Most improvements are transient
By Larry Hand
The findings of a recent Australian study add to early evidence in support of whole body vibration (WBV) as a potentially simple, noninvasive treatment for children with idiopathic toe walking (ITW), with mechanisms still to be worked out.
The study, epublished on April 12 by the Journal of Child Neurology (JCN), found WBV has positive effects on gait in children with ITW, though some of those effects were only seen immediately after treatment.
“This was an exploratory study,” said Cylie M. Williams, PhD, adjunct research fellow in the School of Physiotherapy at Monash University in Victoria. “We wanted to gather evidence prior to setting out to look at it in a larger trial.”
Williams and colleagues assessed the impact of multiple doses of WBV on number of heel strikes as a percentage of total steps, spatial and temporal gait parameters, and ankle range of motion for 15 children (five girls, mean age 5.93 years, mean height 120.3 cm). They applied WBV for five sets of one-minute vibration followed by one minute of rest, as the children stood upright in a semisquat position with their feet flat on the vibration platform. Gait was assessed at baseline and at one, five, 10, and 20 minutes postintervention; ankle range of motion (ROM) was assessed at baseline, immediately postintervention, and 20 minutes postintervention.
The researchers found immediate, statistically significant increases in left and right stride lengths and velocity, all of which were sustained at 20 minutes. Immediate, significant increases in number of heel strikes and ankle ROM were not sustained at 20 minutes. WBV may improve gait via the rapid ankle ROM increase or a response to neuromodulation, the authors wrote.
The results are encouraging enough to continue this line of research, Williams said, though they contrast with the findings of a 2015 study from Georgia State University in Atlanta, also published in JCN. In the US study, which involved a single one-minute dose of WBV at a higher frequency, no significant effect on gait was observed in 15 children with ITW. (See “Toe-walking researchers revisit idiopathic label,” LER: Pediatrics November 2014, page 15.)
The inconsistencies underscore the relative infancy of ITW research into WBV, Williams said.
“I don’t think our understanding of vibration perception and how that may be impacted by physiological changes in the muscle is sophisticated enough to make assumptions on if children have different responses to WBV,” she said. “Particularly not yet in children, and definitely not in children who are idiopathic toe walkers.”
The timing of post-WBV assessment may make a difference, said Mark Geil, PhD, director of the Center for Pediatric Locomotion Sciences at Georgia State University, and coauthor of the previous research paper.
“When we first explored the idea of WBV in children with ITW, we were cautioned by several clinicians that it has a ‘short half-life.’ Consequently, I’m glad that Williams et al conducted a series of measurements over time following the WBV intervention to compare immediate effects to short-term effects,” Geil said.
The baseline visual perception threshold may be a key to further understanding, according to Geil, who noted this is another example of how his group’s findings have contrasted with those of Williams and colleagues. In a 2012 study, the Australians reported that children with ITW were hypersensitive to vibration relative to typically developing children, but the Americans were unable to replicate the results in their 2015 JCN study despite using similar methods.
“This might be the heart of the matter,” Geil said. “We were very interested in [the Australian] results, as theirs might have been the first study to link ITW to a measurable sensory processing issue.”
The contrasting findings may be an indication that there are subgroups of children with ITW, and only some are hypersensitive to vibration, he hypothesized.
“I’ve spoken with many clinicians who are convinced that ITW is a result of either sensory processing issues or low tone, or, I suppose, a combination of the two,” Geil said. “Following this logic, if one study group is primarily sensory, then a particular intervention might be more effective. The baseline visual perception threshold might be a way to determine the nature of the study group.”
The most recent Australian study did not look at vibration perception, as the authors wanted to focus on the physiological effects of WBV on muscle, Williams said.
Overall, Williams is optimistic about the clinical potential of WBV in the ITW population.
“There is more and more research being done on the impact of WBV,” she said. “With more research, and as technology changes and becomes more accessible, this may become an easy home treatment option.”
Larry Hand is a writer in Massachusetts.
Williams CM, Michalitsis J, Murphy AT, et al. Whole-body vibration results in short-term improvement in the gait of children with idiopathic toe walking. J Child Neurol 2016 April 12. [Epub ahead of print]
Fanchiang HD, Geil M, Wu J, et al. The effects of vibration on the gait pattern and vibration perception threshold of children with idiopathic toe walking. J Child Neurol 2015;30(8):1010-1016.
Williams CM, Tinley P, Curtin M, Nielsen S. Vibration perception thresholds in children with idiopathic toe walking gait. J Child Neurol 2012;27(8):1017-1021.