Retraining Sensory Weighting Using Virtual Environment and Vibrotactile Biofeedback
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Purpose: The aim of this study was to evaluate the effectiveness of a balance rehabilitation protocol to retrain the sensory weighting mechanism by utilizing vibrotactile feedback and training in virtual environment (VE). Materials/Methods: 20 participants, 10 non-diabetic young adults (NDYA) and 10 diabetic older adults with peripheral neuropathy (DAPN). We experimentally induced somatosensory loss in NDYA with inflated pressure cuffs on the ankles for 35 min and then placed a vibrotactile system with low and high frequency stimulation. Data was collected at baseline and during the last 15 minutes of the ischemic protocol under three conditions: no vibration, low frequency and high frequency vibrations. Outcome measures included center of pressure (COP) variability, plantar surface pressure sensation and vibratory threshold. The DAPN participated in 6 (1-hour) training sessions with visually engaging VE which progressively challenged walking and balance tasks. Vibratory devices were placed around ankles, above the level of sensory loss, delivering constant sub-threshold white noise stimulation. In visits 1 and 8 pre- and post-training functional assessments of balance and gait function were conducted. Results:In NDYA, ischemia increased COP variability and plantar surface pressure sensation threshold (p=.01 and p= 0.3 respectively) and decreased the vibratory extension threshold measured at the hallux IP joint (p during CTSIB for eyes closed conditions both on stable and foam surface (p Conclusions: The vibratory biofeedback was able to partially compensate for the experimental induced sensory loss and improve balance function in healthy young adults. Results of the training protocol suggest support for the stochastic resonance theory and show that sensory retraining in VE and vibratory device is feasible in diabetic subjects holding promise for improvement of function due to an increased ability to integrate all sensory inputs available and a decreased reliance on visual inputs.