Low-level laser therapy for spinal cord injury in rats: effects of polarization

Abstract

Abstract. The effects of laser polarization on the efficacy of near-infrared low-level laser therapy for spinal cord injury (SCI) are presented. Rat spinal cords were injured with a weight-drop device, and the lesion sites were directly irradiated with a linearly polarized 808-nm diode laser positioned either perpendicular or parallel to the spine immediately after the injury and daily for five consecutive days. Functional recovery was assessed daily by an open-field test. Regardless of the polarization direction, functional scores of SCI rats that were treated with the 808-nm laser irradiation were significantly higher than those of SCI alone group (Group 1) from day 5 after injury. The locomotive function of SCI rats irradiated parallel to the spinal column (Group 3) was significantly improved from day 10 after injury, compared to SCI rats treated with the linear polarization perpendicular to the spinal column (Group 2). There were no significant differences in ATP contents in the injured tissue among the three groups. We speculate that the higher efficacy with parallel irradiation is attributable to the deeper light penetration into tissue with anisotropic scattering. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

The influence of low-level laser irradiation on spinal cord injuries following ischemia- reperfusion in rats

“…It is known that functional recovery after I-R is highly correlated with the volume of remaining normal nerve fibers in spinal tissue 37 . Adno et al 11 , demonstrated transcutaneous application of 810-nm nonpolarized laser significantly promoted axonal regrowth, our results are in agreement with that and show association of improved neurologic status.…”

“…LLLT has been clinically applied to treatment of rheumatoid arthritis, periodontal disease, pain management and healing of wounds and burns [11][12][13] . Many studies approved that LLLT has the potential to be an effective noninvasive therapy for spinal cord injury 14,15 .…”

Low intensity laser therapy on regeneration of nervous tissue after spinal cord injury

“…Um estudo analisou os efeitos da orientação de polarização do laser na eficácia da irradiação no infravermelho próximo em ratos com LM, que foram divididos em 3 grupos: grupo 1 controle ratos lesionados, porém não irradiados; grupo 2 lesionados e irradiados com polarização perpendicular e grupo 3 lesionados e irradiados com polarização paralela 13 . Os ratos passaram por laminectomia de T10, a LM foi promovida seguindo a metodologia de um estudo anterior 15 .…”

“…A possibilidade de irradiação direta na medula espinal lesionada já foi considerada durante a cirurgia de descompressão medular e discectomia endoscópica, sendo que a entrega do laser seria por meio de uma fibra óp-tica com um filtro de polarização em sua extremidade 13 . Um estudo defende o uso não invasivo da laserterapia e suporta a ideia da utilização desta forma de aplicação em humanos 15 .…”

“…A terapia a laser de baixa intensidade (TLBI) tem sido utilizada para o tratamento de várias doenças neurológicas como acidente vascular encefálico, doenças neurodegenerativas, lesão cerebral e também nas lesões do sistema nervoso periférico [8][9][10][11][12] . A TLBI consiste em uma abordagem promissora também no tratamento da LM 7,13 , porém uma pesquisa abrangente da literatura científica mostrou escassez de estudos sobre o assunto, portanto ainda existem questões a serem elucidadas.…”