Massimiliano Pau

Effectiveness and Limitations of Unsupervised Home-Based Balance Rehabilitation with Nintendo Wii in People with Multiple Sclerosis

Balance training represents a critical part of the rehabilitation process of individuals living with multiple sclerosis (MS) since impaired postural control is a distinctive symptom of the disease. In recent years, the use of the Nintendo Wii system has become widespread among rehabilitation specialists for this purpose, but few studies have verified the effectiveness of such an approach using quantitative measures of balance. In this study, we analyzed the postural sway features of a cohort of twenty-seven individuals with MS before and after 5 weeks of unsupervised home-based balance training with the Wii system. Center of pressure (COP) time-series were recorded using a pressure platform and processed to calculate sway area, COP path length, displacements, and velocities in mediolateral (ML) and anteroposterior (AP) directions. Although the results show a significant reduction in sway area, COP displacements, and velocity, such improvements are essentially restricted to the ML direction, as the Wii platform appears to properly stimulate the postural control system in the frontal plane but not in the sagittal one. Available Wii games, although somewhat beneficial, appear not fully suitable for rehabilitation in MS owing to scarce flexibility and adaptability to MS needs and thus specific software should be developed.

Ultrasonic measurements of nominal contact area and contact pressure in a wheel-rail system:

Abstract For more than a century, the contact between wheel and rail has been the subject of careful investigation by scientists and railway technicians. Many efforts have been made to understand a series of phenomena (wear, pitting, fatigue, failures, etc.) that are closely related to processes occurring in such a small contact patch. A huge amount of numerical and theoretical research work (starting from Hertzs theory) has been carried out, but there is a noteworthy lack of experimental tests, which is probably due mainly to difficulties in accessing the contact area with conventional techniques. In the present paper, an experimental investigation dealing with the evaluation of the contact area and stresses transmitted across it is proposed: the technique employed is based on a non-invasive ultrasonic method that analyses the reflection of ultrasonic waves by the contact interface. By using a set-up commonly employed in many non-destructive testing (NDT) analyses it was possible to obtain graphic maps of static contact conditions, and several tests were carried out to evaluate changes with increases in external load. Results show reasonable agreement with Hertzs theoretical predictions and suggest a possible future use of the ultrasonic method to investigate contact during motion.

Novel characterization of gait impairments in people with multiple sclerosis by means of the gait profile score.

The assessment of gait abnormalities in individuals with multiple sclerosis (MS) represents a key factor in evaluating the effectiveness of rehabilitation treatments. Despite the availability of sophisticated equipment to objectively evaluate the kinematic aspects of gait, there are still some difficulties in processing the large and complex amount of data they produce in the daily clinical routine. On the basis of the above-mentioned considerations we propose a novel characterization of gait kinematics in individuals with MS, based on a single measure (gait profile score, GPS) obtained from a quantitative three-dimensional analysis of gait performed using an opto-electronic system. We also investigated the correlation between GPS and the Expanded Disability Status Scale (EDSS) values. Thirty-four patients suffering from relapsing-remitting MS (13 female, 21 male, mean age 46.7 years) with an EDSS score of ≤6 underwent a gait analysis from which the GPS index was calculated. Their results were compared with those of a control group of healthy age- and gender-matched subjects. The GPS of individuals with MS was found significantly higher with respect to controls (9.12° vs. 5.67°, p<0.001) as the result of kinematic differences in gait patterns referring to pelvic tilt and rotation, hip flexion-extension and rotation, knee flexion-extension and ankle dorsi- and plantar-flexion. A moderate correlation was also found between the EDSS score of the participants and their GPS values (r = 0.63, p < 0.001). The GPS index thus appears suitable to represent gait deviations from physiological patterns in individuals affected by MS and potentially useful in assessing the outcomes related both to rehabilitation programs and pharmacologic/physical therapies.

Postural sway modifications induced by backpack carriage in primary school children: a case study in Italy

The aim of this investigation is to assess modifications in sway parameters introduced by backpack carriage in Italian primary school children (6–10 years old, n = 447). Two 30-s trials (without and with backpack) were performed directly at a school on a regular school day to collect data on sway area, centre of pressure path length and maximum displacement range in antero–posterior and medio–lateral directions. The results show a significant load-induced increase in all sway parameters and the existence of a linear relationship between sway area and backpack weight. Since postural sway represents an effective indicator of balance abilities, the alterations observed suggest that backpack carriage originates balance impairment and thus may increase the risk of unintentional falls in children. Statement of Relevance: Loss of balance is among the primary causes of unintentional falls and postural sway represents an effective indicator of balance abilities. In this study, sway parameters were assessed in primary school children wearing backpacks. The differences that were observed show that backpack carriage potentially increases the risk of falls.

Effect of light and vigorous physical activity on balance and gait of older adults

This study aims to quantitatively assess the effects of vigorous and light physical activity (VPA, LPA) on static balance, gait and sit-to-stand (STS) tasks in a cohort of healthy older adults. To this end, 34 individuals of age >65 years were divided into two groups (n=17 each) who underwent 36 sessions (3×12 weeks) of PA characterized by different levels of intensity, assessed through continuous heart rate monitoring during the training session. Their balance and mobility were objectively evaluated on the basis of postural sway and time of STS measurements performed using a force platform. The main spatiotemporal parameters of gait (i.e. speed, stride and gait cycle duration, stance, swing and double support phase duration) were also acquired using a wearable inertial measurement unit. The results show that most gait parameters and STS time significantly improve in the VPA group but not in the LPA one. For the latter group a reduction only of swing phase duration was detected. PA also induced a generalized reduction of postural sway in both groups in the case of absence of visual input. These findings suggest that PA programs characterized by superior levels of intensity might be more suitable in generally improving static and dynamic daily motor tasks, while in terms of static balance acceptable results can be achieved even when only light activity is performed.

Does load carriage differentially alter postural sway in overweight vs. normal-weight schoolchildren?

Among a wide range of negative consequences stemming from excess mass in children, recent studies suggest an impairment of postural control, including basic capabilities such as static and dynamic balance. Such impairment may be compounded when additional tasks are performed, such as carrying localized loads as occurs among children using a backpack. To investigate this, postural control was measured among 77 overweight and obese children (6-11 years old), and an equal number of normal-weight children matched for gender, age, and height. Testing was conducted at school, in which center of pressure (COP) time series during quiet standing were obtained in the presence and absence of each students backpack. A traditional postural control measure derived from COP (mean velocity) did not indicate significant differences between overweight and normal-weight children, regardless of backpack presence. In contrast, a complexity index (derived from multiscale entropy) suggested the existence of different postural strategies and reduced balance capabilities among overweight children, whose consequences need to be further clarified.

Effects of backpack carriage on foot-ground relationship in children during upright stance.

Although the scientific community widely recognizes that backpack carriage in primary school children represents a critical issue, its consequences in terms of postural alterations and possible onset of musculoskeletal pathologies are still not fully understood. In particular, little information is available on the way load carriage modifies the foot-ground relationship in terms of plantar pressure distribution. This issue is of particular relevance, because the presence of a load alters the physiological weightbearing functions and, when mechanical overloading is repeated in time, it can act as a co-factor in promoting foot discomfort or pain. On the basis of these considerations, this study analyzed plantar pressure maps of 359 children attending primary schools (6-10 years old) under static upright posture conditions, to assess the magnitude and features of effects originated by load carriage on the foot-ground relationship. The collected data showed that backpack introduces significant increases in overall contact area (up to 10%) and in the plantar pressure peaks in midfoot and forefoot regions (20-30%). A significant shift in the average position of the center of pressure towards the forefoot was also observed, as an indicator of the bodys attempt to restore the initial balance conditions threatened by the load. These results suggest that heavy loads, in the case of significant exposure times, may increase the risk of foot discomfort and act as a co-factor in the onset of foot structure alterations or pathologies.

Assessment of Nominal Contact Area Parameters by Means of Ultrasonic Waves

In this paper the application of an ultrasonic method to evaluate size and shape of the nominal contact area between two contacting bodies is studied. The technique is based on the analysis of the quota of the ultrasonic wave reflected by the interface, which may be related to the level of contact between the surfaces. A simple deconvolution procedure is applied to the raw ultrasonic data so as to remove the blurring effect introduced by the ultrasonic beam size. The ultrasonic data acquired on a simple sphere-plane contact interface are compared with those obtained by means of a commercial pressure sensitive film and the results are discussed to evaluate the capability of the ultrasonic technique to capture the main contact patch features correctly.

Estimation of real contact area in a wheel-rail system by means of ultrasonic waves

The application of an ultrasonic technique to estimate the Real Contact Area (RCA) in a wheel-rail system is proposed. The method is based on the analysis of the reflection of ultrasonic waves which are sent over the contact region and reflected by it according to the state of contact. The interaction of the experimental data with a theoretical model formulated in the early 1990s by Krolikowski allows us to calculate the RCA for the area illuminated by the ultrasonic beam. By varying the external load and the surface conditions of the contacting elements, it is possible to obtain the trend of the RCA with increasing load (for a certain roughness) as well to explore changes in RCA for different roughness while the load is kept fixed. Results showed that RCA grows almost linearly with the applied load and that an increase of one order of magnitude in combined roughness of the wheel-rail system leads to a roughly sevenfold reduction in RCA under a given load.

Effect of spasticity on kinematics of gait and muscular activation in people with Multiple Sclerosis.

PURPOSE This study proposes to characterize the gait patterns of individuals with Multiple Sclerosis (MS) affected by spasticity using quantitative gait analysis. METHOD Cross-sectional study on 38 individuals with MS, 19 affected by lower limb spasticity and 19 not affected, the latter forming the control group. Both groups were evaluated while walking using three-dimensional gait analysis. Spatio-temporal parameters of gait, kinematic data expressed by means of Gait Profile Score (GPS) and Range of Motion (ROM), as well as muscular activation, were evaluated. RESULTS The results show that spasticity originates a peculiar gait pattern characterized by reduced speed, cadence, stride length, swing phase and increased double support time, but they also reveal specific alterations in kinematics and muscular activation. In particular, significantly higher values of GPS, reduced hip and knee flexion-extension ROM and abnormal activation of the rectus femoris were observed in individuals with spasticity. CONCLUSIONS In people with MS presenting spastic gait, the availability of quantitative data appears crucial in verifying the effectiveness of pharmacologic and rehabilitative treatments, also considering that spasticity scales may not be satisfactory in relating the assessed spasticity with both perception of the patients and the actual body functionalities.