Their solution: vibrating insoles.
In recent tests, patients who were standing still with their eyes closed balanced better when vibratory pads were applied to their insoles.
Boston University's Attila Priplata, PhD, and colleagues describe the insoles in the Annals of Neurology.
The insoles are made of silicone gel. They contain three vibrating elements called "tactors." Two tactors are positioned under the forefoot; one is under the heel.
Participants stood on the insoles as the researchers tweaked the insoles' vibrations. The scientists then set the vibration level just below what the participants could feel.
Meanwhile, the scientists turned the insoles' vibrations off and on. The vibrations were too subtle to feel, so the participants didn't know when the insoles were on.
If participants swayed, reflectors on their shoulders showed it. A motion detector tracked even the slightest sways, down to the millimeter.
Both diabetic and stroke patients swayed less when the insoles vibrated. The study shows that vibration works on patients with nerve damage in the brain (stroke patients) and nerve damage in the limbs (diabetic patients). Past tests on healthy young and elderly people had similar results, the researchers note.
The scientists aren't exactly sure how the vibrating insoles help balance.
Possibly the vibrations "can enhance the detection of pressure changes on the soles of the feet, leading to improved balance control," they write.
In this study, the patients stood still because the insoles couldn't yet be put in shoes.
The scientists have since figured out how to do that. They plan more tests on people who have their eyes open and who move around.