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Geerardyn A, Wils I, Putzeys T, Fierens G, Wouters J, Verhaert N. The impact of round window reinforcement on middle and inner ear mechanics with air and bone conduction stimulation. Hear Res 2024; 450:109049. [PMID: 38850830 DOI: 10.1016/j.heares.2024.109049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 05/24/2024] [Accepted: 05/28/2024] [Indexed: 06/10/2024]
Abstract
The round window (RW) membrane plays an important role in normal inner ear mechanics. Occlusion or reinforcement of the RW has been described in the context of congenital anomalies or after cochlear implantation and is applied as a surgical treatment for hyperacusis. Multiple lumped and finite element models predict a low-frequency hearing loss with air conduction of up to 20 dB after RW reinforcement and limited to no effect on hearing with bone conduction stimulation. Experimental verification of these results, however, remains limited. Here, we present an experimental study measuring the impact of RW reinforcement on the middle and inner ear mechanics with air and bone conduction stimulation. In a within-specimen repeated measures design with human cadaveric specimens (n = 6), we compared the intracochlear pressures in scala vestibuli (PSV) and scala tympani (PST) before and after RW reinforcement with soft tissue, cartilage, and bone cement. The differential pressure (PDIFF) across the basilar membrane - known to be closely related to the hearing sensation - was calculated as the complex difference between PSV and PST. With air conduction stimulation, both PSV and PSTincreased on average up to 22 dB at frequencies below 1500 Hz with larger effect sizes for PST compared to PSV. The PDIFF, in contrast, decreased up to 11 dB at frequencies between 700 and 800 Hz after reinforcement with bone cement. With bone conduction, the average within-specimen effects were less than 5 dB for either PSV, PST, or PDIFF. The inter-specimen variability with bone conduction, however, was considerably larger than with air conduction. This experimental study shows that RW reinforcement impacts air conduction stimulation at low frequencies. Bone conduction stimulation seems to be largely unaffected. From a clinical point of view, these results support the hypothesis that delayed loss of air conduction hearing after cochlear implantation could be partially explained by the impact of RW reinforcement.
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Affiliation(s)
- Alexander Geerardyn
- ExpORL, Department of Neurosciences, KU Leuven, Leuven, Belgium; Department of Otorhinolaryngology-Head and Neck Surgery, University Hospitals Leuven, Leuven Belgium
| | - Irina Wils
- ExpORL, Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Tristan Putzeys
- ExpORL, Department of Neurosciences, KU Leuven, Leuven, Belgium; Laboratory of Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Leuven, Belgium
| | - Guy Fierens
- ExpORL, Department of Neurosciences, KU Leuven, Leuven, Belgium; Cochlear Technology Centre, Mechelen, Belgium
| | - Jan Wouters
- ExpORL, Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Nicolas Verhaert
- ExpORL, Department of Neurosciences, KU Leuven, Leuven, Belgium; Department of Otorhinolaryngology-Head and Neck Surgery, University Hospitals Leuven, Leuven Belgium.
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Mittmann P, Ernst A, Seidl R, Lauer G, Gölz L, Mutze S, Windgassen M, Buschmann C. Implications of intracochlear decomposition gas formation in non-putrefied cadavers. Front Surg 2024; 11:1365535. [PMID: 38948482 PMCID: PMC11211390 DOI: 10.3389/fsurg.2024.1365535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 05/23/2024] [Indexed: 07/02/2024] Open
Abstract
Introduction Postmortem computed tomography (pmCT) prior to forensic autopsy has become increasingly important in recent decades, especially in forensic documentation of single injuries, injury patterns, and causes of death. Postmortem decomposition gas formation can also be detected in pmCT scans, which might affect cochlear implant research in postmortem human temporal bones (TBs). Material and methods Fifty non-putrefied hanging fatalities within a 2-year period (January 2017 to December 2019) were included with 100 TBs. Each body underwent whole-body pmCT prior to forensic autopsy. PmCT scans were analyzed with respect to the presence of intracochlear gas despite the lack of putrefaction at autopsy by an experienced fellow neurotologist. Results PmCT revealed gas formation in two individuals despite the lack of head trauma and putrefaction at postmortem examination and autopsy. Both individuals showed enclosed gas in the vestibule and the cochlea on both sides. Discussion Intracochlear gas formation, most likely related to decomposition, may occur despite the lack of putrefaction at postmortem examination and autopsy and can be detected by pmCT. This finding seems to be rather rare in non-traumatic death cases but might affect cochlear pressure research in postmortem human TB.
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Affiliation(s)
| | - Arne Ernst
- Department of ENT, Unfallkrankenhaus Berlin, Berlin, Germany
| | - Rainer Seidl
- Department of ENT, Unfallkrankenhaus Berlin, Berlin, Germany
| | - Gina Lauer
- Department of ENT, Unfallkrankenhaus Berlin, Berlin, Germany
| | - Leonie Gölz
- Department of Radiology and Neuroradiology, Unfallkrankenhaus Berlin, Berlin, Germany
| | - Sven Mutze
- Department of Radiology and Neuroradiology, Unfallkrankenhaus Berlin, Berlin, Germany
| | - Marc Windgassen
- Institute of Legal Medicine and Forensic Sciences, Charité University Medicine Berlin, Berlin, Germany
| | - Claas Buschmann
- Institute of Legal Medicine and Forensic Sciences, University of Kiel, Kiel, Germany
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Wils I, Geerardyn A, Putzeys T, Denis K, Verhaert N. Lumped element models of sound conduction in the human ear: A systematic review. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2023; 154:1696-1709. [PMID: 37712750 DOI: 10.1121/10.0020841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 08/16/2023] [Indexed: 09/16/2023]
Abstract
Lumped element models facilitate investigating the fundamental mechanisms of human ear sound conduction. This systematic review aims to guide researchers to the optimal model for the investigated parameters. For this purpose, the literature was reviewed up to 12 July 2023, according to the PRISMA guidelines. Seven models are included via database searching, and another 19 via cross-referencing. The quality of the models is assessed by comparing the predicted middle ear transfer function, the tympanic membrane impedance, the energy reflectance, and the intracochlear pressures (ICPs) (scala vestibuli, scala tympani, and differential) with experimental data. Regarding air conduction (AC), the models characterize the pathway from the outer to the inner ear and accurately predict all six aforementioned parameters. This contrasts with the few existing bone conduction (BC) models that simulate only a part of the ear. In addition, these models excel at predicting one observable parameter, namely, ICP. Thus, a model that simulates BC from the coupling site to the inner ear is still lacking and would increase insights into the human ear sound conduction. Last, this review provides insights and recommendations to determine the appropriate model for AC and BC implants, which is highly relevant for future clinical applications.
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Affiliation(s)
- Irina Wils
- Department of Neurosciences, KU Leuven, B-3000 Leuven, Belgium
| | | | - Tristan Putzeys
- Department of Neurosciences, KU Leuven, B-3000 Leuven, Belgium
| | - Kathleen Denis
- Department of Mechanical Engineering, KU Leuven, B-3000 Leuven, Belgium
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Felix TR, Waldmann B, Prenzler NK, Salcher RB, Timm ME, Lenarz T, Maier H. Estimating vibration artifacts in preclinical experimental assessment of actuator efficiency in bone-conduction hearing devices. Hear Res 2023; 433:108765. [PMID: 37094529 DOI: 10.1016/j.heares.2023.108765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 03/26/2023] [Accepted: 04/05/2023] [Indexed: 04/26/2023]
Abstract
OBJECTIVES Test feasibility of a means to distinguish artifact from relevant signal in an experimental method for pre-clinical assessment of bone conduction (BC) stimulation efficiency based on measurement of intracochlear pressure (ICP). METHODS Experiments were performed on fresh-frozen human temporal bones and cadaver heads. In a first step, fiber optic pressure sensors inserted into the cochlea through cochleostomies were intentionally vibrated to generate relative motion versus the stationary specimen, and the resulting ICP artifact recorded, before and after attaching the sensor fiber to the bone with glue. In a second step, BC stimulation was applied in the conventional location for a commercial bone anchored implant, as well as two alternative locations closer to the otic capsule. Again, ICP was recorded and compared with an estimated artifact, calculated from the previous measurements with intentional vibration of the fiber. RESULTS Intentional vibration of the sensor fiber creates relative motion between fiber and bone, as intended, and causes an ICP signal. The stimulus does not create substantial promontory vibration, indicating that the measured ICP is all artifact, i.e. would not occur if the sensor were not in place. Fixating the sensor fiber to the bone with glue reduces the ICP artifact by at least 20 dB. BC stimulation also creates relative motion between sensor fiber and bone, as expected, from which an estimated ICP artifact level can be calculated. The ICP signal measured during BC stimulation is well above the estimated artifact, at least in some specimens and at some frequencies, indicating "real" cochlear stimulation, which would result in an auditory percept in a live subject. Stimulation at the alternative locations closer to the otic capsule appear to result in higher ICP (no statistical analysis performed), indicating a trend towards more efficient stimulation than at the conventional location. CONCLUSIONS Intentional vibration of the fiber optic sensor for measurement of ICP can be used to derive an estimate of the artifact to be expected when measuring ICP during BC stimulation, and to characterize the effectiveness of glues or other means of reducing the artifact caused by relative motion of fiber and bone.
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Affiliation(s)
- Tiago Rocha Felix
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany; Cochlear Deutschland GmbH & Co KG, Germany
| | | | - Nils Kristian Prenzler
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany; Cluster of Excellence "Hearing4all", Hannover, Germany
| | - Rolf Benedikt Salcher
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany; Cluster of Excellence "Hearing4all", Hannover, Germany
| | - Max Eike Timm
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany; Cluster of Excellence "Hearing4all", Hannover, Germany
| | - Thomas Lenarz
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany; Cluster of Excellence "Hearing4all", Hannover, Germany
| | - Hannes Maier
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany; Cluster of Excellence "Hearing4all", Hannover, Germany.
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Mejzlik J, Chrobok V, Homolac M, Valenta T, Svejdova A, Cerny M, Striteska M, Krtickova J, Skoloudik L. The Relationship between Bone Conduction Hearing Threshold Shifts after Surgery for Chronic Otitis Media with Cholesteatoma According to STAM, EAONO/JOS, and SAMEO-ATO Classifications. J Clin Med 2022; 11:jcm11154481. [PMID: 35956098 PMCID: PMC9369348 DOI: 10.3390/jcm11154481] [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: 05/29/2022] [Revised: 07/26/2022] [Accepted: 07/30/2022] [Indexed: 11/26/2022] Open
Abstract
Background: This study focuses on the hearing threshold for bone conduction (BC) after middle-ear surgery. Methods: A total of 92 patients (120 ears) were treated for newly diagnosed chronic otitis media with cholesteatoma (2013−2018). BC was examined at frequencies of 0.5, 1, 2, and 4 kHz prior to and 1 year after surgery. STAM classification for cholesteatoma location, EAONO/JOS for stage, and surgery according to SAMEO-ATO classification were applied. The bone conduction threshold was compared for individual frequencies in patients with occurrence/absence of cholesteatoma in different locations. Results: For the occurrence of cholesteatoma in the attic (A), a statistically significant difference was found at 4 kHz (p < 0.001), in the supratubal recess (S1) at 4 kHz (p = 0.003), and for the mastoid (M) at 0.5 kHz (p = 0.024), at 1 kHz (p = 0.032), and at 2 kHz (p = 0.039). Conclusions: Cholesteatoma location can influence the post-operative hearing threshold for bone conduction.
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Affiliation(s)
- Jan Mejzlik
- Department of Otorhinolaryngology and Head and Neck Surgery, University Hospital Hradec Kralove, 500 05 Hradec Kralove, Czech Republic; (V.C.); (M.H.); (T.V.); (M.C.); (M.S.); (J.K.); (L.S.)
- Faculty of Medicine in Hradec Kralove, Charles University, 500 03 Hradec Kralove, Czech Republic
- Correspondence: (J.M.); (A.S.)
| | - Viktor Chrobok
- Department of Otorhinolaryngology and Head and Neck Surgery, University Hospital Hradec Kralove, 500 05 Hradec Kralove, Czech Republic; (V.C.); (M.H.); (T.V.); (M.C.); (M.S.); (J.K.); (L.S.)
- Faculty of Medicine in Hradec Kralove, Charles University, 500 03 Hradec Kralove, Czech Republic
| | - Michal Homolac
- Department of Otorhinolaryngology and Head and Neck Surgery, University Hospital Hradec Kralove, 500 05 Hradec Kralove, Czech Republic; (V.C.); (M.H.); (T.V.); (M.C.); (M.S.); (J.K.); (L.S.)
- Faculty of Medicine in Hradec Kralove, Charles University, 500 03 Hradec Kralove, Czech Republic
| | - Tomas Valenta
- Department of Otorhinolaryngology and Head and Neck Surgery, University Hospital Hradec Kralove, 500 05 Hradec Kralove, Czech Republic; (V.C.); (M.H.); (T.V.); (M.C.); (M.S.); (J.K.); (L.S.)
- Faculty of Medicine in Hradec Kralove, Charles University, 500 03 Hradec Kralove, Czech Republic
| | - Anna Svejdova
- Department of Otorhinolaryngology and Head and Neck Surgery, University Hospital Hradec Kralove, 500 05 Hradec Kralove, Czech Republic; (V.C.); (M.H.); (T.V.); (M.C.); (M.S.); (J.K.); (L.S.)
- Faculty of Medicine in Hradec Kralove, Charles University, 500 03 Hradec Kralove, Czech Republic
- Correspondence: (J.M.); (A.S.)
| | - Michal Cerny
- Department of Otorhinolaryngology and Head and Neck Surgery, University Hospital Hradec Kralove, 500 05 Hradec Kralove, Czech Republic; (V.C.); (M.H.); (T.V.); (M.C.); (M.S.); (J.K.); (L.S.)
- Faculty of Medicine in Hradec Kralove, Charles University, 500 03 Hradec Kralove, Czech Republic
| | - Maja Striteska
- Department of Otorhinolaryngology and Head and Neck Surgery, University Hospital Hradec Kralove, 500 05 Hradec Kralove, Czech Republic; (V.C.); (M.H.); (T.V.); (M.C.); (M.S.); (J.K.); (L.S.)
- Faculty of Medicine in Hradec Kralove, Charles University, 500 03 Hradec Kralove, Czech Republic
| | - Jana Krtickova
- Department of Otorhinolaryngology and Head and Neck Surgery, University Hospital Hradec Kralove, 500 05 Hradec Kralove, Czech Republic; (V.C.); (M.H.); (T.V.); (M.C.); (M.S.); (J.K.); (L.S.)
- Faculty of Medicine in Hradec Kralove, Charles University, 500 03 Hradec Kralove, Czech Republic
| | - Lukas Skoloudik
- Department of Otorhinolaryngology and Head and Neck Surgery, University Hospital Hradec Kralove, 500 05 Hradec Kralove, Czech Republic; (V.C.); (M.H.); (T.V.); (M.C.); (M.S.); (J.K.); (L.S.)
- Faculty of Medicine in Hradec Kralove, Charles University, 500 03 Hradec Kralove, Czech Republic
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