For the elderly, falling is the leading cause of death due to injury. Now, a biomedical engineer is studying how vibrations can help seniors keep their balance. His work won him a Macarthur Foundation fellowship for creativity.

Lead author Dr. James J. Collins of Boston University states that “The vibration, adjusted to a sub-sensory level, appears to "tickle" neurons, making them more sensitive to stimuli that are present during quiet standing.”

Dr. Collins and his team had previously shown that subsensory mechanical noise delivered to the feet via the insoles could help healthy elderly people, as well as healthy young adults, to maintain better balance.

In the current study, the researchers tested the effects of the vibrating insoles on sway parameters in 15 patients with diabetic neuropathy and 15 patients with stroke. Patients stood on the insoles, which contain two vibrating elements on each forefoot and one on each heel. Because the vibration was delivered at 90% of each foot's sensory threshold level, patients acted as their own controls.

Data from a previous study of the insoles in 12 healthy elderly people was included for comparison.

The researchers looked at five traditional sway parameters and three derived from random-walk analysis. All were reduced significantly with the noise application in all of the patients, the researchers found. And the greater a patient's baseline level of postural sway, the more balance control improved with noise input.

Additional research is needed, Dr. Collins and his colleagues write, to investigate how the technology may benefit patients with stroke lesions affecting different parts of the brain, for example the right versus the left side of the brain.

"The main thing that we're focusing on now is testing whether the insoles provide benefit in dynamic activity such as walking," Dr. Collins said. He and his colleagues have completed prototypes of insoles and shoes incorporating the vibrating elements, and are planning studies to test them as patients walk, climb stairs and negotiate other activities of daily living.

He and his team also plan to investigate whether the vibrating insoles will be helpful to Parkinson's patients and patients with multiple sclerosis.

Audio File: Vibrating Insoles

Source: Diabetes In Control: Ann Neurol 2006;59:4-12.