Foam Support Surface Research Articles

Efficacy of D33 Sealed Foam in Preventing Skin Injury from Surgical Positioning: Randomized Clinical Trial.

Objective: To evaluate the efficacy of density-33 (D33) sealed foam in preventing skin injuries from surgical positioning. Approach: The study, reported according to the Consolidated Standards of Reporting Trials, is characterized as a randomized clinical trial, double mask, with 64 adult patients undergoing elective surgery, 35 allocated to the control group (CG), positioned on a conventional surgical table, and 29 to the experimental group (EG), positioned on a conventional surgical table overlaid with a D33 sealed foam support surface (SS) in the occipital, sacral, and heel regions. Simple randomization was carried out, as was masking of the researcher who evaluated the skin of the patient and the statistician. Data collection was carried out immediately preoperatively, intraoperatively, and postoperatively until the third day or until patient discharge. Statistical analysis included measures of association in contingency tables, χ2, and relative risk to compare the incidence of injuries between groups. Results: Skin injuries were greater in the CG, with blanchable erythema being the main injury. The use of D33 sealed foam reduced the incidence of injury in the EG by 61.2% (relative risk: 0.39; 95% confidence interval: 0.220-0.684; p < 0.001). Innovation: One of the first clinical studies to demonstrate that using a D33 sealed foam SS decreased the incidence of blanchable erythema from surgical positioning. Conclusion: D33 sealed foam was effective in preventing skin injury from surgical positioning in patients undergoing elective surgeries.

Amplitude of Electromyographic Activity of Trunk and Lower Extremity Muscles during Oscillatory Forces of Flexi-Bar on Stable and Unstable Surfaces in People with Nonspecific Low Back Pain.

Background: Recently, the oscillatory bar has been proposed as a new and effective rehabilitation tool in people with nonspecific low back pain (NSLBP), although its effects on muscular control in this population have not been well documented, especially in lower extremity muscles and different support surface conditions.Objective: This study aimed to evaluate and compare the effects of flexi-bar use on stable and unstable surfaces on electromyographic activity of trunk and lower extremity muscles in healthy persons and those with NSLBP.Material and Methods: 18 healthy men and 18 men with NSLBP participated in this cross-sectional study. The root mean square value of electromyographic activity was calculated in the trunk and lower extremity muscles during 4 different task conditions: quiet standing (QS) or flexi-bar use on a rigid or foam support surface. A repeated measures test was used for statistical analysis. Results: The results showed that the amplitude activity of almost all muscles was significantly greater during flexi-bar use than in the QS condition (P<0.05). The rectus femoris, tibialis anterior, and gastrocnemius demands were significantly greater on the foam than the rigid surface (P<0.05).Conclusion: This study showed that oscillatory forces caused by flexi-bar use can increase muscle activation in multiple segments (hip and ankle in addition to trunk muscles) that are crucial for postural stability. Furthermore, the foam surface appeared to target the rectus femoris in addition to the ankle muscles. Using a flexi-bar may be helpful in NSLBP rehabilitation, and exercising on a foam surface may enhance additive hip muscle activity in people with NSLBP.

Decreased Postural Complexity in Overweight to Obese Children and Adolescents: A Cross-Sectional Study.

IntroductionAlthough a few studies suggest that young overweight to obese children and adolescents (YO) may have impaired postural control compared to young normal-weight (YN) peers, little information exists about how these two groups differ in the quality of the underlying balance strategies employed. Hence, the aim of the present study was a first comprehensive examination of the structural complexity of postural sways in these two cohorts during quiet bilateral standing.MethodsNineteen YO secondary school students (13.0 ± 1.4 years; male = 10, female = 9) were carefully matched to YN controls (13.0 ± 1.5 years) for age, sex, height, and school. Mediolateral (ML) and anteriorposterior (AP) acceleration signals were recorded with an inertial measurement unit (IMU) positioned at the trunk while standing barefoot in two conditions: firm and foam support surface. The magnitude of postural fluctuations was obtained using the root mean square (RMS). The temporal structure of the signals was analyzed via sample entropy (SEn), largest Lyapunov exponent (LyE), and detrended fluctuation analysis (α-DFA) algorithm. Reliability was assessed using a test–retest design.ResultsIn both groups, foam standing caused higher postural fluctuations (higher RMS values) and reduced structural complexity (lower SEn values, higher LyE values, higher α-DFA values). In comparison to YN, YO exhibited a higher RMSAP. Especially in ML direction, the acceleration signals of the YO had higher repeatability (smaller SEn values), greater long-range correlations (higher α-DFA values), and lower local stability (higher LyE values). However, these observations were largely independent of the task difficulty. Except for α-DFAAP, the IMU approach proved reliable to characterize posture control.DiscussionOur outcomes confirm postural control deficits in YO compared to their YN peers and indicate impaired regulatory mechanisms reflected as rigidity. Such less complex patterns usually reflect diverse pathologies, are detrimental to compensate for internal or external perturbations, and are attributed to lower adaptability and task performance. Without targeted balance stimuli, YO likely end in a lifelong vicious circle of mutually dependent poor balance regulation and low physical activity.

Comparison of interface pressures on three operating table support surfaces during surgery

Aim of the studyTo investigate the effect of support surface usage and positions on interface pressure during surgery. Materials and methodsThis randomized controlled experimental study was conducted between October 2018 and June 2019. The study included patients who had planned surgery in supine and prone positions. The sample size was 72 patients. Patients were assigned to three groups (gel support surface, viscoelastic support surface and standard operating table) according to the determined randomization table. During the surgery, the pressure in the patients' body was recorded. The statistics program IBM SPSS Statistics 25.0 packaged software was used in the analyses of data. ResultsThere was no statistically significant difference between the total body average interface pressure (mmHg) values between the supporting surfaces in the prone position. There was a statistically significant difference between the total body average interface pressure (mmHg) values between the support surfaces in the supine position, and the average interface pressure measured on the viscoelastic foam support surface was significantly lower than the gel support surface and the standard operating table. ConclusionIn the study, the use of viscoelastic foam support surface was found to be more effective than the use of a standard operating table and gel support surface. Viscoelastic foam support surface is recommended for patients at risk for pressure injury in the operating room.

Sensory integration training improves balance in older individuals.

With the massive growth of the aging population worldwide, of utmost importance is reducing falls. Critical to reducing fall risk is one's ability to weight incoming sensory information towards maintaining balance. The purpose of this research was to investigate if simple, targeted sensory training on aging individuals (50 - 80 years old), including twelve healthy and eight individuals with chronic stroke, could improve their balance. Repeated sensory training targeted visual (via eyesopen/closed) and somatosensory inputs (via light touch to the fingertip as well as hard, soft foam, and hard foam support surfaces to the feet) during standing and dynamic base-ofsupport (BOS) exercises. Study participants underwent six weeks of training. Prior to and post training, standing balance was assessed via a simple, clinical measure: the balance error scoring system (BESS). Following several weeks of training, participants showed significant improvements in BESS errors: healthy participants for small BOS with limited somatosensory information (i.e., tandem and single-leg standing on foam) and participants with stroke in all conditions.Clinical Relevance- This research study demonstrated that simple, accessible exercises, can positively impact balance in the aging population, a pressing need.

TEAM-UP for quality: a cluster randomized controlled trial protocol focused on preventing pressure ulcers through repositioning frequency and precipitating factors

BackgroundPressure ulcers/injuries (PrUs), a critical concern for nursing homes (NH), are responsible for chronic wounds, amputations, septic infections, and premature deaths. PrUs occur most commonly in older adults and NH residence is a risk factor for their development, with at least one of every nine U.S. NH residents experiencing a PrU and many NHs having high incidence and prevalence rates, in some instances well over 20%. PrU direct treatment costs are greater than prevention costs, making prevention-focused protocols critical. Current PrU prevention protocols recommend repositioning residents at moderate, high, and severe risk every 2 h. The advent of visco-elastic (VE) high-density foam support-surfaces over the past decade may now make it possible to extend the repositioning interval to every 3 or 4 h without increasing PrU development. The TEAM-UP (Turn Everyone And Move for Ulcer Prevention) study aims to determine: 1) whether repositioning interval can be extended for NH residents without compromising PrU incidence and 2) how changes in medical severity interact with changes in risk level and repositioning schedule to predict PrU development.MethodsIn this proposed cluster randomized study, 9 NHs will be randomly assigned to one of three repositioning intervals (2, 3, or 4 h) for a 4-week period. Each enrolled site will use a single NH-wide repositioning interval as the standard of care for residents at low, moderate, and high risk of PrU development (N = 951) meeting the following criteria: minimum 3-day stay, without PrUs, no adhesive allergy, and using VE support surfaces (mattresses). An FDA-cleared patient monitoring system that records position/movement of these residents via individual wireless sensors will be used to visually cue staff when residents need repositioning and document compliance with repositioning protocols.DiscussionThis study will advance knowledge about repositioning frequency and clinically assessed PrU risk level in relation to PrU incidence and medical severity. Outcomes of this research will contribute to future guidelines for more precise preventive nursing practices and refinement of PrU prevention guidelines.Trial registrationClinical Trial Registration: NCT02996331.

Correlation Between Center of Pressure Measures Driven from Wii Balance Board and Force Platform

Background: The gold standard for postural stability evaluation is the force platform; which has multiple limitations such as high costs, not being portable and being difficult to implement. Simple balance training devices have been recently tried to take this role. The validity and reliability of such devices have been a major concern. Methods: Twenty symptom-free university students volunteered to take part in this methodological study. The center of pressure, anterior-posterior displacement range and total path length were measured during static standing tasks under four conditions of eyes opened and closed with firm and foam support surface by Bertec force platform and Wii Balance Board. Intra-class correlation coefficient and standard error of measurement were used to assess relative and absolute reliability, respectively. The mean differences of the measurements of the two devices were compared to zero by one sample t-test to check the construct validity of the Wii Balance Board. Bland and Altman plots were also used for descriptive evaluation of the mean and the variability of measurement differences of the two devices. Regression analysis was used to check if there was any systematic bias between the mean values and the differences between the two devices. Results: All center of pressure measures from both devices showed statistically significant relative reliability (P 0.05). Regression analysis of the pooled mean scores and the measurement differences revealed no significant systematic bias between them (P > 0.05). Conclusions: Both Bertec force platform and Wii Balance Board devices showed acceptable reliability. While the center of pressure driven variables measured by the two devices are comparable, there is a trend toward overestimation of these variables by the Wii Balance Board. The difference between the measurements of the two devices was found to be highly variable without any significant systematic bias.

Vibro-tactile and auditory balance biofeedback changes muscle activity patterns: Possible implications for vestibularimplants.

The two different types of balance prostheses being developed, implants and vibro-tactile/auditory feedback prostheses, rely on different measures to prove efficacy (those based on vestibular ocular reflexes versus balance control, respectively). Here we provide evidence that examining muscle activity might provide a useful alternative for both. The muscle activity of 6 bilateral vestibular loss (BVL) and 7 age-matched healthy controls (HC) was examined while standing eyes closed on a foam support surface. Pelvis and upper trunk angular movements were recorded in the roll and pitch planes. Surface EMG was recorded from the lower leg, trunk and upper arm muscles. BVL subjects were first assessed without feedback of pelvis sway, then received training with combined vibro-tactile and auditory feedback, before being re-assessed with feedback. Feedback reduced the amplitudes of pelvis and shoulder sway to values of HC without feedback. Both the level of background EMG activity and the EMG area amplitudes changed when feedback was provided in a manner consistent with the reduced amplitude modulation of muscle synergies of HC. The results of this study indicate that changed muscle synergy amplitudes underlie improvements in sway achieved by BVL subjects. The concept of this investigation may provide a means to prove efficacy for different types of balance prostheses, including implants.

Prevention of pressure ulcers in the intensive care unit: a randomized trial of 2 viscoelastic foam support surfaces.

The aim of this study is to compare whether differences exist between 2 viscoelastic foam support surfaces in the development of new pressure ulcers. There is evidence to support the use of viscoelastic foam over standard hospital foam to reduce pressure. A comparative effectiveness study was done to compare 2 viscoelastic foam support surfaces. A randomized controlled trial was carried out. The study was performed in 2 intensive care units between October 1, 2008, and January 4, 2010. Patients (n = 105) admitted to intensive care unit were randomly assigned to viscoelastic foam 1 (n = 53) or viscoelastic foam 2 support surface (n = 52). In total, 42.8% of all patients developed a new pressure ulcer of stage 1 or worse. By stages, pressure ulcer incidence was 28.6%, 13.3%, and 1.0% for stages 1, 2, and 3, respectively. There was no significant difference in pressure ulcer incidence between the viscoelastic foam 1 and 2 groups (X2 = 0.07, df = 1, P > .05). No difference was found between 2 different viscoelastic foam surfaces in the prevention of pressure ulcers in patients treated in intensive care. Pressure ulcer incidence in critically ill patients remains high. Nurses must compare current products for effectiveness and develop innovative systems, processes, or devices to deliver best practices.

Assessment of postural stability in patients with cerebellar disease using gyroscope data

This study examines a relatively new method of studying and quantifying human postural stability in patients with degenerative cerebellar disease. Trunk sway and feet sway were measured during quiet stance. To test the method, ten patients and eleven healthy subjects performed two different stance tasks: standing with eyes open on a firm surface and standing with eyes closed on a foam support surface. Data were recorded using three body-worn gyroscopes (Xsens Technologies B.V.) to measure roll and pitch angular movements of the lower trunk, and left and right foot. The pitch versus roll plots of the trunk and feet were created, and the areas of the convex hull shapes were calculated. It was found that the area of the convex hull of the pitch versus roll plots is suitable for the identification of postural instability disorders caused by degenerative cerebellar disease.

Effectiveness of different visual biofeedback signals for human balance improvement

The aim of this study was to examine the effectiveness of visual biofeedback (VBF) signals from a force platform and accelerometer sensors placed on different body segments. The study was performed on 20 young subjects during standing on a firm and foam support surface with a VBF signal sensed from CoP, lower trunk (L5) and upper trunk (Th4). The VBF signal was controlled by 2D-movement of chosen body segment, which was presented as a red point on a monitor screen. Location of VBF signal had a significant effect on each postural parameter of CoP and trunk segments. RMS and amplitudes of postural sway in medial–lateral and anterior–posterior directions decreased during standing on both types of support surface due to VBF. L5-VBF and CoP-VBF significantly reduced CoP displacements and lower trunk tilts. Th4-VBF reduced upper trunk tilts. Frequency analysis of postural sway revealed a decrease of power spectral density (PSD) values in low frequency range (0.02–0.3Hz) and an increase of PSD values in higher frequency range (0.5–1.4Hz) in the VBF conditions during the stance on the firm surface in anterior–posterior direction. Reduction of body sway was the most significant in the body segment from which the VBF signal was sensed. The CoP position and L5 position provided the best signals for VBF. Changes in frequency ranges of body sway suggest voluntary activation of balance control. The results open new opportunities to optimize VBF system for balance improvement using accelerometers.

Coordination of the head with respect to the trunk, pelvis, and lower leg during quiet stance after vestibular loss

This study examined the relationship between head and trunk sway and between pelvis and leg sway during quiet stance in subjects with long-standing bilateral peripheral vestibular loss (BVLs) comparing these relationships to those of age-matched healthy controls (HCs). All subjects performed three different stance tasks: standing quietly on a firm or foam support surface, with eyes closed (ECF or eyes closed on normal) and on foam with eyes open. Data were recorded with four pairs of body-worn gyroscopes to measure roll and pitch angular velocities at the head, upper trunk, pelvis and lower-leg. These velocities were spectrally analysed and integrated for angle correlation analysis in three frequency bands: below 0.7Hz (low pass, LP), above 3 Hz (high pass, HP) and in between (band pass, BP). For both groups head motion was greater than trunk and pelvis motion except for BVL subjects (BVLs) under ECF conditions. BVLs had greater motion than HCs at all measurement locations for ECF conditions. Angle correlation analysis indicated that the head was almost "locked" to the trunk for BVLs over the LP and BP frequency bands. Head movements for both groups were relatively independent of the trunk in the HP band. Power spectral density ratios, and transfer functions showed a similar result - head relative to trunk movements were less up to 3 Hz in all tests for BVLs. The resonant frequency of head-on-trunk motion was shifted to a higher frequency for BVLs: from 3.2 to 4.3 Hz in pitch, 4.6 to 5.4 Hz in roll. Both groups show greater lower-leg than pelvis motion. These data indicate that during quiet stance BVLs change the characteristics of their head on shoulder motion, reducing relative motion of the head below 3 Hz and increasing head resonant frequency. Presumably these changes are accomplished with increased use of proprioceptive neck reflexes.

Coordination of the head with respect to the trunk and pelvis in the roll and pitch planes during quiet stance

This study examined the relationship between head and trunk sway during quiet stance and compared this relationship with that of the pelvis to the trunk. Sixteen younger and 14 elderly subjects participated, performing four different sensory tasks: standing quietly on a firm or foam support surface, with eyes open or closed. Roll and pitch angular velocities were recorded with six body-worn gyroscopes; a set of two mounted at the upper trunk, an identical set at the hips, and another set on a head band. Angle correlation analysis was performed in three frequency bands: below 0.7Hz (LP), above 3Hz (HP) and in between (BP) using the integrated angle velocity signals. Angular velocities were spectrally analysed.Greater head than trunk motion was observed in angle correlations, power spectral density (PSD) ratios, and transfer functions (TFs). Head on trunk motion could be divided for all sensory conditions into a low-frequency (<0.7Hz) “head locked to trunk” inverted pendulum mode, a mid-frequency (ca. 3Hz), resonant mode, and a slightly anti-phasic head motion on stabilised trunk, high-frequency (>3Hz) mode. There was coherent motion between head and trunk but not between head and pelvis. Trunk and pelvis data were consistent with previously reported in-phase and anti-phase movements between these segments. Significant age differences were not found.These data indicate that during quiet stance body motion increases in the order of pelvis, trunk, head and quiet stance involves control of at least two separate links: trunk on pelvis and head on trunk dominated by head resonance. The head is locked to the trunk for low-frequency motion possibly because motion is just supra-vestibular threshold. The head is not stabilised in space during stance, rather the pelvis is.

Do somatosensory conditions from the foot and ankle affect postural responses to plantar-flexor muscles fatigue during bipedal quiet stance?

The present study investigated the effects of somatosensory conditions at the foot and ankle on postural responses to plantar-flexor muscle fatigue during bipedal quiet stance. Twenty-two young healthy adults were asked to stand upright as still as possible with their eyes closed in three somatosensory conditions (normal, altered and improved) both prior to and after exercises inducing plantar-flexor muscle fatigue. In the normal condition, the postural task was executed on a firm support surface constituted by the force platform. In the altered condition, a 2-cm thick foam support surface was placed under the subjects’ feet. In the improved condition, increased cutaneous feedback at the foot and ankle was provided by strips of athletic tape applied across both their ankle joints. Muscle fatigue was induced in the plantar-flexor muscles of both legs through the execution of a repeated standing heel raise exercise. Centre of foot pressure displacements were recorded using a force platform. Results showed that plantar-flexor muscle fatigue yielded increased centre of foot pressure displacements under normal foot and ankle sensory conditions. Furthermore, this effect was exacerbated under altered foot and ankle sensory conditions and mitigated under improved foot and ankle sensory conditions. Altogether, the present findings suggested an increased reliance on somatosensory information from the foot and ankle for controlling upright posture in the presence of plantar-flexor muscle fatigue.

Mattress cleanliness: the role of monitoring and maintenance

A clean and tidy environment provides the right setting for good patient care. It is fundamental in preventing and/or controlling the spread of healthcare-associated infections (HCAI). Cleanliness is an essential component for the comfort and dignity of patients, particularly those for whom a hospital is home for any length of time. Patients spend a lot of their time in bed so it is important for them to be provided with well maintained and clean mattresses. Beds, and especially the mattresses, should be cleaned and inspected regularly so patients know they are being cared for in a clean and safe environment. To prolong the life of the mattress and reduce infection risks, inspections for damage and contamination must take place on a regular basis. Assessment criteria for the audit of a mattress can include a visual inspection, a cover permeability test and a foam support surface test. These assessments will ensure the mattress is compliant with current standards and identify whether or not they require condemning. Mattress care can be improved by adopting unified good practices that can be standardized and audited regularly.

Screening for balance disorders in mildly affected multiple sclerosis patients

Multiple sclerosis (MS) patients often complain about balance problems when Romberg's test and tandem gait are normal. The aim of the study was to determine if measures of trunk sway taken during a battery of stance and gait tasks could be used to detect subclinical balance disorders. We recorded trunk angular sway in the pitch and roll directions from 20 MS patients (EDSS 1.4 ± 0.5) and 20 age- and gender-matched healthy controls (HCs), during 12 stance and gait tasks. We filmed 22 subjects simultaneously. Two neurologists assessed the videos, deciding whether task performance was pathological. Sway measures were significantly different between patients and HCs in eight out of 12 balance tasks. The most significant differences between MS patients and HCs were pitch angle range standing on one leg with eyes open on a firm surface (mean 3.13° vs. 2.09°, p = 0.005), and on a foam support surface (mean 6.24° vs. 2.96°, p = 0.006), pitch velocity range walking 8 m with eyes closed (mean 75.5 vs. 50.2°/s, p < 0.001) and pitch velocity range walking 3 m on heels (mean 85.37 vs. 60.9°/s, p = 0.002). Multivariate analysis revealed a model with three tasks which detected balance disorders in 84% of the MS patients and 90% of the HCs correctly. The neurologists achieved accuracies of 30% for the MS patients and 82% for the HCs. Using trunk sway measures during stance and gait tasks is a sensitive screening method for balance problems in MS patients, and is more accurate than assessment by trained neurologists.

Postural control and attentional demand during adolescence

In the present study we aimed to determine the attentional cost of postural control during adolescence by studying the influence of a cognitive task on concurrent postural control. 38 teenagers aged 12 to 17years and 13 young adults (mean age=26.1) stood barefoot on a force platform in a semi-tandem position. A dual-task paradigm consisted of performing a Stroop or a COUNTING BACKWARD task while simultaneously standing quietly on a firm or foam support surface. Different centre of pressure (CoP) measures were calculated (90% confidence ellipse area, mean velocity, root mean square on the antero-posterior (AP) and medio-lateral (ML) axes). The number and percentage of correct responses in the cognitive tasks were also recorded. Our results indicate (1) higher values of surface, ML mean velocity and ML RMS in the COUNTING BACKWARD task in adolescents aged 12 to 15 than in teenagers aged 16 to 17 and in adults, regardless of the complexity of the postural task and, (2) better cognitive performances in the Stroop than in the COUNTING BACKWARD task. The difference in the dual-task performance between the different age groups and particularly the existence of a turning point around 14–15years of age might be due to 1) difficulties in properly allocating attentional resources to two simultaneous tasks and/or, 2) the inability to manage increased cognitive requests because of a limited information processing capacity in adolescents aged 14–15years.

Postural Effects of the Scaled Display of Visual Foot Center of Pressure Feedback Under Different Somatosensory Conditions at the Foot and the Ankle

Vuillerme N, Bertrand R, Pinsault N. Postural effects of the scaled display of visual foot center of pressure feedback under different somatosensory conditions at the foot and the ankle. Objectives To assess the effects of the scaled display of visual foot center of pressure (COP) feedback on upright postural control under different somatosensory conditions at the foot and the ankle. Design Before and after intervention trials. Setting University medical bioengineering laboratory. Participants Young healthy adults (N=8; mean age, 23±2.5y; mean body weight, 76.8±11.2kg; mean height, 179.8±6.8cm). Interventions Participants were asked to stand upright, as immobile as possible, in 3 visual conditions: a stationary cross feedback (SC-FB) condition and 2 different foot COP feedback (COP-FB) conditions involving increasing scale displays of 2:1 (COP-FB2) and of 10:1 (COP-FB10). These latter conditions correspond to the ratio between the COP displacement on the screen and the actual COP displacement measured by the force platform. This postural task was executed on 2 (firm, foam) support surface conditions. In the foam condition, a 2-cm thick foam support surface was placed under the participants' feet to alter the quality and/or quantity of somatosensory information at the foot and the ankle. Main Outcome Measure COP displacements were recorded using a force platform. Results In the firm support surface condition, no significant difference was observed between the COP-FB2 and the SC-FB conditions, whereas the COP-FB10 condition yielded decreased COP displacements relative to the SC-FB condition. In the foam support surface condition, both the COP-FB2 and the COP-FB10 conditions yielded decreased COP displacements relative to the SC-FB condition, with a greater stabilizing effect in the COP-FB10 than COP-FB2 condition. Conclusions The postural effects of the scale display of visual COP feedback differed depending on the somatosensory conditions at the foot and the ankle. These findings suggest that increased reliance on augmented sensory information for controlling upright posture in conditions of altered somatosensory input from the foot and ankle could have implications in clinical and rehabilitative areas.

Vestibular rehabilitation by auditory feedback in otolith disorders

Rehabilitation strategies have been applied successfully over the last few decades to initiate central compensation of the tonus imbalance and to facilitate substitution in different types of peripheral vestibular dysfunction. However, these vestibular rehabilitation strategies are often not successful in patients with isolated otolith disorders. The aim of the present study was therefore to evaluate a specific rehabilitation strategy for patients with an isolated otolith disorder by using an auditory feedback system. Thirteen patients, which suffered from different types of otolith disorders, but no other vestibular pathology and 13 normal controls were included in this study. Vestibular rehabilitation exercises were performed daily over a 2-week period (weekends excluded). During all exercises the patients of the test group ( n = 13) obtained an acoustic feedback signal when their trunk angle velocity exceeded a preset level while the patients of the control group ( n = 13) performed the same exercises without auditory feedback. The most effective exercise in the test group was “walking eight tandem steps on a foam support surface”. Approximately 85% of the patients showed a significant decrease of trunk sway in this condition. In contrast to these results, patients of the control group showed no significant improvement of postural control after the training. The results indicate that an auditory feedback rehabilitation program with exercises related to the specific neurotological disease could significantly improve the postural control in patients with otolith disorders.

Sensory supplementation system based on electrotactile tongue biofeedback of head position for balance control

The present study aimed at investigating the effects of an artificial head position-based tongue-placed electrotactile biofeedback on postural control during quiet standing under different somatosensory conditions from the support surface. Eight young healthy adults were asked to stand as immobile as possible with their eyes closed on two Firm and Foam support surface conditions executed in two conditions of No-biofeedback and Biofeedback. In the Foam condition, a 6-cm thick foam support surface was placed under the subjects’ feet to alter the quality and/or quantity of somatosensory information at the plantar sole and the ankle. The underlying principle of the biofeedback consisted of providing supplementary information about the head orientation with respect to gravitational vertical through electrical stimulation of the tongue. Centre of foot pressure (CoP) displacements were recorded using a force platform. Larger CoP displacements were observed in the Foam than Firm conditions in the two conditions of No-biofeedback and Biofeedback. Interestingly, this destabilizing effect was less accentuated in the Biofeedback than No-biofeedback condition. In accordance with the sensory re-weighting hypothesis for balance control, the present findings evidence that the availability of the central nervous system to integrate an artificial head orientation information delivered through electrical stimulation of the tongue to limit the postural perturbation induced by alteration of somatosensory input from the support surface.