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Surprising Findings from New Concussion Study

No Gender Differences In Concussion Severity Or Outcomes Found in High School Sports

Researchers Find Differences in Symptom Types, Recommend More Detailed Assessment for Girls

No gender differences in concussion outcomes or severity reports a surprising new study, with high school girls and boys who suffer concussions in sports reporting the same number of symptoms, and taking the same time for their symptoms to clear and to return to play. 

The one difference: girls report symptoms that are more subtle and easily missed or attributed to causes other than concussion than those boys.

The study, "Sex Differences in Concussion Symptoms of High School Athletes," is published in the January 2011  Journal of Athletic Training. 

Girl dribbling basketball up court

Unexpected results

Researchers were surprised by the results. Based on earlier studies, they had expected to find that girls, who statistics show suffer concussions at a greater rate than boys, would also report a greater number of symptoms, take longer to become symptom-free and take longer to return to sports than boys.  

"The fact that symptom duration and RTP time-lines were similar ... showed that there was not a drastic difference between the way girls and boys are treated with respect to care, follow-up and return to play," said Susan A. Saliba, PhD, PT, ATC, an Assistant Professor at the Curry School of Education; Physical Medicine and Rehabilitation at the University of Virginia, and one of the study's co-authors.   "We were happy [to find] that girls did not seem to be more adversely affected by concussion symptoms than boys."

No gender differences in symptom prevalence, number

Headache was the primary symptom most commonly reported by both sexes in year 1 and the most consistently reported symptom in year 2 (95% among males; 97% among females).

Loss of consciousness (LOC), once considered a key indicator of a serious concussion and erroneously believed by many to be requiredfor a concussion finding, was one of least-reported symptoms by male and female high school athletes with no apparent difference in severity based on LOC data. 

The study likewise found no difference in the number of symptoms reported between male and female athletes, consistent with some earlier studies.

Other studies had found that females reported more post-concussion symptoms than did males.  The authors of the current study attributed those findings to differences in the populations studied (smaller samples of college athletes versus 800 high school concussions), severity of injury (participants who had been referred by physicians for neuropsychological testing or had symptoms lasting for more than 5 days in the previous studies versus all concussions reported by ATCs that required disqualification for at least one day in the current study), and reporting mechanism (other studies used computerized neuropsychological evaluation tools that relied on self-reporting symptoms, viewed as more subjective and prone to under-reporting versus the current study, which used reports of symptoms to a health care professional using a symptom checklist, which was felt to minimize under-reporting than relying on injured student-athletes to self-report their concussion symptoms).

"We were the first [study] to look at high school sex differences and to document what was actually done in particular injury circumstances," noted Dr. Saliba.  "Most previous researchers looked at much more severe injuries (after referral) or older (collegiate) athletes."

Gender differences in symptom type

Males were more likely than females to report amnesia and confusion/disorientation (both cognitive symptoms) than females in year 1; females did not report any single primary symptom in year 1 of the study with greater frequency than males. 

In year two, boys were again more likely to report amnesia and confusion/disorientation than girls but females reported drowsiness (neurobehavioral symptom) and sensitivity to noise (somatic symptom) more often than males.

The different types of symptoms reported by concussed female athletes prompted the study's authors to express concern that, without adequate symptom assessment, such neurobehavioral or somatic symptoms might be easily missed or be viewed as the result of pre-existing conditions, such as stress, depression or anxiety.

They thus suggested that ATCs view such symptoms as reported by females as evidence of a concussion until such diagnosis could be ruled out by the presence of a pre-existing neuropsychological condition.

"The fact that there is a higher prevalence of different types of symptoms means that athletic trainers and physicians should be more aware that in the post concussion management, the pathology may manifest in different ways. ... What we do learn from this study is that clinicians should be more sensitive to those neurobehavioral symptoms, especially in girls, and investigate further to ensure that a symptom presentation is not excused as mild depression or other factors," said Dr. Saliba.  

Although males continue to participate in sports at a higher rate than females (in 2008 41 percent of high school athletes were female), female athletes are now more likely than male athletes to suffer sport-related concussions. "As more girls and young women participate in rough-and-tumble sports, understanding possible differences in concussion symptoms between the two genders has become increasingly important," said R. Dawn Comstock, PhD, associate professor at The Ohio State University College of Medicine, an author of the study.

No difference by sex in time to symptom resolution, time to RTP

No statistically significant difference in SRT between male and females was noted: most reported resolution of their symptoms within 3 days of injury (72.2% among males; 66.7% among females). That the symptoms of concussions cleared so rapidly was consistent with other findings in college athletes, one of which found more more than 90% of the 1600 college athletes studied were symptom-free within a week of the initial injury.   

The study tempered reporting of these results with a note of caution: although certain concussion symptoms (such as headache and nausea) resolved in one study within 5 days, persistent neuropsychological changes in the same study were still present 5 days postinjury, and, further, that concussions are often accompanied by cognitive problems, such as increased processing time and short-term memory loss, "which can easily overlooked if they are not carefully assessed."  

The median time for RTP for all participants was 3 to 6 days and was not different between males and females. 64% of all student-athletes returned to play by 9 days post-injury (63% of males, 66% of females), with the greatest percentage of males returning to play between 7 and 9 days (29.7%), and the greatest percentage of females returning to play between 3 and 6 days (29.4%).

Advice for parents

"[P]arents should be acutely aware of [concussion] symptoms, potential differences between girls and boys, and alert coaches and healthcare workers to behavioral changes," advises Dr. Saliba.  "Parents have the ability to observe the athlete longer and can perceive changes that may affect the outcome.  Any lethargy, continued headache, change in behavior or affect can be concussion symptoms, especially if agitation or difficulty in concentrating are present.  Many times the parent cannot identify a specific symptom, but alert someone that the athlete is 'not him or herself.'  Early return to play during this time presents the most danger," she says.

Symptom evaluation just one component in concussion assessment

"From a clinical perspective," writes lead author, Leah Frommer, MEd, ATC at UC-Santa Babara, "it is important to evaluate each concussion individually and to record all symptoms reported by the injured athlete.  Some symptoms, especially in the neurobehavioral category, are often overlooked on a sideline or initial assessment of concussion."

While no athlete should be allowed to return to play until all symptoms have cleared, symptom evaluation is not, the study's authors emphasized, it "cannot be the only determining factor in making these decisions. ... Neurocognitive assessments, balance measurements, symptoms, and the physical examination should be used collectively to evaluate concussions and  ensure an athlete - whether male or female - isready to return to the playing field."

"Diagnosing sport-related concussions is one of the most difficult tasks faced by sports medicine clinicians," Comstock added. "No biological markers exist to detect concussion, so diagnosis largely depends on a patient's own report. Diagnosing concussion is further complicated by the tendency of many athletes to under-report or hide symptoms from their doctors, athletic trainers, coaches and parents.

First-of-its-kind study

The study, by researchers at the UC-Santa Barbara, University of Virginia and The Ohio State University/Nationwide Children's Hospital, Columbus, is the first to investigate concussion symptoms, symptom resolution time (SRT) and return to play (RTP) time in a national high school population.

The data was collected by certified athletic trainers (ATCs) using an Internet-based high school injury surveillance system during the 2005-2006 (year 1) andthe 2006-2007 (year 2) school years in nine sports (boys' football, soccer, basketball, wrestling and baseball, and girls' soccer, basketball, volleyball, and softball).

Source: 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 December 7, 2010