Efetividade da estimulação transcraniana por corrente contínua nos ajustes posturais sob perturbação externa em pacientes com doença de Parkinson
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2022-03-21
Autores
Beretta, Victor Spiandor [UNESP]
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Universidade Estadual Paulista (Unesp)
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Introdução: pacientes com doença de Parkinson (DP) apresentam alterações nas respostas posturais e na habituação à perturbação externa devido aos déficits no funcionamento das vias córtico-basais. Apesar da estimulação transcraniana por corrente contínua (ETCC) modular o funcionamento das vias córtico-basais, ainda não está claro seus benefícios nas respostas posturais em pacientes com DP. Objetivos: analisar a efetividade de diferentes intensidades de uma sessão da ETCC nos ajustes posturais durante a habituação às perturbações externas (Estudo 1), e analisar a efetividade de oito sessões de ETCC nas respostas posturais em pacientes com DP (Estudo 2). Metodologia: vinte e quatro pacientes com DP participaram do Estudo 1 (crossover) e 20 do Estudo 2 (ensaio clínico com dois braços paralelos). Os 20 pacientes completaram o estudo e foram distribuídos randomicamente em dois grupos: 10 no grupo da ETCC ativa (a-ETCC) e 10 no grupo sham (s-ETCC). No Estudo 1, a ETCC anódica foi aplicada sobre o córtex motor primário (M1) com intensidades de 1mA, 2mA e sham em três dias diferentes (~2 semanas de intervalo) durante 20 minutos antes da avaliação do controle postural. Perturbação externa (7 tentativas) foi realizada pelo deslocamento posterior da base de suporte. No Estudo 2 foram realizadas oito sessões de ETCC durante três semanas. A partir dos resultados do Estudo 1, a intensidade de 2 mA foi utilizada no Estudo 2. As características das estimulações ativa e sham e as avaliações do controle postural foram semelhantes ao Estudo 1. No Estudo 2, a avaliação foi realizada nos momentos pré, após oito sessões e um mês após o término da intervenção. Os mesmos parâmetros eletromiográficos, do centro de pressão e da atividade do córtex pré-frontal (PFC) nos ajustes posturais preditivos e reativos foram analisados em ambos os estudos. ANOVA two-way com fator para condição de estimulação (1mA x 2mA x sham) e tentativa (1x2x3x4x5x6x7), com medidas repetidas foram realizadas no Estudo 1. No Estudo 2, foram realizadas ANOVAs two-way com o fator para grupo (a-ETCC x s-ETCC) e momento (pré x pós x Follow-up), com medidas repetidas para o último fator. Resultados: habituação à perturbação foi evidenciada independente da condição de estimulação. Pacientes com DP apresentaram menor latência dos músculos gastrocnêmio na condição de 2 mA e bíceps femoral em 1 mA, e menor tempo de reecuperação em ambas as condições em relação à sham. Nos ajustes reativos, a atividade do PFC no hemisfério não-estimulado foi menor na condição de 2 mA quando comparada a sham. No Estudo 2 foi evidenciado diminuição no tempo em posição instável nos momentos pós e Follow-up em relação ao pré para o grupo a-ETCC e menor atividade do PFC no hemisfério estimulado no momento pós quando comparado aos momentos pré e Follow-up. Conclusão: ETCC no M1, principalmente com 2 mA, alterou positivamente as respostas posturais de pacientes com DP. Porém, não foi capaz de promover a habituação à perturbação em menos tentativas. Oito sessões de ETCC parece melhorar o equilíbrio dos pacientes com DP após e um mês após o termino das sessões.
Background: Patients with Parkinson's disease (PD) demonstrate impairments in postural responses and habituation to external perturbation due to deficits in the functioning of the corticobasal pathways. Although transcranial direct current stimulation (tDCS) modulates the functioning of the corticobasal pathways, it is still unclear whether tDCS can benefit postural responses in patients with PD. Aims: To analyze the effectiveness of different intensities of a single session of tDCS on postural adjustments during habituation to external perturbation (Study 1), and to analyze the effectiveness of eight sessions of tDCS on postural responses in patients with PD (Study 2). Methods: Twenty-four patients with PD participated in Study 1 (crossover) and 20 in Study 2 (clinical trial with two parallel arms). Twenty patients completed the study and were randomly assigned into two groups: 10 in the active tDCS group (a-tDCS) and 10 in the sham group (s-tDCS). In Study 1, anodal tDCS was applied over the primary motor cortex (M1) with intensities of 1mA, 2mA, and sham on three different days (~2 weeks apart) for 20 minutes before assessing postural control. External perturbation (7 trials) was performed by posterior displacement of the support base. In Study 2, eight tDCS sessions were performed over three weeks. From the results of Study 1, the intensity of 2 mA was used in Study 2. Characteristics of active and sham stimulations and the postural control assessments were similar to Study 1. In Study 2, the assessment was performed at the pre, after eight sessions, and one month after the end of the tDCS sessions. The same parameters of electromyographic, center of pressure, and prefrontal cortex (PFC) activity in predictive and reactive postural adjustments were analyzed in both studies. Two-way ANOVA with stimulation condition (1mA x 2mA x sham) and trial (1x2x3x4x5x6x7) factors, with repeated measures, were performed in Study 1. In Study 2, two-way ANOVAs were performed with group (a- tDCS x s-tDCS) and moment (pre x post x follow-up) factors, with repeated measures for the moment. Results: habituation to the perturbation was evidenced regardless of the stimulation condition. Patients with PD had lower latency of the medial gastrocnemius at 2 mA and biceps femoris muscles at 1 mA, and shorter time in an unstable position in both conditions compared to sham. In the reactive adjustments, PFC activity in the non-stimulated hemisphere was lower in the 2 mA condition when compared to sham. In Study 2, a decrease in time in unstable position was observed at the post and follow-up moments in relation to the pre for the a-tDCS group and lower PFC activity in the stimulated hemisphere at the post than pre and follow-up moments. Conclusion: tDCS in M1, mainly with 2 mA, improved the postural responses of patients with PD. However, tDCS was not able to promote habituation to the perturbation in fewer trials. Eight sessions of tDCS seem to improve the balance of patients with PD after and one month after the end of the sessions.
Background: Patients with Parkinson's disease (PD) demonstrate impairments in postural responses and habituation to external perturbation due to deficits in the functioning of the corticobasal pathways. Although transcranial direct current stimulation (tDCS) modulates the functioning of the corticobasal pathways, it is still unclear whether tDCS can benefit postural responses in patients with PD. Aims: To analyze the effectiveness of different intensities of a single session of tDCS on postural adjustments during habituation to external perturbation (Study 1), and to analyze the effectiveness of eight sessions of tDCS on postural responses in patients with PD (Study 2). Methods: Twenty-four patients with PD participated in Study 1 (crossover) and 20 in Study 2 (clinical trial with two parallel arms). Twenty patients completed the study and were randomly assigned into two groups: 10 in the active tDCS group (a-tDCS) and 10 in the sham group (s-tDCS). In Study 1, anodal tDCS was applied over the primary motor cortex (M1) with intensities of 1mA, 2mA, and sham on three different days (~2 weeks apart) for 20 minutes before assessing postural control. External perturbation (7 trials) was performed by posterior displacement of the support base. In Study 2, eight tDCS sessions were performed over three weeks. From the results of Study 1, the intensity of 2 mA was used in Study 2. Characteristics of active and sham stimulations and the postural control assessments were similar to Study 1. In Study 2, the assessment was performed at the pre, after eight sessions, and one month after the end of the tDCS sessions. The same parameters of electromyographic, center of pressure, and prefrontal cortex (PFC) activity in predictive and reactive postural adjustments were analyzed in both studies. Two-way ANOVA with stimulation condition (1mA x 2mA x sham) and trial (1x2x3x4x5x6x7) factors, with repeated measures, were performed in Study 1. In Study 2, two-way ANOVAs were performed with group (a- tDCS x s-tDCS) and moment (pre x post x follow-up) factors, with repeated measures for the moment. Results: habituation to the perturbation was evidenced regardless of the stimulation condition. Patients with PD had lower latency of the medial gastrocnemius at 2 mA and biceps femoris muscles at 1 mA, and shorter time in an unstable position in both conditions compared to sham. In the reactive adjustments, PFC activity in the non-stimulated hemisphere was lower in the 2 mA condition when compared to sham. In Study 2, a decrease in time in unstable position was observed at the post and follow-up moments in relation to the pre for the a-tDCS group and lower PFC activity in the stimulated hemisphere at the post than pre and follow-up moments. Conclusion: tDCS in M1, mainly with 2 mA, improved the postural responses of patients with PD. However, tDCS was not able to promote habituation to the perturbation in fewer trials. Eight sessions of tDCS seem to improve the balance of patients with PD after and one month after the end of the sessions.
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Palavras-chave
Equilíbrio postural, Doença de Parkinson, Estimulação cerebral, Distúrbio do movimento, Reabilitação, Neurodegenerative disease, Movement disorders, Postural control, Support-base translation, Eletric stimulation