quality Standards Committee. Practice parameter: The management of concussion in sports. Neurology 1997;48:581-585.

8. Kelly JP, et al. Diagnosis and management of concussion in sports. Neurology 1997;48:575-580.

9. McCrea M, et al. Acute effects and recovery time following concussion in collegiate football players. JAMA 2003;290:2556-2563.