Effect of Mild Head Injury on Cognition and Postural Stability
Principal Investigator: Kevin M. Guskiewicz, PhD
Institution: University of North Carolina Chapel Hill
Contact Information: Sports Medicine Research Laboratory, University of North Carolina Chapel Hill, NC 27599-8700
Title: Effect of Mild Head Injury on Cognition and Postural Stability
Abstract: Athletic trainers and team physicians are often faced with decisions concerning the severity and timing of an athlete’s return to play following mild head injury (MHI). The limited amount of quantitative and/or objective information available following a head injury makes these decisions very difficult. Several authors have published guidelines for return to play following MHI, however, they are based on limited scientific data. The purpose of our research is to examine the effects of MHI on various measures of postural stability and cognitive function and to make recommendations for their use during MHI assessment.
Traditionally clinicians have utilized the Romberg test for assessing disequilibrium in head injured athletes, despite its ability to detect only gross deficits. Within the past decade, computerized posturography has become more readily available to clinicians, and has provided a more objective and challenging assessment for MHI athletes. Data gathered from clinical studies using postural stability has revealed a recovery curve for MHI and suggests that postural stability could be a valuable tool for the assessment of MHI.
Recovery curves based on computerized dynamic posturography have been developed in multiple studies (2,3,4). These studies indicate that athletes recovering from mild head injury demonstrate decreased stability until 3 days postinjury. It appears this deficit is related to a sensory interaction problem, whereby the injured athlete fails to use their visual and/or vestibular systems effectively. These findings suggest that sensitive forceplate measures of postural stability may provide clinicians with a useful tool for determining when an athlete may safely return to competition following MHI (Figure 1). Measures of cognitive functioning, however, have not proven to discriminate between injured and non-injured controls. Additionally, injured athletes have not scored significantly different between baseline cognitive tests and postinjury cognitive tests (4).
Additional methods of assessing MHI using clinical postural stability tests are also being addressed through research (5). The preliminary results reveal that in the absence of balance equipment, the following tasks may be of more value than the standard Romberg test for identifying deficits related to MHI: Single Leg and Tandem stances on a firm surface; and Double (narrow) and Tandem stances on a medium density foam. The benefit of these clinical tests is that they can be performed as part of the sideline evaluation.
Clinicians making return to play decisions following MHI should attempt to gather as much data as possible before making a decision. The status of the postural control system is an important piece to a very large puzzle which should be considered when assessing MHI. While the signs and symptoms may not always be accurately reported, if used in conjunction with objective postural stability and neuropsychological measures they can provide a more detailed portrayal of the injury. Athletes sustaining an MHI should never be permitted to return to participation until all postconcussive symptoms have resolved. Based on these findings, athletes whose symptoms resolve quickly should at the very least, be held from participation for 3 days following any episode that suggests they sustained an MHI. Clinicians should seriously consider whether or not they might be placing an athlete at risk by returning them earlier than 3 days postinjury.
1. Guskiewicz, K., Padua, D., & Myers, J. Return to play decisions following mild head injury in collegiate and high school football players (Abstract). National Athletic Trainers’ Association Annual Meeting, Baltimore, MD., Free Communications, June 1998.
2. Guskiewicz, K., & Perrin. Effect of mild head injury on cognition and postural stability (Abstract). National Athletic Trainers’ Association Annual Meeting, Baltimore, MD., Free Communications, June 1998.
3. Guskiewicz, K., Perrin, D., & Gansneder, B. Effect of mild head injury on postural sway. Journal of Athletic Training.. 31(4):300-306, 1996.
4. Guskiewicz, K., Riemann, B., Perrin, D., & Nashner, L. Alternative approaches to the assessment of mild head injuries in athletes. Medicine & Science in Sports & Exercise. 29(7), S213-S221, 1997.
5. Riemann, B., & Guskiewicz, K. Objective mild head injury evaluation through a battery of clinical postural stability tests (Abstract). National Athletic Trainers’ Association Annual Meeting, Baltimore, MD., Free Communications, June 1998.