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Numerical analysis of intracochlear mechanical auditory stimulation using piezoelectric bending actuators. Med Biol Eng Comput 2017; 56:733-747. [PMID: 28900873 DOI: 10.1007/s11517-017-1720-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 08/28/2017] [Indexed: 10/18/2022]
Abstract
Cochlear implantation can restore a certain degree of auditory impression of patients suffering from profound hearing loss or deafness. Furthermore, studies have shown that in case of residual hearing, patients benefit from the use of a hearing aid in addition to the cochlear implant. The presented studies aim at the improvement of this electromechanical stimulation (EMS) approach by substituting the external hearing aid by an internal stimulus provided by miniaturized piezoelectric actuators. Finite element analyses are performed in order to derive fundamental guidelines for the actuator layout aiming at maximal mechanical stimuli. Further analyses aim at investigating how the actuator position inside the cochlea influences the basilar membrane oscillation profile. While actuator layout guidelines leading to maximized acoustic stimuli could be derived, some of these guidelines are of complementary nature suggesting that further studies under realistic boundary conditions must be performed. Actuator positioning inside the cochlea is shown to have a significant influence on the resulting auditory impression of the patient. Based on the results, the main differences of external and internal stimulation of the cochlea mechanism are identified. It is shown that if the cochlea tonotopy is considered, the frequency selectivity resulting from the mechanical cochlea stimulus may be improved.
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Luo C, Omelchenko I, Manson R, Robbins C, Oesterle EC, Cao GZ, Shen I, Hume CR. Direct Intracochlear Acoustic Stimulation Using a PZT Microactuator. Trends Hear 2015; 19:2331216515616942. [PMID: 26631107 PMCID: PMC4771031 DOI: 10.1177/2331216515616942] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Combined electric and acoustic stimulation has proven to be an effective strategy to improve hearing in some cochlear implant users. We describe an acoustic microactuator to directly deliver stimuli to the perilymph in the scala tympani. The 800 µm by 800 µm actuator has a silicon diaphragm driven by a piezoelectric thin film (e.g., lead-zirconium-titanium oxide or PZT). This device could also be used as a component of a bimodal acoustic-electric electrode array. In the current study, we established a guinea pig model to test the actuator for its ability to deliver auditory signals to the cochlea in vivo. The actuator was placed through the round window of the cochlea. Auditory brainstem response (ABR) thresholds, peak latencies, and amplitude growth were calculated for an ear canal speaker versus the intracochlear actuator for tone burst stimuli at 4, 8, 16, and 24 kHz. An ABR was obtained after removal of the probe to assess loss of hearing related to the procedure. In some animals, the temporal bone was harvested for histologic analysis of cochlear damage. We show that the device is capable of stimulating ABRs in vivo with latencies and growth functions comparable to stimulation in the ear canal. Further experiments will be necessary to evaluate the efficiency and safety of this modality in long-term auditory stimulation and its ability to be integrated with conventional cochlear implant arrays.
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Affiliation(s)
- Chuan Luo
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
- Department of Precision Instruments, Tsinghua University, Beijing, China
| | - Irina Omelchenko
- Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology–Head and Neck Surgery, University of Washington, Seattle, WA, USA
| | - Robert Manson
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | - Carol Robbins
- Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology–Head and Neck Surgery, University of Washington, Seattle, WA, USA
| | - Elizabeth C. Oesterle
- Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology–Head and Neck Surgery, University of Washington, Seattle, WA, USA
| | - Guo Zhong Cao
- Department of Materials Science, University of Washington, Seattle, WA, USA
| | - I.Y. Shen
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | - Clifford R. Hume
- Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology–Head and Neck Surgery, University of Washington, Seattle, WA, USA
- VA Puget Sound, Seattle, WA, USA
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The spread of adenoviral vectors to central nervous system through pathway of cochlea in mimetic aging and young rats. Gene Ther 2015; 22:866-75. [PMID: 26125607 DOI: 10.1038/gt.2015.63] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 06/08/2015] [Accepted: 06/15/2015] [Indexed: 12/11/2022]
Abstract
There is no definitive conclusion concerning the spread of viral vectors to the brain after a cochlear inoculation. In addition, some studies have reported different distribution profiles of viral vectors in the central auditory system after a cochlear inoculation. Thus, rats were grouped into either a mimetic aging group or a young group and transfected with adenoviral vectors (AdVs) by round window membrane injection. The distribution of AdV in central nervous system (CNS) was demonstrated in the two groups with transmission electron microscopy and immunofluorescence. We found that the AdV could disseminate into the CNS and that the neuronal damage and stress-induced GRP78 expression were reduced after transfection with PGC-1α, as compared with the control vectors, especially in the mimetic aging group. We also found that the host immune response was degraded in CNS in the mimetic aging group after transduction through the cochlea, as compared with the young group. These results demonstrate that viral vectors can disseminate into the CNS through the cochlea. Moreover, mimetic aging induced by D-galactose could facilitate the spread of viral vectors into the CNS from the cochlea. These findings may indicate a new potential approach for gene therapy against age-related diseases in the CNS.
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