The prevalence of undiagnosed concussions in athletes

Meehan WP, Mannix RC, O’Brien MJ, Collins WC. Clinical Journal of Sports Medicine. 2013; ahead of print.

Take Home Message: Over 30% of athletes reported a
previously undiagnosed concussion and these athletes may be at risk for more
severe symptoms after a future impact.

Many athletes fail to report their
concussion signs and symptoms (Kauet, 2003
Labotz,2005; McCrea,2004; Williamson, 2006),
which predisposes them to sustaining a second blow when the brain is still
recovering from the first impact. However, we still don’t know how common
undiagnosed concussions may be. Identifying under-reporting rates will help
medical personnel clarify where additional measures can be taken to ensure athletes’
safety. Therefore, the purpose of this study was to determine whether patients
from 2 sport clinics sustained previous concussions that went undiagnosed. The authors evaluated 486 patients that were seen between October 2009 and September 2010 due to a sports-related concussion. The patients provided demographic (e.g., age, gender) and clinical information (e.g., day of injury, sport), and completed
Post Concussion Symptom Scale (part of the Sport Concussion Assessment Tool 2).
Then, they answered the following question: “Have you ever sustained a blow to
the head which was not diagnosed as a concussion, but was followed by one or
more of the signs and symptoms in the Post Concussion Symptoms Scale?” The
patients answering yes to this question were defined as having a previously
undiagnosed concussion. A total of 148 (30%) patients reported that they had
sustained a blow to the head that resulted in concussion signs and symptoms,
but were never diagnosed with a concussion. There were no differences in
gender, age, or number of previous concussions between those that reported an
undiagnosed concussion to those that did not. Athletes who reported a previously
undiagnosed concussion were more likely to have lost consciousness with their
current injury compared with those with no previously undiagnosed concussion
(30.6% vs. 21.8%). Also, athletes that reported undiagnosed concussion had a
higher initial Post Concussion Symptom Scale score (mean = 33) with their
current injury compared to patients that did not report a previously
undiagnosed concussion (mean = 25).

Nearly one-third of the athletes
seen at the 2 sport clinics reported previously undiagnosed concussions. This
rate is lower than previous research, which may be due to the inclusion of all
sports and not just football athletes, who may less likely to report their
concussions. It could also be attributed to the increased media attention and
improved education that resulted in more athletes reporting their concussion symptoms.
However, 30% is still an alarming rate of undiagnosed concussions. Additionally,
those athletes with previously undiagnosed concussions had more symptoms and
higher rates of loss of consciousness with their current injury compared with
athletes without a previously undiagnosed concussion. Failure to report concussion
signs and symptoms may increase the risk of deleterious effects on the brain. A
prospective study designed to determine the reasons behind the undiagnosed
concussions may allow researchers to educate athletes to seek proper medical
attention. In the meantime, we must be aware that almost a third of concussions
may be missed and that these athletes may be at risk for more severe symptoms
after a future impact. This may be valuable information when we educate our
athletes, coaches, and parents about the consequences of missed concussions.

Questions for Discussion: What do you think the best method
is to deliver concussion education to the public? Other than education how can
we reduce the number of undiagnosed concussions?

Written by: Jane McDevitt PhD, ATC,
Reviewed by: Jeffrey Driban

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Meehan WP 3rd, Mannix RC, Oʼbrien MJ, & Collins MW (2013). The Prevalence of Undiagnosed Concussions in Athletes. Clinical Journal of Sport Medicine PMID: 23727697