Visual-auditory Biofeedback Research Articles

A Human-machine-interface Integrating Low-cost Sensors with a Neuromuscular Electrical Stimulation System for Post-stroke Balance Rehabilitation.

A stroke is caused when an artery carrying blood from heart to an area in the brain bursts or a clot obstructs the blood flow to brain thereby preventing delivery of oxygen and nutrients. About half of the stroke survivors are left with some degree of disability. Innovative methodologies for restorative neurorehabilitation are urgently required to reduce long-term disability. The ability of the nervous system to reorganize its structure, function and connections as a response to intrinsic or extrinsic stimuli is called neuroplasticity. Neuroplasticity is involved in post-stroke functional disturbances, but also in rehabilitation. Beneficial neuroplastic changes may be facilitated with non-invasive electrotherapy, such as neuromuscular electrical stimulation (NMES) and sensory electrical stimulation (SES). NMES involves coordinated electrical stimulation of motor nerves and muscles to activate them with continuous short pulses of electrical current while SES involves stimulation of sensory nerves with electrical current resulting in sensations that vary from barely perceivable to highly unpleasant. Here, active cortical participation in rehabilitation procedures may be facilitated by driving the non-invasive electrotherapy with biosignals (electromyogram (EMG), electroencephalogram (EEG), electrooculogram (EOG)) that represent simultaneous active perception and volitional effort. To achieve this in a resource-poor setting, e.g., in low- and middle-income countries, we present a low-cost human-machine-interface (HMI) by leveraging recent advances in off-the-shelf video game sensor technology. In this paper, we discuss the open-source software interface that integrates low-cost off-the-shelf sensors for visual-auditory biofeedback with non-invasive electrotherapy to assist postural control during balance rehabilitation. We demonstrate the proof-of-concept on healthy volunteers.

New Computer Protocol with Subsensory Stimulation and Visual/Auditory Biofeedback for Balance Assessment in Amputees

In this study, we hypothesized that the static standing weight bearing steadiness and dynamic walking weight shifting stability could be improved by providing neuromuscular facilitation using subsensory stimulation and visual–auditory biofeedback in amputee respectively. To test this hypothesis, a computer protocol with sensory feedback neuromuscular facilitation system was developed and used for clinical assessment. Seven unilateral transtibial amputees who consecutively worn prosthetics over two years were recruited. Experimental results show a reduction in all of the postural sway related indices and increase in single-leg holding time index during static quiet standing by applying subsensory stimulation. With visual–auditory biofeedback for providing clue for heel contact and toe push-off condition during dynamic ambulation, an improvement in all four dynamic walking weight shifting stability indices in amputees was verified. This study provided evidence that sensory feedback neuromuscular stimulation may put amputees at better balance capability.

Balance control enhancement using sub-sensory stimulation and visual-auditory biofeedback strategies for amputee subjects

Sub-sensory electrical or mechanical stimulation can enhance the sensitivity of the human somatosensory system to improve the balance control capabilities of elderly. In addition, clinical studies suggest that visual-auditory biofeedback can improve sensory compensation for the elderly. This study hypothesizes that the static balance and gait performance of single leg quiet standing and treadmill walking could be improved for providing proprioceptive neuromuscular facilitation using sub-sensory stimulation and visual-auditory biofeedback in amputee subjects. To test this, a computerized foot pressure biofeedback sensory compensation system using sub-threshold low-level electrical stimulation combined with visual-auditory biofeedback was developed. Seven unilateral trans-tibial amputees who wore prostheses over 2 years were recruited. The subjects performed multiple single leg quiet standing trials with sub-sensory electrical stimulation applied at the quadriceps muscle during half of the trials. Static balance performance was characterized by using a Zebris motion analysis system to measure the sway distance and duration of the centre of mass on the second sacral (S2) of the subjects. In addition, multiple treadmill ambulatory trials with or without visual-auditory biofeedback was performed. Dynamic gait performance was characterized with a Zebris instrumented insole to measure the temporal responses of foot pressure sensors. Experimental results showed an improvement in three balance performance indices (Holding Time Index, HTI, Maximum Sway Distance Index, MSDI, and Average Sway Distance Index, ASDI) during single leg quiet standing by applying sub-sensory stimulation. The improvement ratio of these balance performance indices across subjects for single leg quiet standing tests resulted in 132.34% in HTI, 44.61% in MSDI, and 61.45% in ASDI. With visual-auditory biofeedback as a cue for heel contact and toe push-off condition during treadmill ambulation, the improvement of four dynamic gait performance measures (Double Support Period, DSP, Constant Time Cadence, CTC, Single Support Period, SSP, and Stance/Swing Ratio, SSR) in amputees was verified. This resulted in 7.89% in DSP (affected side), 5.09% in CTC, 16.67% in SSP (sound side), 45.30% in SSR (sound side), and 40.30% in SSR (affected side) respectively. These findings suggest that sub-threshold electrical stimulation and visual-auditory biofeedback rehabilitation strategies may be effective in compensating sensory loss and improving static balance and dynamic ambulation performance for amputees.

New Foot Pressure Activated Sensory Compensation System for Posture-Control Enhancement in Amputees

A computerized foot pressure activated sensory compensation system using subsensory electrical stimulation combined with visual-auditory biofeedback was developed. The proposed system was used for enhancing standing balance and gait performance for amputees. In this pilot study, we hypothesized that the static balance with single limb support and gait performance during treadmill walking could be improved by providing proprioceptive neuromuscular facilitation using subsensory stimulation and visual-auditory biofeedback in amputee, respectively. To test this hypothesis, five unilateral transtibial amputees who consecutively wore prosthetics over two years were recruited. Experimental results show a reduction in all of the postural sway indexes and increase in single-leg support time index during single-leg quiet standing by applying subsensory stimulation. With visual-auditory biofeedback for providing clue for heel contact and toe push-off condition during treadmill ambulation, an improvement in all four dynamic gait performance indexes in amputees was verified. These findings suggest that the proposed system with subsensory electrical stimulation and visual-auditory biofeedback mechanisms may be effective in compensating sensory loss and improving posture control for amputees.

DESIGN OF A NEW BIOFEEDBACK PROPRIOCEPTIVE NEUROMUSCULAR FACILITATION SYSTEM FOR BELOW-KNEE AMPUTEES

Proprioceptive neuromuscular facilitation and foot sensory compensation are critical to balance control and ambulatory performance in below-knee amputees. Sub-sensory stimulation has been shown to be effective in enhancing the sensitivity of the human somatosensory system. In addition, visual-auditory biofeedback to improve foot sensory compensation for amputees was suggested in recent articles. The purpose of this study is to develop a new biofeedback proprioceptive neuromuscular facilitation system for improving balance control and foot sensory compensation in below-knee amputees. The proposed system functioned with sub-threshold electrical stimulation and visual-auditory biofeedback was developed for clinical study. Two unilateral trans-tibial amputees who consecutively wore prosthetics over 10 years were participated in this study. Subjects performed multiple single leg quite standing trails with sub-sensory electrical stimulation applied at the quadriceps muscle during half of the trails. Four static balance performance indices (i.e. Holding Time Index, HTI; Sway Length Index, SLI; Max Sway Distance Index, MSDI; Average Sway Distance Index, ASDI) were characterized using Zebris motion analysis system. The improvement ratio of these static balance performance indices across subjects for single leg quiet standing tests were resulted in a 209.7% in HTI, 39.1% in SLI, 24.3% in MSDI, and 65.4% in ASDI respectively. In addition, multiple treadmill ambulatory trails with or without visual-auditory biofeedback were evaluated. Four dynamic gait performance indices (i.e. Double Support Time Index, DSTI; Constant Time Cadence Index, CTCI; Single Support Time Index, SSTI; Stance/Swing Phase Index, SSPI) were characterized with Zebris instrumented insole and associated FMS analysis software. With visual-auditory biofeedback, the improvement of all four dynamic gait performance indices in below-knee amputees was verified. The improvement ratio of four gait performance indices across subjects resulted in a 14.81% in DSTI (sound side), 14.29% in DSTI (affected side), 14% in CTCI, 13.00% in SSTI (sound side), 6.02% in SSTI (affected side), 45.17% in SSPI (sound side), and 27.49% in SSPI (affected side) respectively. These findings suggest that sub-threshold electrical stimulation and visual-auditory biofeedback proprioceptive neuromuscular facilitation strategies may be effective in compensating foot sensory loss and improving balance control for below-knee amputees.