One of the signs of concussion is poor balance (what doctors call "postural instability"), which published studies have shown last approximately 72 hours (3 days) folowing sport-related concussion (1,2). Most, but not all, concussed athletes have significant balance deficits following injury (2).
An athlete's balance and equilibrium can be tested through use of the Balance Error Scoring System (BESS)(3,4).
The BESS consists of 3 tests lasting 20 seconds each, performed on two different surfaces, firm and foam:
- The athlete first stands with the feet narrowly together, the hands on the hips, and the eyes closed (double leg stance). The athlete holds this stance for 20 seconds while the number of balance errors (opening the eyes, hands coming off hips, a step, stumble or fall, moving the hips more than 30 degrees, lifting the forefoot or heel, or remaining out of testing position for more than 5 seconds) are recorded.
- The test is then repeated with a single-leg stance using the non-dominant foot, and
- A third time using a heel-toe stance with the non-dominant foot in the rear (tandem stance).
Balance testing is considered by the 4th Consensus Statement on Concussion in Sport (1) to be a "useful tool for objectively assessing" neurological functioning and a "reliable and valid addition to the assessment of athletes suffering from concussion, particularly where symptoms or signs indicate a balance component." It is part of the updated Sports Concussion Assessment Tool (SCAT3) issued in conjunction with the Consensus Statement.
Reviewing the peer-reviewed medical literature, a 2013 study (2) found that "the studies show that balance is an important component of the sideline assessment," although the authors noted that the modified BESS (M-BESS) contained in the SCAT3 utilizes three BESS stances on a hard surface only and that "[f]urther research is required to examine the sensitivity and reliability of the M-BESS for the detection of balance deficits in concussed athletes assessed on the sports sideline. By contrast, the new American Academy of Neurology concussion guidelines (5), view the BESS assessment tool as likely to identify concussion with only low to moderate diagnostic accuracy with a low specificity of 34 to 64% (meaning a false positive rate for concussion of 34 to 64%), but a high degree of specificity of 91% (meaning that the test will only miss one out of ten concussions).
While there are other ways of assessing balance, such as machines that measure the amount of sway or rocking a person does when standing in certain positions, those machines, and the accompanying computer software, are expensive and are often cost-prohibitive for smaller, less well-funded athletic programs.
While less expensive alternatives may become available (including the Wii Fit video game player) to assess balance, the modified BESS, says William P. Meehan, III, MD, Director of the Sports Medicine Clinic at Children's Hospital Boston and a MomsTeam concussion expert featured in MomsTEAM's new high school football concussion documentary, "The Smartest Team," "is the most thoroughly studied, most easily understood, and most readily available for use in managing sport-related concussions." (6)
On the basis of studies showing the BESS to have a practice effect, and also that it seems to be affected not only by the environment in which the test is conducted but also by how soon after exercise the test is given, the American Academy of Pediatrics' statement on concussions recommends (7) that the post-concussion testing be performed more than 15 minutes after cessation of exercise, and in a setting in which follow-up assessments can be performed, not on a noisy sports sideline. A recent literature review (8) also noted that BESS performance is affected by exertion and fatigue, the type of sport played, and a history of ankle injury or instability.
As Dr. Meehan notes, the BESS is best used where a baseline BESS score is obtained prior to the start of the season, when an athlete is healthy. Then, repeated scores after concussion can be used to monitor recovery.
In his 2012 book, Concussions and Our Kids (9) Robert Cantu, M.D., one of the country's leading concussion experts, recommends that baseline testing (which most think of solely in terms of computerized neurocognitive testing), routinely performed at the professional and college level and, increasingly at the high school level as well, be expanded to include balance testing.
Poor balance and dizziness are different
Balance problems are often linked to dizziness as objective and subjective impairments of similar nervous system functioning. Dizziness can be the result of multiple organic reasons, including disturbances in vestibular (ie. vertigo), visual, or cardiovascular (ie. fainting) systems.
While postural stability and balance can be tested objectively using such tests as the Romberg, tandem walking, heel-to-toe, BESS, Clinical Test of Sensory Interaction and Balance (CTSIB), and biomechanical force-plate tests, there is no consensus measure for dizziness, which is typically measured using postural/balance testing, self-report dizziness questionnaires, or both.
A 2011 study (10) found that dizziness, but not imbalance, was a risk factor for protracted recovery from concussion. The finding prompted the authors, researchers at the University of Pittsburgh, to suggest that postural/balance testing and dizziness tests should be looked at individually, that postural/balance testing should not be used as a proxy for dizziness, and that clincians should use dizziness questionnaires to augment post-concussion assessment in addition to computerized neurocognitive tests (e.g. ImPACT), symptom reports, and postural/balance tests.
A more recent study (11), however, found no link between dizziness and prolonged recovery.
The two most recent comprehensive studies of concussions in high school athletics (12, 13) found that dizziness (74.6% and 75.6%) was the second-most reported concussion symptom behind only headaches (93.4% and 94.2%).
For the most comprehensive, up-to-date concussion information on the Internet, click here.
1. McCrory P et al. Concussion Statement on concussion in sport: the 4th International Conference on Concussion in Sport held in Zurich, November 2012. Br J Sports Med 2013;47:250-258.
2. McCrea M, Iverson G, Echemendia R, et al. Day of injury assessment of sport-related concussion. Br J Sports Med 2013;47:272-284.
3. Riemann B, Guskiewicz K. Effects of mild head injury on postural stability as measured through clinical balance testing. J Athl Train 2000;35:19-25.
4. Guskiewicz K, Ross S, Marshall S. Postural stability and neuropsychological deficits after concussion in collegiate athletes. J Athl Train 2001;36:263-273.
5. Giza C, Kutcher J, Ashwal S, et al. Summary of evidence-based guideline update: Evaluation and management of concussion in sports: Report of the Guideline Development Subcommittee of the American Academy of Neurology (published online ahead of print, March 18, 2013); DOI: 10.1212/WNL.ob013e31828d57dd (accessed March 25, 2013)
6. Meehan WP, III. Kids, Sports, and Concussions (Praeger 2011), p. 71.
7. Halstead, M, Walter, K. "Clinical Report - Sport-Related Concussion in Children and Adolescents" Pediatrics. 2010;126(3): 597-615 at nn. 52-57.
8. Dziemianowicz MS, Kirschen MP, et. al. Sports-Related Concussion Testing. Curr Neurol Neurosci Rep 2012: DOI 10:1007/s11910-012-0299-y (published online ahead of print)(accessed July 14, 2012).
9. Cantu R and Hyman M. Concussions and Our Kids (Houghton Mifflin Harcourt 2012), p. 63.
10. Lau BC, Kontos AP, Collins MW, Mucha A, Lovell MR. Which On-Field Signs/Symptoms Predict Protracted Recovery From Sport-Related Concussion Among High School Football Players? Am J. Sports Med 2011;20(10) DOI:10.1177/0363546511410655 (published June 28, 2011 online ahead of print)(accessed November 5, 2011).
11. Scopaz KA, Hatzenbuehler JR. Risk Modifiers for Concussion and Prolonged Recovery. Sports Health: A Multidisciplinary Approach 2013;20(10). DOI:10.1177/1941738112473059 (published online ahead of print January 17, 2013).
12. Meehan WP, d'Hemecourt P, Collins C, Comstock RD, Assessment and Management of Sport-Related Concussions in United States High Schools. Am J Sports Med 2011;20(10)(published online on October 3, 2011 ahead of print) as dol:10.1177/0363546511423503 (accessed October 3, 2011).
13. Marar M, McIlvain N, Fields S, Comstock d. Epidemiology of Concussions Among United States High School Athletes in 20 Sports. Am J Sports Med 2012;40(4):747-755.Revised and updated April 23, 2013.