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The Prevalence of Undiagnosed Concussions in Athletes

Meehan, William P. III MD*,†,‡,§; Mannix, Rebekah C. MD, MPH‡,§; O'Brien, Michael J. MD*,†; Collins, Michael W. PhD

Clinical Journal of Sport Medicine: September 2013 - Volume 23 - Issue 5 - p 339–342
doi: 10.1097/JSM.0b013e318291d3b3
Original Research
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Objective: Previous studies suggest athletes underreport concussions. We sought to determine whether athletes in our clinics have sustained previous concussions that went undiagnosed.

Design: Multicentered cross sectional study.

Setting: Two sport concussion clinics.

Patients: Patients diagnosed with sport-related concussions or concussions with injury mechanisms and forces similar to those observed in sports were included.

Main Outcome Measures: The proportion of patients who answered “yes” to the following question were defined as having a previously undiagnosed concussion: “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 listed in the Post Concussion Symptom Scale?”

Results: Of the 486 patients included in the final analysis, 148 (30.5%) patients reported a previously undiagnosed concussion. Athletes reporting previously undiagnosed concussions had a higher mean Post Concussion Symptom Scale (PCSS) score (33 vs 25; P < 0.004) and were more likely to have lost consciousness (31% vs 22%; P = 0.038) with their current injury than athletes without previously undiagnosed concussions.

Conclusions: Nearly one-third of athletes have sustained previously undiagnosed concussions, defined as a blow to the head followed by the signs and symptoms included in the PCSS. Furthermore, these previously undiagnosed concussions are associated with higher PCSS scores and higher loss of consciousness rates when future concussions occur.

Clinical Relevance: Many athletes have sustained previous blows to the head that result in the signs and symptoms of concussion but have not been diagnosed with a concussion. These injuries are associated with increased rates of loss of consciousness and higher symptom scale scores with future concussions.

*Sports Concussion Clinic, Division of Sports Medicine, Department of Orthopaedics, Boston Children's Hospital, Boston, Massachusetts;

The Micheli Center for Sports Injury Prevention, Boston, Massachusetts;

Brain Injury Center, Boston Children's Hospital, Boston, Massachusetts;

§Division of Emergency Medicine, Department of Medicine, Boston Children's Hospital, Boston, Massachusetts; and

Sports Medicine Concussion Program, Department of Orthopaedics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.

Corresponding Author: William P. Meehan III, MD, Sports Concussion Clinic, Division of Sports Medicine, Boston Children's Hospital, 319 Longwood Ave, Floor 6, Boston, MA 02115 (

Supported by National Institutes of Health Grants T32 HD040128 to 06A1 (to W.P. Meehan) and National Institute of Child Health and Human Development Grants K12 HD052896 to 01A1 (to R.C. Mannix).

The authors report no conflicts of interest.

Received October 18, 2012

Accepted February 28, 2013

Copyright © 2013 Wolters Kluwer Health, Inc. All rights reserved.