Simultaneous bilateral laser therapy accelerates recovery after noise-induced hearing loss in a rat model

Abstract

Noise-induced hearing loss is a common type of hearing loss. The effects of laser therapy have been investigated from various perspectives, including in wound healing, inflammation reduction, and nerve regeneration, as well as in hearing research. A promising feature of the laser is its capability to penetrate soft tissue; depending on the wavelength, laser energy can penetrate into the deepest part of the body without damaging non-target soft tissues. Based on this idea, we developed bilateral transtympanic laser therapy, which uses simultaneous laser irradiation in both ears, and evaluated the effects of bilateral laser therapy on cochlear damage caused by noise overexposure. Thus, the purpose of this research was to assess the benefits of simultaneous bilateral laser therapy compared with unilateral laser therapy and a control. Eighteen Sprague-Dawley rats were exposed to narrow-band noise at 115 dB SPL for 6 h. Multiple auditory brainstem responses were measured after each laser irradiation, and cochlear hair cells were counted after the 15th such irradiation. The penetration depth of the 808 nm laser was also measured after sacrifice. Approximately 5% of the laser energy reached the contralateral cochlea. Both bilateral and unilateral laser therapy decreased the hearing threshold after noise overstimulation in the rat model. The bilateral laser therapy group showed faster functional recovery at all tested frequencies compared with the unilateral laser therapy group. However, there was no difference in the endpoint ABR results or final hair cell survival, which was analyzed histologically.

Treatment of peripheral vestibular dysfunction using photobiomodulation

“…The inner ear comprises the cochlea (hearing organ) and the vestibular organ (balancing organ), which are located adjacent to one another and form a fluid-filled cavity with a bony wall. Several recent studies have shown promising effects from photobiomodulation of the cochlea; [8][9][10][11][12][13] however, the effect of photobiomodulation on the vestibular organ is not well understood.…”

“…The irradiation was performed as previously described. [8][9][10][11][12] Only the left ear was irradiated in groups H and L, and groups G and C did not receive photobiomodulation (PBM). PBM parameters were determined considering the penetration rate and the safety of the peripheral sensory organ.…”

“…Group C was untreated, and group H received gentamicin plus laser treatment in the left ear only.Journal of Biomedical Optics088001-2 August 2017 • Vol. 22(8)…”

“…Diamonds represent baseline, rectangles represent 3 days of laser treatment, and triangles represents 7 days of laser treatment.Journal of Biomedical Optics088001-4 August 2017 • Vol. 22(8)…”

O uso do laser de baixa intensidade em indivíduos com zumbido e sem perda auditiva

“…Segundo Gomes e Schapochnik(2017), o laser de baixa intensidade traz muitos benefícios, dentre eles, menciona-se a ação antiinflamatória, cicatrizante, antiedematoso e analgésica que tem apresentado prognóstico altamente satisfatório ao paciente.Além de ser usada como um tratamento para vários sintomas, o uso da TLBI tem aumentado devido à sua natureza não-invasiva, pois esta não tem potencial de produzir efeitos perniciosos nos tecidos ou no sistema biológico, se for realizada com dose correta, por profissional especializado. Assim, ela tem se tornado um recurso de primeira escolha em diversas áreas da saúde, por ser uma facilitadora no processo de reabilitação do paciente e facilmente administrada em ambientes de atenção primária(PENG et al, 2012;LEE et al, 2016a;GOMES;SCHAPOCHNIK, 2017).É importante ressaltar que para que o laser seja considerado de baixa intensidade, o equipamento deve possuir uma potência abaixo de 500mW. Dessa forma, pode-se utilizá-lo como um recurso terapêutico modelador de processos biológicos por bioestimulação ou bioinibição, dependendo da forma que ele será aplicado (GOMES; SCHAPOCHNIK, 2017).…”