Postural Stability and Neuropsychological Deficits After Concussion in Collegiate Athletes

Abstract

OBJECTIVE: Postural stability and neuropsychological testing are gradually becoming integral parts of postconcussion assessment in athletes. Clinicians, however, sometimes question the viability of instituting preseason baseline testing and the value of these results in making return-to-play decisions. Our purpose was to examine the course of recovery on various postural stability and neuropsychological measures after sport-related concussion. A secondary goal was to determine if loss of consciousness and amnesia, both of which are heavily weighted in most of the concussion classification systems, affect the rate of recovery. DESIGN AND SETTING: All subjects underwent a battery of baseline postural stability and neuropsychological tests before the start of their respective seasons. Any athletes subsequently injured were followed up at postinjury days 1, 3, and 5. Matched control subjects were assessed using the same test battery at the same time intervals. SUBJECTS: We studied 36 Division I collegiate athletes who sustained a concussion and 36 matched control subjects. MEASUREMENTS: We assessed postural stability using the Sensory Organization Test on the NeuroCom Smart Balance Master System and the Balance Error Scoring System. Neurocognitive functioning was measured with several neuropsychological tests: Trail-Making Test, Wechsler Digit Span Test, Stroop Color Word Test, and Hopkins Verbal Learning Test. RESULTS: Injured subjects demonstrated postural stability deficits, as measured on both the Sensory Organization Test and Balance Error Scoring System. These deficits were significantly worse than both preseason scores and matched control subjects' scores on postinjury day 1. Only the results on the Trail-Making Test B and Wechsler Digit Span Test Backward resulted in a logical recovery curve that could explain lowered neuropsychological performance due to concussive injury. Significant differences were revealed between the control and injured groups at day 1 postinjury, but a significant decline between baseline and postinjury scores was not demonstrated. Loss of consciousness and amnesia were not associated with increased deficits or slowed recovery on measures of postural stability or neurocognitive functioning. CONCLUSIONS: Athletes with cerebral concussion demonstrated acute balance deficits, which are likely the result of not using information from the vestibular and visual systems effectively. Neurocognitive deficits are more difficult to identify in the acute stages of concussion, although concentration, working memory, immediate memory recall, and rapid visual processing appear to be mildly affected. More research is necessary to determine the best neuropsychological test battery for assessing sport-related concussion.

Figure 1

Smart Balance Master System.

Figure 2

Six testing conditions for Sensory Organization Test used with NeuroCom's Smart Balance Master System.

Figure 3

Balance Error Scoring System (BESS) performed on the firm surface (top, A–C) and foam surface (bottom, D–F).

Figure 4

Composite Score means (±SD) on the NeuroCom Smart Balance Master for 36 injured and 36 control subjects across test sessions (preseason through day 5 postinjury). Higher scores represent better performance.

Figure 5

Vestibular ratio means (±SD) on the NeuroCom Smart Balance Master System for 36 injured and 36 control subjects across test sessions (preseason through day 5 postinjury). Higher scores represent better performance.

Figure 6

Visual ratio means (±SD) on the NeuroCom Smart Balance Master for 36 injured and 36 control subjects across test sessions (preseason through day 5 postinjury). Higher scores represent better performance.

Figure 7

Balance Error Scoring System means (±SD) (combined errors on all 6 trials) for 36 injured and 36 control subjects across test sessions (preseason through day 5 postinjury). Lower scores represent better performance.

Figure 8

Trail-Making Test B means (±SD) for 18 injured and 23 control subjects across test sessions (preseason through day 5 postinjury). Lower scores represent better performance.

Figure 9

Wechsler Digit Span Test Backward means (±SD) (combined errors on all 6 trials) for 36 injured and 36 control subjects across test sessions (preseason through day 5 postinjury). Higher scores represent better performance.