mHealth Research Digest with Tim Bredrup
Current devices to help manage patients with physical balance problems are impractical for home-based rehabilitation for a variety of reasons including their size, complexity, and cost, amongst others.
In an effort to address this issue, a team of researchers at the University of Michigan in Ann Arbor designed, developed, and tested a system using mobile phones for patient use at home for balance rehabilitation training.
The iPhone based system utilizes the phone’s embedded tri-axial linear accelerometer along with custom software to estimate trunk tilt, a measure of imbalance. A custom “tactor bud” hardware accessory was also developed to provide real-time vibro-tactile feedback. The accessory plugs into and receives signals from the phone audio jack.
To evaluate the efficacy of the system, five young healthy subjects (ranging from 21-27 years old) and four subjects with vestibular involvement (ranging from 30-55 years of age) participated in the study.
The healthy subjects used the system with eyes closed during a variety of Romberg stances and positions. Subjects with vestibular involvement used the system with eyes both open and closed while executing a semi-tandem Romberg (single limb) stance.
When the subjects exceeded either an anterior-posterior (A/P) or medial-lateral (M/L) trunk sway threshold, vibro-tactile feedback was provided through a vibration. The participants were told to move away from the vibration. In this manner, the vibration took the place of a health care professional who would typically inform them of their swaying in a rehabilitation center. The iPhone approach allowed them to do the same thing at home.
The researchers reached an interesting conclusion.
“The system was capable of providing real-time vibro-tactile cues that informed corrective trunk tilt responses. When feedback was available, both healthy subjects and those with vestibular involvement significantly reduced their A/P or M/L RMS trunk sway (depending on the direction of feedback), had significantly smaller elliptical area fits to their sway trajectory, spent a significantly greater mean percentage time within the no feedback zone, and showed a significantly greater A/P or M/L mean power frequency.”
The researchers concluded “The results suggest users can use the real-time feedback provided by this system to reduce their trunk sway”. Finally, they stated that “its advantages over more complex laboratory-based and commercial balance training systems in terms of cost, size, weight, functionality, flexibility, and accessibility make it a good candidate for further home-based balance training evaluation.”
Authors: Beom-Chan Lee, Jeonghee Kim, Shu Chen, Kathleen H. Sienko
Institutions: Institute of Gerontology – Departments of Mechanical Engineering, Biomedical Engineering, Electrical Engineering, Computer Science, University of Michigan, Ann Arbor, USA
Original Abstract: PubMed