Home » Health & Safety Channel » Multiple Concussion History, Recent Concussion Increase Risk Of Longer Recovery

Multiple Concussion History, Recent Concussion Increase Risk Of Longer Recovery


Children and adolescents with a history of concussion take significantly longer to recover, and those that have sustained two or more previous concussions or a single concussion within the past year are at even greater risk of prolonged symptoms, finds an important new study. (1)Dr. Meehan examining child

Relatively little is known about risk factors for prolonged postconcussive symptoms in children. Researchers at Boston Children's Hospital studied 280 patients between the ages of 11 and 22 with a mean age of 14 who were treated in the emergency department (ED) for concussion symptoms. The most common symptoms were headache (85%), fatigue (65%) and dizziness (63%).  The majority (63.8%) were injured playing sports, the most common being hockey (14%), soccer (9.4%), football (8.5%) and basketball (8.1%).  

On discharge, two thirds (65.9%) were prescribed a period of cognitive rest.  Nearly all (92.4%) were advised to take time off from sports; two-thirds (63.8%) were asked to follow up with their primary care doctor, nearly half (45.5%) in a sports concussion clinic, and 6.2% with another specialist.

The researchers found that concussion symptoms lasted twice as long for patients with a history of previous concussion as those without such a history (24 versus 12 days); that the median symptom duration for those with a multiple concussion history and who had sustained a concussion within the past year was 2 and 1/2 times longer (28 days) and nearly three times (33 days) longer respectively, compared with patients without such risk factors.

The finding linking multiple previous concussion history and prolonged symptom duration is consistent with a 2005 study (7) led by MomsTEAM's expert sport concussion neuropsychologist, Rosemarie Scolaro Moser, PhD, that showed that high school athletes with two or more concussions performed more poorly on cognitive measures than those athletes with one or no previous concussions, and a 2011 study (8) that revealed that youth athletes with multiple concussions reported more cognitive, emotional, physical and sleep complaints than their less concussed peers,

Hypothesis proven

Based on studies in mice which had suggested that the effect of multiple concussions was cumulative, and that there was a time period after a concussion during which the brain was more vulnerable to the effect of additional trauma, the researchers hypothesized that symptoms for those with a previous concussion would take longer to clear than those without such a history, and that those who sustained a concussion within the previous year would have a longer time to symptom resolution than those whose injuries were more remote in time.

That is exactly what they found. 

"Our study demonstrates this temporary sensitive effect of previous concussion for the first time in humans," wrote lead author Matthew A. Eisenberg, MD, of the Division of Emergency Medicine, Boston Children's Hospital. "This has direct implications on the management of athletes and other at-risk individuals who sustain concussions, supporting the concept that sufficient time to recover from a concussion may improve long-term outcomes."

The findings should help reduce "uncertainty among patients, families, and health care providers as to which patients would benefit from specialist follow-up, extended academic accommodations, prolonged abstinence from athletic participation, and even permanent cessation of high-risk activity," Eisenberg said.

Our study provides "support for the concept that sufficient time to recover from a concussion may improve long-term outcomes," said co-author, William P. Meehan, III, M.D., Director of the Sports Concussion Clinic and the Micheli Center for Sports Injury Prevention in the Division of Sports Medicine at Boston Children's Hospital and a MomsTEAM expert.  "Some have argued that a symptom-free waiting period after a concussion is unnecessary, as their studies did not find an increased risk of concussion for athletes who returned without waiting until their symptoms cleared.  Our study suggests that there may be long-term benefits [to waiting longer before returning to sports]." 

Other findings

  • Cognitive rest: no association was found between physician-advised cognitive or physical rest and duration of symptoms, although the authors speculated that the finding may have been due to limitations in the study's design;
  • Symptom severity: consistent with a recent study (2), patients with more severe initial symptoms had more than double the median duration of symptoms compared with those with lower symptom scores; 
  • Age: Adolescents and young adults aged 13 years and older took longer to recover than children.  Although this finding was consistent with two recent studies (3,4), the authors were "uncertain whether the difference between younger children and adolescents reflects differing neurobiology between the 2 groups or more severe mechanisms of injury in sports such as ice hockey and football, where games between older children involve more contact and higher-force impacts;
  • Loss of consciousness (LOC): Surprisingly, the study found an association between LOC and shorter duration of symptoms, which was in contrast to previous studies showing that LOC was a risk factor for prolonged effect or had no effect at all.  Although they could not rule out a biological basis for this finding, the authors suggested two possible explanations for the anomaly: (1) either that it reflected a "referral bias" in which patients who have suffered a loss of consciousness (which used to be viewed as one of the primary symptoms of a concussion, but studies now show to be involved in less than 10% of concussions) are more likely to be referred to a hospital emergency room, while those who don't suffer LOC "may be referred to the ED only when their symptoms or injury mechanisms are severe." [Note: extended LOC is still considered by the most recent international consensus of concussion experts (5) as a risk factor for a longer recovery. For more on the significance of LOC in concussion management, click here]; or (2) that patients who lose consciousness are more likely to comply with medical recommendations of physical and cognitive rest that those who do not lose consciousness, thus speeding their recovery.  
  • Gender: Female gender did not predict prolonged recovery, although the study suggested that this was likely due to the fact that female patients in the study came to the ED with more severe initial symptoms than males. Whether this was indicative of the fact that female patients had more severe symptoms from concussion in general, as suggested in several previous studies, or due to a referral bias, said Eisenberg, could not be determined from the data.
  • Other factors: A history of migraine headaches, depression, ADHD, and anxiety were not risk factors for longer recovery, although the small sample size limited the ability of the authors to detect relationships in these specific patient populations.

"Thes other findings will need further research and clarification due to confounding variables that may have influenced the statistical analysis," said Moser. "For example, that adolescents seemed to have more difficulties with recovery than pre-adolescents suggests that younger athletes may bounce back sooner, but, as the authors noted, it is possible that older athletes who came to the Emergency Department in this study may have had more significant injuries and been exposed to greater contact risk in their sports, than was the case for the younger athletes. Also, there may have been other factors that resulted in the finding that female athletes did not seem to experience longer recovery times compared to male athletes. Clearly, further research on how age and gender affect concussion recovery is needed."

"The beauty of this research study," says Moser, "is that it supports what sports concussion clinicians already intuitively know: youth athletes experience longer recovery periods and greater symptoms when concussions are close in time proximity or when there is a history of multiple concussions. The study is to be commended for its prospective approach, as previous studies in this area have been retrospective, studying a limited population of participants after the fact."

Study limitations

  • Patients in the study had a longer duration of symptoms than most previous reports in the medical literature, which frequently show symptoms resolving by 7 to 10 days after injury. The authors suggested that this may be because children presenting to an ED may represent a more severe subset of concussed patients than the outpatients in previous studies, or because the concussion symptom scale used (the Rivermead Post-Concussion Symptoms Questionnaire or RSPQ) may be better at detecting ongoing symptoms than the self-assessment tools or neurocognitive testing used in many other studies.
  • Although most (93%) of the patients approached agreed to participate, there were additional patients who were not contacted by the research coordinators, most frequently because they arrived to the ED at a time when none was available and short length of
    ED stay, leading to discharge before a patient could be contacted about enrollment.
  • The results could have been skewed because patients who dropped out of the study either because symptoms were more severe or, conversely, resolved more rapidly.
  • The study relied on self-reported symptoms, which certain sub-groups, especially athletes, may have an incentive to under-report in order to expedite return-to-play, others may have had an incentive to report symptoms that were no longer present in order to avoid schoolwork; still others may have had a difficult time understanding the questions of the RSPQ [Note: the difficulty younger patients have in completing concussion symptom inventories is why, in the new Child-SCAT3 (6), the questions are phrased differently than those posed to teens and adults, and an additional set of questions is asked of the child's parents].

1. Eisenberg M, Andrea J, Meehan W, Mannix R.  Time Interval Between Concussions and Symptom Duration. Pediatrics 2013;132(1):1-10.

2. Meehan W, Mannix R, Straccoilini A, Elbin R, Collins M. Symptom Severity Predicts Prolonged Recovery after Sport-Related Concussion, But Age and Amnesia Do Not. J Pediatrics 2013 DOI 10.1016/j.jpeds.2013.03.012 (published online ahead of print April 25, 2013).

3. Babcock L, et al. Predicting post-concussion syndrome after mild traumatic brain injury in children and adolescents who present to the emergency department.  JAMA Pediatr. 2013;167(2):156-161.

4.  Baillargeon A, Lassonde M, Leclerc S, Ellemberg D. Neuropsychological and neurophysiological assessment of sport concussion in children, adolescents and adults. Brain Injury 2012;26(3):211-220.

5. 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.

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

7. Moser RS, Schatz P, Jordan BD. Prolonged Effects of Concussion in High School Athletes. Neurosurgery 2005; 57(2):300-306.

8. Schatz P, Moser RS, Covassin T, Karpf R. Early Indicators of Enduring Symptoms in High School Athletes with Multiple Previous Concussions. Neurosurgery 2011;68:1562-1567.

Posted June 10, 2013; revised June 11, 2013 to reflect Dr. Moser's comments; further revised June 17, 2013 to include Dr. Meehan's comments