Voluntary Motion Research Articles

Exercise training using hybrid assistive limb (HAL) lumbar type for locomotive syndrome: a pilot study

BackgroundWith a rapidly aging population in Japan, locomotive syndrome is becoming an increasingly serious social problem. Exercise therapy using the lumbar type HAL, which is a wearable robot suit that can assist voluntary hip joint motion, would be expected to cause some beneficial effects for people with locomotive syndrome. The purpose of this study was to assess whether the deterioration of low back pain and any other adverse events would occur following HAL exercise therapy. Moreover, the changes of motor ability variables were evaluated.MethodsWe enrolled 33 participants (16 men, 17 women) with locomotive syndrome in this study. They received exercise training (sit-to-stand, lumbar flexion-extension, and gait training) with HAL (in total 12 sessions). We assessed the change of low back pain (lumbar VAS). More than 50% and 25 mm increase compared to baseline was defined as adverse events. One-leg standing time (OLST), 10-m walking test (10MWT), Timed Up and Go test (TUG), 1-min sit-to-stand test (1MSTS), FIM mobility scores and EQ-5D were measured.ResultsOf the 33 participants, 32 (16 men, 16 women) (97.0%) completed all 12 exercise training sessions using the lumbar type HAL. One woman aged 82 years withdrew because of right upper limb pain after the second session regardless of the use of HAL. There was no participant who had deterioration of low back pain. Any other adverse events including external injuries and/or falling, skin disorders, uncontrollable cardiovascular or respiratory disorders, and other health disorders directly related to this exercise therapy did not occur. Several outcome measures of motion ability including OLST, TUG and 1MSTS, EQ VAS and lumbar pain improved significantly after this HAL training.ConclusionsAlmost all patients with locomotive syndrome completed this exercise training protocol without any adverse events related to HAL. Furthermore, balance function variables including OLST, TUG and 1MSTS improved after this HAL exercise therapy even though mobility function variables including 10MWT and FIM mobility scores did not show any significant change. These findings suggest that the exercise therapy using the lumbar type HAL would be one of the options for the intervention in locomotive syndrome.

A robotized handheld smart tool for orthopedic surgery.

Handheld surgical robots offer functionalities, such as active guidance, tremor suppression and force reflection, for surgeons to enhance their skill in manipulating surgical tools during medical intervention. In orthopedic surgery, the robot additionally has to offer sufficient rigidity and power for bone machining. The size and weight of the mechanical design, together with the control behaviour associated with involuntary hand motion, navigation and reflected force to the human, all influence the overall performance of an orthopedic handheld robot. The paper proposes a miniature and compact design for an embedded robot, which is a similar weight as a handpiece. Then, a shared controller is proposed to address the coupling among involuntary and voluntary hand motions, robot navigation, tool feedback forces and force artefacts from actuation. The handheld robot is able to stabilize the drill positioning by removing involuntary tremors as well as reduce force artefacts from motor actuation in experiments involving pedicle tunnelling on a porcine spine. The paper has successfully realized a compact handheld orthopedic robot which provides high performance of usability, tremor suppression and force reflection for bone drilling.

Design and Preliminary Performance Assessment of a Wearable Tremor Suppression Glove.

Approximately 25% of individualsliving with parkinsonian tremor do not respond to traditional treatments. Wearable tremor suppression devices (WTSD) provide an alternative approach, however, tremor in the fingers has not been given as much attention as tremor in the elbow and the wrist. Therefore, the objective of this study is to design a wearable tremor suppression glove that can suppress tremor simultaneously, but independently, in multiple hand joints without restricting the user's voluntary motion. A WTSD was designed for managing tremor in the index finger metacarpophalangeal (MCP) joint, thumb MCP joint, and the wrist. The prototype was tested and assessed on a participant living with parkinsonian tremor. The experimental evaluation showed an overall suppression of 73.1%, 80.7%, and 85.5% in resting tremor, 70.2%, 79.5%, and 81% in postural tremor, and 60.0%, 58.7%, and 65.0% in kinetic tremor in the index finger MCP joint, the thumb MCP joint, and the wrist, respectively. This first assessment of a WTSD for people living with Parkinson's disease provides confirmation of the feasibility of the approach. The next step requires a comprehensive validation on a broader population in order to evaluate the performance of the WTSD. This study demonstrates the feasibility of using a WTSD to manage hand and finger tremor. The device enriches the field of upper-limb tremor management, as the first WTSD for multiple joints of the hand.

Running or crossing? Children's expression of voluntary motion in English, German, and French.

Much research has focused on the expression of voluntary motion (Slobin, 2004; Talmy, 2000). The present study contributes to this body of research by comparing how children (three to ten years) and adults narrated short, animated cartoons in English and German (satellite-framed languages) vs. French (verb-framed). The cartoons showed agents displacing themselves in variable Manners along different Paths (Path saliency and variance were specifically manipulated in four item types). Results show an increase with age across languages in how much information participants expressed. However, at all ages, more motion information was encoded in English and German than in French. Furthermore, language-specific features impacted the content and its organization within utterances in discourse, showing more variation within and across Path types in French than in the satellite-framed languages, resulting in later achievement of adult-like descriptions in this language. The discussion highlights the joint impact of cognitive and typological features on language development.

Analysis of the Effect of Common Disturbances on the Safety of a Wearable Tremor Suppression Device

The advent of wearable technology has enabled a large number of externally worn mechatronic devices to be developed and tested on people with movement disorders. The complexity of these disorders and the variety of conditions across different patients have resulted in a pressing demand for the incorporation of intelligent control systems, especially for a wearable tremor suppression device (WTSD) that can suppress tremor without impeding the user's voluntary motion. Several devices have been developed to reduce tremor; however, the evaluations of these devices have only been done in a controlled lab setting, while the functionality and ability to avoid user injury under the effect of disturbances during daily use have not been investigated. In this study, the performance of a WTSD was tested with several commonly used tremor suppression control systems, i.e., Weight-frequency Fourier Linear Combiner (WFLC), Bandlimited Multiple Fourier Linear Combiner, and enhanced High-order WFLC-based Kalman Filter, on a bench-top tremor simulator. These systems were also tested under the influence of three simulated disturbances that are commonly seen in real life, i.e., data mutation, sensor drift, and measurement loss. The experimental evaluation showed that none of these systems are safe under the disturbances. The tremor power suppression ratio (67.8%–94.2%) of the WTSD was not significantly lowered by the disturbances; however, the error when tracking voluntary motion significantly increased by 8.8 $^\circ$ –93.6 $^\circ$ , which may present a safety hazard to the users. The results of this study emphasize the importance of integrating safety measures into intelligent WTSDs.

Assistance of a Person with Muscular Weakness Using a Joint-Torque-Assisting Exoskeletal Robot

Robotic systems for gait rehabilitation have been actively developed in recent years; many of the rehabilitation robots have been commercialized and utilized for treatment of real patients in hospitals. The first generation of gait rehabilitation robots was a tethered exoskeleton system on a treadmill. While these robots have become a new trend in rehabilitation medicine, there are several arguments about the effectiveness of such robots due to the passiveness of the motions that the robots generate, i.e., the continuous passive motions may limit the active involvement of patients’ voluntary motion control. In order to let a patient be more actively involved by requiring the self-control of whole-body balance, untethered powered exoskeletons, wearable robots that patients can wear and walk on the ground, are receiving great attention. While several powered exoskeletons have been commercialized already, the question about their effectiveness has not been cleared in the viewpoint of rehabilitation medicine because most of the powered exoskeletons provide still continuous passive motions, even though they are on the ground without tethering. This is due to their control strategy; the joints of a powered exoskeleton are position-controlled to repeatedly follow a predefined angle trajectory. This may be effective when a wearer is completely paraplegic such that the powered exoskeleton must generate full actuation power for walking. For people with muscular weakness due to various reasons, the powered exoskeleton must assist only the lack of muscular force without constraining human motion. For assistance and rehabilitation of people with partial impairment in walking ability, Angel Legs is introduced in this paper. The proposed powered exoskeleton system is equipped with a transparent actuation system such that the assistive force is accurately generated. The overall design and control of Angel Legs are introduced in this paper, and a clinical verification with a human subject is also provided.

Benchmark Device To Mitigate Jaw Tremor Using Gyroscopic Effect

A tremor is a mildly rhythmic muscle contraction and relaxation that predominantly involves involuntary oscillations or twitching movements of one’s body parts. Jaw tremor looks more like shivering although with different amplitude and frequency which can vary. Jaw tremors hinder patients’ day to day activities and hamper confidence, causing social handicaps. There are only drug-based solutions for jaw tremors to date. Currently, there are some surgical treatments like Deep Brain Stimulation (DBS), but, they have side effects. Our solution - the palliator a wearable, ergonomic device that dampens jaw tremors without producing any side effects on patients. The proposed solution uses two accelerometers to detect and distinguish involuntary tremors from the voluntary jaw motion and then uses the gyroscopic principle to control the involuntary motion, thus resisting the tremors.

Robotic Rehabilitation and Assistance for Individuals With Movement Disorders Based on a Kinematic Model of the Upper Limb

Design and development of robotic-assistance must consider the abilities of individuals with disabilities. In this article, a 8-DOF kinematic model of the upper limb complex is derived to evaluate the reachable workspace of the arm during interaction with a planar robot and to serve as the basis for rehabilitation strategies and assistive robotics. Through inverse differential kinematics and by taking account the physical limits of each arm joint, the model determines workspaces where the individual is able to perform tasks and those regions where robotic assistance is required. Next, a learning-from-demonstration strategy via a nonparametric potential field function is derived to teach the robot the required assistance based on demonstrations of functional tasks. This article investigates two applications. First, in the context of rehabilitation, robotic assistance is only provided if the individual is required to move her arm in regions that are not reachable via voluntary motion. Second, in the context of assistive robotics, the demonstrated trajectory is scaled down to match the individual's voluntary range of motion through a nonlinear workspace mapping. Assistance is provided within that workspace only. Experimental results in 5 different experimental scenarios with a person with cerebral palsy confirm the suitability of the proposed framework.

Real-Time Voluntary Motion Prediction and Parkinson's Tremor Reduction Using Deep Neural Networks.

Wearable tremor suppression devices (WTSD) have been considered as a viable solution to manage parkinsonian tremor. WTSDs showed their ability to improve the quality of life of individuals suffering from parkinsonian tremor, by helping them to perform activities of daily living (ADL). Since parkinsonian tremor has been shown to be nonstationary, nonlinear, and stochastic in nature, the performance of the tremor models used by WTSDs is affected by their inability to adapt to the nonlinear behaviour of tremor. Another drawback that the models have is their limitation to estimate or predict one step ahead, which introduces delay when used in real time with WTSDs, which compromises performance. To address these issues, this work proposes a deep neural network model that learns the correlations and nonlinearities of tremor and voluntary motion, and is capable of multi-step prediction with minimal delay. A generalized model that is task and user-independent is presented. The model achieved an average estimation percentage accuracy of 99.2%. The average future voluntary motion prediction percentage accuracy with 10, 20, 50, and 100 steps ahead was 97.0%, 94.0%, 91.6%, and 89.9%, respectively, with prediction time as low as 1.5 ms for 100 steps ahead. The proposed model also achieved an average of 93.8% ± 1.5% in tremor reduction when it was tested in an experimental setup in real time. The tremor reduction showed an improvement of 25% over the Weighted Fourier Linear Combiner (WFLC), an estimator commonly used with WTSDs.

Towards wearable tremor suppression using dielectric elastomer stack actuators

Active wearable tremor suppression devices apply actuators to the human body to produce joint torques that reduce tremor motion. This potential alternative to medications and surgery has the advantage of providing robust tremor treatment that is non-invasive, but the bulkiness of typical engineering actuators currently prohibits clinical implementations. Dielectric elastomer stack actuators (DESAs) offer a potential pathway towards achieving soft, low-profile tremor suppression devices: DESAs have similar mechanical properties as human muscles and can conform to the human limb. However, low actuation levels and a lack of commercial availability limit the development of DESA-based orthoses. Employing a control approach that only suppresses tremor while allowing the actuators to follow voluntary motion passively significantly decreases actuation requirements to improve potential for clinical devices. Still, DESAs that may offer the necessary actuation characteristics require specialized equipment and techniques. This research advances DESA-based tremor suppression by experimentally demonstrating DESA-based suppression of tremor-like signals on a scaled system using easily manufactured DESAs. Further discussion quantifies the DESA parameters that will enable physical implementations of human-scale tremor suppression and identifies pathways towards achieving those parameters.

Tendon vibration changes perceived joint angle independent of voluntary body motion direction in virtual environments

ABSTRACT The consistency between the virtual environment and the real environment perceived by the body is important, and sensory stimulation technologies that can enhance the sense of self-ownership and self-agency for the virtual body are required. The objective of this study is to clarify the effect of tendon vibration stimulation on the perception on the body when the inconsistency of the body motion is generated by virtual reality (VR) experience in which the virtual body motion is equal to or more than the real body motion. We carried out experiments to clarify perceptual characteristics such as the relationship between the intensity of the tendon vibration stimulus and the degree of perceptual angle modulation. When the vibration stimulus provides clarity of illusion, the change was about 17 degrees in flexion and about −12 degrees in extension in the same-direction group. It is suggested that the perceived angle can be changed in any direction by the tendon vibration stimulation, regardless of the actual motion direction. The experimental results suggest that the perceptual modulation by tendon vibration stimulation may be one of the solutions to the inconsistency between virtual and real bodies.

Activation of Superficial and Deep Finger Flexors Through Transcutaneous Nerve Stimulation.

Functional electrical stimulation (FES) is a common technique to elicit muscle contraction and help improve muscle strength. Traditional FES over the muscle belly typically only activates superficial muscle regions. In the case of hand FES, this prevents the activation of the deeper flexor muscles which control the distal finger joints. Here, we evaluated whether an alternative transcutaneous nerve-bundle stimulation approach can activate both superficial and deep extrinsic finger flexors using a high-density stimulation grid. Transverse ultrasound of the forearm muscles was used to obtain cross-sectional images of the underlying finger flexors during stimulated finger flexions and kinematically-matched voluntary motions. Finger kinematics were recorded, and an image registration method was used to capture the large deformation of the muscle regions during each flexion. This deformation was used as a surrogate measure of the contraction of muscle tissue, and the regions of expanding tissue can identify activated muscles. The nerve-bundle stimulation elicited contractions in the superficial and deep finger flexors. Both separate and concurrent activation of these two muscles were observed. Joint kinematics of the fingers also matched the expected regions of muscle contractions. Our results showed that the nerve-bundle stimulation technique can activate the deep extrinsic finger flexors, which are typically not accessible via traditional surface FES. Our nerve-bundle stimulation method enables us to produce the full range of motion of different joints necessary for various functional grasps, which could benefit future neuroprosthetic applications.

Sympathetic and Vagal Responses Elicited by Acute Stress in Rats.

IntroductionAcute emotional stress triggers autonomic responses that affect sympathovagal balance. However, the temporal pattern of changes in each autonomic arm during stress and recovery remains unclear. Therefore, we analyzed separately sympathetic and vagal activity, elicited by acute unpredictable stress in a rat model.MethodsContinuous electrocardiographic recording was performed during (32 minutes) and after (two hours) successive use of restraint and air-jet stress in 10 rats, whereas five rats served as controls. Sympathetic and vagal indices were calculated non-invasively after heart rate variability analysis. Voluntary motion was quantified during recovery, as an index of continuing anxiety.ResultsThe sympathetic nervous system index increased during stress and remained elevated during the initial stage of recovery. The parasympathetic nervous system index decreased immediately after the onset of stress and remained low throughout the observational period. During recovery, voluntary activity was more pronounced in the stress group than in the controls.ConclusionSuccessive restraint and air-jet stress in rats increased sympathetic activity and decreased vagal activity. These changes displayed only partial recovery post-stress and were accompanied by enhanced voluntary motion. Our findings may be important in the evaluation of the cardiac electrophysiologic implications of autonomic changes elicited by acute emotional stress.

Real-time motion and retrospective coil sensitivity correction for CEST using volumetric navigators (vNavs) at 7T.

PurposeTo explore the impact of temporal motion‐induced coil sensitivity changes on CEST‐MRI at 7T and its correction using interleaved volumetric EPI navigators, which are applied for real‐time motion correction.MethodsFive healthy volunteers were scanned via CEST. A 4‐fold correction pipeline allowed the mitigation of (1) motion, (2) motion‐induced coil sensitivity variations, ΔB1‐, (3) motion‐induced static magnetic field inhomogeneities, ΔB0, and (4) spatially varying transmit RF field fluctuations, ΔB1+. Four CEST measurements were performed per session. For the first 2, motion correction was turned OFF and then ON in absence of voluntary motion, whereas in the other 2 controlled head rotations were performed. During post‐processing ΔB1‐ was removed additionally for the motion‐corrected cases, resulting in a total of 6 scenarios to be compared. In all cases, retrospective ∆B0 and ‐ΔB1+ corrections were performed to compute artifact‐free magnetization transfer ratio maps with asymmetric analysis (MTRasym).ResultsDynamic ΔB1‐ correction successfully mitigated signal deviations caused by head motion. In 2 frontal lobe regions of volunteer 4, induced relative signal errors of 10.9% and 3.9% were reduced to 1.1% and 1.0% after correction. In the right frontal lobe, the motion‐corrected MTRasym contrast deviated 0.92%, 1.21%, and 2.97% relative to the static case for Δω = 1, 2, 3 ± 0.25 ppm. The additional application of ΔB1‐ correction reduced these deviations to 0.10%, 0.14%, and 0.42%. The fully corrected MTRasym values were highly consistent between measurements with and without intended head rotations.ConclusionTemporal ΔB1‐ cause significant CEST quantification bias. The presented correction pipeline including the proposed retrospective ΔB1‐ correction significantly reduced motion‐related artifacts on CEST‐MRI.

Motion Robust Imaging Ballistocardiography Through a Two-Step Canonical Correlation Analysis

Imaging ballistocardiography (iBCG) is a video-based noncontact technique to detect heart rate (HR) from weak mechanical head movements caused by heart beating. However, rigid motions caused by voluntary movements and nonrigid motion resulted from facial expressions can easily distort the iBCG measurements. In this article, we propose a novel method, called robust iBCG (RiBCG), to suppress motion artifacts in iBCG with a two-step canonical correlation analysis (CCA). First, feature points are determined and tracked within two regions of interest (ROIs) from the face, where the vertical traces are taken as raw iBCG signals. Next, the first CCA is taken to separately remove the shared rigid motion artifacts between the horizontal and vertical traces in each ROI, where the obtained rigid-motion-free iBCG signals are further compressed by principal component analysis (PCA). Then, CCA is applied again to two sets of principal components to suppress nonrigid motion artifacts with low spatial correlations. Finally, the target HR value is determined as the one with the highest peak of power spectrums among all canonical variates (CVs). Besides, an improved version of RiBCG, termed RiBCG-C, is also proposed to reduce the HR outliers considering the continuity of HR variations. The proposed methods, as well as several other typical video-based HR measurement methods, are evaluated on two public databases, UBFC-RPPG and COHFACE, where the proposed RiBCG-C method achieves overall the best performance. The study provides a promising scheme for RiBCG measurements under realistic application scenarios.

Assessment of Intrafraction Cervico-Uterine Motion in the Definitive Treatment of Locally Advanced Cervical Cancer Using MR-Guided Radiotherapy

To account for intrafraction motion, patients receiving intensity modulated radiation therapy (IMRT) for the definitive treatment of cervical cancer have an internal target volume (ITV) defined from bladder-full and bladder-empty CT simulation scans. We hypothesized that through daily volumetric magnetic resonance (MR) imaging for setup and treatment, we can assess cervico-uterine motion and create an intrafraction-ITV independent of interfraction bladder changes, and therefore dispense with the full-bladder to empty-bladder ITV paradigm. In this IRB-approved, study patients with locally advanced cervical cancer received IMRT with brachytherapy. IMRT was delivered on a clinical MR-guided radiotherapy (MRgRT) Linac. All patients received a pre-treatment (pre-tx) and post-treatment (post-tx) 0.35T balanced steady-state free precession MR scans in treatment position. The intrafraction cervico-uterine motion was assessed through segmentation of the clinical target volume (CTV) by a gynecological radiation oncologist on each scan. The pre-tx and post-tx MR scans were in the same frame of reference, and any residual patient motion was removed through a rigid registration of the post-tx MR scan to the pre-tx MR scan based on bony anatomy. All post-tx contours were rigidly copied to the pre-tx MR scans. The maximum and mean difference in spatial position between the pre-tx and post-tx MR scans were quantified using maximum Hausdorff distance (HD) and mean distance to agreement (MDA), respectively. Mean, standard deviation, and 95% confidence interval were calculated to determine the intrafraction MR-based internal target volume (ITVMRgRT). In total, 19 same day sessions (N = 38 scans) of intrafraction motion were assessed. Minimal patient voluntary motion was observed across rigid registrations with respect to bony anatomy. The average time between the pre-tx and post-tx MR scans was 14.3 ± 7.1 minutes (mean ± standard deviation), resembling a hypothetical time of on-table adaptation and treatment. The average maximum HD was 0.88 ± 0.46 cm (95% CI 0.668 - 1.08) and average MDA was 0.08 ± 0.07 cm (95% CI 0.05- 0.118). Due to HD’s sensitivity to outliers, a more robust metric (i.e., MDA) was utilized for margin calculation. The ITVMRgRT margin necessary to encompass the MDA for 95% of the intrafraction motion was 0.12 cm; therefore, we propose an ITVMRgRT of 0.15 cm given the non-partial voxelization of segmentation. This work supports margin reduction of the ITV to ITVMRgRT of 0.15 cm when using daily MR-guided online adaptive radiotherapy. Given the maximum setup uncertainty is limited in MRgRT to spatial resolution of the real-time cine imaging sequence, we propose an ITVMRgRT-PTV margin of 0.3 cm. Therefore, our total CTV to PTV margin is 0.45 cm.

The Design of a Parkinson's Tremor Predictor and Estimator Using a Hybrid Convolutional-Multilayer Perceptron Neural Network.

Parkinson's Disease (PD) is considered to be the second most common age-related neuroegenerative disorder, and it is estimated that seven to ten million people worldwide have PD. One of the symptoms of PD is tremor, and studies have shown that wearable assistive devices have the potential to assist in suppressing it. However, despite the progress in the development of these devices, their performance is limited by the tremor estimators they use. Thus, a need for a tremor model that helps the wearable assistive devices to increase tremor suppression without impeding voluntary motion remains. In this work, a user-independent and task-independent tremor and voluntary motion detection method based on neural networks is proposed. Inertial measurement units (IMUs) were used to measure acceleration and angular velocity from participants with PD, these data were then used to train the neural network. The achieved estimation percentage accuracy of voluntary motion was 99.0%, and the future prediction percentage accuracy was 97.3%, 93.7%, 91.4% and 90.3% for 10 ms, 20 ms, 50 ms and 100 ms ahead, respectively. The root mean squared error (RMSE) achieved for tremor estimation was an average of 0.00087°/s on new unseen data, and the future prediction average RMSE across the different tasks achieved was 0.001°/s, 0.002°/s, 0.020°/s and 0.049°/s for 1 ms, 2 ms, 5 ms, and 10 ms ahead, respectively. Therefore, the proposed method shows promise for use in wearable suppression devices.

The Relationship Between Hip Displacement In The Anteroposterior Direction And Life-space Mobility Among Older Women

PURPOSE: The ability to recover one’s balance using a hip-based strategy is important to avoid falls, but many older adults have limited hip flexibility. This study aimed to clarify the relationship between hip displacement during voluntary motion (Hip-D) in the anteroposterior direction and life-space mobility, and to examine whether Hip-D could be used to independently distinguish the quality of one’s life-space mobility by comparing the results on the Life-Space Assessment (LSA) scale. METHODS: Hip-D and physical functions related to fall prevention were measured in 319 community-dwelling older women. Hip-D was defined as the maximum moving distance of the great trochanter in the anteroposterior direction. The participants were also classified into good and poor life-space mobility groups based on their LSA scores. The ability of the Hip-D and physical functioning tests to distinguish the above groups was determined using DeLong’s test of the area under the receiver operating characteristic curve (AUC) for each test. RESULTS: Hip-D was significantly greater in the good life-space group (25.2 ± 6.9 cm) than in the poor life-space group (17.3 ± 5.1cm). The LSA score was moderately correlated with Hip-D (r = 0.51, p < 0.05) but only weakly with the fall-related physical functioning parameters (|r| = 0.15-0.39). Hip-D had the highest AUC (0.824, 95%CI: 0.776-0.872) among all parameters, and the Hip-D cutoff value was 20.9 cm. The AUC for Hip-D was significantly greater than those for all fall-related physical functioning parameters (AUC = 0.591-0.754) in an examination based on DeLong’s test. CONCLUSIONS: Hip-D measurements of older adults were easy to obtain and were moderately correlated with life-space mobility. As such, this approach represents a useful way to predict life-space mobility. Hip-D measurements proved to be more reliable for this purpose than the other fall-related physical functioning parameters studied. It will be necessary the care prevention exercise to improve Hip-D (at least over 21 cm) for older adults.

Neurophysiological mechanisms of hypertonia and hypotonia in children with spastic cerebral palsy: surgical implications.

Mechanism of hypertonia in cerebral palsy children is dual: a neural component due to spasticity (velocity dependent) and a biomechanical component linked to soft tissue changes. Their differentiation-which might be clinically difficult-is however crucial, as only the first component will respond to anti-spastic treatments, the second to physiotherapy. Furthermore, spasticity is frequently associated with dystonia, which is a sustained hypertonic state induced by attempts at voluntary motion. Spasticity and dystonia have to be carefully distinguished as dorsal rhizotomy will not significantly influence the dystonic component. Spasticity, which by definition opposes to muscle stretching and lengthening, has two important consequences. First, the muscles tend to remain in a shortened position, which in turn results in soft tissue changes and contracture. The second is that movements are restricted. Thus, both hypertonia and lack of mobilization create a vicious circle leading to severe locomotor disability linked to irreducible musculotendinous retraction and joint ankylosis/bone deformities. These evolving consequences should be highly considered during the child's assessment for decision-making. The hypotonic effects of lumbosacral dorsal rhizotomy, which are not only segmental on the lower limbs but also supra-segmental through the reticular formation, are finally discussed.

Evaluating the impact of motion artifact on noninvasive blood pressure devices.

Most automated sphygmomanometers use oscillometric algorithms. Motion, either patient-based or environmental, will affect the ability of a device to record an accurate blood pressure (BP). Members of the Association for the Advancement of Medical Instrumentation (AAMI) Sphygmomanometer Committee have been studying this problem for more than a decade. The AAMI TIR44 was the first publication to address the challenges of motion tolerance. The concepts described in TIR44 have led to the development of a draft of ISO 81060-4, a new standard for testing devices for which the manufacturer wishes to claim motion tolerance. The current ISO 81060-2 addresses both stress testing and 24-hour ambulatory BP monitoring. Recent publications have reported on testing of devices in response to voluntary and involuntary patient motion. The ISO 81060-4 will address testing in the presence of patient transport by ground, fixed-wing, and rotary (helicopter) ambulances. The protocol will utilize noise profiles recorded under those three conditions. The profiles will be digitally stored on a library with free access. The proposed testing will be performed using patient simulators introducing the noise library files into known BP oscillometric envelopes. The specifications of the data capture and playback devices are specified, as is the evaluation statistical testing. The authors expect that the final draft will be published in 2020.