Using a virtual reality (VR) system, researchers from the University of North Carolina (UNC) have demonstrated clear differences in reactions to falling between people with multiple sclerosis (MS) and people of the same age without MS. The study has been published in PLOS ONE and reveals the potential for this approach to more effectively detect preclinical walking balance deficits in people with MS.
Multiple sclerosis affects approximately 400,000 people in the USA and more than 2 million worldwide. Although some people with MS can show little or no disability when walking, they may already be at twice the risk of falling and injuring themselves, on average, compared with the general population. Previous studies have revealed that individuals with MS fall at least once per year on average.
Recognizing the need for more effective ways to detect preclinical walking balance deficits in people with MS, a team from the UNC School of Medicine sought to develop a test that could reveal balance and gait impairments even in those with MS who may feel they’re able to walk normally.
“When we walk around, our brains use a variety of sensory feedback channels, including force sensors in our feet, to guide our movements and make corrections from one step to the next,” Jason Franz (UNC) explained. “But in people with MS, those force sensors can become less reliable, so people need to rely more on other channels, especially vision.”
The researchers employed a VR device that allows the experimental manipulation of visual perception. Each subject walked on a treadmill facing a virtual hallway through which the subject seemed to be walking, with and without optical flow perturbations in the mediolateral or anterior-posterior directions. Shifts in the scene created the illusion for each participant that they were becoming unstable, triggering a corrective reaction that could be measured as a change in gait and foot placement.
The study involved 14 people with MS and 14 non-MS participants of the same age. The team quantified their reactions and discovered that there was a significant difference between the groups, but only in the presence of mediolateral perturbations – using the VR balance challenge.
“During normal walking without VR – even with our sophisticated lab equipment including a battery of 3D motion capture cameras – we could not effectively distinguish people with MS from the healthy, age-matched individuals,” reported Franz. “So this perturbed-walking approach could have a lot of important clinical and translational applications.”
Franz and his colleagues are now adapting their system as a portable headset for potential use in neurologists’ clinics as a routine diagnostic tool in detecting balance impairments that would otherwise go unnoticed.
“Our promising results suggest that one can use VR to detect balance problems that usually go undetected until the individual starts experiencing real falls at home or work,” commented Franz.
Further application of this device could involve use as a tool of physical therapy, helping people with MS improve their balance and therefore reduce the risk of falls.
Sources: Selgrade BP, Meyer D, Sosnoff JJ et al. Can optical flow perturbations detect walking balance impairment in people with multiple sclerosis? PLOS ONE. doi.org/10.1371/journal.pone.0230202 (2020); http://news.unchealthcare.org/news/2020/march/virtual-reality-shows-promise-for-early-detection-of-ms-balance-problems