According to the most recent international consensus of concussion experts (1), concussion signs (those noticed by coaches, parents and teammates) and symptoms (feelings or problems experienced by the athlete) fall into five "clusters":

       1. Symptoms

• somatic (headache, nausea, vomiting, dizziness, visual problems, sensitivity to light/noise, balance problems [1]); 
• cognitive (feeling mentally "foggy," feeling slowed down, difficulty concentrating and remembering);
• emotional (involuntary crying or uncontrollable episodes of crying and/or laughing)

       2. Physical signs (loss of consciousness (LOC) [2], amnesia [3])

       3. Behavioral changes (irritability, sadness, nervousness, more emotional, depression) 

       4. Cognitive impairments (slowed reaction times etc.) 

       5. Sleep disturbance (insomnia, drowsiness, sleeping less than usual, sleeping more than usual) (1).

Despite widespread concerns about chronic under-reporting [4] by athletes of concussion symptoms, a 2013 review of the medical literature (2) says that "symptom assessment remains a critical component of concussion assessment."

Potential signs of concussion requiring removal from play 

A concussion should be suspected on the sports sideline, and the athlete immediately removed from play and not permitted to return the same day, if any of the following signs are observed after a direct or indirect blow to the head:

• loss of consciousness (LOC) [2] 
• lying motionless on the ground/slow to get up
• balance or motor coordination problems (athlete stumbles, has slow/labored movements or unsteady gait)
• disorientation or confusion (inability to respond appropriately to questions; not aware of plays or events)
• loss of memory (post-traumatic amnesia [3] (1, 2)
• dazed, blank or vacant look;
• visible facial injury in combination with any of the other signs.

Three symptoms scales

There are three main symptom scales currently in use:  the Post-Concussion Symptom Scale (PCSS)(13), the Sport Concussion Assessment Tool 3 [6](SCAT) - Versions 2 and 3 (3), and the Concussion Symptom Inventory (CSI), a 12-item scale derived from the PCS and SCAT2. All have been found to be sensitive to the acute effects of concussion in high school, college, and professional athletes. (2)

                                                                      Post-Concussion Symptom Scale 

Grading symptom severity

In using the PCSS, the athlete is asked to rate or score the severity of the symptom on a 6 point (Lykert) scale:

   0 =  not experiencing symptom

   1 =  very minor

   2 =  annoyingly present

   3 =  moderate level

   4 =  more significant

   5 =  intense and disruptive, and

   6 = worst and unbearable (5).  

The PCSS has gained widespread recognition in concussion evaluation. A modified PCSS is used for self-assessment by the athlete on the Sport Concussion Assessment Tool 3 (SCAT3) [6](3) and some computerized neurocognitive tests [8] used by health care professionals in managing concussions, and is an important factor in making return to play decisions.  

Athletes with pre-injury depression, sleep disturbances, and/or attention-deficit/hyperactivity disorder should not be expected to have a total score of 0 on the PCSS symptom scale before they are medically cleared for a return to play because of their elevated baselines.

In addition, because the PCS contains 22 symptoms that are not specific to concussion, some non-injured athletes may report symptoms.  One 2005 study (6) found, for instance, that the mean symptom score for non-injured high school males was 5.8, despite the fact that such athletes had never suffered a concussion. As a result, the generally accepted threshold for return to play is 7. (6)(7)

Whatever the symptom scale, it should be used not only for the initial evaluation but for each subsequent follow-up assessment until all signs and symptoms have cleared both at rest and with physical exertion [9].  Symptom checklist scores and the ability of the scales to detect concussion typically diminish with the passage of time due to natural recovery. (2)

Difficult to spot or diagnose

The process of determining whether an athlete has suffered a concussion (sometimes called mild traumatic brain injury or mTBI, although the use of that term interchangeably with concussion has generated controversy [10]) is complicated by a number of factors:

• Because athletes who suffer concussions are not functioning at their cognitive baseline, they may not recognize they have suffered injury;
• There may be no specific impact event to alert the athlete or sideline personnel to concussion (a third of diagnosed concussions in a 2012 study of college athletes (8) were not associated with a specific impact event);
• Many athletes do not experience symptoms right away after an impact event: of 31 diagnosed concussions in a 2012 study associated with an identified specific impact (8), 19 experienced immediate or near-immediate onset of symptoms, but 3 had delayed onset on the same day, 2 first experienced symptoms the next day, and in 7 the timing of onset of concussion symptoms was unknown.  Of the 13 players with diagnosed concussion without a specific identified single impact, 6 had delayed symptom onset after play (after play or in subsequent days), and in 2 the timing of symptom onset was unknown.  Commenting on the results of that study, one prominent concussion expert  was left to "wonder[ ] how many concussions were missed ... given that 23% of the diagnoses reported were delayed (average of 17 hours) and another 27% had unspecified onset." (9)

Can vary by gender 

The symptoms also can vary by gender. 

A 2011 study [11] in the Journal of Athletic Training, for instance, found that female high school athletes were more likely than males to report drowsiness and sensitivity to noise which, "[w]ithout adequate symptom assessment ... may be more easily missed or attributed to other conditions, such as stress, depression or anxiety." (10) As a result, the study says such symptoms reported by females should be considered signs of concussion until they can be more definitively attributed to pre-existing neuropsychological conditions and concussion ruled out.

In patients with pre-existing mental health disorders, concussion may make symptoms such as depression, anxiety or attention-deficit disorder worse and make them more difficult to control.

While one recent study found that LOC occurs in fewer than 5% of concussions at the high school level (less than half the 10-11% rate found in earlier studies) (11), LOC, especially for a minute or more, is still considered an important sign of a more serious concussion and a head injury that may require further imaging [12] and intervention.

No same day return to play

The  most recent international conference of concussion experts (1) unanimously agreed that no RTP [return to play] on the day of suspected concussive injury should occur for high school and college athletes, especially as studies show that college and high school athletes allowed to return to play on the same day may demonstrate neuropsychological deficits that may not be evident during an initial sideline evaluation [5] and are more likely than adult athletes to have delayed onset of symptoms. (1)(citing studies @ notes 59-65)

As a result, the Zurich Consensus Statement emphasizes the importance of treating athletes under 18-years-old more conservatively (such as by extending the amount of time of asymptomatic rest and/or the length of time for completing the symptom-limited, exercise program [9] it recommends before return to play), even if the resources (e.g. the presence of team physicians or athletic trainers experienced in concussion management, access to neuropsychologists, consultants, neuroimaging etc.) are the same as for an older, professional athlete.

The Zurich Consensus Statement recommendations are embodied in the laws of a growing number of states [13](42 and the District of Columbia as of February 4, 2013) which require immediate removal of an athlete from a game or practice if a concussion is suspected, ban same day return to play, and require written clearance from a concussion specialist before an athlete is allowed to begin practicing or playing again.

For more about the 6-step, exercise-limited, program experts recommend that an athlete complete before a full return to play, click here [9]. 

Different symptoms for children aged 5 to 12: Child SCAT3 

The use of these symptom scales has yet to be adequately studied in the grade-school athlete.  Because athletes below age 13 report symptoms different from adults, and a clinical evaluation by the health care professional should include input not only from the athlete but from parents, and possibly teachers and school personnel (1), the Zurich concussion conference resulted in the issuance of a new Child SCAT3 (12) for use in assessing concussion for children aged 5-12 years, which includes symptom scales to be completed by the child and their parent: 

                                                            Child - SCAT3 Symptom Evaluation

As with the other symptoms scales, however, the child- and parent-symptom scales have not yet been the subject of large scale, controlled studies to establish their effectiveness in identifying young athletes with concussion. 

Critical component of concussion assessment

Symptom scales by themselves do not diagnose whether a concussion has occurred; rather, they provide information that can help a health care professional in making an overal diagnosis, gauging injury severity, assessing recovery, and in making the all-important return-to-play determination, although because of the unreliability of athletes' reports [14] of being symptom-free (14), they are only one factor. (2).  

As the authors of a 2013 study (2) noted, "[a]lthough concerns are routinely expressed about athletes under-reporting concussion [4] or the resulting symptoms (15)," their "review suggests that symptom assessment remains a critical component of concussion assessment. ... In sum, the literature clearly supports the continued use of symptom scales in the assessment of concussed athletes, ideally in combination with other functional [(e.g. neurocognitive [8], balance [1])] tests."

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Looking for more information about concussions? For the most up-to-date and comprehensive concussion information for sports parents on the web, check out the MomsTeam Concussion Center [15].

To purchase a DVD of The Smartest Team, click here [16]. 

To purchase a digital download [17] of the documentary,  

1. McCrory P, et al. Consensus statement on concussion in sport: the 4th International Conference on Concussion in Sport held in Zurich, November 2012.  Br J Sports Med 2013;47:250-258.

2. Mcrea M, Iverson G, Echemendia, et al. Day of injury assessment of sport-related concussion.  Br J Sports Med 2013;47:272-284.

3.  SCAT3. Br J Sports Med 2013;47:259 [18].   

4. Marar M, McIlvain NM, Fields SK, Comstock RD. Epidemiology of Concussions Among United States High School Athletes in 20 Sports. Am J Sports Med 2012;40(4):747-755. 

5. Symptom descriptions courtesy of Robin Karpf,M.D., Medical Director, Al Rashid Health and Wellness Center, The Lawrenceville School, Lawrenceville, New Jersey.

6.  Iverson GL, Lovell MR, Collins MW. Validity of ImPACT for measuring processing speed following sports-related concussion. J Clin Exp Neuropsychol. 2005; 27(6):683-689.

7.  Lau BC, Kontos AP, Collisn MW, Mucha A, Lovell MR. Which On-Field Signs/Symptoms Predict Protracted Recovery From Sport-Related Concussion Among High School Football Players?  Am J. Sports Med 2011;20(10) DOI:10.1177/0363546511410655 (published June 28, 2011 online ahead of print)(accessed November 5, 2011).

8. Duhaime A, Beckwith J, Maerlender A, McAllister T, Crisco J, Duma S, et. al.  Spectrum of acute clinical characteristics of diagnosed concussions in college athletes wearing instrumented helmets.  J Neurosurg 2012;117:1092-1099. 

9. Ellenbogen R.  Sports and concussion.  J Neurosurg 2012;117:1089-1091. 

10.  Frommer L, Gurka K, Cross K, Ingersoll C, Comstock R.D., Saliba S. Sex Differences in Concussion Symptoms of High School Athletes. Journal Ath. Train. 2011; 46(1):000-000.  

11. Meehan W, d'Hemecourt P, Comstock D, High School Concussions in the 2008-2009 Academic Year: Mechanism, Symptoms, and Management. Am. J. Sports. Med. 2010; 38(12): 2405-2409 (accessed December 2, 2010 at http://ajs.sagepub.com/content/38/12/2405.abstract?etoc).

12.  Child SCAT3. Br J Sports Med 2013;47:263.

13. Pardini D, Stump JE, Lovell MR, Collins MW, Moritz K, Fu FH. The post-concussion symptom scale (PCSS): a factor analysis. Br. J Sports Med. 2004;38:661-662. 

14.  Sandel N, Lovell M, Kegel N, Collins M, Kontos A. The Relationship Of Symptoms and Neurocognitive Performance to Perceived Recovery From Sports-Related Concussion Among Adolescent Athletes. Applied Neuropsychology: Child. 2012; DOI:10.1080/21622965.201 2.670680 (published online ahead of print 22 May 2012)(accessed June 5, 2012)

15. McCrea M, Hammeke T, Olsen G, Leo P, Guskiewicz K. Unreported concussion in high school football players - Implications for prevention. Clin J Sport Med 2004;14:13-17. 

Other sources:

Blinman TA, Houseknecht E, Snyder C, Wiebe DJ, Nance ML. Postconcussive symptoms in hospitalized pediatric patients after
mild traumatic brain injury. J Pediatr Surg. 2009;44(6):1223-1228.

Halstead, M, Walter, K. Clinical Report - Sport-Related Concussion in Children and Adolescents.  Pediatrics 2010;126(3): 597-615 at notes 40-42.

Sport Concussion Assessment Tool 2 (SCAT2) [19], Br. J. Sports Med. 2009; 43: i85-i88;

Guskiewicz, KM, Bruce SL, Cantu RC et al. National Athletic Trainers' Association position statement: management of sport-related concussion.  J. Athl. Train. 2004; 29(3): 280-287.

Gioia, GA. Schneider JC. Vaughan CG. Isquith PK. Which symptom assessments and approaches are uniquely appropriate for pediatric concussion? Br. J. Sports Med. 2009; 43 (suppl1): i13-i22.

Concussion Statement on Concussion in Sport: the 3rd International Conference on Concussion in Sport held in Zurich, November 2008 [20], P. McCrory et. al, Br. J. Sports Med. 2009; 43; i76-i84.

Meehan WP, Kids, Sports, and Concussion [21] (Praeger 2011).

Pocket Concussion Recognition Tool. Br J Sports Med 2013;47:267. 

Most recently revised and substantially updated April 22, 2013

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