title: 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.
authors.affiliation: College of Medicine, Dankook University, Beckman Laser Institute Korea , Cheonan , South Korea.
authors.forename: Jae-Hun
authors.initials: JH
authors.lastname: Lee
authors.affiliation: College of Medicine, Dankook University, Beckman Laser Institute Korea , Cheonan , South Korea.
authors.forename: So-Young
authors.initials: SY
authors.lastname: Chang
authors.affiliation: Beckman Laser Institute and Medical Clinic, University of California , Irvine , CA , United States.
authors.forename: Wesley J
authors.initials: WJ
authors.lastname: Moy
authors.affiliation: Beckman Laser Institute and Medical Clinic, University of California , Irvine , CA , United States.
authors.forename: Connie
authors.initials: C
authors.lastname: Oh
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Jeju National University School of Medicine , Jeju , South Korea.
authors.forename: Se-Hyung
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, College of Medicine, Dankook University , Cheonan , South Korea.
authors.forename: Chung-Ku
authors.initials: CK
authors.lastname: Rhee
authors.affiliation: Department of Biomedical Science, College of Medicine, Dankook University , Cheonan , South Korea.
authors.forename: Jin-Chul
authors.initials: JC
authors.lastname: Ahn
authors.affiliation: College of Medicine, Dankook University, Beckman Laser Institute Korea, Cheonan, South Korea; Department of Otolaryngology-Head & Neck Surgery, College of Medicine, Dankook University, Cheonan, South Korea.
authors.forename: Phil-Sang
authors.initials: PS
authors.lastname: Chung
authors.affiliation: College of Medicine, Dankook University, Beckman Laser Institute Korea, Cheonan, South Korea; Department of Otolaryngology-Head & Neck Surgery, College of Medicine, Dankook University, Cheonan, South Korea.
authors.forename: Jae Yun
authors.initials: JY
authors.lastname: Jung
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, College of Medicine, Dankook University , Cheonan , South Korea.
authors.forename: Min Young
authors.initials: MY
authors.lastname: Lee
keywords: ABR; Bilateral LLLT; Hair cell survival; Noise induced hearing loss