BACKGROUND
Gait and balance are frequently altered in concussed youth. These dysfunctions can be assessed clinically as well as with biomechanical force-plate devices. While studies comparing these approaches have been conducted in collegiate athletes, this comparison has yet to be performed in the pediatric population. Our objective was to compare the ability of the modified balance error scoring system (mBESS), tandem gait, and a modified clinical test of sensory interaction and balance (mCTSIB) to discriminate concussed from non-concussed youth.

METHODS
We enrolled 81 cases and 90 controls age 14-18 years old from August 2017-June 2018. Controls were recruited from a suburban high school, and cases were recruited from the sports medicine clinics of a tertiary care academic pediatric center and a suburban high school.  Balance tests included: (1) mBESS, scored as total number of errors on three standing tasks (feet together, feet in tandem, on one foot); (2) Tandem gait, with errors defined as either sway or steps off line during 4 conditions of walking (five steps forward and backward, with eyes open [EO] and closed [EC]); and (3) mCTSIB, performed on the Biosway Portable Balance System (Biodex Medical Systems) and scored as a sway index, the standard deviation of the average center of gravity for four conditions (EO and EC on a firm or dynamic surface). P-values were obtained for tests between proportions, medians (Wilcoxon rank test), and means (T-test). Area under the receiver operating curve (AUC) was used to describe the discriminatory ability of each approach.

RESULTS
Age, sex, race/ethnicity, and insurance were similar among cases and controls.  Cases were seen a median of 11 (IQR: 5,17) days after injury. The median number of total mBESS errors was 4 (IQR: 1,7) for cases and 2 (IQR: 1,4) for controls (p = 0.003), AUC=0.65. On tandem gait, 25% of cases versus 5% of controls had sway/error walking forward EO (p=0.0001); 40% of cases versus 17% of controls had sway/error walking backward EO (p=0.003); 64% of cases versus 48% of controls had sway/error walking forward EC (p=0.04); and 82% of cases versus 59% of controls had sway/error walking backward EC (p=0.003). AUC for total number of conditions provoking sway was 0.65. The mean (SD) sway index on the mCTSIB was 1.3 (0.5) for cases versus 1.1 (0.3) for controls (p=0.003), AUC=0.61.

CONCLUSIONS
Significant differences between cases and controls were present on three different gait and balance assessments. Objective measures of balance produced similar discriminatory ability as the two clinical assessments. While more concussed adolescents demonstrated balance difficulties than non-concussed controls, no balance test showed more than mild discriminatory ability. Balance deficits should be taken in context of a patient’s history and additional physical examination findings when diagnosing concussion.

The utility of clinical and biomechanical metrics of gait and balance in distinguishing pediatric concussion from healthy controls