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Neural Plasticity
Volume 2016, Article ID 3034963, 11 pages
http://dx.doi.org/10.1155/2016/3034963
Research Article

Is the Frequency in Somatosensory Electrical Stimulation the Key Parameter in Modulating the Corticospinal Excitability of Healthy Volunteers and Stroke Patients with Spasticity?

1Laboratório de Instrumentação Biomédica, Programa de Engenharia Biomédica, COPPE, Universidade Federal do Rio de Janeiro, Avenida Horácio Macedo 2030, CT, Bloco H, Sala 327, Cidade Universitária, 21941-914 Ilha do Fundão, RJ, Brazil
2Laboratório de Neurobiologia II, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Avenida Carlos Chagas Filho 373, CCS, Bloco G, Sala G1-019, Cidade Universitária, 21941-902 Ilha do Fundão, RJ, Brazil
3Departamento de Biociências da Atividade Física, Escola de Educação Física e Desportos, Universidade Federal do Rio de Janeiro, Avenida Carlos Chagas Filho 540, Cidade Universitária, 21941-599 Ilha do Fundão, RJ, Brazil
4Departamento de Fisioterapia, Faculdade de Medicina, Universidade Federal do Rio de Janeiro, Avenida Carlos Chagas Filho 373, CCS, Bloco K, Sala K2-49, Cidade Universitária, 21941-902 Ilha do Fundão, RJ, Brazil
5Instituto de Comunicação e Informação Científica e Tecnológica em Saúde (ICICT), Fundação Oswaldo Cruz (FIOCRUZ), Avenida Brasil 4365, 21040-900 Manguinhos, RJ, Brazil

Received 9 July 2015; Accepted 23 November 2015

Academic Editor: Ela Plow

Copyright © 2016 Marco Antonio Cavalcanti Garcia et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Somatosensory electrical stimulation (SES) has been proposed as an approach to treat patients with sensory-motor impairment such as spasticity. However, there is still no consensus regarding which would be the adequate SES parameters to treat those deficits. Therefore, the aim of this study was to evaluate the effects of applying SES over the forearm muscles at four different frequencies of stimulation (3, 30, 150, and 300 Hz) and in two intervals of time (5′ and 30′) by means of transcranial magnetic stimulation and Hoffmann’s reflex (H-reflex) in healthy volunteers (Experiments  I and II). A group of stroke patients (Experiment  III) was also preliminary evaluated to ascertain SES effects at a low frequency (3 Hz) applied for 30′ over the forearm spastic flexors muscles by measuring the wrist joint passive torque. Motor evoked potentials and the H-reflex were collected from different forearm and hand muscles immediately before and after SES and up to 5′ (Experiment  I) and 10′ (Experiments  I and II) later. None of the investigated frequencies of SES was able to operate as a key in switching modulatory effects in the central nervous system of healthy volunteers and stroke patients with spasticity.