Is postural control associated with mental functioning in the persistent postconcussion syndrome?

Abstract

Objective: To investigate whether balance is associated with mental functioning after mild traumatic brain injury (MTBI). Design: Experimental two-group design. Setting: Outpatient rehabilitation department. Patients and Other Participants: From a consecutive sample of referred MTBI patients, 15 subjects who complained of imbalance were included (8 men and 7 women, age 35.9 ± 8.6yrs). Subjects with detectable neurologic impairments were excluded. Twenty healthy control subjects of the same age group also were tested. Main Outcome Measures: In both groups, a force platform recorded center-of-pressure (CP) fluctuations during standing and weight shifting in different conditions. For the patients, attention and mental speed were assessed with the Symbol-Digit Substitution Test of the Wechsler Adult Intelligence Scale (Dutch version), verbal learning and memory were assessed with the 15-Words Test, and emotional distress was assessed with the Symptom Checklist-90. Results: Compared with controls, patients showed an overall increase of 60% in CP velocity and an overall weight-shifting speed 25% slower ( p < .005), indicating static and dynamic postural instability. Only performance on the Symbol-Digit Substitution Test was associated with both static and dynamic balance ( p < .02), giving an explained variance of over 40%. Conclusion: The results indicate a possible association of balance with cognitive performance but not with emotional well-being after MTBI, suggesting an organic rather than a functional cause of postural instability. Further research is needed to assess the possible clinical implications.