The effect of mechanical vestibular stimulation on muscle tone and spasticity in individuals with neurological impairment

In the desire to better understand spasticity mainly in Cerebral Palsy (CP) and to examine vestibular stimulation as a future intervention for .muscle tone reduction, and to be able to describe the change in level of spasticity in subjects with disability and describe interventions effects, a series of experiments are done on children with spasticity. In addition to understanding the otoliths in the vestibular system and their projections, properties and pathways a more important major objective of this work is to validate the changes in otoliths signal caused by vestibular stimulation based on the Equilibrium Point Hypothesis and the inclusion of EMG data in assessing the level of spasticity. Stimulation to the saccule in the otolith is induced to reduce spasticity. The otoliths are sensitive to acceleration, and detect the direction and magnitude of gravity, as well as transient linear accelerations due to movement. This is a form of a biological accelerometer. The vestibular mechanical stimulation is provided using a vertical stimulation chair that moves up/down at a constant frequency of 2 Hz and amplitude of ~ 7.5 centimeter for time duration of 15 minutes. This form of stimulation targets the saccule organ in the vestibular system, which results in alterations of the descending signals of the vestibular system responsible for setting tone of the antigravity muscles. Electromyography (EMG) is simultaneously recorded from the quadriceps (Vastus Lateralis) and hamstring (Biceps Femoris) muscles along with the PKD test. The activation of EMG during PKD can be understood in relationship to the flexion and extension of the lower leg. It is interesting that EMG activity for quadriceps is seen at every flexion cycle in the post stimulation data, while on the other hand EMG activity is nearly continuous in the initial cycles of PKD in the pre stimulation. This may be an indication of a change in the activation pattern of EMG from the agonist and antagonist muscles as a result of the vestibular stimulation, which is caused by neural changes in the vestibular descending signal. Preliminary studies done on subjects without disability comparing NASA jump test pre and post riding a rollercoaster indicate that there are significant differences in the knee and hip angles, which can be explained as a result of the change in muscle tone caused by the exposure to microgravity or cyclic gravity while being on rides. A preliminary study done on a 35 year old subject with CP, showed promising results in reducing spasticity after stimulating the vestibular system using the vestibular stimulation chair. Data from the Pendulum Knee Drop (PKD) test show a significant reduction in the knee stiffness (K), and virtual trajectory (θvt) that is noticed as a change in the shape of knee trajectory post stimulation when compared to pre stimulation. The final work presented in this study includes seven subjects with spasticity due to cerebral palsy. The PKD test, along with EMG, is used to assess their level of spasticity. Alterations to the vestibular descending signals while passing through the vestibular nuclei and going down toward the alpha motor neurons command a change in the muscle activation patterns that are responsible for setting the level of spasticity or muscle tone. Furthermore, this effect was found to be retained for at least 15 minutes post stimulation. One subject’s data is excluded from the study due to her high initial baseline measure of muscle tone and spasticity which is determined with the extreme firing of EMG bursts. In all the other six subjects of this study, the knee stiffness and damping parameters show a dramatic decrease post vestibular stimulation, and a smaller change is also noticed in the virtual trajectory (θvt) specifically in two subjects who have no dystonia. Four of the subjects have dystonic spasticity and the other three do not have dystonia along with spasticity. The vestibular stimulation effect is different between the two groups, and it is found that stimulation do not have the same effect on the level of dystonia as much as it do on spasticity. Subsequent analyses of EMG lead to a potential linkage between the EPH and the muscle reflexes (EMG). It is important to note that: 1) this work cannot be claimed as a permanent treatment for children with CP, but a combination of the described stimulation along with the proper physical therapy might have a very positive effect on the disorder. 2) Another path that can have a similar impact on the described population is by changing the stimulation duration intensity and providing the stimulation more frequently for at least five consecutive weeks might have a major impact on reducing the level of spasticity in children with CP

Quantification of abnormal muscle tone following spinal cord injury: A clinical perspective

Abnormal muscle tone is a frequent complication following traumatic spinal cord injury with subsequent upper motor neurone paralysis. Treatment of this complex problem presents many difficulties for the clinician and appropriate assessment is a vital pre-requisite when devising a pertinent treatment regimen. The purpose of this study was to examine a variety of measures and to create a comprehensive assessment programme to quantify abnormal muscle tone in this patient group which was compatible with use in the clinical environment. The study examined the reliability of the five measurement techniques: therapist rating, patient rating, electrogoniometry and dynamometry augmented by polyelectromyography, prior to implementing the combined assessment programme in a group of spinal cord injured and neurologically intact subjects. The relationships between the findings of each assessment were examined and the suitability of the combined assessment programme was considered for routine use in the clinical environment. All the measures examined in the study proved to be reliable, able to differentiate between the spinal cord injured and neurologically intact subjects and practical for implementation within the clinical environment. The lack of correlation between the findings of the singular components of the assessment programme supports the hypothesis that it is necessary to include all the measures investigated if the clinician wishes to undertake a comprehensive evaluation of the individual person presenting with abnormal muscle tone following spinal cord injury

Muscle co-activation during gait in children with cerebral palsy

La paralysie cérébrale (PC) est un trouble non progressif causé par une lésion cérébrale. La PC survient tôt dans la vie et présente une atteinte hétérogène et une altération fonctionnelle. Chez les personnes atteintes de PC, les modifications du Contrôle neuronal et des muscles entraînent des modifications permanentes de la fonction motrice, entraînant des déficits de mouvement. L'une des raisons des patrons de marche atypiques chez les enfants atteints de PC est l'altération l'activation musculaire. Un niveau anormal d'activation simultanée des muscles agonistes et antagonistes des muscles agonistes et antagonistes entourant une même articulation la même articulation empêche une performance de marche optimale chez les enfants atteints de PC. Ce phénomène est connu sous le nom de co-contraction musculaire (CoM) ou de co-activation musculaire (CaM) dans toutes les études. L'identification des schémas musculaires les plus détériorés, à savoir CoM/CaM, chez les enfants atteints de PC est essentielle pour une rééducation efficace de la marche. L'objectif de ce projet de maîtrise était donc de distinguer CoM/CaM chez les enfants atteints de PC de leurs pairs en développement typique (DT) pendant la marche. Cet objectif a été atteint en deux étapes ; Premièrement, nous avons décrit la CoM/CaM chez les personnes atteintes de PC via la réalisation d'une revue de littérature ; Ensuite, nous avons appliqué nos résultats de la première étape à une étude transversale pour comparer CoM/CaM pendant la marche entre des enfants atteints de CP et de DT. Une revue de littérature suivant la méthodologie en 6 étapes du Joanna Briggs Institute a été effectué. Les bases de données ont été consultées à l'aide de mots-clés pertinents. Toutes les études publiées sur CoM/CaM chez les personnes atteintes de PC pendant la marche ont été recueillies. Après un examen de la pertinence des titres et des résumés, un deuxième examen des textes intégraux des sources par deux examinateurs a été appliqué. Enfin, les données ont été extraites des articles inclus (n=21). Ensuite, à l'étape suivante, les principales méthodes utilisées pour quantifier la MCa identifiées à l'étape précédente ont été codées dans Matlab (The Mathworks Inc., Natick, États-Unis) et appliquées à nos données de 12 enfants atteints de CP et 23 enfants TD. Nous avons comparé le CaM moyen de deux groupes de muscles de la cuisse et de la jambe (Rectus Femoris (RF)/Semitendinosus (ST) et Tibialis Anterior (TA)/Lateral gastrocnemius (LG), respectivement) via des tests t non appariés (ou son équivalent non paramétrique). La revue de littérature a suggéré une CaM plus élevée chez les personnes atteintes de PC par rapport à leurs pairs en bonne santé dans toutes les études. Bien qu'il y ait eu une terminologie et des approches méthodologiques incohérentes, nous avons pu discriminer les terminologies (c'est-à-dire CoM et CaM) en fonction des méthodologies de calcul (c'est-à-dire moment et EMG) utilisées par les études. En outre, cette étude nous a permis de résumer les modèles de CaM chez les individus atteints de PC et d'identifier la relation entre certains des paramètres de marche avec CaM. Enfin, les résultats de cette étude ont révélé des informations précieuses concernant les lacunes de la recherche dans ce domaine. La deuxième étude a identifié une augmentation de la CaM pendant la marche (la foulée entière, la phase d’appuie et la phase oscillante) chez les enfants atteints de PC par rapport à leurs pairs TD. Cette augmentation n'a été observée que dans les muscles de la jambe (pendant la phase d’appuie et la phase oscillante) et dans les muscles de la cuisse (pendant la phase oscillante) lorsque nous avons normalisé les signaux d'électromyographie. Les groupes CP et DT n'avaient pas de CaM différent en utilisant l'EMG normalisé pour l'ensemble de la foulée. Cette différence met en évidence l'effet de la normalisation EMG sur les valeurs de CaM. De plus, les enfants avec le niveau II du système de classification de la fonction motrice globale (SCFMG) avaient un CaM plus élevé dans les muscles de la cuisse pendant le swing que ceux avec le niveau I. Dans l'ensemble, ce projet de maîtrise révèle de nouvelles preuves soutenant une plus grande CaM chez les enfants atteints de PC par rapport à DT pendant la marche. Néanmoins, il est important d'étudier la CaM dans différentes phases de marche car elle affecte la comparaison entre les groupes. En outre, ce projet justifie l'importance de la méthodologie (par exemple, le traitement EMG et le calcul CaM) dans les études CaM. Plus précisément, il est fort probable que les résultats changent avec différentes approches de normalisation EMG. De plus, les enfants atteints de SCFMG I et II peuvent éprouver différents niveaux de CaM pendant la phase oscillante. Davantage de comparaisons dans des recherches futures, telles qu'entre les SCFMG I, II et III dans la PC hémiplégique et diplégique pendant les sous-phases de la marche (le contact initial, le « mid-stance »), peuvent fournir de meilleures informations sur les modèles de CaM dans cette population.Cerebral palsy (CP) is a nonprogressive disorder caused by a brain injury. CP occurs early in life, before, during, or after birth, and has heterogeneous involvement and functional impairment. In individuals with CP, changes in neural drive and muscles lead to lifelong changes in motor function, leading to movement deficits. One of the reasons for atypical gait patterns in children with CP is altered muscle activation patterns. An abnormal level of simultaneous activation of agonist and antagonist muscles crossing the same joint prevents optimal gait performance in children with CP. This phenomenon is known as muscle co-contraction (MCo) or muscle co-activation (MCa) across studies. Identification of the most deteriorated muscular patterns, namely, MCo/MCa, in children with CP is vital for effective gait rehabilitation. The objective of this master’s project, therefore, was to distinguish MCo/MCa in children with CP from their typically developing (TD) peers during gait. This objective was achieved through two studies; first, we described MCo/MCa in individuals with CP via the conduction of a scoping review; then, we applied our findings to inform a cross-sectional study to compare MCo/MCa during gait between children with CP and TD. A scoping review following the 6-stage Joanna Briggs Institute methodology was conducted. Databases were searched using relevant keywords. All published studies on MCo/MCa in individuals with CP during gait were collected. After title and abstract relevance screening, a second screening for the full texts of the sources by two reviewers was applied. Finally, data were extracted from the included articles (n=21). Then, leading methods used to quantify MCa identified from the previous study were coded in Matlab (The Mathworks Inc., Natick, USA) and applied to our data from 12 children with CP and 23 TD children. We compared the average MCa of two thigh and shank muscle groups Rectus Femoris (RF)/Semitendinosus (ST) and Tibialis Anterior (TA)/Lateral gastrocnemius (LG), respectively, via unpaired t-tests (or its non-parametric equivalent). According to our scoping review, higher MCa in individuals with CP compared to healthy peers across studies was found. Although there were inconsistent terminology and methodological approaches, we could discriminate terminologies (i.e., MCo and MCa) according to the methodologies in the calculation (i.e., moment and EMG) used by studies. Also, this study enabled us to summarize MCa patterns within individuals with CP and identify the effect of the some of the gait parameters on MCa. Finally, the findings of this study revealed valuable information regarding the research gaps in this area. The second study identified increased MCa around the knee and ankle joints for the following muscles (i.e., RF/ST and TA/LG, respectively) during walking (i.e., entire stride, stance, and swing) in children with CP compared to their TD peers. This increase was seen only in shank muscles (i.e., during stance and swing) and in thigh muscles (i.e., during the swing) when we normalized electromyography (EMG) signals. CP and TD groups did not have different MCa using normalized EMG for the entire stride. This difference highlights the effect of EMG normalization on MCa values. Also, children with Gross Motor Function Classification System (GMFCS) level II had higher MCa around the knee during swing than those with level I. Overall, this master’s project reveals new evidence supporting greater MCa in children with CP compared to TD peers during walking. Nevertheless, it is recommended to investigate MCa within different gait phases as it affects the comparison across groups. Also, this project justifies the importance of methodology (e.g., EMG processing and MCa calculation) in MCa studies. More specifically, it is likely that the results alter with different EMG normalization approaches. Moreover, children with GMFCS I and II can experience various levels of MCa during the swing phase. More comparisons in future research, such as between GMFCS I, II, and III in hemiplegic and diplegic CP during gait sub-phases (i.e., initial stance, mid-stance), can provide better information regarding MCa patterns in this population

A Review of EMG Techniques for Detection of Gait Disorders

Electromyography (EMG) is a commonly used technique to record myoelectric signals, i.e., motor neuron signals that originate from the central nervous system (CNS) and synergistically activate groups of muscles resulting in movement. EMG patterns underlying movement, recorded using surface or needle electrodes, can be used to detect movement and gait abnormalities. In this review article, we examine EMG signal processing techniques that have been applied for diagnosing gait disorders. These techniques span from traditional statistical tests to complex machine learning algorithms. We particularly emphasize those techniques are promising for clinical applications. This study is pertinent to both medical and engineering research communities and is potentially helpful in advancing diagnostics and designing rehabilitation devices

Development of a biological signal-based evaluator for robot-assisted upper-limb rehabilitation: a pilot study

Bio-signal based assessment for upper-limb functions is an attractive technology for rehabilitation. In this work, an upper-limb function evaluator is developed based on biological signals, which could be used for selecting different robotic training protocols. Interaction force (IF) and participation level (PL, processed surface electromyography (sEMG) signals) are used as the key bio-signal inputs for the evaluator. Accordingly, a robot-based standardized performance testing (SPT) is developed to measure these key bio-signal data. Moreover, fuzzy logic is used to regulate biological signals, and a rules-based selector is then developed to select different training protocols. To the authors’ knowledge, studies focused on biological signal-based evaluator for selecting robotic training protocols, especially for robot-based bilateral rehabilitation, has not yet been reported in literature. The implementation of SPT and fuzzy logic to measure and process key bio-signal data with a rehabilitation robot system is the first of its kind. Five healthy participants were then recruited to test the performance of the SPT, fuzzy logic and evaluator in three different conditions (tasks). The results show: (1) the developed SPT has an ability to measure precise bio-signal data from participants; (2) the utilized fuzzy logic has an ability to process the measured data with the accuracy of 86.7% and 100% for the IF and PL respectively; and (3) the proposed evaluator has an ability to distinguish the intensity of biological signals and thus to select different robotic training protocols. The results from the proposed evaluator, and biological signals measured from healthy people could also be used to standardize the criteria to assess the results of stroke patients later

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