Evaluation and management of concussion involves many factors, some of which may predict the potential for prolonged or persistent post-concussion symptoms and long-term health effects.
The current international consensus of concussion experts1 is that concussion in sport should be considered a single entity, with the previous classification of concussion as "simple" or "complex" replaced by the following list of potential modifying factors:
| Factors | Modifier |
| Symptoms |
Number Duration (greater than 10 days) Severity |
| Signs |
Prolonged loss of consciousness (more than 1 minute duration) |
| Sequelae | Concussive convulsions |
| Temporal |
Frequency - repeated concussions over time Timing - injuries close together in time "Recency" - recent concussion or traumatic brain injury
|
| Threshold | Repeated concussions occurring with progressively less impact force or slower recovery after each successive concussion |
| Age | Child and adolescent (less than 18 years old) |
| Co- and pre-morbidities |
Migraine, depression or other mental health disorders, attention deficit hyperactivity disorder, learning disabilities, sleep disorders |
| Medication | Psychoactive drugs, anticoagulants |
| Behavior | Dangerous style of play |
| Sport | High risk activity, contact and collision sport, high competitive level |
The presence of any of these modifying factors at the time of injury should alert the treatingpractitioner to the possibility that the recovery period will be longer than the 7 to 10 day period typical of the majority (80-90%) of concussions, or a poor long-term prognosis.
Because of the different physiological response and longer recovery after concussion and specific risks related to head injuries during childhood and adolescence, these modifying factors apply even more to kids than adults and may mandate more cautious return to play advice.
Is gender a modifying factor?
The consensus statement viewed gender as apossible risk factor for injury and/or influence injury severity, but did not list it as a modifying factor based on then available research.
Significantly, a later study from 2010 in the Journal of Athletic Training2 contradicts a finding from a 2008study that girls take much longer than boys for concussion symptomsto resolve and return to play, finding instead no gender difference when it comes to time to symptom resolution and return to play among the large group of high school athletes in the study. Such finding would suggest that, had the study been available at the time of the Zurich statement, the statement might not have viewed gender as even a risk factor, much less a modifying factor.
The 2010 study does show, however, that female high school athletes present with different symptoms from male athletes, and because they are more likely to report drowsiness (neurbehavioral symptoms) and sensitivity to noise (somatic symptom) than males - symptoms which may be more easily missed on a sideline or initial assessment, or attributed to other conditions, such as stress, depression, or anxiety - the authors of the later study, including Dawn Comstock, one of the authors of the earlier study, recommend that, wheresuch symptoms are reported, they be viewed as symptoms of concussion until pre-existing neurobehavioral conditions are ruled out on more detailed examination.
1. Consensus Statement on Concussion in Sport: the 3rd InternationalConference on Concussion in Sport held in Zurich, November 2008. Br.J. Sports Med. 2009: 43:i76-i84.
2. Frommer L, Gurka K, Cross K, Ingersoll C, Comstock R.D., Saliba S. "Sex Differences in Concussion Symptoms of High School Athletes" Journal Ath. Training 2011; 46(1):000-000.
Created June 19, 2009; revised October 9, 2011
