Pathway-specific modulatory effects of neuromuscular electrical stimulation during pedaling in chronic stroke survivors.

BACKGROUND: Neuromuscular electrical stimulation (NMES) is extensively used in stroke motor rehabilitation. How it promotes motor recovery remains only partially understood. NMES could change muscular properties, produce altered sensory inputs, and modulate fluctuations of cortical activities; but the potential contribution from cortico-muscular couplings during NMES synchronized with dynamic movement has rarely been discussed. METHOD: We investigated cortico-muscular interactions during passive, active, and NMES rhythmic pedaling in healthy subjects and chronic stroke survivors. EEG (128 channels), EMG (4 unilateral lower limb muscles) and movement parameters were measured during 3 sessions of constant-speed pedaling. Sensory-level NMES (20 mA) was applied to the muscles, and cyclic stimulation patterns were synchronized with the EMG during pedaling cycles. Adaptive mixture independent component analysis was utilized to determine the movement-related electro-cortical sources and the source dipole clusters. A directed cortico-muscular coupling analysis was conducted between representative source clusters and the EMGs using generalized partial directed coherence (GPDC). The bidirectional GPDC was compared across muscles and pedaling sessions for post-stroke and healthy subjects. RESULTS: Directed cortico-muscular coupling of NMES cycling was more similar to that of active pedaling than to that of passive pedaling for the tested muscles. For healthy subjects, sensory-level NMES could modulate GPDC of both ascending and descending pathways. Whereas for stroke survivors, NMES could modulate GPDC of only the ascending pathways. CONCLUSIONS: By clarifying how NMES influences neuromuscular control during pedaling in healthy and post-stroke subjects, our results indicate the potential limitation of sensory-level NMES in promoting sensorimotor recovery in chronic stroke survivors.

Speed-adaptive control of functional electrical stimulation for dropfoot correction.

BACKGROUND: Functional electrical stimulation is an important therapy technique for dropfoot correction. In order to achieve natural control, the parameter setting of FES should be associated with the activation of the tibialis anterior. METHODS: This study recruited nine healthy subjects and investigated the relations of walking speed with the onset timing and duration of tibialis anterior activation. Linear models were built for the walking speed with respect to these two parameters. Based on these models, the speed-adaptive onset timing and duration were applied in FES-assisted walking for nine healthy subjects and ten subjects with dropfoot. The kinematic performance of FES-assisted walking triggered by speed-adaptive stimulation were compared with those triggered by the heel-off event, and no-stimulation walking at different walking speeds. RESULTS: Higher ankle dorsiflexion angle was observed in heel-off stimulation and speed-adaptive stimulation conditions than that in no-stimulation walking condition at all the speeds. For subjects with stroke, the ankle plantarflexion angle in speed-adaptive stimulation condition was similar to that in no-stimulation walking condition, and it was significant larger than that in heel-off stimulation condition at all speeds. CONCLUSIONS: The improvement in ankle dorsiflexion without worsening ankle plantarflexion in speed-adaptive stimulation condition could be attributed to the appropriate stimulation timing and duration. These results provide evidence that the proposed stimulation system with speed-related parameters is more physiologically appropriate in dropfoot correction, and it may have great potential value in future clinical applications. TRIAL REGISTRATION: Medical Ethics Committee of Guangdong Work Injury Rehabilitation Center, AF/SC-07/2016.22 . Registered 26 May 2016.

Randomized controlled trial of robot-assisted gait training with dorsiflexion assistance on chronic stroke patients wearing ankle-foot-orthosis.

BACKGROUND: Robot-assisted ankle-foot-orthosis (AFO) can provide immediate powered ankle assistance in post-stroke gait training. Our research team has developed a novel lightweight portable robot-assisted AFO which is capable of detecting walking intentions using sensor feedback of wearer's gait pattern. This study aims to investigate the therapeutic effects of robot-assisted gait training with ankle dorsiflexion assistance. METHODS: This was a double-blinded randomized controlled trial. Nineteen chronic stroke patients with motor impairment at ankle participated in 20-session robot-assisted gait training for about five weeks, with 30-min over-ground walking and stair ambulation practices. Robot-assisted AFO either provided active powered ankle assistance during swing phase in Robotic Group (n = 9), or torque impedance at ankle joint as passive AFO in Sham Group (n = 10). Functional assessments were performed before and after the 20-session gait training with 3-month Follow-up. Primary outcome measure was gait independency assessed by Functional Ambulatory Category (FAC). Secondary outcome measures were clinical scores including Fugl-Meyer Assessment (FMA), Modified Ashworth Scale (MAS), Berg Balance Scale (BBS), Timed 10-Meter Walk Test (10MWT), Six-minute Walk Test (SMWT), supplemented by gait analysis. All outcome measures were performed in unassisted gait after patients had taken off the robot-assisted AFO. Repeated-measures analysis of covariance was conducted to test the group differences referenced to clinical scores before training. RESULTS: After 20-session robot-assisted gait training with ankle dorsiflexion assistance, the active ankle assistance in Robotic Group induced changes in gait pattern with improved gait independency (all patients FAC ≥ 5 post-training and 3-month follow-up), motor recovery, walking speed, and greater confidence in affected side loading response (vertical ground reaction force + 1.49 N/kg, peak braking force + 0.24 N/kg) with heel strike instead of flat foot touch-down at initial contact (foot tilting + 1.91°). Sham Group reported reduction in affected leg range of motion (ankle dorsiflexion - 2.36° and knee flexion - 8.48°) during swing. CONCLUSIONS: Robot-assisted gait training with ankle dorsiflexion assistance could improve gait independency and help stroke patients developing confidence in weight acceptance, but future development of robot-assisted AFO should consider more lightweight and custom-fit design. TRIAL REGISTRATION: ClinicalTrials.gov NCT02471248 . Registered 15 June 2015 retrospectively registered.

Interfacial Modulation of Spin-Orbit Torques Induced by Two-Dimensional van der Waals Material ZrSe3.

Two-dimensional van der Waals (2D vdW) materials are widely used in spin-orbit torque (SOT) devices. Recent studies have demonstrated the low crystal symmetry and large spin Hall conductivity of 2D vdW ZrSe3, indicating its potential applications in low-power SOT devices. Here, we study the interfacial contribution of SOTs and current-induced magnetization switching in the ZrSe3/Py (Ni80Fe20) and ZrSe3/Cu/Py heterostructures. SOT efficiencies of samples are detected by the spin-torque ferromagnetic resonance (ST-FMR), and out-of-plane damping-like torque (τB) is observed. The ratio between τB and the field-like torque (τA) decreases from 0.175 to 0.138 when inserting 1 nm Cu at the interface and then drops to 0.001 when the thickness of Cu intercalation is 2 nm, indicating that Cu intercalation inhibits the τB component of SOT. Moreover, the SOT efficiency is increased from 3.05 to 5.21, which may be attributed to the Cu intercalation being beneficial to improve the interface between Py and ZrSe3. Theoretical calculation has shown that the Cu spacer can change the conductivity of ZrSe3 from semiconductor to conductor, thereby decreasing the Schottky barrier and increasing the transmission efficiency of the spin current. Furthermore, magneto-optical Kerr effect (MOKE) microscopy is employed to verify the current-driven magnetization switching in these structures. In comparison to the ZrSe3/Py bilayer, the critical current density of ZrSe3/Cu/Py is reduced when inserting 1 nm Cu, demonstrating the higher SOT efficiency and lower power consumption in ZrSe3/Cu/Py structures.

Arm-eye coordination test to objectively quantify motor performance and muscles activation in persons after stroke undergoing robot-aided rehabilitation training: a pilot study.

This study designed an arm-eye coordination test to investigate the effectiveness of the robot-aided rehabilitation for persons after stroke. Six chronic poststroke subjects were recruited to attend a 20-session robot-aided rehabilitation training of elbow joint. Before and after the training program, subjects were asked to perform voluntary movements of elbow flection and extension by following sinusoidal trajectories at different velocities with visual feedback on their joint positions. The elbow angle and the electromyographic signal of biceps and triceps as well as clinical scores were evaluated together with the parameters. Performance was objectively quantified by root mean square error (RMSE), root mean square jerk (RMSJ), range of motion (ROM), and co-contraction index (CI). After 20 sessions, RMSE and ROM improved significantly in both the affected and the unaffected side based on two-way ANOVA (P < 0.05). There was significant lower RMSJ in the affected side at higher velocities (P < 0.05). There was significant negative correlation between average RMSE with different tracking velocities and Fugl-Meyer shoulder-elbow score (P < 0.05). There was also significant negative correlation between average RMSE and average ROM (P < 0.05), and moderate nonsignificant negative correlation with RMSJ, and CI. The characterization of velocity-dependent deficiencies, monitoring of training-induced improvement, and the correlation between quantitative parameters and clinical scales could enable the exploration of effects of different types of treatment and design progress-based training method to accelerate the processes of recovery.

The effects of training intensities on motor recovery and gait symmetry in a rat model of ischemia.

PRIMARY OBJECTIVE: This study investigated the effects of moderate and excessive gait training intensities on motor recovery in sub-acute stroke. METHODS: Sprague-Dawley rats after stroke surgery were randomized into two groups: moderate training group (MTG) and excessive training group (ETG). MTG had 15 minutes of body weight support (BWS) treadmill training per session with three sessions per day on alternative days until 8 days after stroke; and in the ETG, rats had to run until they could not keep up with the treadmill speed for one session on each training day. The intramuscular EMG signal from medial gastrocnemius was used to monitor the muscle activation patterns on both unaffected and affected sides during training. RESULTS: After 4 days post-stroke, the results showed a better recovery in the symmetry gait pattern in the MTG, but there is no such trend observed in the ETG. Moreover, the MTG has a better motor behaviour score and the affected side could bear more body weight. These results were reflected in the increase in the EMG burst duration and increase in EMG mean power frequency (MPF) drop rate on the affected side in the MTG. CONCLUSION: This study shows the moderate gait training intensity by avoiding muscular fatigue has better motor recovery for sub-acute stroke rehabilitation.

Neural correlates of motor impairment during motor imagery and motor execution in sub-cortical stroke.

OBJECTIVE: This study aims at identifying the neural substrates for motor execution (ME) and motor imagery (MI) in patients after stroke and their correlations with functional outcomes. METHODS: 10 chronic stroke patients with left sub-cortical lesions and 10 unimpaired subjects were recruited. Their cortical processes were studied when they were asked to perform ME and MI unimanually using their unaffected and affected wrists during fMRI. RESULTS: From correlation results, the supplementary motor area (SMA), its activation volume and congruence in functional neuroanatomy associated with ME and MI using affected wrist positively correlated with motor performance. During ME of the affected wrist, the precuneus, its activation volume and congruence in functional neuroanatomy between patient and unimpaired groups showed a negative correlation, while, in non-primary motor areas, the hemispheric balance of premotor cortex and the congruence in functional neuroanatomy of contralesional inferior parietal lobule between patient and unimpaired groups showed a positive correlation with motor performance. CONCLUSIONS: The non-primary motor-related areas were revealed to play a critical role in determining motor outcomes after left sub-cortical stroke, which was demonstrated in the stroke patients. In particular, SMA might be the key neural substrate associated with motor recovery.

Myoelectrically controlled wrist robot for stroke rehabilitation.

BACKGROUND: Robot-assisted rehabilitation is an advanced new technology in stroke rehabilitation to provide intensive training. Post-stroke motor recovery depends on active rehabilitation by voluntary participation of patient's paretic motor system as early as possible in order to promote reorganization of brain. However, voluntary residual motor efforts to the affected limb have not been involved enough in most robot-assisted rehabilitation for patients after stroke. The objective of this study is to evaluate the feasibility of robot-assisted rehabilitation using myoelectric control on upper limb motor recovery. METHODS: In the present study, an exoskeleton-type rehabilitation robotic system was designed to provide voluntarily controlled assisted torque to the affected wrist. Voluntary intention was involved by using the residual surface electromyography (EMG) from flexor carpi radialis(FCR) and extensor carpi radialis (ECR)on the affected limb to control the mechanical assistance provided by the robotic system during wrist flexion and extension in a 20-session training. The system also applied constant resistant torque to the affected wrist during the training. Sixteen subjects after stroke had been recruited for evaluating the tracking performance and therapeutical effects of myoelectrically controlled robotic system. RESULTS: With the myoelectrically-controlled assistive torque, stroke survivors could reach a larger range of motion with a significant decrease in the EMG signal from the agonist muscles. The stroke survivors could be trained in the unreached range with their voluntary residual EMG on the paretic side. After 20-session rehabilitation training, there was a non-significant increase in the range of motion and a significant decrease in the root mean square error (RMSE) between the actual wrist angle and target angle. Significant improvements also could be found in muscle strength and clinical scales. CONCLUSIONS: These results indicate that robot-aided therapy with voluntary participation of patient's paretic motor system using myoelectric control might have positive effect on upper limb motor recovery.

Effects of Slit Edge Notches on Mechanical Properties of 3D-Printed PA12 Nylon Kirigami Specimens.

Kirigami structures, a Japanese paper-cutting art form, has been widely adopted in engineering design, including robotics, biomedicine, energy harvesting, and sensing. This study investigated the effects of slit edge notches on the mechanical properties, particularly the tensile stiffness, of 3D-printed PA12 nylon kirigami specimens. Thirty-five samples were designed with various notch sizes and shapes and printed using a commercial 3D printer with multi-jet fusion (MJF) technique. Finite element analysis (FEA) was employed to determine the mechanical properties of the samples computationally. The results showed that the stiffness of the kirigami samples is positively correlated with the number of edges in the notch shape and quadratically negatively correlated with the notch area of the samples. The mathematical relationship between the stretching tensile stiffness of the samples and their notch area was established and explained from an energy perspective. The relationship established in this study can help fine-tune the stiffness of kirigami-inspired structures without altering the primary parameters of kirigami samples. With the rapid fabrication method (e.g., 3D printing technique), the kirigami samples with suitable mechanical properties can be potentially applied to planar springs for hinge structures or energy-absorbing/harvesting structures. These findings will provide valuable insights into the development and optimization of kirigami-inspired structures for various applications in the future.

Impact of anodal high-definition transcranial direct current stimulation of medial prefrontal cortex on stroop task performance and its electrophysiological correlates. A pilot study.

Medial prefrontal cortex (MPC) has been associated with a wide range of cognitive functions; however, its specific role in interference control is not fully understood. The current study investigates the role of MPC in interference control by externally stimulating it with an electric current and studying associated behavioral and neurophysiological markers. Participants randomly assigned to experimental and sham groups were administered with a high-definition transcranial direct current stimulation (HD-tDCS) of 2 mA for 15 min. They performed a classic color-word Stroop task before, during, and immediately after the stimulation, while electroencephalography (EEG) was acquired throughout the experiment. A decrease in reaction time (RT) for incongruent and neutral trials of the Stroop task was observed in the experimental group compared to the sham group with a significant reduction in the Stroop Effect after stimulation; however, no significant change was observed in the amplitude and latency of N200, P200, and N450 event related potentials. Furthermore, the resting state complexity of the neural signals in the medial frontal region was decreased in the experimental group with a decrease in theta frequency band during the Stroop task. We conclude that the stimulation of MPC increases its efficiency in resolving the conflict by reducing theta power during the Stroop task, which is also reflected in the reduced complexity in the resting state EEG. (ClinicalTrials.gov Identifier: NCT04318522).

Cortico-muscular interaction to monitor the effects of neuromuscular electrical stimulation pedaling training in chronic stroke.

Neuromuscular electrical stimulation (NMES) has been widely utilized in post-stroke motor restoration. However, its impact on the closed-loop sensorimotor control process remains largely unclear. This is the first study to investigate the directional changes in cortico-muscular interactions after repetitive rehabilitation training by measuring the noninvasive electroencephalogram (EEG) and electromyography (EMG) signals. In this study, 10 subjects with chronic stroke received 20 sessions of NMES-pedaling interventions, and each training session included three 10-min NMES-driven pedaling trials. In addition, pre- and post-intervention assessments of lower limb isometric contraction were conducted before and after the whole NMES-pedaling interventions. The EEG (128 channels) and EMG (3 bilateral lower limb sensors) signals were collected during the isometric contraction tasks for the paretic and non-paretic lower limbs. Both the cortico-muscular coherence (CMC) and generalized partial directed coherence (GPDC) values were analyzed between eight selected EEG channels in the central primary motor cortex and EMG channels. The results revealed significant clinical improvements. Additionally, rehabilitation training facilitated cortico-muscular interaction of the ipsilesional brain and paretic lower limbs (p = 0.004). Moreover, both the descending and ascending cortico-muscular pathways were altered after NMES-training (p = 0.001, p < 0.001). Therefore, the results implied potential applications of EEG-EMG in understanding neuromuscular changes during the post-stroke motor rehabilitation process.

Wavelet coherence analysis of muscle coupling during reaching movement in stroke.

Agonist-antagonist coordination is essential to ensure the accuracy and stability of voluntary movement, which can be presented by time-varying coupling between agonist-antagonist electromyographic (EMG) signals. To discover the stroke-induced neurological change in paretic muscles, the wavelet coherence is firstly compared with coherence by simulated data and is utilized to represent the time-varying coupling of experimental data during elbow-tracking tasks. The simulation in this study demonstrates that the wavelet coherence is superior to coherence in the detection of short-time coupling between simulated signals. In addition, the experiment in this study is designed to explore the coupling between agonist-antagonist activations during the dynamic process. In the experiment, 10 post-stroke patients and 10 age-matched adults serving as controls were recruited and asked to perform elbow sinusoidal trajectory tracking tasks. Both the elbow angle and EMG signals of biceps and triceps were recorded simultaneously. Experimental results showed that wavelet coherence could represent the time-varying coupling between two EMG signals in the time-frequency domain, and its dynamic character was appropriate in the dynamic process to discover the functional coupling. According to the time and frequency analysis, the lower functional coupling in the post-stroke group and the obvious wavelet coherence difference between the two groups in the lower frequency range suggested a possible hypothesis mechanism that the weakening of coupling between agonist-antagonist muscles in the affected sides might in fact be stroke-induced damage in the direct corticospinal pathways.

Interface Engineering of Flexible Piezoresistive Sensors via Near-Field Electrospinning Processed Spacer Layers.

The interface contact between the active material and its neighboring metal electrodes dominates the sensing response of mainstream high-sensitivity piezoresistive pressure sensors. However, the properties of such interface are often difficult to control and preserve owing to the limited strategies to precisely engineer the surface structure and mechanical property of the active material. Here, a top-down fabrication method to create a grid-like polyurethane fiber-based spacer layer at the interface between a piezoresistive layer and its contact electrodes is proposed. The tuning of the period and thickness of the spacer layer is conveniently achieved by a programmable near-field electrospinning process, and the influence of the spacer structure on the sensing performance is systematically investigated. The sensor with the optimized spacer layer shows a widened sensing range (230 kPa) while maintaining a high sensitivity (1.91 kPa-1 ). Furthermore, the output current fluctuation of the sensors during a 74 000-cycle test is drastically reduced from 14.28% (without a spacer) to 3.63% (with a spacer), demonstrating greatly enhanced long-term reliability. The new near-field electrospinning-based strategy is capable of tuning sensor responses without changing the active material, providing a universal and scalable path to engineer the performances of contact-dominant sensors.

Changes in electroencephalography complexity and functional magnetic resonance imaging connectivity following robotic hand training in chronic stroke.

Introduction: In recent years, robotic training has been utilized for recovery of motor control in patients with motor deficits. Along with clinical assessment, electrical patterns in the brain have emerged as a marker for studying changes in the brain associated with brain injury and rehabilitation. These changes mainly involve an imbalance between the two hemispheres. We aimed to study the effect of brain computer interface (BCI)-based robotic hand training on stroke subjects using clinical assessment, electroencephalographic (EEG) complexity analysis, and functional magnetic resonance imaging (fMRI) connectivity analysis. Method: Resting-state simultaneous EEG-fMRI was conducted on 14 stroke subjects before and after training who underwent 20 sessions robot hand training. Fractal dimension (FD) analysis was used to assess neuronal impairment and functional recovery using the EEG data, and fMRI connectivity analysis was performed to assess changes in the connectivity of brain networks. Results: FD results indicated a significant asymmetric difference between the ipsilesional and contralesional hemispheres before training, which was reduced after robotic hand training. Moreover, a positive correlation between interhemispheric asymmetry change for central brain region and change in Fugl Meyer Assessment (FMA) scores for upper limb was observed. Connectivity results showed a significant difference between pre-training interhemispheric connectivity and post-training interhemispheric connectivity. Moreover, the change in connectivity correlated with the change in FMA scores. Results also indicated a correlation between the increase in connectivity for motor regions and decrease in FD interhemispheric asymmetry for central brain region covering the motor area. Conclusion: In conclusion, robotic hand training significantly facilitated stroke motor recovery, and FD, along with connectivity analysis can detect neuroplasticity changes.

A hybrid network for automatic hepatocellular carcinoma segmentation in H&E-stained whole slide images.

Hepatocellular carcinoma (HCC), as the most common type of primary malignant liver cancer, has become a leading cause of cancer deaths in recent years. Accurate segmentation of HCC lesions is critical for tumor load assessment, surgery planning, and postoperative examination. As the appearance of HCC lesions varies greatly across patients, traditional manual segmentation is a very tedious and time-consuming process, the accuracy of which is also difficult to ensure. Therefore, a fully automated and reliable HCC segmentation system is in high demand. In this work, we present a novel hybrid neural network based on multi-task learning and ensemble learning techniques for accurate HCC segmentation of hematoxylin and eosin (H&E)-stained whole slide images (WSIs). First, three task-specific branches are integrated to enlarge the feature space, based on which the network is able to learn more general features and thus reduce the risk of overfitting. Second, an ensemble learning scheme is leveraged to perform feature aggregation, in which selective kernel modules (SKMs) and spatial and channel-wise squeeze-and-excitation modules (scSEMs) are adopted for capturing the features from different spaces and scales. Our proposed method achieves state-of-the-art performance on three publicly available datasets, with segmentation accuracies of 0.797, 0.923, and 0.765 in the PAIP, CRAG, and UHCMC&CWRU datasets, respectively, which demonstrates its effectiveness in addressing the HCC segmentation problem. To the best of our knowledge, this is also the first work on the pixel-wise HCC segmentation of H&E-stained WSIs.

[Research on control technology of functional electrical stimulation in wrist movements based on Hammerstein model].

For most of nonlinear systems, control strategy is complicated. The adaptive control methods based on the model identification can effectively improve the control precision and stability. According to the nonlinear and time-changeable characteristics of the wrist movement in the functional electrical stimulation, modeling and identification of wrist movement based on Hammerstein model were implemented. By using M sequence and invert-repeated M sequence as excitation signal, the wrist model is divided into the linear dynamic part and the nonlinear static part. The characteristics of nonlinear part being taken into consideration, an adaptive control method based on time-changeable characteristics of linear part is presented. This method simplifies the control strategy, and it is validated by the simulation experiment of FES.

Anodal Transcranial Direct Current Stimulation of Anterior Cingulate Cortex Modulates Subcortical Brain Regions Resulting in Cognitive Enhancement.

Transcranial direct current stimulation (tDCS) has been widely utilized in research settings and modulates brain activity. The application of anodal tDCS on the prefrontal cortex has indicated improvement in cognitive functioning. The cingulate cortex, situated in the medial aspect of the prefrontal cortex, has been identified as a core region performing cognitive functions. Most of the previous studies investigating the impact of stimulation on the prefrontal cortex stimulated the dorsolateral prefrontal cortex (DLPFC), however, the impact of stimulation on cingulate has not been explored. The current study investigates the effect of stimulation on the resting-state functional connectivity of the anterior cingulate cortex with other regions of the brain and changes in behavioral results in a color-word Stroop task, which has repeatedly elicited activation in different regions of the cingulate. Twenty subjects were randomly assigned to the experimental and sham group, and their medial prefrontal area was stimulated using MRI compatible tDCS. Resting-state functional magnetic resonance imaging (rs-fMRI) and cognitive Stroop task were monitored before, during, and after the stimulation. Neuroimaging results indicated a significant decrease in resting-state functional connectivity in the experimental group during and after stimulation as compared to before stimulation in two clusters including right insular cortex, right central operculum cortex, right frontal operculum cortex and right planum polare with the left anterior cingulate cortex (L-ACC) selected as the seed. The behavioral results indicated a significant decrease in reaction time (RT) following stimulation in the experimental group compared to the sham group. Moreover, the change in functional connectivity in subcortical regions with L-ACC as the seed and change in RT was positively correlated. The results demonstrated that ACC has a close functional relationship with the subcortical regions, and stimulation of ACC can modulate these connections, which subsequently improves behavioral performance, thus, providing another potential target of stimulation for cognitive enhancement. Clinical Trial Registration: ClinicalTrials.gov Identifier: NCT04318522.

Postural Stability in Obese Preoperative Bariatric Patients Using Static and Dynamic Evaluation.

INTRODUCTION: Globally, 300 million adults have clinical obesity. Heightened adiposity and inadequate musculature secondary to obesity alter bipedal stance and gait, diminish musculoskeletal tissue quality, and compromise neuromuscular feedback; these physiological changes alter stability and increase injury risk from falls. Studies in the field focus on obese patients across a broad range of body mass indices (BMI >30 kg/m2) but without isolating the most morbidly obese subset (BMI ≥40 kg/m2). We investigated the impact of obesity in perturbing postural stability in morbidly obese subjects elected for bariatric intervention, harboring a higher-spectrum BMI. SUBJECTS AND METHODS: Traditional force plate measurements and stabilograms are gold standards employed when measuring center of pressure (COP) and postural sway. To quantify the extent of postural instability in subjects with obesity before bariatric surgery, we assessed 17 obese subjects with an average BMI of 40 kg/m2 in contrast to 13 nonobese subjects with an average BMI of 30 kg/m2. COP and postural sway were measured from static and dynamic tasks. Involuntary movements were measured when patients performed static stances, with eyes either opened or closed. Two additional voluntary movements were measured when subjects performed dynamic, upper torso tasks with eyes opened. RESULTS: Mean body weight was 85% (p < 0.001) greater in obese than nonobese subjects. Following static balance assessments, we observed greater sway displacement in the anteroposterior (AP) direction in obese subjects with eyes open (87%, p < 0.002) and eyes closed (76%, p = 0.04) versus nonobese subjects. Obese subjects also exhibited a higher COP velocity in static tests when subjects' eyes were open (47%, p = 0.04). Dynamic tests demonstrated no differences between groups in sway displacement in either direction; however, COP velocity in the mediolateral (ML) direction was reduced (31%, p < 0.02) in obese subjects while voluntarily swaying in the AP direction, but increased in the same cohort when swaying in the ML direction (40%, p < 0.04). DISCUSSION AND CONCLUSION: Importantly, these data highlight obesity's contribution towards increased postural instability. Obese subjects exhibited greater COP displacement at higher AP velocities versus nonobese subjects, suggesting that clinically obese individuals show greater instability than nonobese subjects. Identifying factors contributory to instability could encourage patient-specific physical therapies and presurgical measures to mitigate instability and monitor postsurgical balance improvements.

A comparison between electromyography-driven robot and passive motion device on wrist rehabilitation for chronic stroke.

BACKGROUND: The effect of using robots to improve motor recovery has received increased attention, even though the most effective protocol remains a topic of study. OBJECTIVE: . The objective was to compare the training effects of treatments on the wrist joint of subjects with chronic stroke with an interactive rehabilitation robot and a robot with continuous passive motion. METHODS: . This study was a single-blinded randomized controlled trial with a 3-month follow-up. Twenty-seven hemiplegic subjects with chronic stroke were randomly assigned to receive 20-session wrist training with a continuous electromyography (EMG)-driven robot (interactive group, n = 15) and a passive motion device (passive group, n = 12), completed within 7 consecutive weeks. Training effects were evaluated with clinical scores by pretraining and posttraining tests (Fugl-Meyer Assessment [FMA] and Modified Ashworth Score [MAS]) and with session-by-session EMG parameters (EMG activation level and co-contraction index). RESULTS: . Significant improvements in FMA scores (shoulder/elbow and wrist/hand) were found in the interactive group (P < .05). Significant decreases in the MAS were observed in the wrist and elbow joints for the interactive group and in the wrist joint for the passive group (P < .05). These MAS changes were associated with the decrease in EMG activation level of the flexor carpi radialis and the biceps brachii for the interactive group (P < .05). The muscle coordination on wrist and elbow joints was improved in the interactive groups in the EMG co-contraction indexes across the training sessions (P < .05). CONCLUSIONS: . The interactive treatment improved muscle coordination and reduced spasticity after the training for both the wrist and elbow joints, which persisted for 3 months. The passive mode training mainly reduced the spasticity in the wrist flexor.

What Kind of Brain Structural Connectivity Remodeling Can Relate to Residual Motor Function After Stroke?

Recent findings showed that brain networks far away from a lesion could be altered to adapt changes after stroke. This study examined 13 chronic stroke patients with moderate to severe motor impairment and 13 age-comparable healthy controls using diffusion tensor imaging to investigate the stroke impact on the reorganization of structural connectivity. Each subject's brain was segmented into 68 cortical and 12 subcortical regions of interest (ROIs), and connectivity measures including fractional anisotropy (FA), regional FA (rFA), connection weight (CW) and connection strength (CS) were adopted to compare two subject groups. Correlations between these measures and clinical scores of motor functions (Action Research Arm Test and Fugl-Meyer Assessment for upper extremity) were done. Network-based statistic (NBS) was conducted to identify the connectivity differences between patients and controls from the perspective of whole-brain network. The results showed that both rFAs and CSs demonstrated significant differences between patients and controls in the ipsilesional sensory-motor areas and subcortical network, and bilateral attention and default mode networks. Significant positive correlations were found between the paretic motor functions and the rFAs/CSs of the contralesional medial orbitofrontal cortex (mOFC) and rostral anterior cingulate cortex (rACC), and remained significant even after removing the effect of the ipsilesional corticospinal tract. Additionally, all the connections linked with the contralesional mOFC and rACC showed significantly higher FA/CW values in the stroke patients compared to the healthy controls from the NBS results. These findings indicated that these contralesional prefrontal areas exhibited stronger connections after stroke and strongly related to the residual motor function of the stroke patients.