Researchers at the University of North Carolina School of Medicine found that falls simulated through virtual reality could enable early detection of balance problems in patients with multiple sclerosis (MS), according to a study published in PLoS One.
Researchers at the University of North Carolina School of Medicine found that falls simulated through virtual reality (VR) could enable early detection of balance problems in patients with multiple sclerosis (MS), according to a study published in PLoS One.
It is estimated that 56% of people with MS fall annually due to impaired proprioceptive acuity. Compounding the high risk of falls is the fact that those with MS often have “deficiencies in bone density and vitamin D (which makes them nearly 3 times more likely than the general population to suffer hip fracture),” authors noted.
Researchers used a VR system to trick patients with MS and age-matched controls into thinking they were falling while walking on a treadmill. Researchers then analyzed differences in reactions by quantifying foot placement kinematics, gait variability, lateral margin of stability, and performance on the standing sensory organization test.
“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,” explained an author of the study, Jason Franz, PhD. “But in people with MS, those force sensors can become less reliable, so people need to rely more on other channels, especially vision.”
Specifically, the test aimed to reveal balance or gait impairments in individuals with MS who may not yet experience difficulties or falls in normal walking. Researchers targeted this population because “people with MS who exhibit minimal to no disability are still over twice as likely to fall as the general population and many of these falls occur during walking,” authors said.
Fourteen individuals with MS and 14 controls walked normally on a treadmill while viewing a virtual hallway. Tests were conducted with and without optical flow perturbations. In unperturbed walking tests, researchers found no significant differences step width, step length, or their respective variabilities in controls compared with patients with MS.
However, when falling was simulated through VR, researchers found that “[people with MS] adopted 29.1% higher step width variability (P = .022), 17.2% higher mediolateral center of mass variability (P= .040), and 21.4% higher mediolateral seventh cervical vertebra (a surrogate for trunk motion) variability (P = .019) than their age-matched controls.”
From these results, researchers concluded that VR optical flow perturbations could be used as a tool for detecting preclinical walking balance impairment in people with MS that might otherwise go undetected.
“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,” said Franz. “So this perturbed-walking approach could have a lot of important clinical and translational applications.”
Researchers note larger studies should be conducted on the technology in the future, including patients representing a wider range of ages, disease progressions, and balance impairments.
Selgrade BP, Meyer D, Sosnoff JJ, et al. Can optical flow perturbations detect walking balance impairment in people with multiple sclerosis? [published online March 10, 2020]. PLoS One. doi: 10.1371/journal.pone.0230202.