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Sorg K, Stahn P, Pillong L, Hinsberger MP, Heimann L, Foth HJ, Schick B, Wenzel GI. First biocompatibility margins for optical stimulation at the eardrum via 532-nm laser pulses in a mouse model. JOURNAL OF BIOMEDICAL OPTICS 2019; 24:1-10. [PMID: 31436071 PMCID: PMC6983485 DOI: 10.1117/1.jbo.24.8.085003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 07/29/2019] [Indexed: 06/10/2023]
Abstract
Hearing impairment affects ∼460 million people worldwide. Conservative therapies, such as hearing aids, bone conduction systems, and middle ear implants, do not always sufficiently compensate for this deficit. The optical stimulation is currently under investigation as an alternative stimulation strategy for the activation of the hearing system. To assess the biocompatibility margins of this emerging technology, we established a method applicable in whole-mount preparations of murine tympanic membranes (TM). We irradiated the TM of anesthetized mice with 532-nm laser pulses at an average power of 50, 89, 99, and 125 mW at two different locations of the TM and monitored the hearing function with auditory brainstem responses. Laser-power-dependent negative side effects to the TM were observed at power levels exceeding 89 mW. Although we did not find any significant negative effects of optical stimulation on the hearing function in these mice, based on the histology results further studies are necessary for optimization of the used parameters.
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Affiliation(s)
- Katharina Sorg
- Saarland University, Department of Otolaryngology, Faculty of Medicine, Homburg, Germany
| | - Patricia Stahn
- Saarland University, Department of Otolaryngology, Faculty of Medicine, Homburg, Germany
| | - Lukas Pillong
- Saarland University, Department of Otolaryngology, Faculty of Medicine, Homburg, Germany
| | - Marius P. Hinsberger
- Saarland University, Department of Otolaryngology, Faculty of Medicine, Homburg, Germany
| | - Larissa Heimann
- Saarland University, Department of Otolaryngology, Faculty of Medicine, Homburg, Germany
| | - Hans-Jochen Foth
- University of Kaiserslautern, Department of Physics, Kaiserslautern, Germany
| | - Bernhard Schick
- Saarland University, Department of Otolaryngology, Faculty of Medicine, Homburg, Germany
| | - Gentiana I. Wenzel
- Saarland University, Department of Otolaryngology, Faculty of Medicine, Homburg, Germany
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Stahn P, Lim HH, Hinsberger MP, Sorg K, Pillong L, Kannengießer M, Schreiter C, Foth HJ, Langenbucher A, Schick B, Wenzel GI. Frequency-specific activation of the peripheral auditory system using optoacoustic laser stimulation. Sci Rep 2019; 9:4171. [PMID: 30862850 PMCID: PMC6414650 DOI: 10.1038/s41598-019-40860-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 02/22/2019] [Indexed: 11/09/2022] Open
Abstract
Hearing impairment is one of the most common sensory deficits in humans. Hearing aids are helpful to patients but can have poor sound quality or transmission due to insufficient output or acoustic feedback, such as for high frequencies. Implantable devices partially overcome these issues but require surgery with limited locations for device attachment. Here, we investigate a new optoacoustic approach to vibrate the hearing organ with laser stimulation to improve frequency bandwidth, not requiring attachment to specific vibratory structures, and potentially reduce acoustic feedback. We developed a laser pulse modulation strategy and simulated its response at the umbo (1-10 kHz) based on a convolution-based model. We achieved frequency-specific activation in which non-contact laser stimulation of the umbo, as well as within the middle ear at the round window and otic capsule, induced precise shifts in the maximal vibratory response of the umbo and neural activation within the inferior colliculus of guinea pigs, corresponding to the targeted, modelled and then stimulated frequency. There was also no acoustic feedback detected from laser stimulation with our experimental setup. These findings open up the potential for using a convolution-based optoacoustic approach as a new type of laser hearing aid or middle ear implant.
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Affiliation(s)
- Patricia Stahn
- Saarland University, Faculty of Medicine, Department of Otolaryngology, Kirrbergerstr. 100, 66421, Homburg, Germany.
| | - Hubert H Lim
- University of Minnesota, Department of Biomedical Engineering, Department of Otolaryngology, Minnesota, USA
| | - Marius P Hinsberger
- Saarland University, Faculty of Medicine, Department of Otolaryngology, Kirrbergerstr. 100, 66421, Homburg, Germany
| | - Katharina Sorg
- Saarland University, Faculty of Medicine, Department of Otolaryngology, Kirrbergerstr. 100, 66421, Homburg, Germany
| | - Lukas Pillong
- Saarland University, Faculty of Medicine, Department of Otolaryngology, Kirrbergerstr. 100, 66421, Homburg, Germany
| | - Marc Kannengießer
- Saarland University, Faculty of Medicine, Department of Otolaryngology, Kirrbergerstr. 100, 66421, Homburg, Germany
- Saarland University, Experimental Ophthalmology, Homburg, Germany
| | - Cathleen Schreiter
- Saarland University, Faculty of Medicine, Department of Otolaryngology, Kirrbergerstr. 100, 66421, Homburg, Germany
| | - Hans-Jochen Foth
- Technische Universität Kaiserslautern, Department of Physics, Kaiserslautern, Germany
| | | | - Bernhard Schick
- Saarland University, Faculty of Medicine, Department of Otolaryngology, Kirrbergerstr. 100, 66421, Homburg, Germany
| | - Gentiana I Wenzel
- Saarland University, Faculty of Medicine, Department of Otolaryngology, Kirrbergerstr. 100, 66421, Homburg, Germany.
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Optoacoustic effect is responsible for laser-induced cochlear responses. Sci Rep 2016; 6:28141. [PMID: 27301846 PMCID: PMC4908384 DOI: 10.1038/srep28141] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 05/27/2016] [Indexed: 12/17/2022] Open
Abstract
Optical stimulation of the cochlea with laser light has been suggested as an alternative to conventional treatment of sensorineural hearing loss with cochlear implants. The underlying mechanisms are controversially discussed: The stimulation can either be based on a direct excitation of neurons, or it is a result of an optoacoustic pressure wave acting on the basilar membrane. Animal studies comparing the intra-cochlear optical stimulation of hearing and deafened guinea pigs have indicated that the stimulation requires intact hair cells. Therefore, optoacoustic stimulation seems to be the underlying mechanism. The present study investigates optoacoustic characteristics using pulsed laser stimulation for in vivo experiments on hearing guinea pigs and pressure measurements in water. As a result, in vivo as well as pressure measurements showed corresponding signal shapes. The amplitude of the signal for both measurements depended on the absorption coefficient and on the maximum of the first time-derivative of laser pulse power (velocity of heat deposition). In conclusion, the pressure measurements directly demonstrated that laser light generates acoustic waves, with amplitudes suitable for stimulating the (partially) intact cochlea. These findings corroborate optoacoustic as the basic mechanism of optical intra-cochlear stimulation.
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