Vibrating insoles improve balance in neuropathic patients

[Guest guest]

Biomechanics March 2006

Vibrating insoles improve balance in neuropathic patients

By: Lori Rochelle Roniger

http://biomech.com/showArticle.jhtml?articleID=181502895

The standing balance of individuals with diabetic neuropathy was

improved while wearing insoles that vibrated at levels the patients

could not detect, according to a study from Boston University. The

research was based on the principle that subsensory noise can boost

the perception of relatively weak stimuli.

" The insoles increase the sensitivity of neurons on the soles of the

feet to weak pressure and other mechanical load signals during quiet

standing, " said J. , PhD, a professor of biomedical

engineering at BU and one of the study's authors. " This serves to

enhance sensory information and the (body's) balance control system

can react to this to maintain more stable posture. "

Balance was also improved in healthy elderly subjects and stroke

patients on whom the insoles were tested.

developed the idea for the insoles after hearing that

researchers had demonstrated the use of stochastic resonance in

animal mechanoreceptor cells. Stochastic resonance is a phenomenon by

which a noise signal, in this case vibrations undetectable to the

wearer emitted by insoles, can cause other proprioceptive information

to be amplified.

Nine women and six men with diabetic neuropathy (mean age 60), and 10

women and five men who had experienced unilateral stroke at least 10

months earlier (mean age 61), served as subjects in the current

study.

In laboratory trials, the subjects were asked to stand barefoot with

their eyes closed on two insoles. Each insole had been molded with a

viscoelastic silicone gel and embedded with three tactors-

electromechanical transducers manufactured by Engineering Acoustics

(Winter Park, FL) that produce random vibrations-two under the

forefoot and one under the heel. A noise generator sent signals to

each of the insoles. The vibration levels were increased until the

subject could sense the stimuli. The tactors were then set at 90% of

this level. Postural sway and foot center-of-pressure displacement

data were collected for each subject during 10 30-second trials.

Mechanical noise was present during five of the trials, with the

order of the noise and non-noise control trials randomized. The data

were compared to results from 12 healthy elderly subjects, eight

women and four men (mean age 73), from a previous study on the

insoles.

All of the postural sway parameters measured decreased significantly

for all three subject groups during the noise trials compared to the

control trials, the researchers reported in the January issue of the

ls of Neurology. No adverse effects of the vibration have been

seen, said.

The insoles may improve balance in diabetic neuropathy and stroke

patients through different mechanisms. In patients with diabetes, the

vibrations may enhance the dampened ability to detect sensory data.

Stroke patients, said, require more information from the

periphery, and the insoles may boost the amount of information

arriving at the central nervous system.

Afferent Corporation of Providence, RI, which licensed the vibrating

insole technology from BU, is working to commercialize the insoles

and eventually to use this technology in other products.

, previously a science founder of the company, is no longer

directly involved in Afferent, but serves as a science advisor for

the firm and is conducting independent academic research on vibrating

insole and footwear technology.

and his colleagues are beginning to study the effectiveness

of vibrating insoles during walking, conducting tests with portable

vibrating insoles that can be inserted into any shoes. Additional

research could involve examining the effectiveness of the vibrational

technology at reducing the incidence of falls.

Other potential users of the insoles include Parkinson's disease and

multiple sclerosis patients and healthy older adults. also

foresees the technology's application in knee or ankle braces to

enhance the sensory feedback of individuals undergoing sports

medicine rehabilitation.

[Guest guest]

I can see how these insoles would help with balance.

Thank you for the info. I will get some when they are available.