Publicação
Lesão da via corticoespinhal e variabilidade no recrutamento de unidades motoras
| Resumo: | The immense repertoire of movements that the human being is able to perform originates from the activity of several hundreds of skeletal muscles, which are under the control of the central nervous system. After processing the information regarding the spatial position of the body and the external environment, the motor centers of the brain and spinal cord produce the volitional commands responsible for the desired movements. This electrical neurotransference is done by the motor units. Through recent electromyographic techniques, the study of the control of motor functioning by the nervous system, through the analysis of the action potentials of the motor units, becomes relatively simple. The force exerted by a muscle during a voluntary contraction is the result of the recruitment of motor units and the modulation of the frequency of its recruitment, which are altered in clinical situations associated with corticospinal tract damage. It is speculated that patients with amyotrophic lateral sclerosis (ALS) have a long preclinical phase before clinical manifestation; however, the current methods for detecting corticospinal tract involvement are complex and costly. The objective of this study was to evaluate the usefulness of a new method developed in our laboratory, which allows the analysis of the motor unit recruitment variability, in order to detect signs of corticospinal tract dysfunction. The study population consisted of 4 groups: healthy controls (30), patients with spinal cord injury (13), patients with primary lateral sclerosis (23) and patients suffering from amyotrophic lateral sclerosis (66). ALS group patients was split in patients with (32) and without upper motor neuron signs in lower limbs (34). The study of the recruitment of motor units was carried out using concentric needle electromyography in the tibialis anterior muscle, and advanced analysis of the motor unit recruitment through the calculation of Mean Consecutive Difference of consecutive pairs. It was found that in patients with lower limb spasticity, the first recruited motor units generally had lower recruitment frequencies when compared to healthy subjects; in addition, in these patients the frequencies of the second recruited motor units were closer to the frequencies of the first motor units compared to healthy individuals. Although this observation is in agreement with the literature, the proposed method represents an original approach to investigate this topic. However, this novel technique does not present the necessary sensitivity to be applied in the clinical practice for diagnosis, unless further refinements are developed. |
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| Autores principais: | Poliakov, Artiom Viatcheslavovitch, 1993- |
| Assunto: | Esclerose Lateral Amiotrófica (ELA) Esclerose lateral primária Frequência de recrutamento Lesão medular Recrutamento de unidades motoras Teses de mestrado - 2018 |
| Ano: | 2018 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | português |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | The immense repertoire of movements that the human being is able to perform originates from the activity of several hundreds of skeletal muscles, which are under the control of the central nervous system. After processing the information regarding the spatial position of the body and the external environment, the motor centers of the brain and spinal cord produce the volitional commands responsible for the desired movements. This electrical neurotransference is done by the motor units. Through recent electromyographic techniques, the study of the control of motor functioning by the nervous system, through the analysis of the action potentials of the motor units, becomes relatively simple. The force exerted by a muscle during a voluntary contraction is the result of the recruitment of motor units and the modulation of the frequency of its recruitment, which are altered in clinical situations associated with corticospinal tract damage. It is speculated that patients with amyotrophic lateral sclerosis (ALS) have a long preclinical phase before clinical manifestation; however, the current methods for detecting corticospinal tract involvement are complex and costly. The objective of this study was to evaluate the usefulness of a new method developed in our laboratory, which allows the analysis of the motor unit recruitment variability, in order to detect signs of corticospinal tract dysfunction. The study population consisted of 4 groups: healthy controls (30), patients with spinal cord injury (13), patients with primary lateral sclerosis (23) and patients suffering from amyotrophic lateral sclerosis (66). ALS group patients was split in patients with (32) and without upper motor neuron signs in lower limbs (34). The study of the recruitment of motor units was carried out using concentric needle electromyography in the tibialis anterior muscle, and advanced analysis of the motor unit recruitment through the calculation of Mean Consecutive Difference of consecutive pairs. It was found that in patients with lower limb spasticity, the first recruited motor units generally had lower recruitment frequencies when compared to healthy subjects; in addition, in these patients the frequencies of the second recruited motor units were closer to the frequencies of the first motor units compared to healthy individuals. Although this observation is in agreement with the literature, the proposed method represents an original approach to investigate this topic. However, this novel technique does not present the necessary sensitivity to be applied in the clinical practice for diagnosis, unless further refinements are developed. |
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