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Jenkins HA, Greene N, Tollin DJ. Round Window Stimulation of the Cochlea. Front Neurol 2022; 12:777010. [PMID: 34970211 PMCID: PMC8712317 DOI: 10.3389/fneur.2021.777010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 11/11/2021] [Indexed: 11/14/2022] Open
Abstract
Mixed hearing loss associated with a sensorineural component and an impaired conductive mechanism for sound from the external ear canal to the cochlea represents a challenge for rehabilitation using either surgery or traditional hearing amplification. Direct stimulations of the ossicular chain and the round window (RW) membrane have allowed an improved hearing in this population. The authors review the developments in basic and clinical research that have allowed the exploration of new routes for inner ear stimulation. Similar changes occur in the electrophysiological measures in response to auditory stimulation through the traditional route and direct mechanical stimulation of the RW. The latter has proven to be very effective as a means of hearing rehabilitation in a group of patients with significant difficulties with hearing and communication.
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Affiliation(s)
- Herman A Jenkins
- Department of Otolaryngology-Head and Neck Surgery, University of Colorado School of Medicine, Aurora, CO, United States
| | - Nathaniel Greene
- Department of Otolaryngology-Head and Neck Surgery, University of Colorado School of Medicine, Aurora, CO, United States
| | - Daniel J Tollin
- Department of Otolaryngology-Head and Neck Surgery, University of Colorado School of Medicine, Aurora, CO, United States.,Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, United States
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2
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Stimulation efficiency of an actuator driven piston at the biological interface to the inner ear. Sci Rep 2021; 11:23734. [PMID: 34887508 PMCID: PMC8660844 DOI: 10.1038/s41598-021-03195-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 11/22/2021] [Indexed: 12/02/2022] Open
Abstract
Direct acoustic cochlear stimulation uses piston motion to substitute for stapes footplate (SFP) motion. The ratio of piston to stapes footplate motion amplitude, to generate the same loudness percept, is an indicator of stimulation efficiency. We determined the relationship between piston displacement to perceived loudness, the achieved maximum power output and investigated stapes fixation and obliteration as confounding factors. The electro-mechanical transfer function of the actuator was determined preoperatively on the bench and intraoperatively by laser Doppler vibrometry. Clinically, perceived loudness as a function of actuator input voltage was calculated from bone conduction thresholds and direct thresholds via the implant. The displacement of a 0.4 mm diameter piston required for a perception equivalent to 94 dB SPL at the tympanic membrane compared to normal SFP piston displacement was 27.6–35.9 dB larger, consistent with the hypothesis that the ratio between areas is responsible for stimulation efficiency. Actuator output was 110 ± 10 eq dB SPLFF @1Vrms ≤ 3 kHz and decreased to 100 eq dB SPLFF at 10 kHz. Output was significantly higher for mobile SFPs but independent from obliteration. Our findings from clinical data strongly support the assumption of a geometrical dependency on piston diameter at the biological interface to the cochlea.
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Banakis Hartl RM, Jenkins HA. Implantable Hearing Aids: Where are we in 2020? Laryngoscope Investig Otolaryngol 2020; 5:1184-1191. [PMID: 33364411 PMCID: PMC7752069 DOI: 10.1002/lio2.495] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 09/29/2020] [Accepted: 10/29/2020] [Indexed: 12/04/2022] Open
Abstract
Beginning in the late 20th century, implantable hearing aids were developed and used as an alternative for individuals who were unable to tolerate conventional hearing aids. Since that time, several devices have been developed, with four currently remaining on the international market (Med-el Vibrant Soundbridge, Envoy Esteem, Ototronix MAXUM, and Cochlear Carina). This review will briefly examine the history of middle ear implant development, describe current available devices, evaluate the benefits and limits of the technology, and consider the future directions of research in the field of implantable hearing aids.
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Affiliation(s)
| | - Herman A. Jenkins
- Department of OtolaryngologyUniversity of Colorado School of MedicineAuroraColoradoUSA
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Raufer S, Gamm UA, Grossöhmichen M, Lenarz T, Maier H. Middle Ear Actuator Performance Determined From Intracochlear Pressure Measurements in a Single Cochlear Scala. Otol Neurotol 2020; 42:e86-e93. [PMID: 33044336 DOI: 10.1097/mao.0000000000002836] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
HYPOTHESIS Intracochlear pressure measurements in one cochlear scala are sufficient as reference to determine the output of an active middle ear implant (AMEI) in terms of "equivalent sound pressure level" (eqSPL). BACKGROUND The performance of AMEIs is commonly calculated from stapes velocities or intracochlear pressure differences (PDiff). However, there are scenarios where measuring stapes velocities or PDiff may not be feasible, for example when access to the stapes or one of the scalae is impractical. METHODS We reanalyzed data from a previous study of our group that investigated the performance of an AMEI coupled to the incus in 10 human temporal bones. We calculated eqSPL based on stapes velocities according to the ASTM standard F2504-05 and based on intracochlear pressures in scala vestibuli, scala tympani, and PDiff. RESULTS The AMEI produced eqSPL of ∼100 to 120 dB at 1 Vrms. No significant differences were found between using intracochlear pressures in scala vestibuli, scala tympani, or PDiff as a reference. The actuator performance calculated from stapes displacements predicted slightly higher eqSPLs at frequencies above 1000 Hz, but these differences were not statistically significant. CONCLUSION Our findings show that pressure measurements in one scala can be sufficient to evaluate the performance of an AMEI coupled to the incus. The method may be extended to other stimulation modalities of the middle ear or cochlea when access to the stapes or one of the scalae is not possible.
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Affiliation(s)
- Stefan Raufer
- Department of Otolaryngology and Institute of Audioneurotechnology (VIANNA), Hannover Medical School, Hannover.,DFG Cluster of Excellence, Hearing4all
| | - Ute A Gamm
- Cochlear Deutschland GmbH & Co. KG, Hannover, Germany
| | - Martin Grossöhmichen
- Department of Otolaryngology and Institute of Audioneurotechnology (VIANNA), Hannover Medical School, Hannover.,DFG Cluster of Excellence, Hearing4all
| | - Thomas Lenarz
- Department of Otolaryngology and Institute of Audioneurotechnology (VIANNA), Hannover Medical School, Hannover.,DFG Cluster of Excellence, Hearing4all
| | - Hannes Maier
- Department of Otolaryngology and Institute of Audioneurotechnology (VIANNA), Hannover Medical School, Hannover.,DFG Cluster of Excellence, Hearing4all
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Abstract
The advances in technology leading to rapid developments in implantable auditory devices are constantly evolving. Devices are becoming smaller, less visible, and more efficient. The ability to preserve hearing outcomes with cochlear implantation will continue to evolve as surgical techniques improve with the use of continuous feedback during the procedure as well as with intraoperative delivery of drugs and robot assistance. As engineering methods improve, there may one day be a totally implantable aid that is self-sustaining in hearing-impaired patients making them indistinguishable from patients without hearing loss.
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Affiliation(s)
- Robert M Rhodes
- The Department of Otolaryngology Head and Neck Surgery, The University of Oklahoma Health Sciences Center, 800 Stanton L Young Boulevard, Suite 1400, Oklahoma City, OK 73104, USA
| | - Betty S Tsai Do
- The Department of Otolaryngology Head and Neck Surgery, The University of Oklahoma Health Sciences Center, 800 Stanton L Young Boulevard, Suite 1400, Oklahoma City, OK 73104, USA.
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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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Stieger C, Alnufaily YH, Candreia C, Caversaccio MD, Arnold AM. In situ Probe Microphone Measurement for Testing the Direct Acoustical Cochlear Stimulator. Front Neurosci 2017; 11:450. [PMID: 28860963 PMCID: PMC5559539 DOI: 10.3389/fnins.2017.00450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Accepted: 07/24/2017] [Indexed: 11/24/2022] Open
Abstract
Hypothesis: Acoustical measurements can be used for functional control of a direct acoustic cochlear stimulator (DACS). Background: The DACS is a recently released active hearing implant that works on the principle of a conventional piston prosthesis driven by the rod of an electromagnetic actuator. An inherent part of the DACS actuator is a thin titanium diaphragm that allows for movement of the stimulation rod while hermetically sealing the housing. In addition to mechanical stimulation, the actuator emits sound into the mastoid cavity because of the motion of the diaphragm. Methods: We investigated the use of the sound emission of a DACS for intra-operative testing. We measured sound emission in the external auditory canal (PEAC) and velocity of the actuators stimulation rod (Vact) in five implanted ears of whole-head specimens. We tested the influence various positions of the loudspeaker and a probe microphone on PEAC and simulated implant malfunction in one example. Results: Sound emission of the DACS with a signal-to-noise ratio >10 dB was observed between 0.5 and 5 kHz. Simulated implant misplacement or malfunction could be detected by the absence or shift in the characteristic resonance frequency of the actuator. PEAC changed by <6 dB for variations of the microphone and loudspeaker position. Conclusion: Our data support the feasibility of acoustical measurements for in situ testing of the DACS implant in the mastoid cavity as well as for post-operative monitoring of actuator function.
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Affiliation(s)
- Christof Stieger
- ARTORG Center, Artificial Hearing Research, University of BernBern, Switzerland.,University Department of ENT, Head and Neck Surgery, Inselspital, University Hospital of BernBern, Switzerland.,Department of ENT, University Hospital BaselBasel, Switzerland
| | - Yasser H Alnufaily
- University Department of ENT, Head and Neck Surgery, Inselspital, University Hospital of BernBern, Switzerland
| | - Claudia Candreia
- ARTORG Center, Artificial Hearing Research, University of BernBern, Switzerland.,University Department of ENT, Head and Neck Surgery, Inselspital, University Hospital of BernBern, Switzerland
| | - Marco D Caversaccio
- ARTORG Center, Artificial Hearing Research, University of BernBern, Switzerland.,University Department of ENT, Head and Neck Surgery, Inselspital, University Hospital of BernBern, Switzerland
| | - Andreas M Arnold
- ARTORG Center, Artificial Hearing Research, University of BernBern, Switzerland.,University Department of ENT, Head and Neck Surgery, Inselspital, University Hospital of BernBern, Switzerland
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Direct Acoustic Stimulation at the Lateral Canal: An Alternative Route to the Inner Ear? PLoS One 2016; 11:e0160819. [PMID: 27500399 PMCID: PMC4976884 DOI: 10.1371/journal.pone.0160819] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 07/26/2016] [Indexed: 11/19/2022] Open
Abstract
Severe to profound mixed hearing loss is associated with hearing rehabilitation difficulties. Recently, promising results for speech understanding were obtained with a direct acoustic cochlear implant (DACI). The surgical implantation of a DACI with standard coupling through a stapedotomy can however be regarded as challenging. Therefore, in this experimental study, the feasibility of direct acoustic stimulation was investigated at an anatomically and surgically more accessible inner ear site. DACI stimulation of the intact, blue-lined and opened lateral semicircular canal (LC) was investigated and compared with standard oval window (OW) coupling. Additionally, stapes footplate fixation was induced. Round window (RW) velocity, as a measure of the performance of the device and its coupling efficiency, was determined in fresh-frozen human cadaver heads. Using single point laser Doppler vibrometry, RW velocity could reliably be measured in low and middle frequency range, and equivalent sound pressure level (LE) output was calculated. Results for the different conditions obtained in five heads were analyzed in subsequent frequency ranges. Comparing the difference in RW membrane velocity showed higher LE in the LC opened condition [mean: 103 equivalent dB SPL], than in LC intact or blue-lined conditions [63 and 74 equivalent dB SPL, respectively]. No difference was observed between the LC opened and the standard OW condition. Inducing stapes fixation, however, led to a difference in the low frequency range of LE compared to LC opened. In conclusion, this feasibility study showed promising results for direct acoustic stimulation at this specific anatomically and surgically more accessible inner ear site. Future studies are needed to address the impact of LC stimulation on cochlear micromechanics and on the vestibular system like dizziness and risks of hearing loss.
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Grossöhmichen M, Salcher R, Kreipe HH, Lenarz T, Maier H. The Codacs™ direct acoustic cochlear implant actuator: exploring alternative stimulation sites and their stimulation efficiency. PLoS One 2015; 10:e0119601. [PMID: 25785860 PMCID: PMC4364953 DOI: 10.1371/journal.pone.0119601] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 01/14/2015] [Indexed: 11/19/2022] Open
Abstract
This work assesses the efficiency of the Codacs system actuator (Cochlear Ltd., Sydney Australia) in different inner ear stimulation modalities. Originally the actuator was intended for direct perilymph stimulation after stapedotomy using a piston prosthesis. A possible alternative application is the stimulation of middle ear structures or the round window (RW). Here the perilymph stimulation with a K-piston through a stapes footplate (SFP) fenestration (N = 10) as well as stimulation of the stapes head (SH) with a Bell prosthesis (N = 9), SFP stimulation with an Omega/Aerial prosthesis (N = 8) and reverse RW stimulation (N = 10) were performed in cadaveric human temporal bones (TBs). Codacs actuator output is expressed as equivalent sound pressure level (eq. SPL) using RW and SFP displacement responses, measured by Laser Doppler velocimetry as reference. The axial actuator coupling force in stimulation of stapes and RW was adjusted to ~ 5 mN. The Bell prosthesis and Omega/Aerial prosthesis stimulation generated similar mean eq. SPLs (Bell: 127.5–141.8 eq. dB SPL; Omega/Aerial: 123.6–143.9 eq. dB SPL), being significantly more efficient than K-piston perilymph stimulation (108.6–131.6 eq. dB SPL) and RW stimulation (108.3–128.2 eq. dB SPL). Our results demonstrate that SH, SFP and RW are adequate alternative stimulation sites for the Codacs actuator using coupling prostheses and an axial coupling force of ~ 5 mN. Based on the eq. SPLs, all investigated methods were adequate for in vivo hearing aid applications, provided that experimental conditions including constant coupling force will be implemented.
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Affiliation(s)
- Martin Grossöhmichen
- Department of Otolaryngology and Institute of Audioneurotechnology (VIANNA), Hannover Medical School, Hannover, Germany
| | - Rolf Salcher
- Department of Otolaryngology and Institute of Audioneurotechnology (VIANNA), Hannover Medical School, Hannover, Germany
| | | | - Thomas Lenarz
- Department of Otolaryngology and Institute of Audioneurotechnology (VIANNA), Hannover Medical School, Hannover, Germany
| | - Hannes Maier
- Department of Otolaryngology and Institute of Audioneurotechnology (VIANNA), Hannover Medical School, Hannover, Germany
- * E-mail:
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Clamp PJ, Briggs RJS. The Cochlear Baha 4 Attract System – design concepts, surgical technique and early clinical results. Expert Rev Med Devices 2014; 12:223-30. [DOI: 10.1586/17434440.2015.990375] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
Implantable hearing aids are gaining importance for the treatment of sensorineural hearing loss and also for mixed hearing loss. The various hearing aid systems, combined with different middle ear situations, give rise to a wide range of different reconstructions. This article attempts to summarize the current knowledge concerning the mechanical interaction between active middle ear implants (AMEIs) and the normal or reconstructed middle ear. Some basic characteristics of the different AMEIs are provided in conjunction with the middle ear mechanics. The interaction of AMEIs and middle ear and the influence of various boundary conditions are discussed in more detail.
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