Sports Medicine Research: In the Lab & In the Field: Concussion Indicators of a Phenomenon Yet to be Defined (Sports Med Res)
Monday, August 4, 2014

Concussion Indicators of a Phenomenon Yet to be Defined

Concussion Guidelines Step 1: Systematic Review of Prevalent Indicators

Carney N., Ghajar J., Jagoda A., Bedrick S., Davis-O’Reilly, C., Coudray Hd., Hack D., Helfand N., Huddleston A., Nettleton T., Riggio S. Neurology.2014;7(3):S3-S15.

Take Home Message: Prevalent and consistent indicators of a concussion include observing disorientation or confusion immediately after the injury, and slower reaction time, poor balance, and impaired verbal learning and memory within 2 days after the injury.

We lack a widely accepted definition for a concussion. An evidence-based development of a standardized concussion definition would enable medical personnel to determine a concussion injury using specific diagnostic criteria as well as prognostic indicators such as signs and symptoms. Therefore, the purpose of the current systematic review is to provide evidence-based data on indicators of a concussion injury. The authors performed an electronic literature search, which included articles from 1980-2012 in Medline, Sports Discus, PsychINFO, and Cochrane. For a study to be included in the review, the authors required a study to include a broad definition of concussion and that the presence of any particular signs and symptoms or deficit be reported at a fixed time point. Twenty-six articles met the criteria and 11 articles were included in the conclusion. The authors found that loss of consciousness following a concussion injury was not very common (1 to 14% of injuries). The occurrence of disorientation/confusion ranged from 18% to 45%, and the frequency of headache, dizziness, blurred vision, and nausea exceeded 50% of injuries. Thirty-one percent of individuals who were tested for balance deficits immediately after the event demonstrated decrements in function. Balance deficits remained affected 2 days after injury, and it was not until 7 days post injury that there were no significant dysfunctions detected. Many injured individuals (42 to 71%) had deficits with some measure of reaction time within 24 hours and this persisted through 2 days after injury. The occurrence of deficits in attention/processing speeding/working memory ranged from 0-30% to 50-52.2% within 24 hours after injury. Measures of memory deficits within the first 24 hours of injury occurred in 0% to 42% of injured individuals.

The goal of this project was to establish an evidence-based foundation to derive a definition of concussion as well as diagnostic criteria and prognostic indicators of a concussion. This study found that the most common and persistent indicators of a concussion are observing disorientation/confusion immediately after the event, impaired balance within 1 day, slower reaction time within 2 days of injury, and/or impaired verbal learning and memory within 2 days after injury. It should be noted that most of the participants included in this review were athletes, and generalizing these findings to the general population may not be applicable. In addition, without a definition for concussion the common indicators the authors are reporting can only be attributed to a concussion-like injury. Lastly, the authors excluded a considerable amount of the concussion literature because of various methodological or reporting issues. Medical professionals should be cognizant of these indicators when assessing a potential sports-related concussion injury. Including a measure of balance, reaction time, memory, and verbal learning could help identify concussed athletes.

Questions for Discussion: Do you think these indicators at these times points are helpful with diagnosing a concussion? What time points are the most important to measure following a concussion injury? 

Written by: Jane McDevitt, PhD
Reviewed by: Jeff Driban

Related Posts:
The Effectiveness of Computerized Neurocognitive Testing 


Carney N, Ghajar J, Jagoda A, Bedrick S, Davis-O╩╝Reilly C, du Coudray H, Hack D, Helfand N, Huddleston A, Nettleton T, & Riggio S (2014). Concussion guidelines step 1: systematic review of prevalent indicators. Neurosurgery, 75 Suppl 1 PMID: 25006974

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