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CC BY-NC-ND 4.0 · Arq Neuropsiquiatr 2016; 74(03): 223-227
DOI: 10.1590/0004-282X20160018
ARTICLE

Activation of C-fiber nociceptors by low-power diode laser

Ativação por laser de diodo de baixa potência de nociceptores relacionados a fibras C
Eduardo Azevedo
1   Universidade Federal de São Paulo, Departamento de Psicobiologia, Sao Paulo SP, Brazil;
,
Andressa Silva
1   Universidade Federal de São Paulo, Departamento de Psicobiologia, Sao Paulo SP, Brazil;
,
Raquel Martins
1   Universidade Federal de São Paulo, Departamento de Psicobiologia, Sao Paulo SP, Brazil;
,
Monica L. Andersen
1   Universidade Federal de São Paulo, Departamento de Psicobiologia, Sao Paulo SP, Brazil;
,
Sergio Tufik
1   Universidade Federal de São Paulo, Departamento de Psicobiologia, Sao Paulo SP, Brazil;
,
Gilberto M. Manzano
2   Universidade Federal de São Paulo, Setor de Neurofisiologia Clínica, Sao Paulo SP, Brazil.
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ABSTRACT

Objective The evaluation of selective activation of C-fibers to record evoked potentials using the association of low-power diode laser (810 nm), tiny-area stimulation and skin-blackening.

Method Laser-evoked potentials (LEPs) were obtained from 20 healthy young subjects. An aluminum plate with one thin hole was attached to the laser probe to provide tiny-area stimulation of the hand dorsum and the stimulated area was covered with black ink.

Results The mean intensity used for eliciting the ultra-late laser-evoked potential (ULEP) was 70 ± 32 mW. All subjects showed a clear biphasic potential that comprised a negative peak (806 ± 61 ms) and a positive deflection (1033 ± 60 ms), corresponding to the ULEP related to C-fiber activation.

Conclusion C-fiber-evoked responses can be obtained using a very low-power diode laser when stimulation is applied to tiny areas of darkened skin. This strategy offers a non-invasive and easy methodology that minimizes damage to the tissue.

RESUMO

Objetivo Avaliação da ativação de fibras C para o registro de potenciais evocados utilizando-se laser de baixa potência, áreas pequenas de estimulação e escurecimento da pele.

Método Potenciais evocados foram obtidos de 20 sujeitos. Uma placa de alumínio com uma pequena abertura foi acoplada à ponteira do laser para estimular área escurecida do dorso da mão.

Resultados A intensidade média utilizada para estimulação foi de 70 ± 32 mW. Todos os sujeitos apresentaram respostas claras compreendendo dois picos um negativo (806 ± 61 ms) seguido por outro positivo (1033 ± 60 ms), correspondendo ao potencial evocado tardio por estimulação de fibras C.

Conclusão Respostas de fibras C podem ser obtidas utilizando-se laser de baixa potência quando a estimulação é aplicada a pequenas áreas de pele escurecida. Esta estratégia oferece uma metodologia não invasiva que minimiza danos teciduais.

laser-evoked potentials - C-fibers - nociception - pain perception
potenciais evocados a laser - fibras C - nocicepção - percepção dolorosa


Publication History

Received: 05 October 2015

Accepted: 28 October 2015

Article published online:
06 September 2023

© 2023. Academia Brasileira de Neurologia. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commecial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/)

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