Center of pressure measures during standing tasks in minimally impaired persons with multiple sclerosis.

BACKGROUND AND PURPOSE: Balance impairments are common in persons with multiple sclerosis (MS), but clinical balance tests may not detect subtle deficits in adults with MS who are not yet experiencing functional limitations or disability. The purpose of this study was to determine if center of pressure (COP) displacement during standing tasks could be a useful performance-based evaluative measure for adults with MS who have minimal or no balance deficits on clinical examination using the Berg Balance Scale (BBS). SUBJECTS AND METHODS: Twenty-one adults with MS were compared with 21 age- and gendermatched healthy adults. Subjects with MS were tested with the BBS, Mini-mental State Exam, Expanded Disability Status Scale (EDSS), and Multiple Sclerosis Functional Composite (MSFC). They also performed voluntary leaning and reaching movements while kinematic and kinetic data were collected. Control subjects performed the same tasks with the exception of the EDSS and MSFC. RESULTS: COP displacement during reaching and leaning was less in adults with MS when compared to control subjects. There were no differences in anthropometric, kinematic, or foot position variables that could account for this difference. Furthermore, there was no difference between groups when COP displacement during reaching was expressed as a percentage of the maximum COP displacement during leaning. DISCUSSION AND CONCLUSION: COP measures show clear differences when comparing healthy adults with minimally impaired adults with MS. The lack of between-group differences when COP displacement during reaching was expressed as a percentage of the maximum COP displacement during leaning suggests that the subjects with MS adopt a reaching strategy that allows them to stay within their reduced limits of stability. COP measures during standing tasks appear well-suited to quantifying changes in postural control over time or in response to intervention for minimally impaired persons with MS.