Many people with multiple sclerosis (MS) have trouble with balance and a fear of falling, which can have severe negative effects on their quality of life by keeping them away from social events, regular exercise, and community activities. Now, a new pilot study conducted within the UMass Amherst School of Public Health and Health Sciences, funded by a one-year, $39,000 grant from the National Multiple Sclerosis Society, will investigate how sensation in the feet while standing relates to balance ability and whether vibrating insoles might aid walking and improve balance.
Research assistant professor of kinesiology Dr. Stephanie Jones and professor of kinesiology Dr. Richard van Emmerik will test sensation in two areas on the soles of the feet of people with and without MS as they stand and sit and use the data to determine how this relates to their balance ability. The researchers believe this study will be the first ever conducted with people both sitting and standing to determine whether thresholds differ with weight bearing.
As Dr. Jones explains, “There is a lot of evidence that the somatosensory system, that is the skin’s sensation and body awareness or proprioception, is affected in people with MS, who often report peripheral sensory loss, for example.”
In the study, the kinesiology researchers will build upon recent technology that can improve skin sensation by applying a vibration to the soles of the feet at a level below the detection threshold. Such small, irregular vibrations have been shown to restore some of the lost sensation and improve balance in people with sensory loss in their feet because of diabetes or stroke, the researchers note.
“This method exploits the phenomenon of stochastic resonance of the nervous system,” Dr. Jones explains. “It applies a kind of ‘noise’ that can enhance a person’s skin sensation.”
For these experiments, small devices called “tactors” placed in the subject’s shoes will produce the slight vibrations. Each subject will be tested to find the most sensitive parts of their sole. With tactors in place, each subject will take a blinded test, that is without knowing whether the vibration is on or off, during five different postural conditions. Then after a five-minute wait, the five conditions will be tested again to see if there is any carryover effect of the vibration.
The final phase of the study will test the ability of tactors to help people with MS as they detect and respond to a sudden balance challenge. Dr. Jones explains, “Because their nervous system is compromised, people with MS show a much greater delay in detecting and responding to unexpected balance disturbances. One of our goals is to see if we can enhance the ability to detect and respond to a sudden challenge and in doing so, improve balance. In this case, the challenge will be a shift of the surface underfoot, a bit like what you get when you step onto an escalator.”
Subjects will stand on a platform that will suddenly move about three inches. “This is not enough to cause most people to fall but it’s enough to see the muscles fire that are needed to keep you upright. We hope tactors might reduce that delay so that these muscles will fire sooner and the person would be less de-stabilized with them in place,” Dr. Jones notes.
Someday in the future people with balance challenges might be wearing vibrating insoles powered by a tiny battery that would help them navigate the world, she adds. “If we identify this mechanism of somatosensory impairment in MS, perhaps we can develop other interventions to try to do more,” says Dr. Jones.