Relationship between clinical and instrumental balance assessments in chronic post-stroke hemiparesis subjects

BACKGROUND: Stroke is often associated with balance deficits that increase the risk of falls and may lead to severe mobility disfunctions or death. The purpose of this study is to establish the relation between the outcome of instrumented posturography and of the most commonly used clinical balance tests, and investigate their role for obtaining reliable feedback on stroke patients’ balance impairment. METHODS: Romberg test was performed on 20 subjects, 10 hemiplegic post-stroke subjects (SS, 69.4 ± 8.2 years old) and 10 control subjects (CS, 61.6 ± 8.6 years old), with 1 Bertec force plate. The following parameters were estimated from the centre of pressure (CoP) trajectory, which can be used to define subjects’ performance during the balance task: sway area; ellipse (containing 95% of the data); mean CoP path and velocity in the anterior-posterior and medio-lateral directions. The following clinical scales and tests were administered to the subjects: Tinetti Balance test (TB); Berg Balance test (BBT); Time up and go test (TUG), Fugl-Meyer (lower limbs) (FM), Motricity Index (lower limbs), Trunk Control Test, Functional Independence Measure. Comparison between SS and CS subjects was performed by using the Student t-test. The Pearson Correlation coefficient was computed between instrumental and clinical parameters. RESULTS: Mean ± standard deviation for the balance scales scores of SS were: 12.5 ± 3.6 for TB, 42.9 ± 13.1 for BBT, 24 s and 75 cent ± 25 s and 70 cent for TUG. Correlation was found among some CoP parameters and both BBT and TUG in the eyes open and closed conditions (0.9 ≤ R ≤ 0.8). Sway area correlated only with TUG. Statistically significant differences were found between SS and CS in all CoP parameters in eyes open condition (p < 0.04); whereas in eyes closed condition only CoP path and velocity (p < 0.02) differed significantly. CONCLUSIONS: Correlation was found only among some of the clinical and instrumental balance outcomes, indicating that they might measure different aspects of balance control. Consistently with previous findings in healthy and pathological subjects, our results suggest that instrumented posturography should be recommended for use in clinical practice in addition to clinical functional tests.