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1.
Front Cell Neurosci ; 16: 836093, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35480960

RESUMO

Background: Endolymphatic hydrops (EH) is considered as the pathological correlate of Menière's disease (MD) and cause of hearing loss. The mechanism of EH, remaining unrevealed, poses challenges for formalized clinical trials. Objective: This study aims to investigate the development of hearing loss, as well as the effect of dehydration treatment on EH animal models. Methods: In this study, different severity EH animal models were created. The laser Doppler vibrometer (LDV) and auditory brainstem responses (ABR) were used to study the effects of EH and the dehydration effects of mannitol. The LDV was used to measure the vibration of the round window membrane (RWM) reflecting the changes in inner ear impedance. ABR was used to evaluate the hearing changes. Furthermore, tissue section and scanning electron microscopy (SEM) observations were used to analyze the anatomical change to the cochlea and outer hair cells. Results: The RWM vibrations decreased with the severity of EH, indicating an increase in the cochlear impedance. The dehydration therapy lowered the impedance to restore acoustic transduction in EH 10- and 20-day animal models. Simultaneously, the ABR thresholds increased in EH models and were restored after dehydration. Moreover, a difference in the hearing was found between ABR and LDV results in severe EH animal models, and the dehydration therapy was less effective, indicating a sensorineural hearing loss (SNHL). Conclusion: Endolymphatic hydrops causes hearing loss by increasing the cochlear impedance in all tested groups, and mannitol dehydration is an effective therapy to restore hearing. However, SNHL occurs for the EH 30-day animal models, limiting the effectiveness of dehydration. Our results suggest the use of dehydrating agents in the early stage of EH.

2.
J Otol ; 17(1): 39-45, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35140757

RESUMO

OBJECTIVES: To quantify the progression of otosclerosis in the unoperated ear between two stapedotomy procedures for patients with bilateral otosclerosis which can help to determine whether a HRCT scan should be re-performed before the second surgery for patients who already received HRCT imaging before the initial surgery. METHODS: 35 patients who underwent bilateral stapedotomy were included. Two rounds of HRCT examination and audiometry were performed at the time of the first surgery and second surgery on the ear that was not operated on during the initial surgery. The relationship between the changes in HRCT densitometry and audiometry over time was analyzed. RESULTS: The second round of HRCT did not add significant information about the changes to the otosclerosis lesions in either the imaging diagnosis or the HRCT density values except for small changes in the HRCT densitometry readings at the area anterior to the inner auditory (P = 0.01). While the changes in HRCT manifestation are small, changes near the fissula ante fenestram (FAF) were still positively correlated with the air bone gap (ABG) of patients (p = 0.031, r = 0.388). CONCLUSIONS: The progression of lesions in otosclerosis is slow resulting in small and insignificant changes to the HRCT features. Therefore, a repeat HRCT evaluations prior to surgery is not necessary for patients who have had a previous HRCT evaluation within 2 years of the operation. The small changes in HRCT manifestation near the FAF were still correlated with negative effects on the ABG which could cause worsened hearing thresholds over this timeframe.

4.
Eur J Cell Biol ; 100(7-8): 151178, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34555639

RESUMO

Mast cells (MCs) play important roles in multiple pathologies, including fibrosis; however, their behaviors in different extracellular matrix (ECM) environments have not been fully elucidated. Accordingly, in this study, the migration of MCs on substrates with different stiffnesses was investigated using time-lapse video microscopy. Our results showed that MCs could appear in round, spindle, and star-like shapes; spindle-shaped cells accounted for 80-90 % of the total observed cells. The migration speed of round cells was significantly lower than that of cells with other shapes. Interestingly, spindle-shaped MCs migrated in a jiggling and wiggling motion between protrusions. The persistence index of MC migration was slightly higher on stiffer substrates. Moreover, we found that there was an intermediate optimal stiffness at which the migration efficiency was the highest. These findings may help to improve our understanding of MC-induced pathologies and the roles of MC migration in the immune system.


Assuntos
Matriz Extracelular , Mastócitos , Contagem de Células , Movimento Celular , Fibrose , Humanos
6.
Biomech Model Mechanobiol ; 20(4): 1251-1265, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33786715

RESUMO

Besides the normal hearing pathway known as air conduction (AC), sound can also transmit to the cochlea through the skull, known as bone conduction (BC). During BC stimulation, the cochlear walls demonstrate rigid body motion (RBM) and compressional motion (CPM), both inducing the basilar membrane traveling wave (TW). Despite numerous measuring and modeling efforts for the TW phenomenon, the mechanism remains unclear, especially in the case of BC. This paper proposes a 3D finite element cochlea model mimicking the TW under BC. The model uses a traditional "box model" form, but in a spiral shape, with two fluid chambers separated by the long and flexible BM. The cochlear fluid was enclosed by bony walls, the oval and round window membranes. Contingent boundary conditions and stimulations are introduced according to the physical basis of AC and BC. Particularly for BC, both RBM and CPM of the cochlea walls are simulated. Harmonic numerical solutions are obtained at multiple frequencies among the hearing range. The BM vibration amplitude ([Formula: see text]) and its relation with volume displacement difference between the oval and round windows [Formula: see text], as well as the pressure difference at the base of the cochlea ([Formula: see text]), are analyzed. The simulated BM response at 12 mm from the base is peaked at about 3 k Hz, which is consistent with published experimental data. The TW properties under AC and BC are the same and have a common mechanism. (1) [Formula: see text] is proportional to [Formula: see text] at low frequencies. (2) [Formula: see text] is also proportional to [Formula: see text], within 5 dB error at high frequencies such as 16 k Hz. This study partly reveals the common quantitative relations between the TW and related factors under AC and BC hearing.


Assuntos
Condução Óssea/fisiologia , Cóclea/fisiologia , Audição , Acústica , Membrana Basilar/fisiologia , Simulação por Computador , Análise de Elementos Finitos , Humanos , Imageamento Tridimensional , Modelos Anatômicos , Pressão , Crânio/fisiologia , Som , Vibração
7.
Eur Arch Otorhinolaryngol ; 278(3): 645-652, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32524207

RESUMO

PURPOSE: The aims of this article are: (1) is there an ideal incudostapedial joint (ISJ) angle after stapedotomy? (2) is there any difference between pre- and postoperative ISJ angle? and (3) what is the significance of the ISJ angle in postoperative hearing outcomes? METHODS: Forty six ears from 39 different adult patients (28 women and 11 men; 21 left and 25 right ears) with a mean age of 39 years with clinical otosclerosis who underwent stapedotomy between May 2017 and May 2019 were retrospectively registered, including seven bilateral surgery cases. ISJ angle and intravestibular depth of the stapes prosthesis were measured from multiple planar reconstruction-computed tomography images and the length of the prosthesis was measured during surgery. Relationships between the ISJ angle parameters and postoperative hearing outcomes and parameters of the prosthesis were analyzed. RESULTS: The mean ISJ angle was 93.3° ± 8.8° preoperatively and 101.9° ± 6.3° postoperatively, increasing by 8.6° during stapedotomy (p < 0.01). There were weak and negative correlations between ISJ angle changes and postoperative air conduction gains at frequencies ≤1 kHz and bone conduction gains at 0.5 kHz. When the postoperative ISJ angle changed more than 20°, the success rate of the procedure decreased to 0%. CONCLUSION: The stapedotomy operation increased the ISJ angle. The success of postoperative auditory outcomes had more to do with the ISJ angle change than the value of the angle itself, indicating there is no universal ideal ISJ angle that surgeons should aim for during stapedotomy.


Assuntos
Cirurgia do Estribo , Adulto , Condução Óssea , Feminino , Audição , Humanos , Bigorna/diagnóstico por imagem , Bigorna/cirurgia , Masculino , Prótese Ossicular , Otosclerose/diagnóstico por imagem , Otosclerose/cirurgia , Estudos Retrospectivos , Resultado do Tratamento
8.
Acta Otolaryngol ; 139(5): 403-408, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30888236

RESUMO

BACKGROUND: The synovial stapedio-vestibular joint (SVJ), which serves as a bridge between the stape and oval window, can be found in guinea pigs and most human adults. Unlike the fibrous SVJs in other animals, the contribution of the synovial SVJ to middle ear sound transmission remains unknown. AIMS/OBJECTIVES: In this study, we investigate whether sclerosis of the synovial SVJ contributes to frequency-dependent vibration of the ossicular chain and round window membrane (RWM). MATERIALS AND METHODS: A model of SVJ sclerosis model was established in the guinea pig using 75% ethanol. A laser Doppler vibrometer was then used to measure vibrations of the RWM and the long process of the incus (LPI) under pure tone sound stimulations of 0.25-16 kHz. The influence of SVJ sclerosis was analysed by comparing structural vibration displacement between the normal and sclerosis groups. RESULTS: Both LPI and RWM vibrations significantly decreased at low frequencies after infiltration of ethanol, which caused SVJ sclerosis. CONCLUSIONS: SVJ sclerosis reduces low-frequency vibration of the ossicular chain and RWM in the guinea pig, which indicates that the synovial SVJ is vital to low-frequency sound transmission in the middle ear. SIGNIFICANCE: Providing useful data for further research regarding middle ear biomechanics.


Assuntos
Audição/fisiologia , Articulações/fisiologia , Janela da Cóclea/fisiologia , Estribo/fisiologia , Animais , Etanol , Cobaias , Masculino , Vibração
9.
Hear Res ; 378: 101-107, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30773325

RESUMO

BACKGROUND: As an alternative pathway to air conduction, bone conduction is a multipathway process that transmits sound energy to the inner ear through the skull in general. Based on this mechanism, bone conduction devices (BCDs) have been used widely in the rehabilitation of hearing loss. Although great efforts have been devoted to improving BCDs, drawbacks still exist in most categories of BCDs due to the complicated process of bone conduction. We hypothesized that if a bone conduction transducer was placed on the cochlea to stimulate it directly, the attenuation would be minimized, and the frequency dependency would be different from that of the vibratory response induced by traditional BCDs. This study aimed to explore the feasibility of direct promontory stimulation and to investigate its frequency-response characteristics. METHODS: Measurements were conducted in twelve cat ears. To stimulate the promontory directly, the floating mass transducer (FMT) of the Vibrant Soundbridge© (VSB) implant was glued to the promontory coupled with an oval window (OW) coupler. Auditory brainstem response (ABR) and laser Doppler vibrometry (LDV) measurements were used to evaluate the auditory response induced by the FMT. In both measurements, the FMT was driven by direct voltage stimuli. RESULTS: ABR waves could be induced under direct promontory stimulation by the FMT. In the frequency range of 1-12 kHz, the variation in the voltage threshold level were limited to 16 dB SPL with a maximum of 0.2 V at 1 kHz and a minimum of 0.04 V at 10 kHz. In the LDV measurements and the relative motion of the round window membrane (RWM) and the promontory were used to evaluate the cochlear response. The LDV results indicated a weak frequency dependency from 1 to 12 kHz. CONCLUSION: Different from traditional stimulation via transcranial bone conduction, direct promontory stimulation is a new method in which a small bone conduction transducer stimulates the cochlear shell directly. The current experimental data demonstrate that it is feasible to generate sensations through bone conduction by stimulating the cochlea directly. Furthermore, the cochlear response induced by this type of stimulus in cats was weakly frequency dependent at frequencies ranging from 1 to 12 kHz. This study may provide a basis for the design of new transducers that can perform well over a wide range of frequencies.


Assuntos
Condução Óssea , Cóclea/fisiologia , Potenciais Evocados Auditivos do Tronco Encefálico , Auxiliares de Audição , Estimulação Acústica , Animais , Limiar Auditivo , Gatos , Cóclea/diagnóstico por imagem , Desenho de Equipamento , Estudos de Viabilidade , Fluxometria por Laser-Doppler , Movimento (Física) , Pressão , Som , Fatores de Tempo , Vibração , Microtomografia por Raio-X
10.
Hear Res ; 353: 97-103, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28666703

RESUMO

The Vibrant Soundbridge© (VSB) active middle-ear implant provides an effective treatment for mild-to-severe sensorineural hearing loss in the case of normal middle ear anatomy and mixed hearing loss in middle ear malformation. The VSB floating mass transducer (FMT), with proper couplers, can be installed on various structures of the ossicular chain, e.g., the short and long process of the incus, the stapes head, and the stapes footplate. A long process (LP) coupler is most commonly used for FMT attachment to the long process of the incus with intact ossicular chain, while CliP and Bell couplers are two standardized and reliable methods for FMT attachment to the stapes head with missing incus and malleus. However, the difference and relationship of the vibration properties among these three FMT couplers remain unclear. In the present study, the stapes footplate velocity responses of the LP, CliP, and Bell couplers have been investigated in eight fresh temporal bones (TBs) to evaluate the vibration properties of these three couplers. Normal and reconstructed middle ear transfer functions (METFs) were determined from laser Doppler vibrometer (LDV) measurements. A mastoidectomy and a posterior tympanotomy were performed to expose the ossicular chain. The METFs of the normal middle ear and middle ear with LP-FMT-coupler were compared under acoustic stimulation, thus the mass effect of the FMT with LP coupler was evaluated. Additional comparisons were made between the stapes footplate vibrations of the LP-FMT-coupler (with the intact ossicular chain at the long process of the incus), CliP-FMT-coupler and Bell-FMT-coupler on the stapes head (after incus and malleus removed) under active electromechanical stimulation. After the installation of CliP-FMT-coupler and Bell-FMT-coupler to the middle ear, the average velocity amplitude of the stapes footplate, comparing to the LP-FMT-coupler, was about 15 dB higher between 1 and 6 kHz, and 10 dB lower at about 0.5 kHz. Quantitatively, there was no significant difference between the CliP-FMT-coupler and Bell-FMT-coupler. According to our study, installation of CliP-FMT-coupler or Bell-FMT-coupler on the stapes head provides considerable improvement of the middle ear mechanical and functional responses, comparing with the LP-FMT-coupler in the temporal bone experiments. Moreover, the installation of the Bell-FMT-coupler to the stapes head produces essentially the same footplate velocity responses in comparison to the CliP-FMT-coupler.


Assuntos
Orelha Média/cirurgia , Perda Auditiva Condutiva-Neurossensorial Mista/reabilitação , Perda Auditiva Neurossensorial/reabilitação , Audição , Prótese Ossicular , Implantação de Prótese/instrumentação , Cirurgia do Estribo/instrumentação , Estimulação Acústica , Cadáver , Orelha Média/fisiopatologia , Perda Auditiva Condutiva-Neurossensorial Mista/fisiopatologia , Perda Auditiva Neurossensorial/fisiopatologia , Humanos , Mastoidectomia , Movimento (Física) , Desenho de Prótese , Som , Osso Temporal/cirurgia , Fatores de Tempo , Vibração
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