Muscle synergies after stroke are correlated with perilesional high gamma.

Movements can be factored into modules termed "muscle synergies". After stroke, abnormal synergies are linked to impaired movements; however, their neural basis is not understood. In a single subject, we examined how electrocorticography signals from the perilesional cortex were associated with synergies. The measured synergies contained a mix of both normal and abnormal patterns and were remarkably similar to those described in past work. Interestingly, we found that both normal and abnormal synergies were correlated with perilesional high gamma. Given the link between high gamma and cortical spiking, our results suggest that perilesional spiking may organize synergies after stroke

Alignment of magnetic sensing and clinical magnetomyography

Neuromuscular diseases are a prevalent cause of prolonged and severe suffering for patients, and with the global population aging, it is increasingly becoming a pressing concern. To assess muscle activity in NMDs, clinicians and researchers typically use electromyography (EMG), which can be either non-invasive using surface EMG, or invasive through needle EMG. Surface EMG signals have a low spatial resolution, and while the needle EMG provides a higher resolution, it can be painful for the patients, with an additional risk of infection. The pain associated with the needle EMG can pose a risk for certain patient groups, such as children. For example, children with spinal muscular atrophy (type of NMD) require regular monitoring of treatment efficacy through needle EMG; however, due to the pain caused by the procedure, clinicians often rely on a clinical assessment rather than needle EMG. Magnetomyography (MMG), the magnetic counterpart of the EMG, measures muscle activity non-invasively using magnetic signals. With super-resolution capabilities, MMG has the potential to improve spatial resolution and, in the meantime, address the limitations of EMG. This article discusses the challenges in developing magnetic sensors for MMG, including sensor design and technology advancements that allow for more specific recordings, targeting of individual motor units, and reduction of magnetic noise. In addition, we cover the motor unit behavior and activation pattern, an overview of magnetic sensing technologies, and evaluations of wearable, non-invasive magnetic sensors for MMG

Clinical Relevance of State-of-the-Art Analysis of Surface Electromyography in Cerebral Palsy

Surface electromyography (sEMG) can be used to assess the integrity of the neuromuscular system and its impairment in neurological disorders. Here we will consider several issues related to the current clinical applications, difficulties and limited usage of sEMG for the assessment and rehabilitation of children with cerebral palsy. The uniqueness of this methodology is that it can determine hyperactivity or inactivity of selected muscles, which cannot be assessed by other methods. In addition, it can assist for intervention or muscle/tendon surgery acts, and it can evaluate integrated functioning of the nervous system based on multi-muscle sEMG recordings and assess motor pool activation. The latter aspect is especially important for understanding impairments of the mechanisms of neural controllers rather than malfunction of individual muscles. Although sEMG study is an important tool in both clinical research and neurorehabilitation, the results of a survey on the clinical relevance of sEMG in a typical department of pediatric rehabilitation highlighted its limited clinical usage. We believe that this is due to limited knowledge of the sEMG and its neuromuscular underpinnings by many physiotherapists, as a result of lack of emphasis on this important methodology in the courses taught in physical therapy schools. The lack of reference databases or benchmarking software for sEMG analysis may also contribute to the limited clinical usage. Despite the existence of educational and technical barriers to a widespread use of, sEMG does provide important tools for planning and assessment of rehabilitation treatments for children with cerebral palsy

A spinal cord neuroprosthesis for locomotor deficits due to Parkinson’s disease

People with late-stage Parkinson’s disease (PD) often suffer from debilitating locomotor deficits that are resistant to currently available therapies. To alleviate these deficits, we developed a neuroprosthesis operating in closed loop that targets the dorsal root entry zones innervating lumbosacral segments to reproduce the natural spatiotemporal activation of the lumbosacral spinal cord during walking. We first developed this neuroprosthesis in a non-human primate model that replicates locomotor deficits due to PD. This neuroprosthesis not only alleviated locomotor deficits but also restored skilled walking in this model. We then implanted the neuroprosthesis in a 62-year-old male with a 30-year history of PD who presented with severe gait impairments and frequent falls that were medically refractory to currently available therapies. We found that the neuroprosthesis interacted synergistically with deep brain stimulation of the subthalamic nucleus and dopaminergic replacement therapies to alleviate asymmetry and promote longer steps, improve balance and reduce freezing of gait. This neuroprosthesis opens new perspectives to reduce the severity of locomotor deficits in people with PD

Understanding the modulation of walking speed and exploring how this differs in people with Parkinson’s disease.

Background: Parkinson's disease (PD) affects the ability of individuals to initiate movement and change muscle activity during gait initiation (GI) and during variations in walking speed. The present study aims to investigate the biomechanics parameters (kinetics and kinematics) and muscle activity characteristics during GI and variation in speed while walking on a treadmill and overground (OG) for PD-affected individuals and physically fit people. Methods: In this study, participants (n=17) included a physical fit (n= 11, aged 31.72 +/17.91 years) and a Parkinson’s (n= 6, aged 67.33 +/-11.57 years, disease duration 13.5 +/8.69). Both groups were evaluated while walking on the treadmill and over the ground for two phases. The first phase was Gait initiation, where the participants were asked to start walking at their comfortable speed for two gait cycles on the treadmill and OG. The second phase was speed variation, where the participants also walked at their comfortable speed, and increased their speed in response to visual instruction on screen. However, on the ground, they were asked to change their speed after their fifth walking step. A self-pacing treadmill synchronised with a virtual reality screen (MotekMedical, the Netherlands) and A 12-camera motion capture system (Vicon Motion Systems, UK) integrated with two embedded force plates and a wireless EMG system (Trigno, Delsys, USA) collected the biomechanical and muscle excitation data. Three gait cycles; before, during and immediately after the speed change was used for the analysis of the speed variation. Data were limited to lower limb joints and three muscles (tibialis anterior, gastrocnemius and soleus. Differences in the percentage of contraction and magnitude of muscle activation (area under the curve, AUC) were compared before and during the speed change. Results: PD-affected individuals spent less time on GI during treadmill walking (2.06 s ± 0.39) than the healthy reference group (2.25 s ± 0.42) but more time with OG walking (1.95s ±0.25) compared to the reference group (1.49s ±0.56). The reference group had a greater range of lower limb joint movement than the PD group during GI on both walking surfaces. The power produced at the hip and ankle joint by the reference group was higher than the overall PD group. The magnitude of muscle activation was lower in the PD group than the reference group, and the severity of the disease affected the magnitude of the muscle activation. At speed variation, both the reference and PD groups showed an increase in speed. Cadence declined in the reference group but elevated in the PD group. Soleus muscle activity increased with an increase in speed in PD-affected individuals, particularly in severely affected individuals compared to the reference group. Discussion/Conclusion: The mechanism for increasing speed appears to differ between PD-affected individuals and physically fit individuals. Soleus excitation during stance may be a control parameter for walking speed that is disturbed in PD, although age is likely to be a confounding factor. Further research is needed to understand the mechanisms underpinning these positive responses to interactive treadmill training and its impact on community walking. Keywords: Parkinson's disease, Gait initiation, Gait Cycles, treadmill walking, speed change.Background: Parkinson's disease (PD) affects the ability of individuals to initiate movement and change muscle activity during gait initiation (GI) and during variations in walking speed. The present study aims to investigate the biomechanics parameters (kinetics and kinematics) and muscle activity characteristics during GI and variation in speed while walking on a treadmill and overground (OG) for PD-affected individuals and physically fit people. Methods: In this study, participants (n=17) included a physical fit (n= 11, aged 31.72 +/17.91 years) and a Parkinson’s (n= 6, aged 67.33 +/-11.57 years, disease duration 13.5 +/8.69). Both groups were evaluated while walking on the treadmill and over the ground for two phases. The first phase was Gait initiation, where the participants were asked to start walking at their comfortable speed for two gait cycles on the treadmill and OG. The second phase was speed variation, where the participants also walked at their comfortable speed, and increased their speed in response to visual instruction on screen. However, on the ground, they were asked to change their speed after their fifth walking step. A self-pacing treadmill synchronised with a virtual reality screen (MotekMedical, the Netherlands) and A 12-camera motion capture system (Vicon Motion Systems, UK) integrated with two embedded force plates and a wireless EMG system (Trigno, Delsys, USA) collected the biomechanical and muscle excitation data. Three gait cycles; before, during and immediately after the speed change was used for the analysis of the speed variation. Data were limited to lower limb joints and three muscles (tibialis anterior, gastrocnemius and soleus. Differences in the percentage of contraction and magnitude of muscle activation (area under the curve, AUC) were compared before and during the speed change. Results: PD-affected individuals spent less time on GI during treadmill walking (2.06 s ± 0.39) than the healthy reference group (2.25 s ± 0.42) but more time with OG walking (1.95s ±0.25) compared to the reference group (1.49s ±0.56). The reference group had a greater range of lower limb joint movement than the PD group during GI on both walking surfaces. The power produced at the hip and ankle joint by the reference group was higher than the overall PD group. The magnitude of muscle activation was lower in the PD group than the reference group, and the severity of the disease affected the magnitude of the muscle activation. At speed variation, both the reference and PD groups showed an increase in speed. Cadence declined in the reference group but elevated in the PD group. Soleus muscle activity increased with an increase in speed in PD-affected individuals, particularly in severely affected individuals compared to the reference group. Discussion/Conclusion: The mechanism for increasing speed appears to differ between PD-affected individuals and physically fit individuals. Soleus excitation during stance may be a control parameter for walking speed that is disturbed in PD, although age is likely to be a confounding factor. Further research is needed to understand the mechanisms underpinning these positive responses to interactive treadmill training and its impact on community walking. Keywords: Parkinson's disease, Gait initiation, Gait Cycles, treadmill walking, speed change

Methodological considerations in assessing interlimb coordination on poststroke gait: a scoping review of biomechanical approaches and outcomes

To identify and summarize biomechanical assessment approaches in interlimb coordination on poststroke gait. Interlimb coordination involves complex neurophysiological mechanisms that can be expressed through the biomechanical output. The deepening of this concept would have a significant contribution in gait rehabilitation in patients with an asymmetric neurological impairment as poststroke adults. Poststroke adults (>19 years old), with assessment of interlimb coordination during gait, in an open context, according to the Population, Concept, Context framework. A literature search was performed in PubMed, Web of Science™, Scopus, and gray literature in Google Scholar™, according to the PRISMA-ScR recommendations. Studies written in Portuguese or English language and published between database inception and 14 November 2021 were included. Qualitative studies, conference proceedings, letters, and editorials were excluded. The main conceptual categories were “author/year”, “study design”, “participant’s characteristics”, “walking conditions”, “instruments” and “outcomes”. The search identified 827 potentially relevant studies, with a remaining seven fulfilling the established criteria. Interlimb coordination was assessed during walking in treadmill (n = 3), overground (n = 3) and both (n = 1). The instruments used monitored electromyography (n = 2), kinetics (n = 2), and kinematics (n = 4) to assess spatiotemporal parameters (n = 4), joint kinematics (n = 2), anteroposterior ground reaction forces (n = 2), and electromyography root mean square (n = 2) outcomes. These outcomes were mostly used to analyze symmetry indices or ratios, to calculate propulsive impulse and external mechanical power produced on the CoM, as well as antagonist coactivation. Assessment of interlimb coordination during gait is important for consideration of natural auto-selected overground walking, using kinematic, kinetic, and EMG instruments. These allow for the collection of the main biomechanical outcomes that could contribute to improve better knowledge of interlimb coordination assessment in poststroke patients.info:eu-repo/semantics/publishedVersio

Slow Potentials of the Sensorimotor Cortex during Rhythmic Movements of the Ankle

The objective of this dissertation was to more fully understand the role of the human brain in the production of lower extremity rhythmic movements. Throughout the last century, evidence from animal models has demonstrated that spinal reflexes and networks alone are sufficient to propagate ambulation. However, observations after neural trauma, such as a spinal cord injury, demonstrate that humans require supraspinal drive to facilitate locomotion. To investigate the unique nature of lower extremity rhythmic movements, electroencephalography was used to record neural signals from the sensorimotor cortex during three cyclic ankle movement experiments. First, we characterized the differences in slow movement-related cortical potentials during rhythmic and discrete movements. During the experiment, motion analysis and electromyography were used characterize lower leg kinematics and muscle activation patterns. Second, a custom robotic device was built to assist in passive and active ankle movements. These movement conditions were used to examine the sensory and motor cortical contributions to rhythmic ankle movement. Lastly, we explored the differences in sensory and motor contributions to bilateral, rhythmic ankle movements. Experimental results from all three studies suggest that the brain is continuously involved in rhythmic movements of the lower extremities. We observed temporal characteristics of the cortical slow potentials that were time-locked to the movement. The amplitude of these potentials, localized over the sensorimotor cortex, revealed a reduction in neural activity during rhythmic movements when compared to discrete movements. Moreover, unilateral ankle movements produced unique sensory potentials that tracked the position of the movement and motor potentials that were only present during active dorsiflexion. In addition, the spatiotemporal patterns of slow potentials during bilateral ankle movements suggest similar cortical mechanisms for both unilateral and bilateral movement. Lastly, beta frequency modulations were correlated to the movement-related slow potentials within medial sensorimotor cortex, which may indicate they are of similar cortical origin. From these results, we concluded that the brain is continuously involved in the production of lower extremity rhythmic movements, and that the sensory and motor cortices provide unique contributions to both unilateral and bilateral movemen

Gait analysis in neurological populations: Progression in the use of wearables

Gait assessment is an essential tool for clinical applications not only to diagnose different neurological conditions but also to monitor disease progression as it contributes to the understanding of underlying deficits. There are established methods and models for data collection and interpretation of gait assessment within different pathologies. This narrative review aims to depict the evolution of gait assessment from observation and rating scales to wearable sensors and laboratory technologies, and provide possible future directions. In this context, we first present an extensive review of current clinical outcomes and gait models. Then, we demonstrate commercially available wearable technologies with their technical capabilities along with their use in gait assessment studies for various neurological conditions. In the next sections, a descriptive knowledge for existing inertial based algorithms and a sign based guide that shows the outcomes of previous neurological gait assessment studies are presented. Finally, we state a discussion for the use of wearables in gait assessment and speculate the possible research directions by revealing the limitations and knowledge gaps in the literature

Spatiotemporal Sparse Bayesian Learning with Applications to Compressed Sensing of Multichannel Physiological Signals

Energy consumption is an important issue in continuous wireless telemonitoring of physiological signals. Compressed sensing (CS) is a promising framework to address it, due to its energy-efficient data compression procedure. However, most CS algorithms have difficulty in data recovery due to non-sparsity characteristic of many physiological signals. Block sparse Bayesian learning (BSBL) is an effective approach to recover such signals with satisfactory recovery quality. However, it is time-consuming in recovering multichannel signals, since its computational load almost linearly increases with the number of channels. This work proposes a spatiotemporal sparse Bayesian learning algorithm to recover multichannel signals simultaneously. It not only exploits temporal correlation within each channel signal, but also exploits inter-channel correlation among different channel signals. Furthermore, its computational load is not significantly affected by the number of channels. The proposed algorithm was applied to brain computer interface (BCI) and EEG-based driver's drowsiness estimation. Results showed that the algorithm had both better recovery performance and much higher speed than BSBL. Particularly, the proposed algorithm ensured that the BCI classification and the drowsiness estimation had little degradation even when data were compressed by 80%, making it very suitable for continuous wireless telemonitoring of multichannel signals.Comment: Codes are available at: https://sites.google.com/site/researchbyzhang/stsb