Enhancing Sensation in Diabetic Neuropathic Foot With Mechanical Noise

Abstract

OBJECTIVE -Localized low-level mechanical or electrical noise can significantly enhance tactile sensitivity in healthy young subjects and older adults. This phenomenon is termed stochastic resonance (SR). In this study, we examined the effect of SR on vibratory and tactile sensation in patients with moderate to severe diabetic peripheral neuropathy. RESEARCH DESIGN AND METHODS-A total of 20 subjects were included in the study. The vibration perception threshold (VPT) test and the Semmes-Weinstein filament (SWF) threshold at the plantar surface of the left foot and the big toe were determined under two mechanical noise stimulus conditions: null (no noise) condition and at 10% lower than each subject's mechanical noise threshold of perception. RESULTS -The baseline values (mean Ϯ SD) were as follows: Neuropathy Symptom Score (NSS) 5.2 Ϯ 2.5, Neuropathy Disability Score (NDS) 5.0 Ϯ 2.1, VPT 24 Ϯ 11 V, and SWF threshold 5.6 Ϯ 0.8 at the plantar surface of the foot and 5.3 Ϯ 0.9 at the big toe. The VPT improved significantly from 24 Ϯ 11 under null condition to 19 Ϯ 10 V with mechanical noise (P Ͻ 0.0001). Mechanical noise also significantly increased the number of detections of the SWF at the plantar surface of the foot (detection rate 66 Ϯ 11 vs. 59 Ϯ 15%, P Ͻ 0.02) but not at the big toe (63 Ϯ 10 vs. 61 Ϯ 16%, P ϭ NS).CONCLUSIONS -Mechanical noise stimulation improves vibration and tactile perception in diabetic patients with moderate to severe neuropathy. Additional studies are required to examine the effect of long-term noise stimulation on parameters of nerve function. Diabetes Care 26:3280 -3283, 2003D iabetic neuropathy is the most common neuropathy in western countries. This condition is estimated to occur in 20 -50% of diabetic patients, depending on the patient population studied and the criteria used for diagnosis (1-5). When compounded by peripheral vascular disease and impaired wound healing, the result is a classic cascade of skin and other medical problems in the affected areas (6). Seemingly innocuous circumstances such as ill-fitting shoes and minor skin lacerations progress into serious medical problems such as slowh e a l i n g s k i n u l c e r s . P e r i p h e r a l neuropathy can also lead to deformity of the foot and Charcot arthropathy (7,8). In severe cases, which are all too common, amputation of the affected extremity becomes necessary. In the U.S., Ͼ50,000 amputations are performed annually for these reasons (9). The cost to the U.S. health care system for diabetic foot problems exceeds $3,000,000,000 annually.Recently, a wide range of studies from computer models to human experiments have shown conclusively that low-level mechanical or electrical noise presented directly to sensory neurons can significantly enhance their ability to detect weak stimuli. This phenomenon of noise improving system performance is termed stochastic resonance (SR) and has been seen to occur in a variety of physical and biological systems. From a clinical perspective, one particularly important finding is that ...

Wearable sensorimotor enhancer for a fingertip based on stochastic resonance

“…Some studies have also reported that SR improves visual [9], aural [10] and haptic [11] ability. The SR effect in tactile sensitivity has also been confirmed in feet [12], [13], hands and fingers [14], [15], and improved tactile sensitivity is known to influence the sensorimotor functions of humans [7], [8]. It has further been reported that SR improves balance control in humans [16], [17].…”

Wearable Sensorimotor Enhancer for Fingertip Based on Stochastic Resonance Effect

“…Some studies have also reported that SR improves visual [9], aural [10], and haptic [11] ability. The SR effect in tactile sensitivity has also been confirmed in feet [12], [13], hands, and fingers [14], [15], and improved tactile sensitivity is known to influence the sensorimotor functions of humans. It has further been reported that SR improves balance control in humans [16], [17].…”

Pelvic floor stimulation: What are the good vibrations?

“…Fontana et al 21 was able to show that low frequency whole body vibration improved proprioception in the lumbosacral area, and Khaodhiar et al 22 demonstrated an improvement of tactile perception using SRV. We have not tested pelvic floor proprioception in the current study but this subject will be addressed in the future.…”