Commentary on "Postconcussion Postural Sway Variability Changes in Youth: The Benefit of Structural Variability Analyses".

Abstract

“How could I apply this information?” The limitations of current measures used to assess postural stability in adolescents are well documented. Previous researchers advocate for reexamination of the postural stability assessment in adolescents who have sustained concussion. Instrumented measures that include testing with force plates, accelerometers, and gyroscopes have the potential to provide more quantifiable information on the effects of concussion on postural stability than tests that do not provide such objective data. This work is an important step to examine whether variability in the postural stability “system” discriminates between adolescents with a history of concussion and participants who were age-matched and serving as controls. Contrary to several previous studies, the authors report that participants with a history of concussion exhibit less variability in postural stability compared with the age-matched control group. The authors propose several theories for the unexpected finding. Thus, the effects of concussion on postural sway variability are far from resolved. “What should I be mindful of when applying this information?” The authors compared the utility of postural sway variability metrics to the Balance Error Scoring System (BESS). Given the ceiling effect of the BESS and the duration of time since concussion for most participants in this study, the discriminative utility of variability metrics compared with the BESS was expected. This study does not address whether the use of postural sway variability metrics is superior to other established measures such as the Sensory Organization Test (SOT), sway velocity, and sway area. Furthermore, sensitivity and specificity of variability metrics are necessary to confirm their clinical utility. Access to force plates and software to compute variability metrics as well as the inconclusive evidence to support its utility are additional key factors to consider when implementing postural sway variability metrics in clinical practice. Clinicians must exercise due diligence when using variability metrics and other measures in determining return to play after concussion. Michele Lambaria, PT, MPT, NCS Bara Alsalaheen, PT, PhD University of Michigan-Flint, Flint, Michigan