NASHVILLE—A rapid foot-tapping task can distinguish between healthy controls and people with multiple sclerosis (MS), as well as between MS subtypes, according to a study presented at the 2018 CMSC Annual Meeting. “The associations between foot-tap speed and mobility measures such as the Timed Up and Go [TUG] test and the 25-Foot Walk test [25FWT] suggest that rapid foot tapping may be a useful marker for tracking or predicting progression of mobility dysfunction in people with MS, regardless of their ability to ambulate,” said Sumire Sato, a graduate student in the Neuroscience and Behavior Program at the University of Massachusetts Amherst, and colleagues.
The TUG test and the 25FWT are common clinical measurements that require ambulation and are used to assess mobility in people with MS. Not all people with MS are ambulatory, however. Preliminary, unpublished work by Ms. Sato and colleagues suggests that while the TUG test and the 25FWT can distinguish individuals with MS from controls without MS, they cannot distinguish between nonprogressive (MS-NP) and progressive (MS-P) MS subtypes. “Therefore, there is a critical need to identify a sensitive and nonambulatory task that can distinguish MS subtypes,” said the investigators.
Ms. Sato and colleagues recruited 30 participants with MS-NP, 30 participants with MS-P, and 17 age- and sex-matched controls for a study to determine whether rapid foot tapping ability can distinguish people with MS from controls and between MS subtypes. Each participant wore inertial sensors (manufactured by APDM) on the foot to measure angular velocity and acceleration. Participants were instructed to tap one foot as fast as possible for 10 seconds. Participants performed three trials on each foot while seated with self-selected knee and ankle angle.
The researchers analyzed sensor data using a custom MATLAB program that identified taps as acceleration peaks that occurred after every other zero-crossing of angular velocity. They administered the TUG test and 25FWT to participants to compare mobility to rapid foot tapping. Analysis of variance was used to analyze main effects of group and to make pairwise comparisons between groups. Ms. Sato and colleagues evaluated associations between foot tap count and mobility measures in MS groups using Spearman’s rho.
The researchers observed a main effect of group for foot-tap count, such that tap count differed between controls and participants with MS-NP and MS-P. The tap count also differed between participants with MS-NP and those with MS-P. Foot-tap count was negatively correlated with the 25FWT and the TUG test, thus indicating an association between the slowing of tapping speed and mobility measures.