Evaluation of postural stability in the elderly with stroke.

OBJECTIVE

To compare clinical and biomechanical measures of balance in elderly stroke patients with those of healthy elderly people.

DESIGN

Two-group comparison design.

SETTING

Laboratory environment.

PARTICIPANTS

Fifteen poststroke patients and 15 healthy age-matched older adults (N=30).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The biomechanical variable COP-COM, which represents the distance between the center of pressure (COP) and the center of mass (COM) in terms of root mean square. The mean of 4 trials of the COP-COM variable for each test condition was used for statistical analysis. Furthermore, the different systems (sensory, motor, central processor) related to postural stability were evaluated.

RESULTS

Statistical significance of the COP-COM variable was larger in the stroke group than in healthy subjects, in both the anteroposterior (AP) and mediolateral (ML) directions. Furthermore, statistically, stroke subjects showed amplitudes of the COP-COM variable that were significantly larger in the eyes-closed condition. The significant negative correlation demonstrated between COP-COM amplitude and the balance scales (Berg, Tinetti) indicated that the patients with larger COP-COM amplitudes had lower clinical balance score. Furthermore, correlation coefficient scores between COP-COM variables in both AP and ML directions and motor performance using Fugl-Meyer Assessment (rho=-.53, rho=-.51, respectively) and reaction time (rho=-.53, rho=-.44, respectively) were significant. Vibration (rho=.41) and touch-pressure (rho=.42) perception thresholds correlated significantly only in the AP direction.

CONCLUSIONS

Evaluating postural stability with COP-COM variable provided an accurate measure of postural stability in poststroke elderly people. Furthermore, postural stability in quiet stance, as measured by COP-COM amplitude, was related to functional measures of balance as well as physiologic factors relating to balance, such as visual conditions, lower-extremity peripheral sensibility, motor recovery, and simple reaction time.