Effets de la vibration des muscles sur les mécanismes neuronaux et la fonction du membre supérieur et inférieur des personnes ayant une hémiparésie chronique

Cette thèse vise à répondre à trois questions fondamentales: 1) La diminution de l’excitabilité corticospinale et le manque d’inhibition intracorticale observés suite à la stimulation magnétique transcrânienne (SMT) du cortex moteur de la main atteinte de sujets hémiparétiques sont-ils aussi présents suite à la SMT du cortex moteur de la jambe atteinte? 2) Est-ce que les altérations dans l’excitabilité corticomotrice sont corrélées aux déficits et incapacités motrices des personnes ayant subi un accident vasculaire cérébral depuis plus de 6 mois? 3) La vibration musculaire, étant la source d’une forte afférence sensorielle, peut-elle moduler l’excitabilité corticomotrice et améliorer la performance motrice de ces personnes? Premièrement, afin d’appuyer notre choix d’intervention et d’évaluer le potentiel de la vibration mécanique locale pour favoriser la réadaptation des personnes ayant une atteinte neurologique, nous avons réalisé une révision en profondeur de ses applications et intérêts cliniques à partir d’informations trouvées dans la littérature scientifique (article 1). La quantité importante d’information sur les effets physiologiques de la vibration contraste avec la pauvreté des études qui ont évalué son effet thérapeutique. Nous avons trouvé que, malgré le manque d’études, les résultats sur son utilisation sont encourageants et positifs et aucun effet adverse n’a été rapporté. Dans les trois autres articles qui composent cette thèse, l’excitabilité des circuits corticospinaux et intracorticaux a été étudiée chez 27 sujets hémiparétiques et 20 sujets sains sans atteintes neurologiques. Les fonctions sensorimotrices ont aussi été évaluées par des tests cliniques valides et fidèles. Tel qu’observé à la main chez les sujets hémiparétiques, nous avons trouvé, par rapport aux sujets sains, une diminution de l’excitabilité corticospinale ainsi qu’un manque d’inhibition intracorticale suite à la SMT du cortex moteur de la jambe atteinte (article 2). Les sujets hémiparétiques ont également montré un manque de focus de la commande motrice lors de l’activation volontaire des fléchisseurs plantaires. Ceci était caractérisé par une augmentation de l’excitabilité nerveuse des muscles agonistes, mais aussi généralisée aux synergistes et même aux antagonistes. De plus, ces altérations ont été corrélées aux déficits moteurs au membre parétique. Le but principal de cette thèse était de tester les effets potentiels de la vibration des muscles de la main (article 3) et de la cuisse (article 4) sur les mécanismes neuronaux qui contrôlent ces muscles. Nous avons trouvé que la vibration augmente l’amplitude de la réponse motrice des muscles vibrés, même chez des personnes n’ayant pas de réponse motrice au repos ou lors d’une contraction volontaire. La vibration a également diminué l’inhibition intracorticale enregistrée au quadriceps parétique (muscle vibré). La diminution n’a cependant pas été significative au niveau de la main. Finalement, lors d’un devis d’investigation croisé, la vibration de la main ou de la jambe parétique a résulté en une amélioration spécifique de la dextérité manuelle ou de la coordination de la jambe, respectivement. Au membre inférieur, la vibration du quadriceps a également diminuée la spasticité des patients. Les résultats obtenus dans cette thèse sont très prometteurs pour la rééducation de la personne hémiparétique car avec une seule séance de vibration, nous avons obtenu des améliorations neurophysiologiques et cliniques.This thesis aims to answer three basic questions: 1) Are the decrease in corticospinal excitability and the lack of intracortical inhibition observed following transcranial magnetic stimulation (TMS) of the affected hand motor cortex of stroke patients present after TMS of the affected leg motor cortex? 2) Are the alterations in corticomotor excitability correlated with motor impairments and disabilities of subjects who have suffered a stroke for over six months? 3) Can muscle vibration, as a source of strong sensory afference modulate corticomotor excitability and improve motor performance of these subjects? First of all, to support our choice of intervention and to assess the potential of local mechanical vibration to promote the recovery of persons with neurological impairment, we conducted a thorough review of its physiological effects and clinical applications in the scientific literature (article 1). The wealth of information on the physiological effects of vibration contrasts with the lack of studies that have evaluated its therapeutic effects. Nevertheless, we found that, despite the paucity of studies, the results on its clinical use are encouraging and positive and no adverse effects were reported. In the other three articles included in this thesis, the excitability of corticospinal and intracortical circuits has been studied in 27 hemiparetic patients and in 20 healthy subjects without neurological disease or injury. Sensorimotor functions were also evaluated with valid and reliable clinical tests. Similar to that observed in the hand of hemiparetic patients, we found, compared to the healthy subjects, a decrease of corticospinal excitability and a lack of intracortical inhibition following TMS of the affected leg motor cortex (Article 2). The hemiparetic patients also showed a lack of focus of the motor output during voluntary activation of plantar flexors. This was characterized by an increase in the neural excitability not only of the agonist muscles, but also of the synergists and even the antagonist muscles. The main goal of this thesis was to test the potential effects of vibrating hand (Article 3) and thigh (Article 4) muscles on the neural mechanisms that control these muscles. We found that vibration increases the amplitude of motor responses in the vibrated muscles and even produces a response in subjects with no motor response at rest or during a voluntary contraction. The vibration also decreased the intracortical inhibition recorded in the paretic quadriceps muscle (vibrated muscle). The decrease was however not significant at the hand. Finally, using a cross-over design study, the vibration of the paretic hand or leg resulted in specific improvements in hand dexterity or leg coordination, respectively. In the lower limb, quadriceps vibration also reduced the spasticity in patients. The results obtained in this thesis are very promising for stroke rehabilitation because with a single session of vibration, we obtained neurophysiological and clinical improvements

Étude pilote des effets de la vibration de la main sur l'excitabilité corticospinale et la force musculaire chez des sujets hémiparétiques chroniques

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal

Abnormal coactivation of knee and ankle extensors is related to changes in heteronymous spinal pathways after stroke

<p>Abstract</p> <p>Background</p> <p>Abnormal coactivation of leg extensors is often observed on the paretic side of stroke patients while they attempt to move. The mechanisms underlying this coactivation are not well understood. This study (1) compares the coactivation of leg extensors during static contractions in stroke and healthy individuals, and (2) assesses whether this coactivation is related to changes in intersegmental pathways between quadriceps and soleus (Sol) muscles after stroke.</p> <p>Methods</p> <p>Thirteen stroke patients and ten healthy individuals participated in the study. Levels of coactivation of knee extensors and ankle extensors were measured in sitting position, during two tasks: maximal isometric voluntary contractions in knee extension and in plantarflexion. The early facilitation and later inhibition of soleus voluntary EMG evoked by femoral nerve stimulation were assessed in the paretic leg of stroke participants and in one leg of healthy participants.</p> <p>Results</p> <p>Coactivation levels of ankle extensors (mean ± SEM: 56 ± 7% of Sol EMG max) and of knee extensors (52 ± 10% of vastus lateralis (VL) EMG max) during the knee extension and the ankle extension tasks respectively were significantly higher in the paretic leg of stroke participants than in healthy participants (26 ± 5% of Sol EMG max and 10 ± 3% of VL EMG max, respectively). Early heteronymous facilitation of Sol voluntary EMG in stroke participants (340 ± 62% of Sol unconditioned EMG) was significantly higher than in healthy participants (98 ± 34%). The later inhibition observed in all control participants was decreased in the paretic leg. Levels of coactivation of ankle extensors during the knee extension task were significantly correlated with both the increased facilitation (Pearson r = 0.59) and the reduced inhibition (r = 0.56) in the paretic leg. Measures of motor impairment were more consistently correlated with the levels of coactivation of biarticular muscles than those of monoarticular muscles.</p> <p>Conclusion</p> <p>These results suggest that the heteronymous pathways linking quadriceps to soleus may participate in the abnormal coactivation of knee and ankle extensors on the paretic side of stroke patients. The motor impairment of the paretic leg is strongly associated with the abnormal coactivation of biarticular muscles.</p

Análise da ativação neuromuscular do vasto medial oblíquo e vasto lateral com o uso da bandagem funcional

Muscular and anatomical changes are mostly responsible for patella femoral syndrome (PFPS). Knowing that the quadriceps muscles are very important to stabilize the patella, studies have questioned the influence of the Vastus Medialis Oblique (VMO) in the patellar stabilization avoiding the PFPS. Many researchers have investigated the use of taping as a means of muscle activation. Objective: The present study aimed to analyze the use of functional taping to activate the VMO during the squat exercise. Method: The activity of the VMO and Vastus Lateralis (VL) was assessed by electromyography during squats and squats with adduction using functional taping. The sample composed for 39 individuals was divided into four groups: sedentary males and athletes, and females also divided into sedentary and athletes. Results: Although it has been found greater activation of VMO in comparison with the VL, with the applied methodology and variables, we could not demonstrate a statistical difference between groups in squats with and without the use of functional taping. However, it is important to emphasize that the lack of difference in the activation of VMO during squats with adduction and tapping suggest a positive effect of the tapping in muscle activation. This result is very important in the treatment of acute injuries where active movement is limited. Conclusion: Future studies should be done with other electromyography parameters and reflex activation in order to investigate the actual role of functional taping on muscle activation.Alterações musculares e anatômicas são em sua maioria responsáveis pela síndrome patelofemoral (SDPF). Sabendo que a musculatura do quadríceps é de grande importância na estabilização da patela, questiona-se como o músculo Vasto Medial Oblíquo (VMO) influencia na estabilização patelar evitando a SDPF. Muitos pesquisadores tem investigado o uso da bandagem funcional como meio de ativação muscular. Objetivo: O presente estudo teve como objetivo analisar o uso da bandagem como meio de ativação do VMO no exercício de agachamento. Método: A atividade dos músculos VMO e Vasto lateral (VL) foi avaliada através de eletromiografia durante o agachamento com adução e o agachamento com o uso de bandagem. A amostra composta por 39 indivíduos foi dividida em quatro grupos: indivíduos do sexo masculino sedentários e atletas, e indivíduos do sexo feminino sedentárias e atletas. Resultados: Embora tenha sido encontrada uma maior ativação do VMO em relação ao VL, com a presente metodologia e variáveis estudadas, não foi possível demonstrar diferença estatística entre os grupos nos agachamentos com e sem o uso da bandagem. No entanto, é importante ressaltar que a ausência de diferença na ativação do VMO durante o agachamento com adução e com bandagem sugerem um efeito positivo e facilitador da bandagem na ativação muscular. Este resultado é muito importante no tratamento de lesões agudas onde o movimento ativo está limitado. Conclusão: Sugere-se a execução de novos estudos aonde outros parâmetros da eletromiografia e estimulação reflexa sejam abordados, a fim de investigar o real papel da bandagem funcional na ativação muscular

Transmission in Heteronymous Spinal Pathways Is Modified after Stroke and Related to Motor Incoordination

Changes in reflex spinal pathways after stroke have been shown to affect motor activity in agonist and antagonist muscles acting at the same joint. However, only a few studies have evaluated the heteronymous reflex pathways modulating motoneuronal activity at different joints. This study investigates whether there are changes in the spinal facilitatory and inhibitory pathways linking knee to ankle extensors and if such changes may be related to motor deficits after stroke. The early facilitation and later inhibition of soleus H reflex evoked by the stimulation of femoral nerve at 2 times the motor threshold of the quadriceps were assessed in 15 healthy participants and on the paretic and the non-paretic sides of 15 stroke participants. The relationships between this reflex modulation and the levels of motor recovery, coordination and spasticity were then studied. Results show a significant (Mann-Whitney U; P<0.05) increase in both the peak amplitude (mean±SEM: 80±22% enhancement of the control H reflex) and duration (4.2±0.5 ms) of the facilitation on the paretic side of the stroke individuals compared to their non-paretic side (36±6% and 2.9±0.4 ms) and to the values of the control subjects (33±4% and 2.8±0.4 ms, respectively). Moreover, the later strong inhibition observed in all control subjects was decreased in the stroke subjects. Both the peak amplitude and the duration of the increased facilitation were inversely correlated (Spearman r = −0.65; P = 0.009 and r = −0.67; P = 0.007, respectively) with the level of coordination (LEMOCOT) of the paretic leg. Duration of this facilitation was also correlated (r = −0.58, P = 0.024) with the level of motor recovery (CMSA). These results confirm changes in transmission in heteronymous spinal pathways that are related to motor deficits after stroke

Tradução e adaptação cultural à língua portuguesa do American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) para avaliação da função do ombro Translation and cultural adaptation to the portuguese language of the American Shoulder and Elbow Surgeons Standardized Shoulder assessment form (ASES) for evaluation of shoulder function

Dores na região do ombro estão presentes em grande parte da população. Um instrumento de medida utilizado para avaliar a função do ombro, independente da enfermidade ou do distúrbio, é o American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES). No entanto, até o presente estudo, o ASES não contava com uma versão em português. O objetivo deste trabalho é realizar a tradução e a adaptação cultural do ASES à língua portuguesa.A versão original do ASES passou pelo processo específico de tradução e adaptação cultural, constituído pelas etapas de tradução inicial, retrotradução, comitê, pré-teste e aprovação do autor da versão original. O pré-teste foi aplicado em vinte pacientes com distúrbios variados na articulação do ombro (9 mulheres; 41,1 ± 13,0 anos de idade; 11,2 ± 8,9 meses de acometimento; 12,5 ± 3,1 anos de escolaridade). A versão definitiva do ASES em português foi estabelecida após os pacientes julgarem todos os seus itens compreensíveis e claros, e o autor do questionário original considerar a versão adequada. O resultado deste trabalho auxiliará os profissionais de reabilitação e os pesquisadores brasileiros, que passam a contar com mais um instrumento de medida a ser aplicado em pacientes com alterações funcionais no ombro.<br>Shoulder pain affects a significant percentage of the population. The American Shoulder and Elbow Surgeons Standardized Shoulder assessment form (ASES) is an outcome tool used to assess shoulder function, regardless of the disorder. However, at the moment the current study was undertaken, a Portuguese version of the ASES was not available. The objective of this work was to translate and make a cultural validation of the ASES to the Portuguese language. The original version of the ASES underwent the specific process of translation and cultural adaptation, comprising of the initial translation, back translation, committee, pre-test and the approval by the original author. The pre-test was applied in 20 patients with shoulder disorders (9 women, 41.1 ± 13.0 years of age, 11.2 ± 8.9 months with the disorder, and 12.5 ± 3.1 schooling years). The final Portuguese version of the ASES was established after patients considered all items of this tool comprehensible and clear, and the author of the original questionnaire considered it adequate. The results obtained with this study will help Brazilian rehabilitation professionals and researchers, since they have one more outcome measure to be applied in patients with functional disabilities of the shoulder

Mean time course of soleus H reflex modulation in 15 hemiparetic and 15 healthy participants Mean modulations are expressed in % of the control H reflex and plotted against the different interstimulus intervals (ms) between femoral nerve stimulation and posterior tibial nerve stimulation.

<p>Vertical bars = 1 SEM. Asterisks represent significant difference in modulation between the paretic side or non-paretic side of stroke participants and the tested side of control participants (* p≤0.05; ** p≤0.01; *** p≤0.001). Crosses represent significant difference between the paretic and non-paretic sides of stroke participants († p≤0.05).</p