Noise-enhanced balance control in patients with diabetes and patients with stroke.
OBJECTIVE: Somatosensory function declines with diabetic neuropathy and often with stroke, resulting in diminished motor performance. Recently, it has been shown that input noise can enhance human sensorimotor function. The goal of this study was to investigate whether subsensory mechanical noise applied to the soles of the feet via vibrating insoles can be used to improve quiet-standing balance control in 15 patients with diabetic neuropathy and 15 patients with stroke. Sway data of 12 healthy elderly subjects from a previous study on vibrating insoles were added for comparison. METHODS: Five traditional sway parameters and three sway parameters from random-walk analysis were computed for each trial (no noise or noise). RESULTS: Application of noise resulted in a statistically significant reduction in each of the eight sway parameters in the subjects with diabetic neuropathy, the subjects with stroke, and the elderly subjects. We also found that higher levels of baseline postural sway in sensory-impaired individuals was correlated with greater improvements in balance control with input noise. INTERPRETATION: This work indicates that noise-based devices could ameliorate diabetic and stroke impairments in balance control.