Abstract
The authors evaluated how history of concussion affects symptom reporting prior to and after sustaining a concussion. At baseline, athletes with a positive concussion history reported more current symptomatology than athletes who had never been concussed. At 2 hours postinjury, concussed athletes with a history of previous concussion (PC) reported fewer symptoms than concussed athletes with no previous concussion history (NPC). By 1 week postinjury, however, PC athletes reported more symptoms than NPC athletes.
Athletes with a history of concussion are up to four times more likely to be concussed again when compared to athletes with no history of concussion.1 There is widespread consensus that concussed athletes should not return to competition until all neurocognitive symptoms have abated.2 In conjunction with neuropsychological and neurologic evaluations, symptom reporting remains an integral part of the assessment and treatment of concussed athletes. Most clinical guidelines require that athletes are asymptomatic for at least 24 hours prior to returning to play.3 However, these guidelines do not account for the individual differences demonstrated in recovering athletes. We examined the relationship between concussion history and symptom reporting before and after a concussive event in a multi-sport sample of collegiate athletes.
Methods.
Participants.
We administered questionnaires to 433 male Division I athletes designed to assess their concussion history and current symptoms as part of a concussion management program. A total of 57 male athletes sustained concussions during the study period. Of these, 30 had a previous history of concussion (PC) and 27 had no history of previous concussion (NPC). Athletes were given a neuropsychological test battery and symptom reporting measure at 2 hours, 48 hours, and 1 week postinjury. Twenty-nine non-injured athlete controls were drawn from the same sample and tested at the same time intervals as the concussed athletes. The table outlines the sample characteristics.
Table Descriptive characteristics of baseline, recently concussed, and control groups
Measures.
The Post-Concussion Symptom Scale (PCS) is widely used in the sports concussion literature and contains 21 items designed to assess physical, emotional, and cognitive symptoms of concussion. Exploratory factor analysis of the PCS revealed three factors that comprise cognitive/balance, sensory/physical, and emotional disturbances.4
The Previous Head Injury Questionnaire assesses the number of concussions someone has experienced, the circumstances surrounding the concussions, symptoms, and how the concussions were treated.
Detailed information regarding the methods employed in this study can be found in appendix E-1, available on the Neurology Web site at www.neurology.org.
Results.
Baseline analyses.
Because most athletes report few or no symptoms at baseline, nonparametric statistical procedures were used. Athletes with a history of more than one concussion reported more PCS symptoms at baseline (mean = 6.82, SD = 7.88) than athletes who had never been concussed (mean = 4.22, SD = 7.18; p < 0.01). A trend also showed that athletes who reported a history of one concussion reported significantly more symptoms (mean = 5.29, SD = 6.93) than athletes who had never been concussed (mean = 4.22, SD = 7.18; p < 0.1). No significant difference on PCS total score was found between athletes who reported one previous concussion and athletes who reported more than one previous concussion.
Analyses between recently concussed groups.
We expected that recently concussed PC athletes would report more symptoms than recently concussed NPC athletes. Contrary to predictions, a Levene corrected t-test revealed that PC athletes reported significantly fewer PCS symptoms than NPC athletes at 2 hours postinjury (p < 0.05). PC athletes had a mean symptom total score of 9.4 (SD = 9.4) and NPC athletes obtained a mean symptom total score of 19.8 (SD = 20.2). No significant differences were found between PC and NPC athletes at 48 hours postinjury. At 1 week postinjury, PC athletes reported more cognitive/balance symptoms than NPC athletes (p < 0.05). Thirty-two percent of PC athletes and 8% of NPC athletes endorsed one or more cognitive/balance symptoms at the 1 week assessment.
Comparisons of concussion and control groups.
It was expected that concussed athletes would report more symptoms than control athletes at each postconcussion assessment. This was found at 2 hours and 48 hours postinjury with both PC and NPC athletes reporting significantly more total symptoms than controls (figures 1 and 2⇓). In contrast, no significant differences were found between PC athletes and controls at 1 week postinjury. However, NPC athletes reported fewer cognitive/balance and emotional symptoms than control athletes at 1 week postinjury (p < 0.05).
Figure 1. Percentages of control athletes, no previous concussion history (NPC) athletes, and previous concussion history (PC) athletes falling within specified ranges of the Post-Concussion Symptom Scale (PCS) total score at the 2-hour assessment. Light gray bars (control) = athletes who had not sustained a concussion in the previous 6 months; black bars (NPC) = recently concussed athletes with no history of previous concussion; dark gray bars (PC) = recently concussed athletes with a history of previous concussion.
Figure 2. Percentages of control athletes, no previous concussion history (NPC) athletes, and previous concussion history (PC) athletes falling within specified ranges of the Post-Concussion Symptom Scale (PCS) total score at the 48-hour assessment. Light gray bars (control) = athletes who had not sustained a concussion in the previous 6 months; black bars (NPC) = recently concussed athletes with no history of previous concussion; dark gray bars (PC) = recently concussed athletes with a history of previous concussion.
Detailed information regarding the statistical methods employed in this study can be found in appendix E-2, available on the Neurology Web site at www.neurology.org.
Discussion.
This study explored the relationship between concussion history and symptom reporting before and after concussion. Symptom reporting remains an important tool when assessing the concussed athlete. Despite its central importance, little information has been published relating concussion history and symptom reporting. In this study, PC athletes reported more symptoms than NPC athletes at baseline. These findings are consistent with research that indicates cerebral concussion may have long-term neurocognitive sequelae.
We hypothesized that PC athletes would report more symptoms than NPC athletes at each postinjury assessment. Contrary to our expectations, NPC athletes reported more symptoms than PC athletes at 2 hours postinjury. There are several explanations for these unexpected findings. Because NPC athletes are unaccustomed to concussion symptoms, they may be more frightened than PC athletes and hence increase symptom reporting. Alternately, PC athletes may be less distressed by their emerging, but familiar symptoms. Finally, it is commonly held that athletes may minimize their symptoms in order to return to play more quickly. This may be especially true of PC athletes because they are aware that history of prior concussions often increases the amount of time athletes must remain on the sideline.
At 1 week postinjury, PC athletes reported more cognitive/balance symptoms than NPC athletes. This finding shows that, although NPC athletes reported more symptoms directly after the concussion, PC athletes reported symptoms for a longer period of time. Concussed athletes with a previous history of concussions appear to have increased symptom duration. This lends credence to return-to-play guidelines that prescribe longer periods of inactivity for concussed athletes who have experienced previous concussions.5 Because players in this study who had a concussion within 6 months of the current concussion were excluded, these data suggest that return to play criteria should examine total concussion history, not just the concussions that occur within the same season.
We expected that recently concussed athletes would report more symptoms than controls. Indeed, recently concussed athletes reported more symptoms at the 2 hours and 48 hours assessment than controls. These findings indicate that measuring symptom reports using the PCS is a useful method of accurately distinguishing concussed from control athletes up to 2 days postinjury.
At the 1-week assessment, no significant differences were found between PC and controls. In contrast, controls reported more symptoms than NPC athletes. This finding appears to support the notion that concussed athletes may minimize symptoms in order to return to play more quickly.
The findings of this study have important implications for the clinical management of concussed athletes. Foremost, PC and NPC athletes have distinct symptom courses. When a NPC athlete presents with multiple complaints, the clinician may want to normalize the magnitude of symptoms and reassure both the athlete and coaching staff that symptoms typically subside within 1 week. Conversely, PC athletes experience fewer symptoms and longer recovery. Caution would be encouraged if an eager PC athlete reported no symptoms relatively soon after a concussion. In either case, additional means of assessment, including neuropsychological testing, can prove to be beneficial.6
Concussion history in this study was based solely on the self-report of athletes. Although this is a common approach in sports concussion research, self-report is likely a less valid approach to determining concussion history than prospective data or thorough reviews of medical records. Future studies would benefit from examining these same issues with prospective designs. Despite these limitations, the findings of this study underscore the need for careful and systematic assessment of symptoms in the management of the concussed athlete.
Footnotes
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Additional material related to this article can be found on the Neurology Web site. Go to www.neurology.org and scroll down the Table of Contents for the October 26 issue to find the title link for this article.
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Presented in part at the 50th annual meeting of the American College of Sports Medicine; San Francisco, CA.
- Received January 6, 2004.
- Accepted June 9, 2004.
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