Nicolas Vuillerme

Controlling posture using a plantar pressure-based, tongue-placed tactile biofeedback system

The present paper introduces an original biofeedback system for improving human balance control, whose underlying principle consists in providing additional sensory information related to foot sole pressure distribution to the user through a tongue-placed tactile output device. To assess the effect of this biofeedback system on postural control during quiet standing, ten young healthy adults were asked to stand as immobile as possible with their eyes closed in two conditions of No-biofeedback and Biofeedback. Centre of foot pressure (CoP) displacements were recorded using a force platform. Results showed reduced CoP displacements in the Biofeedback relative to the No-biofeedback condition. The present findings evidenced the ability of the central nervous system to efficiently integrate an artificial plantar-based, tongue-placed tactile biofeedback for controlling control posture during quiet standing.

iBalance-ABF: A Smartphone-Based Audio-Biofeedback Balance System

This paper proposes an implementation of a Kalman filter, using inertial sensors of a smartphone, to estimate 3-D angulation of the trunk. The developed system monitors the trunk angular evolution during bipedal stance and helps the user to improve balance through a configurable and integrated auditory-biofeedback (ABF) loop. A proof-of-concept study was performed to assess the effectiveness of this so-called iBalance-ABF-smartphone-based audio-biofeedback system-in improving balance during bipedal standing. Results showed that young healthy individuals were able to efficiently use ABF on sagittal trunk tilt to improve their balance in the medial-lateral direction. These findings suggest that the iBalance-ABF system as a telerehabilitation system could represent a suitable solution for ambient assisted living technologies.

Behavioral Telemonitoring of the Elderly at Home: Detection of Nycthemeral Rhythms Drifts from Location Data

Supporting ageing in place and staying at home, delaying institutionalization, lightening the caregivers burden, improving the elderly quality of life are as many expectations that TeleHealthCare aims at coming up to. This paper proposes a method for Telemonitoring to detect abnormal changes in behavior which may lead to an early entrance in dependency. This method allows to detect and quantify a possible nycthemeral shift in daily routine. Such a disorder is common with elderly but in severe cases, it may be a marker of pathological behavior. Particularly, in individuals with Alzheimer disease, it appears to be an indicator for more rapid decline. In all the cases, the detection of a disruption in the activity circadian clock needs a follow-up visit. The method introduced is fast and cost-effective in computation. It measures the dissimilarity between sequences of activity using a variant of the Hamming distance traditionally used in information theory. Then results are interpreted according to the circular Gumbel distribution. This method is illustrated through a longitudinal study of the successive locations of an elderly woman within her own flat. In this preliminary work, the records were captured by passive infrared sensors placed in each room allowing only the detection of elementary activities of daily living. The method was tested by varying the timebox width of the study (i. e. the duration of the watched activities) and in a second time by distinguishing the day of the week. In both cases, it provides interesting insights into the behavior and the daily routine of the watched person as well as deviations from this routine. Important deviations will trigger alarms to alert the care providers. Diagnosing early abnormal behaviors is crucial for the person management and treatment effectiveness and consequently his/her maintaining at home.

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

OBJECTIVESnTo 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.nnnDESIGNnBefore and after intervention trials.nnnSETTINGnUniversity medical bioengineering laboratory.nnnPARTICIPANTSnYoung healthy adults (N=8; mean age, 23+/-2.5 y; mean body weight, 76.8+/-11.2 kg; mean height, 179.8+/-6.8 cm).nnnINTERVENTIONSnParticipants 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.nnnMAIN OUTCOME MEASUREnCOP displacements were recorded using a force platform.nnnRESULTSnIn 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.nnnCONCLUSIONSnThe 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.

Performance Evaluation of Smartphone Inertial Sensors Measurement for Range of Motion.

Over the years, smartphones have become tools for scientific and clinical research. They can, for instance, be used to assess range of motion and joint angle measurement. In this paper, our aim was to determine if smartphones are reliable and accurate enough for clinical motion research. This work proposes an evaluation of different smartphone sensors performance and different manufacturer algorithm performances with the comparison to the gold standard, an industrial robotic arm with an actual standard use inertial motion unit in clinical measurement, an Xsens product. Both dynamic and static protocols were used to perform these comparisons. Root Mean Square (RMS) mean values results for static protocol are under 0.3° for the different smartphones. RMS mean values results for dynamic protocol are more prone to bias induced by Euler angle representation. Statistical results prove that there are no filter effect on results for both protocols and no hardware effect. Smartphones performance can be compared to the Xsens gold standard for clinical research.

Degradation of cervical joint position sense following muscular fatigue in humans.

Study Design. Before and after intervention trials. Objective. To investigate the effect of cervical muscular fatigue on joint position sense. Summary of Background Data. Although fatigue-related degradation of proprioceptive acuity at lower and upper limbs is well documented, to date no study has investigated whether muscular fatigue induced at the neck could modify joint position sense. Methods. A total of 9 young healthy adults were asked to perform the cervicocephalic relocation test to the neutral head position, that is, to relocate the head on the trunk, as accurately as possible, after full active cervical rotation to the left and right sides. This experimental task was executed in 2 conditions of No fatigue and Fatigue of the scapula elevator muscles. Absolute and variable errors were used to assess the cervical joint repositioning accuracy and consistency, respectively. Results. Less accurate and less consistent repositioning performances were observed in Fatigue relative to No fatigue condition, as indicated by increased absolute and variable errors, respectively. Conclusion. Results of the present experiment evidence that cervical joint position sense, assessed through the cervicocephalic relocation test to the neutral head position, is degraded by muscular fatigue.

The Effects of Scale Display of Visual Feedback on Postural Control During Quiet Standing in Healthy Elderly Subjects

OBJECTIVEnTo assess the effects of scale display of visual feedback (VFB) on postural control during quiet standing in healthy elderly subjects.nnnDESIGNnBefore and after intervention trials.nnnSETTINGnMedical university bioengineering laboratory.nnnPARTICIPANTSnTwelve healthy elderly subjects (mean age, 70.2+/-2.8 y; mean body weight, 65.5+/-4.1 kg; mean height, 163.4+/-6.5 cm).nnnINTERVENTIONnParticipants were asked to stand upright as immobile as possible in an eyes-open condition and 3 VFB conditions involving increasing scale displays: 2 to 1 (VFB(2)), 5 to 1 (VFB(5)), and 10 to 1 (VFB(10)). These latter conditions correspond to the ratio between the real displacements of the center of pressure (COP), as measured by the force platform, and their visualization on the monitor screen.nnnMAIN OUTCOME MEASUREnCOP displacements were recorded using a force platform.nnnRESULTSnVFB had different effects on the COP displacements depending on the scale display; no significant difference was observed between the VFB(2) and the eyes-open conditions, whereas the VFB(5) and VFB(10) conditions yielded decreased COP displacements relative to the eyes-open condition.nnnCONCLUSIONSnThe effectiveness of the VFB system in improving postural control during quiet standing in elderly subjects depends on the scale display. These findings could have implications in clinical and rehabilitative areas.

Wegoto: A Smartphone-based approach to assess and improve accessibility for wheelchair users

This paper proposes a description of a Smartphone-based approach to assess and improve accessibility for wheelchair users. The developed system employs a dedicated Smartphone application that records various complementary sensor measurements (acceleration, deceleration, inclination, orientation, speed, GPS position) and permits obstacle denunciation. Then, accessibility information are reported on maps in a Geographic Information System which can calculate the most accessible route for wheelchair users taking into account their profiles and capabilities. A case study involving a wheelchair-dependent paraplegic was performed to preliminary assess the feasibility of our Smartphone-based approach to provide an accessibility index for wheelchair users. Although preliminary, our results do suggest that the Wegoto system could be used as an innovative assistive navigation system for wheelchair users and ultimately could help to improve their autonomy and quality of life.

Mobile Phone-Based Joint Angle Measurement for Functional Assessment and Rehabilitation of Proprioception

Assessment of joint functional and proprioceptive abilities is essential for balance, posture, and motor control rehabilitation. Joint functional ability refers to the capacity of movement of the joint. It may be evaluated thereby measuring the joint range of motion (ROM). Proprioception can be defined as the perception of the position and of the movement of various body parts in space. Its role is essential in sensorimotor control for movement acuity, joint stability, coordination, and balance. Its clinical evaluation is commonly based on the assessment of the joint position sense (JPS). Both ROM and JPS measurements require estimating angles through goniometer, scoliometer, laser-pointer, and bubble or digital inclinometer. With the arrival of Smartphones, these costly clinical tools tend to be replaced. Beyond evaluation, maintaining and/or improving joint functional and proprioceptive abilities by training with physical therapy is important for long-term management. This review aims to report Smartphone applications used for measuring and improving functional and proprioceptive abilities. It identifies that Smartphone applications are reliable for clinical measurements and are mainly used to assess ROM and JPS. However, there is lack of studies on Smartphone applications which can be used in an autonomous way to provide physical therapy exercises at home.

Is one trial sufficient to obtain excellent pressure pain threshold reliability in the low back of asymptomatic individuals?: a test-retest study

The assessment of pressure pain threshold (PPT) provides a quantitative value related to the mechanical sensitivity to pain of deep structures. Although excellent reliability of PPT has been reported in numerous anatomical locations, its absolute and relative reliability in the lower back region remains to be determined. Because of the high prevalence of low back pain in the general population and because low back pain is one of the leading causes of disability in industrialized countries, assessing pressure pain thresholds over the low back is particularly of interest. The purpose of this study study was (1) to evaluate the intra- and inter- absolute and relative reliability of PPT within 14 locations covering the low back region of asymptomatic individuals and (2) to determine the number of trial required to ensure reliable PPT measurements. Fifteen asymptomatic subjects were included in this study. PPTs were assessed among 14 anatomical locations in the low back region over two sessions separated by one hour interval. For the two sessions, three PPT assessments were performed on each location. Reliability was assessed computing intraclass correlation coefficients (ICC), standard error of measurement (SEM) and minimum detectable change (MDC) for all possible combinations between trials and sessions. Bland-Altman plots were also generated to assess potential bias in the dataset. Relative reliability for both intra- and inter- session was almost perfect with ICC ranged from 0.85 to 0.99. With respect to the intra-session, no statistical difference was reported for ICCs and SEM regardless of the conducted comparisons between trials. Conversely, for inter-session, ICCs and SEM values were significantly larger when two consecutive PPT measurements were used for data analysis. No significant difference was observed for the comparison between two consecutive measurements and three measurements. Excellent relative and absolute reliabilities were reported for both intra- and inter-session. Reliable measurements can be equally achieved when using the mean of two or three consecutive PPT measurements, as usually proposed in the literature, or with only the first one. Although reliability was almost perfect regardless of the conducted comparison between PPT assessments, our results suggest using two consecutive measurements to obtain higher short term absolute reliability.