Multiple Concussions: Important Factor In Treatment

In addition to taking a history of post-concussion signs or symptoms and conducting a neurological examination during a pre-participation physical evaluation (PPE), it is critically important to your child's treatment of and recovery from a suspected concussion to provide the physician with as much information as possible about all prior concussions, including severity of impact and duration of symptoms.

While some research suggests that those with prior concussions do not necessarily suffer more neurocognitive impairment following a re-injury,¹ other studies have found that athletes who have suffered multiple concussons are at increased risk for subsequent concussion and more likely to develop persistent post-concussion signs or symptoms, including depression, that require careful management and may have life-long health consequences. A 2009 study¹ of high school soccer players, for example, found that athletes with a reported history of concussions performed significantly worse on tests of memory, visual processing and reaction time than those who reported no prior concussion

Under the consensus statement issued after the 3rd International Conference on Concussion in Sport in Zurich in November 2008,² repeated concussions over time, and repeated concussions occurring with progressively less impact force or slower recovery after each successive concussion are considered important "modifying factors" in concussion management which may, in some cases, predict the potential for prolonged or persistent symptoms.

The importance of finding out about concussion history is underscored by studies showing that a significant percentage of athletes, especially in contact sports like football, suffer multiple concussions over the course of their athletic career:

• College football players with a history of 3 or more previous concussions were 3 times more likely to sustain another concussion than those with no concussion history, with an increased likelihood of recurrent concussions increasing with the number of previous concussions³;
• The same study suggested that a multiple concussion history was associated with a slower recovery of neurological function after another concussion. The study also found that, within a given season, there may be increased susceptibility to another concussion in the first 7 to 10 days after the initial concussion; 
• 16.8% of high school athletes suffering a concussion had previously suffered a sport-related concussion, either that season or in a previous season; 
• More than 20% of concussions in boys' and girls' soccer and basketball were recurrent concussions;
• Once an athlete has suffered an initial concussion, his or her chances of a second one are 3 to 6 times greater than an athlete who has never sustained a concussion;
• A third of high school players in one recent survey reported two or more concussions in a season. 
• High school athletes who have been concussed are three times more likely to suffer another concussion in the same season.³ 
• High school athletes who suffer 3 or more concussions are at increased risk of experiencing loss of consciousness (8-fold greater risk),⁴ anterograde amnesia (reduced ability to form new memories after a brain injury) (5.5-fold greater risk), and confusion (5.1-fold greater risk) after a subsequent concussion.
• Healthy high school students with a history of two or more concussions exhibited poorer performance on cognitive testing than healthy students with a history of one or no concussion.⁵
• After recovering from a concussion, high school students with a history of two or more concussions continue to report significantly more physical, cognitive, and sleep-related concussion symptoms than healthy students with a history of one or no concussion.⁶
• Children who are seen in a hospital emergency room for a head injury (concussion, skull fracture or intracranial injury) are more than twice as likely to sustain a subsequent head injury of similar type within 6 months as are children seeking care for an injury not related to the head, regardless of their age.

1. Colvin AC, Mullen J, Lovell MR, West RV, Collins MW, Groh M. The Role of Concussion History and Gender in Recovery from Soccer-Related Concussion. Am. J. Sports Med. 2009; 37(9): 1699-1704.
2. Consensus Statement on Concussion in Sport: the 3rd International Conference on Concussion in Sport held in Zurich, November 2008. Br. J. Sports Med. 2009; 43:i76-i84.
3. Gissel LM, Fields SK, Collins CL, Dick RW, Comstock RD. Concussions among United States high school and collegiate athletes. J Ath. Training 2007; 42(4): 495-503.
4. Collins MW, Lovell MR, Iverson GL, Cantu RC, Maroon JC, Field M. Cumulative effects of concussion in high school athletes. Neursurgery. 2002;51(5):1175-1181.
5. Moser RS, Schatz P, Jordan B. Prolonged effects of concussion in high school athletes. Neurosurgery 2005;57:300-306.
6. Schatz P, Moser RS, Covassin T, Karpf R. Early Indicators of Enduring Symptoms in High School Athletes with Multiple Previous Concussions. Neurosurgery 2011: 000 (in process).

Revised and updated August 24, 2011