Primary outcomes consisted of two indicators of postural stability — maximum excursion and directional control — as measured by computerized dynamic posturography (Balance Master System, NeuroCom). Maximum excursion is an assessment of the limits of self-initiated movements as patients shift or lean their center of gravity, without falling, toward the theoretical limit (100%) in each of eight target directions. Directional control, a measure of movement accuracy, is calculated by comparing the amount of movement toward the target with the amount of extraneous movement. Scores on both measures range from 0 to 100%, with higher percentages indicating better balance or control