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1
Balkany, Thomas, Bruce J. Gantz, Ronald L. Steenerson e Noel L. Cohen. "Systematic Approach to Electrode Insertion in the Ossified Cochlea". Otolaryngology–Head and Neck Surgery 114, n. 1 (gennaio 1996): 4–11. http://dx.doi.org/10.1016/s0194-59989670275-9.
Testo completoAbstract (sommario):
Ossification of the fluid spaces of the cochlea occurs often in candidates for cochlear implantation, especially children. When noted before surgery on computerized tomography, ossification previously was thought to contraindicate cochlear implantation because of possible mechanical obstruction and uncertainty about the level of function that could be achieved by stimulating an ossified cochlea. However, during the preceding 6 years, techniques have been developed that permit implantation in ossified cochleas. We present a systematic approach that has been developed to treat the three clinically important categories of cochlear ossification: round window niche obliteration, inferior segment obstruction, and upper segment obstruction. Case reports are presented for each of these three drill-out procedures, demonstrating results often similar to those expected for implantation of the nonossified cochlea.
2
Englisch, Colya N., Jakob Steinhäuser, Silke Wemmert, Martin Jung, Joshua Gawlitza, Gentiana Wenzel, Bernhard Schick e Thomas Tschernig. "Immunohistochemistry Reveals TRPC Channels in the Human Hearing Organ—A Novel CT-Guided Approach to the Cochlea". International Journal of Molecular Sciences 24, n. 11 (26 maggio 2023): 9290. http://dx.doi.org/10.3390/ijms24119290.
Testo completoAbstract (sommario):
TRPC channels are critical players in cochlear hair cells and sensory neurons, as demonstrated in animal experiments. However, evidence for TRPC expression in the human cochlea is still lacking. This reflects the logistic and practical difficulties in obtaining human cochleae. The purpose of this study was to detect TRPC6, TRPC5 and TRPC3 in the human cochlea. Temporal bone pairs were excised from ten body donors, and the inner ear was first assessed based on computed tomography scans. Decalcification was then performed using 20% EDTA solutions. Immunohistochemistry with knockout-tested antibodies followed. The organ of Corti, the stria vascularis, the spiral lamina, spiral ganglion neurons and cochlear nerves were specifically stained. This unique report of TRPC channels in the human cochlea supports the hypothesis of the potentially critical role of TRPC channels in human cochlear health and disease which has been suggested in previous rodent experiments.
3
Yu, J.-F., K.-C. Lee, Y.-L. Wan e Y.-C. Peng. "Curvature measurement of human bilateral cochleae". Journal of Laryngology & Otology 129, n. 11 (21 settembre 2015): 1085–90. http://dx.doi.org/10.1017/s0022215115002480.
Testo completoAbstract (sommario):
AbstractObjective:This study aimed to characterise the geometry of the human bilateral spiral cochlea by measuring curvature and length.Method:Eight subjects were recruited in this study. Magnetic resonance imaging was used to visualise the right and left cochlea. Visualisation of the cochlear spiral was enhanced by T2 weighting and further processing of the raw images. The spirals were divided into three segments: the basal turn, the middle turn and the apex turn. The length and curvature of each segment were non-invasively measured.Results:The mean left and right cochlear lengths were 3.11 cm and 3.95 cm, respectively. The measured lengths of the cochlear spiral are consistent with data in the literature derived from anatomical dissections. Overall, the apex turn segment of the cochlea had the greatest degree of curvature (p < 0.05). The mean apex turn segment curvatures for left and right cochleae were 9.65 cm−1 and 10.09 cm−1, respectively.Conclusion:A detailed description of the cochlear spiral is provided, using measurements of curvature and length. These data will provide a valuable reference in the development of cochlear implantation procedures for minimising the potential damage during implantation.
4
Dong, Wei, e Nigel P. Cooper. "An experimental study into the acousto-mechanical effects of invading the cochlea". Journal of The Royal Society Interface 3, n. 9 (2 marzo 2006): 561–71. http://dx.doi.org/10.1098/rsif.2006.0117.
Testo completoAbstract (sommario):
The active and nonlinear mechanical processing of sound that takes place in the mammalian cochlea is fundamental to our sense of hearing. We have investigated the effects of opening the cochlea in order to make experimental observations of this processing. Using an optically transparent window that permits laser interferometric access to the apical turn of the guinea-pig cochlea, we show that the acousto-mechanical transfer functions of the sealed (i.e. near intact) cochlea are considerably simpler than those of the unsealed cochlea. Comparison of our results with those of others suggests that most previous investigations of apical cochlear mechanics have been made under unsealed conditions, and are therefore likely to have misrepresented the filtering of low-frequency sounds in the cochlea. The mechanical filtering that is apparent in the apical turns of sealed cochleae also differs from the filtering seen in individual auditory nerve fibres with similar characteristic frequencies. As previous studies have shown the neural and mechanical tuning of the basal cochlea to be almost identical, we conclude that the strategies used to process low frequency sounds in the apical turns of the cochlea might differ fundamentally from those used to process high frequency sounds in the basal turns.
5
Robles, Luis, e Mario A. Ruggero. "Mechanics of the Mammalian Cochlea". Physiological Reviews 81, n. 3 (1 luglio 2001): 1305–52. http://dx.doi.org/10.1152/physrev.2001.81.3.1305.
Testo completoAbstract (sommario):
In mammals, environmental sounds stimulate the auditory receptor, the cochlea, via vibrations of the stapes, the innermost of the middle ear ossicles. These vibrations produce displacement waves that travel on the elongated and spirally wound basilar membrane (BM). As they travel, waves grow in amplitude, reaching a maximum and then dying out. The location of maximum BM motion is a function of stimulus frequency, with high-frequency waves being localized to the “base” of the cochlea (near the stapes) and low-frequency waves approaching the “apex” of the cochlea. Thus each cochlear site has a characteristic frequency (CF), to which it responds maximally. BM vibrations produce motion of hair cell stereocilia, which gates stereociliar transduction channels leading to the generation of hair cell receptor potentials and the excitation of afferent auditory nerve fibers. At the base of the cochlea, BM motion exhibits a CF-specific and level-dependent compressive nonlinearity such that responses to low-level, near-CF stimuli are sensitive and sharply frequency-tuned and responses to intense stimuli are insensitive and poorly tuned. The high sensitivity and sharp-frequency tuning, as well as compression and other nonlinearities (two-tone suppression and intermodulation distortion), are highly labile, indicating the presence in normal cochleae of a positive feedback from the organ of Corti, the “cochlear amplifier.” This mechanism involves forces generated by the outer hair cells and controlled, directly or indirectly, by their transduction currents. At the apex of the cochlea, nonlinearities appear to be less prominent than at the base, perhaps implying that the cochlear amplifier plays a lesser role in determining apical mechanical responses to sound. Whether at the base or the apex, the properties of BM vibration adequately account for most frequency-specific properties of the responses to sound of auditory nerve fibers.
6
Hosoya, Makoto, Masato Fujioka, Hideyuki Okano e Kaoru Ogawa. "Distinct Expression Pattern of a Deafness Gene,KIAA1199, in a Primate Cochlea". BioMed Research International 2016 (2016): 1–8. http://dx.doi.org/10.1155/2016/1781894.
Testo completoAbstract (sommario):
Deafness is one of the most common types of congenital impairments, and at least half of the cases are caused by hereditary mutations. Mutations of the geneKIAA1199are associated with progressive hearing loss. Its expression is abundant in human cochlea, but interestingly the spatial expression patterns are different between mouse and rat cochleae; the pattern in humans has not been fully investigated. We performed immunohistochemical analysis of a nonhuman primate, common marmoset (Callithrix jacchus), cochlea with a KIAA1199-specific antibody. In the common marmoset cochlea, KIAA1199 protein expression was more widespread than in rodents, with all epithelial cells, including hair cells, expressing KIAA1199. Our results suggest that the primate pattern of KIAA1199 expression is wider in comparison with rodents and may play an essential role in the maintenance of cochlear epithelial cells.
7
Toulemonde, Philippine, Michaël Risoud, Pierre Emmanuel Lemesre, Cyril Beck, Jean Wattelet, Meryem Tardivel, Juergen Siepmann e Christophe Vincent. "Evaluation of the Efficacy of Dexamethasone-Eluting Electrode Array on the Post-Implant Cochlear Fibrotic Reaction by Three-Dimensional Immunofluorescence Analysis in Mongolian Gerbil Cochlea". Journal of Clinical Medicine 10, n. 15 (28 luglio 2021): 3315. http://dx.doi.org/10.3390/jcm10153315.
Testo completoAbstract (sommario):
Cochlear implant is the method of choice for the rehabilitation of severe to profound sensorineural hearing loss. The study of the tissue response to cochlear implantation and the prevention of post-cochlear-implant damages are areas of interest in hearing protection research. The objective was to assess the efficacy of dexamethasone-eluting electrode array on endo canal fibrosis formation by three-dimensional immunofluorescence analysis in implanted Mongolian gerbil cochlea. Two trials were conducted after surgery using Mongolian gerbil implanted with dexamethasone-eluting or non-eluting intracochlear electrode arrays. The animals were then euthanised 10 weeks after implantation. The cochleae were prepared (electrode array in place) according to a 29-day protocol with immunofluorescent labelling and tissue clearing. The acquisition was carried out using light-sheet microscopy. Imaris software was then used for three-dimensional analysis of the cochleae and quantification of the fibrotic volume. The analysis of 12 cochleae showed a significantly different mean volume of fibrosis (2.16 × 108 μm3 ± 0.15 in the dexamethasone eluting group versus 3.17 × 108 μm3 ± 0.54 in the non-eluting group) (p = 0.004). The cochlear implant used as a corticosteroid delivery system appears to be an encouraging device for the protection of the inner ear against fibrosis induced by implantation. Three-dimensional analysis of the cochlea by light-sheet microscopy was suitable for studying post-implantation tissue damage.
8
Soliman, A. M. "An improved technique for the study of immunofluorescence using non-decalcified frozen guinea pig cochlea". Journal of Laryngology & Otology 102, n. 3 (marzo 1988): 215–18. http://dx.doi.org/10.1017/s0022215100104554.
Testo completoAbstract (sommario):
SummaryA technique for producing frozen sections from the non-decalcified guinea pig cochlea is described. The sections can be utilised or various immunofluorescent studies, including the detection of humoral anti-bodies against different cellular elements in patients with cochleo-vestibular disorders. The technique assures the preservation of the cochlear architecture and the tissue antigenicity, and it avoids damage to the fine cochlear structural details.
9
Moore, David R., Nina J. Rogers e Stephen J. O'Leary. "Loss of Cochlear Nucleus Neurons following Aminoglycoside Antibiotics or Cochlear Removal". Annals of Otology, Rhinology & Laryngology 107, n. 4 (aprile 1998): 337–43. http://dx.doi.org/10.1177/000348949810700413.
Testo completoAbstract (sommario):
This study compared the effects of aminoglycoside ototoxicity and surgical ablation of the cochlea in infancy on the survival of neurons in the rat cochlear nucleus (CN). Ototoxicity was induced by a single, systemic dose of gentamicin sulfate and furosemide on postnatal day 6 (P6), P7, or P10, and assessed by the elevation of auditory brain stem response thresholds, as described in a companion paper. Unilateral cochlear removals were performed under Saffan anesthesia on P6, P9, and P12. Rats were painlessly sacrificed in adulthood, and the formalin-perfused brains and cochleas were embedded in wax, sectioned, and stained. Ototoxic treatment at P6 through P10 did not reduce neuron counts in the CN. Cochlear removal at P6 resulted in a 40% loss of CN neurons, but removal at P12 did not result in CN neuron loss. These data suggest that the critical period for the dependence of CN neurons on afferent input from the cochlea ends at the same time that susceptibility to aminoglycoside ototoxicity begins.
10
Lin, Wei-Ching, Anes Macic e Jong-Hoon Nam. "Characterizing the primary resonator in the cochlea". Journal of the Acoustical Society of America 155, n. 3_Supplement (1 marzo 2024): A308. http://dx.doi.org/10.1121/10.0027608.
Testo completoAbstract (sommario):
The cochlear traveling waves are explained by a bank of independent resonators coupled longitudinally by lymphatic fluids. Many cochlear models require at least two resonators to account for observed responses. To investigate the resonators in the cochlea, we used high-resolution optical coherence tomography to measure 2-D vibration patterns of the organ of Corti in acutely excised cochleae from young Mongolian gerbils. The excised tissues were acoustically stimulated. The transverse and radial vibrations of the basilar membrane (BM) and the tectorial membrane (TM) were obtained over their radial span. The BM vibrated from the primary to a higher mode transversely as the stimulating frequency increased. The higher-order mode appeared near the best frequency (BF) of the measured location. Meanwhile, the TM showed no sign of a mode transition up to 1 octave above the BF in radial or transverse vibrating patterns. Within the physiological frequency range, the BM exhibits the characteristic behavior of a resonator. In contrast, the TM does not. Our results suggest that the TM as the second resonator is not the universal mechanism across the entire cochlea.
11
Szczepek, Agnieszka J., Tatyana Dudnik, Betül Karayay, Valentina Sergeeva, Heidi Olze e Alina Smorodchenko. "Mast Cells in the Auditory Periphery of Rodents". Brain Sciences 10, n. 10 (1 ottobre 2020): 697. http://dx.doi.org/10.3390/brainsci10100697.
Testo completoAbstract (sommario):
Mast cells (MCs) are densely granulated cells of myeloid origin and are a part of immune and neuroimmune systems. MCs have been detected in the endolymphatic sac of the inner ear and are suggested to regulate allergic hydrops. However, their existence in the cochlea has never been documented. In this work, we show that MCs are present in the cochleae of C57BL/6 mice and Wistar rats, where they localize in the modiolus, spiral ligament, and stria vascularis. The identity of MCs was confirmed in cochlear cryosections and flat preparations using avidin and antibodies against c-Kit/CD117, chymase, tryptase, and FcεRIα. The number of MCs decreased significantly during postnatal development, resulting in only a few MCs present in the flat preparation of the cochlea of a rat. In addition, exposure to 40 µM cisplatin for 24 h led to a significant reduction in cochlear MCs. The presence of MCs in the cochlea may shed new light on postnatal maturation of the auditory periphery and possible involvement in the ototoxicity of cisplatin. Presented data extend the current knowledge about the physiology and pathology of the auditory periphery. Future functional studies should expand and translate this new basic knowledge to clinics.
12
Sargsyan, Liana, Austin R. Swisher, Alisa P. Hetrick e Hongzhe Li. "Effects of Combined Gentamicin and Furosemide Treatment on Cochlear Macrophages". International Journal of Molecular Sciences 23, n. 13 (1 luglio 2022): 7343. http://dx.doi.org/10.3390/ijms23137343.
Testo completoAbstract (sommario):
Combining aminoglycosides and loop diuretics often serves as an effective ototoxic approach to deafen experimental animals. The treatment results in rapid hair cell loss with extended macrophage presence in the cochlea, creating a sterile inflammatory environment. Although the early recruitment of macrophages is typically neuroprotective, the delay in the resolution of macrophage activity can be a complication if the damaged cochlea is used as a model to study subsequent therapeutic strategies. Here, we applied a high dose combination of systemic gentamicin and furosemide in C57 BL/6 and CBA/CaJ mice and studied the ototoxic consequences in the cochlea, including hair cell survival, ribbon synaptic integrity, and macrophage activation up to 15-day posttreatment. The activity of macrophages in the basilar membrane was correlated to the severity of cochlear damage, particularly the hair cell damage. Comparatively, C57 BL/6 cochleae were more vulnerable to the ototoxic challenge with escalated macrophage activation. In addition, the ribbon synaptic deterioration was disproportionately limited when compared to the degree of outer hair cell loss in CBA/CaJ mice. The innate and differential otoprotection in CBA/CaJ mice appears to be associated with the rapid activation of cochlear macrophages and a certain level of synaptogenesis after the combined gentamicin and furosemide treatment.
13
Zhang, Guoping, Yiling Gao, Zhen Zhao, Ilmari Pyykko e Jing Zou. "Low-Molecular-Weight Hyaluronic Acid Contributes to Noise-Induced Cochlear Inflammation". Audiology and Neurotology 28, n. 5 (2023): 380–93. http://dx.doi.org/10.1159/000530280.
Testo completoAbstract (sommario):
Introduction: Our previous work indicated that the activation of the Toll-like receptor (TLR) 4 signaling pathway contributed to noise-induced cochlear inflammation. Previous studies have reported that low-molecular-weight hyaluronic acid (LMW-HA) accumulates during aseptic trauma and promotes inflammation by activating the TLR4 signaling pathway. We hypothesized that LMW-HA or enzymes synthesizing or degrading HA might be involved in noise-induced cochlear inflammation. Methods: The present study included two arms. The first arm was the noise exposure study, in which TLR4, proinflammatory cytokines, HA, hyaluronic acid synthases (HASs), and hyaluronidases (HYALs) in the cochlea as well as auditory brainstem response (ABR) thresholds were measured before and after noise exposure. The second arm was analysis of HA delivery-induced reactions, in which control solution, high-molecular-weight HA (HMW-HA), or LMW-HA was delivered into the cochlea by cochleostomy or intratympanic injection. Then, the ABR threshold and cochlear inflammation were measured. Results: After noise exposure, the expression of TLR4, proinflammatory cytokines, HAS1, and HAS3 in the cochlea significantly increased over the 3rd to 7th day post-noise exposure (PE3, PE7). The expression of HYAL2 and HYAL3 dramatically decreased immediately after noise exposure, gradually increased thereafter to levels significantly greater than the preexposure level on PE3, and then rapidly returned to the preexposure level on PE7. The expression of HA, HAS2, and HYAL1 in the cochlea remained unchanged after exposure. After cochleostomy or intratympanic injection, both the hearing threshold shifts and the expression of TLR4, TNF-α, and IL-1β in the cochleae of the LMW-HA group were obviously greater than those of the control group and HMW-HA group. The expression of proinflammatory cytokines in the LMW-HA and control groups on the 7th day (D7) after cochleostomy tended to increase compared to that on the 3rd day (D3), whereas levels in the HMW-HA group tended to decrease on D7 compared to D3. Conclusion: HAS1, HAS3, HYAL2, and HYAL3 in the cochlea are involved in acoustic trauma-induced cochlear inflammation through the potential proinflammatory function of LMW-HA.
14
Langman, Alan W., e Suzanne M. Quigley. "Accuracy of High-Resolution Computed Tomography in Cochlear Implantation". Otolaryngology–Head and Neck Surgery 114, n. 1 (gennaio 1996): 38–43. http://dx.doi.org/10.1016/s0194-59989670281-4.
Testo completoAbstract (sommario):
Multichannel cochlear implants are a proven method for the auditory rehabilitation of individuals who have severe-to-profound sensorineural hearing loss. These devices typically require insertion into the scala tympani of the cochlea to provide auditory stimulations. A patent scala provides the best chance for an adequate insertion of the electrode array. Preoperative high-resolution computed tomography imaging has traditionally been used to determine the patency of the scala tympani. Its ability to accurately predict the patency of the cochlea has been questioned in several retrospective studies. A prospective study was undertaken in 28 consecutive individuals undergoing cochlear implant surgery to compare the findings on high-resolution computed tomography with the surgical findings in an attempt to determine high-resolution computed tomography's accuracy. Cochlear obstruction caused by ossification was accurately predicted in six of six individuals but overestimated in the round window region in three individuals. High-resolution computed tomography accurately predicted patent cochleas in 19 individuals. No false-negative results were encountered. In this study sensitivity of high-resolution computed tomography was 100%, and specificity was 86%. High-resolution computed tomography appears to be more helpful than previously reported for determining cochlear patency.
15
Martins, Maria Clara Iruzun, Travis Park, Rachel Racicot e Natalie Cooper. "Intraspecific variation in the cochleae of harbour porpoises (Phocoena phocoena) and its implications for comparative studies across odontocetes". PeerJ 8 (13 aprile 2020): e8916. http://dx.doi.org/10.7717/peerj.8916.
Testo completoAbstract (sommario):
In morphological traits, variation within species is generally considered to be lower than variation among species, although this assumption is rarely tested. This is particularly important in fields like palaeontology, where it is common to use a single individual as representative of a species due to the rarity of fossils. Here, we investigated intraspecific variation in the cochleae of harbour porpoises (Phocoena phocoena). Interspecific variation of cochlear morphology is well characterised among odontocetes (toothed whales) because of the importance of the structure in echolocation, but generally these studies use only a single cochlea to represent each species. In this study we compare variation within the cochleae of 18 specimens of P. phocoena with variations in cochlear morphology across 51 other odontocete species. Using both 3D landmark and linear measurement data, we performed Generalised Procrustes and principal component analyses to quantify shape variation. We then quantified intraspecific variation in our sample of P. phocoena by estimating disparity and the coefficient of variation for our 3D and linear data respectively. Finally, to determine whether intraspecific variation may confound the results of studies of interspecific variation, we used multivariate and univariate analyses of variance to test whether variation within the specimens of P. phocoena was significantly lower than that across odontocetes. We found low levels of intraspecific variation in the cochleae of P. phocoena, and that cochlear shape within P. phocoena was significantly less variable than across odontocetes. Although future studies should attempt to use multiple cochleae for every species, our results suggest that using just one cochlea for each species should not strongly influence the conclusions of comparative studies if our results are consistent across Cetacea.
16
Ni, Guangjian, Stephen J. Elliott, Mohammad Ayat e Paul D. Teal. "Modelling Cochlear Mechanics". BioMed Research International 2014 (2014): 1–42. http://dx.doi.org/10.1155/2014/150637.
Testo completoAbstract (sommario):
The cochlea plays a crucial role in mammal hearing. The basic function of the cochlea is to map sounds of different frequencies onto corresponding characteristic positions on the basilar membrane (BM). Sounds enter the fluid-filled cochlea and cause deflection of the BM due to pressure differences between the cochlear fluid chambers. These deflections travel along the cochlea, increasing in amplitude, until a frequency-dependent characteristic position and then decay away rapidly. The hair cells can detect these deflections and encode them as neural signals. Modelling the mechanics of the cochlea is of help in interpreting experimental observations and also can provide predictions of the results of experiments that cannot currently be performed due to technical limitations. This paper focuses on reviewing the numerical modelling of the mechanical and electrical processes in the cochlea, which include fluid coupling, micromechanics, the cochlear amplifier, nonlinearity, and electrical coupling.
17
Li, Jianan, Shuoshuo Kang, Haiqiao Du, Shuwei Wang, Dandan Wang, Mengyu Liu e Shiming Yang. "Analysis of Cochlear Parameters in Paediatric Inner Ears with Enlarged Vestibular Aqueduct and Patent Cochlea". Journal of Personalized Medicine 12, n. 10 (7 ottobre 2022): 1666. http://dx.doi.org/10.3390/jpm12101666.
Testo completoAbstract (sommario):
Is cochlear implant (CI) electrode selection for cochleae with an enlarged vestibular aqueduct (EVA) the same as that for patent cochleae with a normal inner ear structure? Preoperative high-resolution computed tomography (HRCT) images of 247 ears were assessed retrospectively. The A-value, B-value, and H-value were measured with OTOPLAN, and Bell curves were created to show the distribution. All ears with EVA were re-evaluated using a 3D slicer to confirm whether incomplete partition type II (IP II) existed. The Mann–Whitney U-test was applied to determine a statistically significant difference. After adjustment with the Bonferroni correction method, a p-value ≤ 0.006 was considered significant. In total, 157 ears with patent cochlea and 90 ears with EVA were assessed. Seventy (82%) of the EVA ears had an IP II malformation, and 14 (19%) of these were not detected by CT scan but were later seen through the 3D reconstruction. A significant difference was found for the A value and B value between the patent cochleae and EVA-only and between the patent cochleae and EVA with IP II. Most EVA cases had an IP II malformation. The basal turn of the cochlea may be smaller in EVA cases than in the patent cochleae. Electrode selection should be adjusted accordingly.
18
Swain, Santosh Kumar. "Cochlear deformities and its implication in cochlear implantation: a review". International Journal of Research in Medical Sciences 10, n. 10 (27 settembre 2022): 2339. http://dx.doi.org/10.18203/2320-6012.ijrms20222547.
Testo completoAbstract (sommario):
Hearing loss is one of the world’s leading causes of chronic health conditions. Cochlea plays a vital role in the hearing mechanisms and it converts sound energy into electrical stimuli which are transmitted to the brain through the neural pathway. The human cochlea is difficult to explore because of its vulnerability and bordering bony capsule. Congenital malformation of the inner ear or cochlea is an important cause of congenital sensorineural hearing loss. The deformity of the cochlea may result from arrested development of cochlea at different stages of fetal life or from abnormal development due to genetic abnormalities. There are hair cells responsible for converting sound energy into electrical impulses. These hair cells are easily damaged, which results in permanent hearing loss. Cochlear implants are surgically implantable biomedical devices that bypass the sensory hair cells and directly stimulate the remaining fibers of the auditory nerve with an electric current. Cochlear implantation is capable of restoring a surprisingly large degree of auditory perception to patient that is suffering from severe to profoundly deaf. Children with cochlear anomalies are thought to have poorer outcomes with cochlear implantations, therefore would be poorer candidates due to their diminished ability to interpolate and use auditory information provided through a cochlear implant. Parents should be counselled to establish realistic post-implant expectations in case of children with cochlear deformity. So, patient selection has emerged as one of the most vital determinants of successful outcomes after pediatric cochlear implantation.
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Deep, Nicholas, Baishakhi Choudhury e J. Roland. "Auditory Brainstem Implantation: An Overview". Journal of Neurological Surgery Part B: Skull Base 80, n. 02 (14 febbraio 2019): 203–8. http://dx.doi.org/10.1055/s-0039-1679891.
Testo completoAbstract (sommario):
AbstractAn auditory brainstem implant (ABI) is a surgically implanted central neural auditory prosthesis for the treatment of profound sensorineural hearing loss in children and adults who are not cochlear implant candidates due to a lack of anatomically intact cochlear nerves or implantable cochleae. The device consists of a multielectrode surface array which is placed within the lateral recess of the fourth ventricle along the brainstem and directly stimulates the cochlear nucleus, thereby bypassing the peripheral auditory system. In the United States, candidacy criteria for ABI include deaf patients with neurofibromatosis type 2 (NF2) who are 12 years or older undergoing first- or second-side vestibular schwannoma resection. In recent years, several non-NF2 indications for ABI have been explored, including bilateral cochlear nerve avulsion from trauma, complete ossification of the cochlea due to meningitis, or a severe cochlear malformation not amenable to cochlear implantation. In addition, growing experience with ABI in infants and children has been documented with encouraging outcomes. While cochlear implantation generally remains the first-line option for hearing rehabilitation in NF2 patients with stable tumors or post hearing preservation surgery where hearing is lost but a cochlear nerve remains accessible for stimulation, an ABI is the next alternative in cases where the cochlear nerve is absent and/or if the cochlea cannot be implanted. Herein, we review ABI device design, clinical evaluation, indications, operative technique, and outcomes as it relates to lateral skull base pathology.
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Neagoș, Cristian Mircea, Eugenia Maria Domuța, Anca Gabriela Vlad e Adriana Neagoș. "The Role of Imaging Investigations in Evaluation of Cochlear Dimensions in Candidates for Cochlear Implantation—Our Experience". Medicina 59, n. 12 (27 novembre 2023): 2086. http://dx.doi.org/10.3390/medicina59122086.
Testo completoAbstract (sommario):
Background and Objectives: The Cochlear implant is the first approved cranial nerve stimulator that works by directly stimulating the cochlear nerve. Various attempts have been made to evaluate the dimensions of the cochlea related to cochlear implantation. The preoperative computed tomographic examination is essential not only in assessing the anatomical aspect of the cochlea, but also in determining its dimensions to choose an appropriate electrode and obtain the best possible audiological performance. Materials and Methods: In the present paper, we aimed to carry out an observational study regarding the role of cochlear measurements in the preoperative evaluation of patients proposed for cochlear implants. The purpose of the study was to measure the cochlea and establish the existence of a correlation between the size of the cochlea and the age and gender of the patients. Results: From the group of 35 examined patients, 54% (n = 19) were male and 46% (n = 16) were female. The average length of the cochlea in the age group 0–4 years is 7.82 mm in the left ear and 7.86 mm in the right ear; in the age group 4–7 years, it is 7.82 mm and 7.94 mm, respectively; for the age group 7–14 years, the dimensions increase to 8.48 mm and 8.77 mm, respectively; and after 14 years, these dimensions reach 9.12 mm and 9.18 mm, respectively. Comparative measurements of the length of the cochlea by age groups show an increase in length with the patient’s age, but this increase does not exceed 1.5 mm for both the right and left ears. The measurements of the width of the cochlea, by age group, start from 6.84 mm in the left ear and 6.81 mm in the right ear at 0–4 years, 6.94 mm and 6.97 mm, respectively, in the group 4–7 years, 7.71 mm and 7.55 mm at 7–14 years, and reaching 8.19 mm and 8.12 mm at the age of 14 years and over. Conclusions: From the study carried out, it can be concluded that the evaluation of the dimensions of the cochlea is important for cochlear implantation. The size variables, although small, are still an element to be considered in correlation with the age of the patient and the implanted ear. This increase is statistically insignificant, but it still exists, even if, from a theoretical point of view, it is considered that the dimensions of the cochlea remain constant.
21
Lyu, Ah-Ra, Tae Hwan Kim, Sung Jae Park, Sun-Ae Shin, Seong-Hun Jeong, Yang Yu, Yang Hoon Huh, A. Reum Je, Min Jung Park e Yong-Ho Park. "Mitochondrial Damage and Necroptosis in Aging Cochlea". International Journal of Molecular Sciences 21, n. 7 (3 aprile 2020): 2505. http://dx.doi.org/10.3390/ijms21072505.
Testo completoAbstract (sommario):
Age-related hearing loss (ARHL) is an irreversible, progressive neurodegenerative disorder and is presently untreatable. Previous studies using animal models have suggested mitochondrial damage and programmed cell death to be involved with ARHL. Thus, we further investigated the pathophysiologic role of mitochondria and necroptosis in aged C57BL/6J male mice. Aged mice (20 months old) exhibited a significant loss of hearing, number of hair cells, neuronal fibers, and synaptic ribbons compared to young mice. Ultrastructural analysis of aged cochleae revealed damaged mitochondria with absent or disorganized cristae. Aged mice also showed significant decrease in cochlear blood flow, and exhibited increase in gene expression of proinflammatory cytokines (IL-1β, IL-6, and TNF-α), receptor-interacting serine/threonine-protein kinase 1 and 3 (RIPK1 and RIPK3) and the pseudokinase mixed-lineage kinase domain-like (MLKL). Immunofluorescence (IF) assays of cytochrome C oxidase I (COX1) confirmed mitochondrial dysfunction in aged cochleae, which correlated with the degree of mitochondrial morphological damage. IF assays also revealed localization and increased expression of RIPK3 in sensorineural tissues that underwent significant necroptosis (inner and outer hair cells and stria vascularis). Together, our data shows that the aging cochlea exhibits damaged mitochondria, enhanced synthesis of proinflammatory cytokines, and provides new evidence of necroptosis in the aging cochlea in in vivo.
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Zaluzec, Daniel, Joseph Ramzy, Robert Wotring e Lincoln Gray. "Microsphere Determination of Cochlear Blood Flow in Chickens". Otolaryngology–Head and Neck Surgery 96, n. 4 (aprile 1987): 341–48. http://dx.doi.org/10.1177/019459988709600407.
Testo completoAbstract (sommario):
Chickens were injected with 9-micron-diameter radioactive microspheres. Cochleas were removed through the external auditory meatus, and the positions of all embedded microspheres were drawn under camera-lucida. Constant measurements of arterial pressures and postinjection blood-gas determinations confirmed that injections were made into normal circulatory systems. The averaged estimate of cochlear blood flow in chickens is 0.75 μl/min. Variability in these data from chickens is similar to that reported from mammals. A potentially important but puzzling observation is an inverse relationship between blood flow to the cochlea and to the brain. The ease of cochlear extraction makes chickens ideal models for study of cochlear blood flow.
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Chen, Penghui, Yongchuan Chai, Haijin Liu, Gen Li, Longhao Wang, Tao Yang e Hao Wu. "Postnatal Development of Microglia-Like Cells in Mouse Cochlea". Neural Plasticity 2018 (31 luglio 2018): 1–5. http://dx.doi.org/10.1155/2018/1970150.
Testo completoAbstract (sommario):
Microglial cells are involved in surveillance and cleaning of the central nervous system. Recently, microglial-like cells (MLC) have been found in an adult cochlea and investigated for their role in cochlear inflammation. The presence and potential roles of MLCs during the development of the cochlea, however, remain unclear. In this study, immunostaining was performed using the MLC-specific marker IBA1 to characterize the presence, distribution, and morphology of MLCs in the developing cochlea. From P0 to P14, MLCs were present in a variety of cochlear regions including the modiolus, spiral lamina, spiral ganglion, spiral ligament, and the organ of Corti. Interestingly, the overall number of MLCs in a mouse cochlea steadily increased since P0, peaks at P5, then gradually decreased from P5 to P14. In the spiral ligament, the distribution of the MLCs trends to shift from the type I/II fibrocyte-rich regions to the type III/IV fibrocyte-rich regions during the course of cochlear development, accompanied by the morphological changes of MLCs from the amoeboid, activated form to the ramified, quiescent form. Our results suggested that MLCs experience drastic morphological and distributional changes during postnatal cochlear development, which may play a role in the maturing and remodeling of the cochlea.
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Balkany, Thomas, Bruce Gantz e Joseph B. Nadol. "Multichannel Cochlear Implants in Partially Ossified Cochleas". Annals of Otology, Rhinology & Laryngology 97, n. 5_suppl2 (settembre 1988): 3–7. http://dx.doi.org/10.1177/00034894880975s201.
Testo completoAbstract (sommario):
Deposition of bone within the fluid spaces of the cochlea is encountered commonly in cochlear implant candidates and previously has been considered a relative contraindication to the use of multichannel intracochlear electrodes. This contraindication has been based on possible mechanical difficulty with electrode insertion as well as uncertainty about the potential benefit of the multichannel device in the patient. Fifteen profoundly deaf patients with partial ossification of the basal turn of the cochlea received implants with long intracochlear electrodes (11, Nucleus; 1, University of California at San Francisco/Storz; and 3, Symbion/Inneraid). In 11 cases, ossification had been predicted preoperatively by computed tomographic scan. Electrodes were completely inserted in 14 patients, and partial insertion was accomplished in one patient. All patients currently are using their devices and nine of 12 postlingually deaf patients have achieved some degree of open-set speech discrimination. This series demonstrates that in experienced hands, insertion of long multichannel electrodes into partially ossified cochleas is possible and that results are similar to those achieved in patients who have nonossified cochleas.
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Keppeler, Daniel, Christoph A. Kampshoff, Anupriya Thirumalai, Carlos J. Duque-Afonso, Jannis J. Schaeper, Tabea Quilitz, Mareike Töpperwien et al. "Multiscale photonic imaging of the native and implanted cochlea". Proceedings of the National Academy of Sciences 118, n. 18 (26 aprile 2021): e2014472118. http://dx.doi.org/10.1073/pnas.2014472118.
Testo completoAbstract (sommario):
The cochlea of our auditory system is an intricate structure deeply embedded in the temporal bone. Compared with other sensory organs such as the eye, the cochlea has remained poorly accessible for investigation, for example, by imaging. This limitation also concerns the further development of technology for restoring hearing in the case of cochlear dysfunction, which requires quantitative information on spatial dimensions and the sensorineural status of the cochlea. Here, we employed X-ray phase-contrast tomography and light-sheet fluorescence microscopy and their combination for multiscale and multimodal imaging of cochlear morphology in species that serve as established animal models for auditory research. We provide a systematic reference for morphological parameters relevant for cochlear implant development for rodent and nonhuman primate models. We simulate the spread of light from the emitters of the optical implants within the reconstructed nonhuman primate cochlea, which indicates a spatially narrow optogenetic excitation of spiral ganglion neurons.
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Barker, Emma, Keith Trimble, Harley Chan, James Ramsden, Sajendra Nithiananthan, Adrian James, Gideon Bachar, Mike Daly, Jonathan Irish e Jeff Siewerdsen. "Intraoperative use of cone-beam computed tomography in a cadaveric ossified cochlea model". Otolaryngology–Head and Neck Surgery 140, n. 5 (maggio 2009): 697–702. http://dx.doi.org/10.1016/j.otohns.2008.12.046.
Testo completoAbstract (sommario):
Objectives: To describe a cadaveric temporal bone model of labyrinthitis ossificans and investigate the utility of intraoperative cone-beam computed tomography (CBCT) in the facilitating cochlear implantation. Design: Cadaveric temporal bone study. Methods: Five cadaveric heads had cement introduced into the 10 cochleas. CBCT and a conventional CT scan were compared to assess the extent of cochlear obliteration. The cement was drilled-out (under CBCT guidance, if required) and cochlear implant electrode arrays (from 3 different manufacturers) inserted. Results: CBCT images demonstrated temporal bone anatomy and the extent of cochlear obliteration as clearly as conventional CT in all cases. Intraoperative CBCT guided drilling and facilitated electrode placement in two of five heads (3 of 10 ears). Streak-artifact from the electrodes of two devices partially obscured image clarity. Conclusions: The obliterated cochlear model reproduced a disease-ossified cochlear both radiographically and surgically. CBCT is useful for intraoperative imaging to facilitate electrode array placement in the obliterated or congenitally abnormal cochlea.
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Jeong, Sung-Wook, e Lee-Suk Kim. "A New Classification of Cochleovestibular Malformations and Implications for Predicting Speech Perception Ability after Cochlear Implantation". Audiology and Neurotology 20, n. 2 (2015): 90–101. http://dx.doi.org/10.1159/000365584.
Testo completoAbstract (sommario):
Objectives: The aims of this study were to introduce a new classification of cochleovestibular malformation (CVM) and to investigate how well this classification can predict speech perception ability after cochlear implantation in children with CVM. Methods: Fifty-nine children with CVM who had used a cochlear implant for more than 3 years were included. CVM was classified into 4 subtypes based on the morphology of the cochlea and the modiolus on temporal bone computed tomography (TBCT): normal cochlea and normal modiolus (type A, n = 16), malformed cochlea and partial modiolus (type B, n = 31), malformed cochlea and no modiolus (type C, n = 6), and no cochlea and no modiolus (type D, n = 6). Speech perception test scores were compared between the subtypes of CVM using analysis of covariance with post hoc Bonferroni test. Univariate and multivariate regression analyses were used to identify the significant predictors of the speech perception test scores. Results: The speech perception test scores after implantation were significantly better in children with CVM type A or type B than in children with CVM type C or type D. The test scores did not differ significantly between the implanted children with CVM type A or type B and those without CVM. In univariate regression analysis, the type of CVM was a significant predictor of the speech perception test scores in implanted children with CVM. Multivariate regression analysis revealed that the age at cochlear implantation, cochlear nerve size and preimplantation speech perception test scores were significant predictors of the postimplantation speech perception test scores. The chance of cochlear nerve deficiency increased progressively from CVM type A to type D. Conclusion: The new classification of CVM based on the morphology of the cochlea and the modiolus is simple and easy to use, and correlated well with postimplantation speech perception ability and cochlear nerve status. This simple classification of CVM using TBCT with cochlear nerve assessment by magnetic resonance imaging is helpful in the preoperative evaluation of children with CVM.
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Perényi, Ádám, Roland Nagy, Bence Horváth, Bálint Posta, Balázs Dimák, Miklós Csanády, József Géza Kiss e László Rovó. "Új műtéti képalkotó lehetőség a belsőfül-implantátum elektródasorának dinamikus helyzetmeghatározására". Orvosi Hetilap 162, n. 22 (30 maggio 2021): 878–83. http://dx.doi.org/10.1556/650.2021.32085.
Testo completoAbstract (sommario):
Összefoglaló. Bevezetés: A cochlearis implantátum egy műtétileg behelyezett elektromos eszköz, amely az akusztikus hanghullámokat elektromos jelekké alakítja, közvetlenül a hallóideget stimulálja, így segíti a súlyos fokú hallássérüléssel vagy teljes hallásvesztéssel élők életét. Cochlearis implantációt követően a legjobb rehabilitációs eredmény elérésének technikai feltétele többek között az esetre szabott elektródaválasztás és az elektródasor teljes, kontrollált, szövődménymentes bejuttatása a scala tympaniba, miközben a cochlea belső struktúrája a lehető legkisebb mértékben sérül. A rutin intraoperatív elektrofiziológiai tesztek fontos információt adnak a készülék működőképességéről és a hallóideg stimulációjáról, azonban nem hagyatkozhatunk rájuk az elektródasor cochleán belüli helyzetének igazolásában. Mivel előfordulhat, hogy a rendelkezésre álló elektrofiziológiai vizsgálatok eredménye megfelelő, és mégis rendellenes helyzetbe kerül az elektróda, az arany standardot a képalkotó vizsgálatok jelentik. Módszer: Közleményünkben egy modern, hibrid műtő által nyújtott technológiai háttér új alkalmazási területét mutatjuk be. Szimultán kétoldali cochlearis implantációt végeztünk Cochlear Nucleus Slim Modiolar típusú perimodiolaris elektródasorral, a belső fül fejlődési rendellenességével rendelkező betegen. Az intraoperatív képalkotást Siemens Artis pheno C-karos robot digitális szubtrakciós angiográfiás rendszer biztosította valós idejű átvilágító és volumentomográfiás funkcióval. Eredmények: Az intraoperatív képalkotás által dinamikusan követhető az elektródasor bevezetésének folyamata, ellenőrizhető az elektródasor statikus helyzete, így kiváltható a rutinnak számító posztoperatív képalkotó vizsgálat. A rendellenes helyzetbe kerülő elektródasor pozíciója egy ülésben korrigálható, az újból bevezethető, így elkerülhető az újabb altatással járó, bizonytalan kimenetelű revíziós műtét. Következtetés: A hibrid műtő jól kontrollált, minimálisan invazív eljárások elvégzését biztosítja. Különösen a hallószerv fejlődési rendellenessége vagy egyéb, az elektródának a cochleába vezetését nehezítő rendellenesség esetén javasolt a műtői képalkotó diagnosztika. Orv Hetil. 2021; 162(22): 878–883. Summary. Introduction: The cochlear implant is a surgically inserted electrical device that converts acoustic sound waves into electrical signals to stimulate the cochlear nerve, thus helps the rehabilitation of people with severe to total hearing loss. One of the most important technical conditions for achieving the best rehabilitation result after cochlear implantation is the personalized choice of electrodes. Additionally, it is vital that there is a complete, controlled, uncomplicated delivery of the electrode array to the scala tympani while minimizing damage to the inner structures of the cochlea. Routine electrophysiological tests provide important information about device functionality and auditory nerve stimulation. However, they probably do not show an abnormal position of the electrode array within the cochlea. Thus, imaging studies remain the gold standard. Method: In our paper, we present a novel application field of the modern technological background provided by a hybrid operating room. Simultaneous bilateral cochlear implantation was performed with cochlear implants with perimodiolar electrode array (Nucleus Slim Modiolar) in a patient with cochlear malformation. Intraoperative imaging was provided by a Siemens Artis pheno C-arm robot digital subtraction angiography system with real-time fluoroscopy and volume tomography function. Results: Intraoperative imaging ensures dynamic follow-up of the introduction and static determination of the position of the electrode array and replaces routine postoperative imaging. If the electrode array was inserted in an abnormal position, the revision can be performed in the same sitting. Also, the revision surgery with a potential risk of uncertain outcome, alongside additional anaesthesia, can be prevented. Conclusion: The hybrid operating room ensures that well-controlled, minimally invasive procedures are performed. Intraoperative imaging can be imperative in malformed cochleae and conditions that may complicate electrode insertion. Orv Hetil. 2021; 162(22): 878–883.
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Xu, D.-Y., Q.-X. Zhang, Y.-Q. Ma, X.-L. Zheng e S.-X. Liu. "Immunohistochemical localisation of endothelin receptor subtypes in the cochlear lateral wall". Journal of Laryngology & Otology 124, n. 10 (8 giugno 2010): 1073–77. http://dx.doi.org/10.1017/s0022215110001428.
Testo completoAbstract (sommario):
AbstractObjective:Endothelin has many biological activities, including regulation of the functions of the cochlear lateral wall. The present study aimed to analyse the expression of endothelin receptors in the cochlear lateral wall, and to investigate the significance of such receptors in maintaining the homeostatic environment of the cochlea.Methods:The cochleae of healthy guinea pigs were fixed, decalcified, embedded in paraffin and serially sectioned. Expression of the endothelin receptor subunits A and B in the cochlear lateral wall was examined using an immunohistochemical technique.Results:Different degrees of endothelin receptor subunit A and endothelin receptor subunit B like activity were found distributed in the cells of the cochlear lateral wall.Conclusion:These findings support the theory that endothelin, via its receptors, plays an important role in maintaining the homeostatic environment of the cochlea.
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Carswell, V., J. A. Crowther, R. Locke, W. Taylor e G. Kontorinis. "Cochlear patency following translabyrinthine vestibular schwannoma resection: implications for hearing rehabilitation". Journal of Laryngology & Otology 133, n. 7 (luglio 2019): 560–65. http://dx.doi.org/10.1017/s0022215119001087.
Testo completoAbstract (sommario):
AbstractObjectiveTo examine when cochlear fibrosis occurs following a translabyrinthine approach for vestibular schwannoma resection, and to determine the safest time window for potential cochlear implantation in cases with a preserved cochlear nerve.MethodsThis study retrospectively reviewed the post-operative magnetic resonance imaging scans of patients undergoing a translabyrinthine approach for vestibular schwannoma resection, assessing the fluid signal within the cochlea. Cochleae were graded based on the Isaacson et al. system (from grade 0 – no obstruction, to grade 4 – complete obliteration).ResultsThirty-nine patients fulfilled the inclusion criteria. The cochleae showed no evidence of obliteration in: 75 per cent of patients at six months, 38.5 per cent at one year and 27 per cent beyond one year. Most changes happened between 6 and 12 months after vestibular schwannoma resection, with cases of an unobstructed cochlear decreasing dramatically, from 75 per cent to 38.5 per cent, within this time.ConclusionThe progress of cochlear obliteration that occurred between 6 and 12 months following vestibular schwannoma resection indicates that the first 6 months provides a safer time window for cochlear patency.
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Massager, Nicolas, Ouzi Nissim, Carine Delbrouck, Isabelle Delpierre, Daniel Devriendt, Françoise Desmedt, David Wikler, Jacques Brotchi e Marc Levivier. "Irradiation of cochlear structures during vestibular schwannoma radiosurgery and associated hearing outcome". Journal of Neurosurgery 107, n. 4 (ottobre 2007): 733–39. http://dx.doi.org/10.3171/jns-07/10/0733.
Testo completoAbstract (sommario):
Object The purpose of this study was to measure the dose of radiation delivered to the cochlea during a Gamma knife surgery (GKS) procedure for treatment of patients with vestibular schwannomas (VSs), and to analyze the relationship between cochlear irradiation and the hearing outcome of these patients. Methods Eighty-two patients with VSs were treated with GKS using a marginal dose of 12 Gy. No patient had neurofibromatosis Type 2 disease, and all had a Gardner–Robertson hearing class of I to IV before treatment, and a radiological and audiological follow-up of at least 1-year after GKS. The dosimetric data of the volume of the cochlea were retrospectively analyzed and were correlated with the auditory outcome of patients. Results The mean radiation dose delivered to the cochlear volume ranged from 1.30 to 10.00 Gy (median 4.15 Gy). The cochlea received significantly higher radiation doses in patients with worsening of hearing after GKS. A highly significant association between the cochlear and the intracanalicular dose of radiation delivered during GKS was found. Conclusions During GKS for VSs, relatively high doses of radiation can be delivered to the cochlea. Worsening of hearing after GKS can be the consequence of either radiation injury to the cochlea or the irradiation dose delivered into the auditory canal, or both.
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Kuzovkov, V. E., A. S. Lilenko, S. B. Sugarova, V. A. Tanaschishina, P. R. Kharitonova e Yu S. Korneva. "Preoperative and intraoperative measurements of ossification length of cochlea canal". Russian Otorhinolaryngology 23, n. 1 (2024): 31–36. http://dx.doi.org/10.18692/1810-4800-2024-1-31-36.
Testo completoAbstract (sommario):
Cochlear implantation is a high-tech method of rehabilitation of patients with progressive hearing loss, up to deafness. Ossification of the cochlear spiral canal is no longer considered a surgical contraindication for cochlear implantation (CI). However, performing the surgical stage of CI in patients with ossification of the cochlea spiral canal may be accompanied by a number of difficulties. The advanced process of ossification and remodeling can lead to significant difficulty in inserting the electrode into the cochlea, leading to the risk of incomplete insertion. Today, the introduction of an electrode represents the greatest problem during ossification or remodeling of the cochlea since it carries the risk of complications and determines the prospects for subsequent rehabilitation. In addition to incomplete insertion of the electrode, special attention is paid to possible post-implantation stimulation of the facial nerve. Despite the achievement of significant results in the development of surgical techniques for the cochlea ossification management, there are still frequent discrepancies in the assessment of the length of the ossification of the descending segment of the basal coil according to the temporal bones computed tomography (CT) performed at the preoperative stage and the results of intraoperative assessment of the length of the ossification area of the cochlea spiral canal.
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Kim, Seong Min, Ho Yun Lee, Han Kyu Kim e Joseph M. Zabramski. "Cochlear line: a novel landmark for hearing preservation using the anterior petrosal approach". Journal of Neurosurgery 123, n. 1 (luglio 2015): 9–13. http://dx.doi.org/10.3171/2014.12.jns132840.
Testo completoAbstract (sommario):
OBJECT The goal of this study was to develop a practical landmark for the safe and easy identification of the cochlea when performing anterior petrosectomy based on cadaver dissection results. METHODS The cochlear line was defined as the line drawn from the crossing point between the greater superficial petrosal nerve (GSPN) and the petrous internal carotid artery to the line drawn over the apex of the superior circumference of the dura of the internal auditory canal at a right angle. The validity of the cochlear line marking the anteromedial perimeter of the cochlea at the angle of the GSPN and the internal acoustic canal as a practical landmark were evaluated using 5 cadaver heads. RESULTS The mean distance (± SD) measured from the cochlear line to the margin of the cochlear cavity was 2.25 ± 0.51 mm (range 1.50–3.00 mm). CONCLUSIONS Anterior petrosectomy can be performed more efficiently by using the cochlear line as a key landmark to preserve the cochlea.
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Swain, Santosh Kumar. "Vertigo following cochlear implantation: a review". International Journal of Research in Medical Sciences 10, n. 2 (29 gennaio 2022): 572. http://dx.doi.org/10.18203/2320-6012.ijrms20220310.
Testo completoAbstract (sommario):
Cochlear implantation may cause a detrimental effect on vestibular function and residual hearing. A significant number of patients with a cochlear implant present with vertigo. There are several mechanisms for dizziness following cochlear implantations. The causes may be surgical trauma, disruption of normal cochlear physiology, or ensuing endolymphatic hydrops. Vibratory trauma affecting the cochlea during cochleostomy plays a vital role in causing paroxysmal vertigo in patients with a cochlear implant. In addition, the vibrations affecting the cochlea are enough to dislodge otoconia particles. During cochlear implantation, it is necessary to insert an electrode array into the cochlea and thus the chance of damage to cochlear and function may happen. Dizziness or vertigo may develop after cochlear implantation. It usually occurs due to vestibular hypofunction. Vertigo following cochlear implantation has not frequently been documented in the literature previously. However, the increasing number of cochlear implantations in the current scenario is showing different postoperative complications like vestibular symptoms among patients with an implant. The vestibular symptoms following cochlear implantation range from a gradual sense of mild unsteadiness or lightheadedness to brief attacks of whirling vertigo. Vertigo following cochlear implantations affects the quality of life although vestibular therapy is often helpful to manage this condition. The article aims to provide a comprehensive review of vertigo following cochlear implantation.
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Hang, Jianfeng, Wenlu Pan, Aoshuang Chang, Shun Li, Cuixian Li, Mingyu Fu e Jie Tang. "Synchronized Progression of Prestin Expression and Auditory Brainstem Response during Postnatal Development in Rats". Neural Plasticity 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/4545826.
Testo completoAbstract (sommario):
Prestin is the motor protein expressed in the cochlear outer hair cells (OHCs) of mammalian inner ear. The electromotility of OHCs driven by prestin is responsible for the cochlear amplification which is required for normal hearing in adult animals. Postnatal expression of prestin and activity of OHCs may contribute to the maturation of hearing in rodents. However, the temporal and spatial expression of prestin in cochlea during the development is not well characterized. In the present study, we examined the expression and function of prestin from the OHCs in apical, middle, and basal turns of the cochleae of postnatal rats. Prestin first appeared at postnatal day 6 (P6) for basal turn, P7 in middle turn, and P9 for apical turn of cochlea. The expression level increased progressively over the next few days and by P14 reached the mature level for all three segments. By comparison with the time course of the development of auditory brainstem response for different frequencies, our data reveal that prestin expression synchronized with the hearing development. The present study suggests that the onset time of hearing may require the expression of prestin and is determined by the mature function of OHCs.
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Köles, László, Judit Szepesy, Eszter Berekméri e Tibor Zelles. "Purinergic Signaling and Cochlear Injury-Targeting the Immune System?" International Journal of Molecular Sciences 20, n. 12 (18 giugno 2019): 2979. http://dx.doi.org/10.3390/ijms20122979.
Testo completoAbstract (sommario):
Hearing impairment is the most common sensory deficit, affecting more than 400 million people worldwide. Sensorineural hearing losses currently lack any specific or efficient pharmacotherapy largely due to the insufficient knowledge of the pathomechanism. Purinergic signaling plays a substantial role in cochlear (patho)physiology. P2 (ionotropic P2X and the metabotropic P2Y) as well as adenosine receptors expressed on cochlear sensory and non-sensory cells are involved mostly in protective mechanisms of the cochlea. They are implicated in the sensitivity adjustment of the receptor cells by a K+ shunt and can attenuate the cochlear amplification by modifying cochlear micromechanics. Cochlear blood flow is also regulated by purines. Here, we propose to comprehend this field with the purine-immune interactions in the cochlea. The role of harmful immune mechanisms in sensorineural hearing losses has been emerging in the horizon of cochlear pathologies. In addition to decreasing hearing sensitivity and increasing cochlear blood supply, influencing the immune system can be the additional avenue for pharmacological targeting of purinergic signaling in the cochlea. Elucidating this complexity of purinergic effects on cochlear functions is necessary and it can result in development of new therapeutic approaches in hearing disabilities, especially in the noise-induced ones.
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Schurzig, Daniel, Max Eike Timm, Cornelia Batsoulis, Rolf Salcher, Daniel Sieber, Claude Jolly, Thomas Lenarz e Masoud Zoka-Assadi. "A Novel Method for Clinical Cochlear Duct Length Estimation toward Patient-Specific Cochlear Implant Selection". OTO Open 2, n. 4 (ottobre 2018): 2473974X1880023. http://dx.doi.org/10.1177/2473974x18800238.
Testo completoAbstract (sommario):
Objective In the field of cochlear implantation, the current trend toward patient-specific electrode selection and the achievement of optimal audiologic outcomes has resulted in implant manufacturers developing a large portfolio of electrodes. The aim of this study was to bridge the gap between the known variability of cochlea length and this electrode portfolio. Design Retrospective analysis on cochlear length and shape in micro–computed tomography and cone beam computed tomography data. Setting Tertiary care medical center. Subjects and Methods A simple 2-step approach was developed to accurately estimate the individual cochlear length as well as the projected length of an electrode array inside the cochlea. The method is capable of predicting the length of the cochlea and the inserted electrode length at any specific angle. Validation of the approach was performed with 20 scans of human temporal bones (micro–computed tomography) and 47 pre- and postoperative clinical scans (cone beam computed tomography). Results Mean ± SD absolute errors in cochlear length estimations were 0.12 ± 0.10 mm, 0.38 ± 0.26 mm, and 0.71 ± 0.43 mm for 1, 1.5, and 2 cochlea turns, respectively. Predicted insertion angles based on clinical cone beam computed tomography data showed absolute deviations of 27° ± 18° to the corresponding postoperative measurements. Conclusion With accuracy improvements of 80% to 90% in comparison with previously proposed approaches, the method is well suited for the use in individualized cochlear implantation.
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Honda, Tomoko, Norihito Kawasaki, Rei Yanagihara, Ryo Tamura, Karin Murakami, Tomomi Ichimiya, Naoki Matsumoto, Shoko Nishihara e Kazuo Yamamoto. "Involvement of cochlin binding to sulfated heparan sulfate/heparin in the pathophysiology of autosomal dominant late-onset hearing loss (DFNA9)". PLOS ONE 17, n. 7 (28 luglio 2022): e0268485. http://dx.doi.org/10.1371/journal.pone.0268485.
Testo completoAbstract (sommario):
Late-onset non-syndromic autosomal dominant hearing loss 9 (DFNA9) is a hearing impairment caused by mutations in the coagulation factor C homology gene (COCH). COCH encodes for cochlin, a major component of the cochlear extracellular matrix. Though biochemical and genetic studies have characterized the properties of wild-type and mutated cochlins derived from DFNA9, little is known about the underlying pathogenic mechanism. In this study, we established a cochlin reporter cell, which allowed us to monitor the interaction of cochlin with its ligand(s) by means of a β-galactosidase assay. We found a class of highly sulfated glycosaminoglycans (GAGs), heparin, that were selectively bound to cochlin. The interaction was distinctly abrogated by N-desulfation, but not by 2-O- or 6-O-desulfation. The binding of cochlin to GAG was diminished by all of the point mutations found in DFNA9 patients. Through GAG composition analysis and immunostaining using mouse cochlin/immunoglobulin-Fc fusion protein, we identified moderately sulfated GAGs in mouse cochlea tissue; this implies that cochlin binds to such sulfated GAGs in the cochlea. Since GAGs play an important role in cell growth and survival as co-receptors of signal transduction mechanisms, the interaction of cochlin with GAGs in the extracellular matrix could aid the pathological research of autosomal dominant late-onset hearing loss in DFNA9.
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Ren, DongDong, JingWU Sun, GuangLun Wan, Feng Yang e Fang Shen. "Influence of carbon dioxide laser irradiation on the morphology and function of guinea pig cochlea". Journal of Laryngology & Otology 119, n. 9 (settembre 2005): 684–92. http://dx.doi.org/10.1258/0022215054797899.
Testo completoAbstract (sommario):
Both experimental and clinical studies have demonstrated that carbon dioxide laser is suitable for stapedotomy. The aim of this study was to investigate morphological, electrophysiological and functional changes in the inner ear after irradiation with CO2 laser set with different energy parameters.A cochleostomy in the basal cochlear turn of guinea pig cochleae was performed with CO2 laser of 1, 2 and 3 w, respectively. The cochleae were removed three weeks after laser irradiation. The auditory evoked brainstem response (ABR) was measured before and after laser application and immediately before removal of the cochlea. Immunohistochemical methods were used to examine inducible nitric oxide synthase (iNOS/NOSII) and heat-shock protein 70(Hsp70) concentrations in the cochlea after laser application. The organ of Corti was studied by scanning electron microscopy.Worse hearing loss was observed in animals receiving higher-power CO2 laser. These findings correlated with more intense injury of the cochlear ultrastructure and with positiveexpression of iNOS and Hsp70 in spiral ganglion cells, nerve fibres, supporting cells of the organ of Corti and cells of the spiral ligament.The CO2 laser as a noncontact procedure is shown to be effective and safe if the total amount of energy is kept within the limits applied in this study. Nitric oxide and stressproteins play important roles in the traumatic mechanism of the inner ear, which are related tohearing loss and injury of the ultrastructure of the inner ear.
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Fernando, Adrian F., Brian Joseph dG De Jesus, Alejandro P. Opulencia, Gil M. Maglalang e Antoio H. Chua. "An Anatomical Study of the Cochlea among Filipinos using High-Resolution Computed Tomography Scans". Philippine Journal of Otolaryngology-Head and Neck Surgery 26, n. 1 (27 giugno 2011): 6–9. http://dx.doi.org/10.32412/pjohns.v26i1.591.
Testo completoAbstract (sommario):
Objective: To describe the cochlear anatomy among Filipinos through high resolution computed
tomography (HRCT) imaging.
Methods:
Design: Retrospective Study
Setting: Tertiary Private University Hospital
Patients: Cochlear images retrospectively obtained from computed tomography (CT) scans of subjects who underwent cranial, facial, paranasal sinus and temporal bone computed tomography from October 2009 to July 2010 were reconstructed and analyzed.
Results: 388 cochlear images were obtained from the scans of 194 subjects (101 males and 93 females, aged 1 to 90 years old, mean = 52 years) and reconstructed for analysis. The mean coiled cochlear height measured 4.36 mm on the right (A.D.) and 4.34 mm on the left (A.S.). Measurement from the oval window to the distal end of the basal turn (equivalent to the horizontal dimension of the cochlea or the mean length of the basal turn) was 7.55 mm A.D. and 7.60 mm A.S. The vertical and horizontal dimensions of right and left cochleas were identical in all subjects (S.D. = 0.35). The right and left cochlear turns were identical in each subject, exhibiting 2 ½ turns in 92.3% of subjects and 2 ¾ turns in 7.7% of subjects.The cochlear dimensions were similar in all subjects, regardless of age. No cochlear ossification or malformation was noted on any CT image.
Conclusion: The 7.55 mm mean length of the cochlear basal turn among Filipinos in this study was 1.24 mm shorter than the average length of the basal turn of 8.81 mm reported elsewhere. Further studies of the cochlear dimensions in specific age groups and its correlation to audiometric status are recommended to determine other significant physiologic correlations.
Keywords: cochlea, cochlear turn, high-resolution computed tomography (HRCT), magnetic resonance imaging (MRI)
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Bassiouni, Mohamed, Alina Smorodchenko, Heidi Olze e Agnieszka J. Szczepek. "Identification and Characterization of TMEM119-Positive Cells in the Postnatal and Adult Murine Cochlea". Brain Sciences 13, n. 3 (20 marzo 2023): 516. http://dx.doi.org/10.3390/brainsci13030516.
Testo completoAbstract (sommario):
Transmembrane protein 119 (TMEM119) is expressed in a subset of resident macrophage cells of the brain and was proposed as a marker for native brain microglia. The presence of cells expressing TMEM119 in the cochlea has not yet been described. Thus, the present study aimed to characterize the TMEM119-expressing cells of the postnatal and adult cochlea, the latter also after noise exposure. Immunofluorescent staining of cochlear cryosections detected TMEM119 protein in the spiral limbus fibrocytes and the developing stria vascularis at postnatal Day 3. Applying the macrophage marker Iba1 revealed that TMEM119 is not a marker of cochlear macrophages or a subset of them. In the adult murine cochlea, TMEM119 expression was detected in the basal cells of the stria vascularis and the dark mesenchymal cells of the supralimbal zone. Exposure to noise trauma was not associated with a qualitative change in the types or distributions of the TMEM119-expressing cells of the adult cochlea. Western blot analysis indicated a similar TMEM119 protein expression level in the postnatal cochlea and brain tissues. The findings do not support using TMEM119 as a specific microglial or macrophage marker in the cochlea. The precise role of TMEM119 in the cochlea remains to be investigated through functional experiments. TMEM119 expression in the basal cells of the stria vascularis implies a possible role in the gap junction system of the blood–labyrinth barrier and merits further research.
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XU, LIFU, XINSHENG HUANG, NA TA, ZHUSHI RAO e JIABIN TIAN. "FINITE ELEMENT MODELING OF THE HUMAN COCHLEA USING FLUID–STRUCTURE INTERACTION METHOD". Journal of Mechanics in Medicine and Biology 15, n. 03 (giugno 2015): 1550039. http://dx.doi.org/10.1142/s0219519415500396.
Testo completoAbstract (sommario):
In this paper, a 3D finite element (FE) model of human cochlea is developed. This passive model includes the structure of oval window, round window, basilar membrane (BM) and cochlear duct which is filled with fluid. Orthotropic material property of the BM is varying along its length. The fluid–structure interaction (FSI) method is used to compute the responses in the cochlea. In particular, the viscous fluid element is adopted for the first time in the cochlear FE model, so that the effects of shear viscosity in the fluid are considered. Results on the cochlear impedance, BM response and intracochlear pressure are obtained. The intracochlear pressure includes the scala vestibule and scala tympani pressure are extracted and used to calculate the transfer functions from equivalent ear canal pressures to scala pressures. The reasonable agreements between the model results and the experimental data in the literature prove the validity of the cochlear model for simulating sound transmission in the cochlea. Moreover, this model predicted the transfer function from equivalent ear canal pressures to scala pressures which is the input to the cochlear partition.
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Uenaka, Miku, Hidekazu Nagamura, Aya Okamoto, Shizuko Hiryu, Kohta I. Kobayasi e Yuta Tamai. "Feasibility evaluation of transtympanic laser stimulation of the cochlea from the outer ear". Journal of the Acoustical Society of America 152, n. 3 (settembre 2022): 1850–55. http://dx.doi.org/10.1121/10.0014241.
Testo completoAbstract (sommario):
Infrared laser stimulation has been studied as an alternative approach to auditory prostheses. This study evaluated the feasibility of infrared laser stimulation of the cochlea from the outer ear, bypassing the middle ear function. An optic fiber was inserted into the ear canal, and a laser was used to irradiate the cochlea through the tympanic membrane in Mongolian gerbils. A pulsed infrared laser (6.9 mJ/cm2) and clicking sound (70 peak-to-peak equivalent sound pressure level) were presented to the animals. The amplitude of the laser-evoked cochlear response was systematically decreased following insertion of a filter between the tympanic membrane and cochlea; however, the auditory-evoked cochlear response did not decrease. The filter was removed, and the laser-evoked response returned to around the original level. The amplitude ratio and the relative change in response amplitude before and during filter insertion significantly decreased as the absorbance of the infrared filter increased. These results indicate that laser irradiation could bypass the function of the middle ear and directly activate the cochlea. Therefore, laser irradiation from the outer ear is a possible alternative for stimulating the cochlea, circumventing the middle ear.
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Balkany, Thomas, Annelle V. Hodges, Martin Whitehead, Faramarz Memari e Glen K. Martin. "Cochlear Endoscopy with Preservation of Hearing in Guinea Pigs". Otolaryngology–Head and Neck Surgery 111, n. 4 (ottobre 1994): 439–45. http://dx.doi.org/10.1177/019459989411100408.
Testo completoAbstract (sommario):
Advances in fiberoptic technology have revolutionized the way many disorders are treated by otolaryngologists. We have previously described our experiences with cochlear endoscopy during cochlear Implantation. However, endoscopy of the functioning cochlea has not previously been reported. To test the hypothesis that endoscopy of the guinea pig cochlea is possible without catastrophic loss of auditory function, we subjected 20 ears of 10 Hartley-strain albino guinea pigs to limited endoscopy of the cochlea through the round window with evaluation of distortion product otoacoustic emissions and auditory brain stem responses. Insertion of the endoscope caused measurable changes in auditory brain stem response latency and amplitude. Distortion product otoacoustic emission amplitudes were reduced an average of 6 dB with greater loss close to the round window. Frequencies above 18 kHz, corresponding to the region of endoscopy, were not evaluated in this preliminary study and are suspected to have sustained more damage. Results demonstrate that endoscopy of the guinea pig cochlea is possible without major loss of the above physiologic measures in the regions tested. If endoscopy of the cochlea is to become a tool with clinical and basic science applications, refinements in techniques to avoid damage are necessary.
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Wang, Jian, Fumitaka Yoshioka, Wonil Joo, Noritaka Komune, Vicent Quilis-Quesada e Albert L. Rhoton. "The cochlea in skull base surgery: an anatomy study". Journal of Neurosurgery 125, n. 5 (novembre 2016): 1094–104. http://dx.doi.org/10.3171/2015.8.jns151325.
Testo completoAbstract (sommario):
OBJECTIVEThe object of this study was to examine the relationships of the cochlea as a guide for avoiding both cochlear damage with loss of hearing in middle fossa approaches and injury to adjacent structures in approaches directed through the cochlea.METHODSTwenty adult cadaveric middle fossae were examined using magnifications of ×3 to ×40.RESULTSThe cochlea sits below the floor of the middle fossa in the area between and below the labyrinthine segment of the facial nerve and greater petrosal nerve (GPN) and adjacent to the lateral genu of the petrous carotid. Approximately one-third of the cochlea extends below the medial edge of the labyrinthine segment of the facial nerve, geniculate ganglion, and proximal part of the GPN. The medial part of the basal and middle turns are the parts at greatest risk in drilling the floor of the middle fossa to expose the nerves in middle fossa approaches to the internal acoustic meatus and in anterior petrosectomy approaches. Resection of the cochlea is used selectively in extending approaches through the mastoid toward the lateral edge of the clivus and front of the brainstem.CONCLUSIONSAn understanding of the location and relationships of the cochlea will reduce the likelihood of cochlear damage with hearing loss in approaches directed through the middle fossa and reduce the incidence of injury to adjacent structures in approaches directed through the cochlea.
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Richardson, H. C., M. Beliaeff, G. Clarke e M. Hawthorne. "A three-array cochlear implant: a new approach for the ossified cochlea". Journal of Laryngology & Otology 113, n. 9 (settembre 1999): 811–14. http://dx.doi.org/10.1017/s002221510014527x.
Testo completoAbstract (sommario):
AbstractThe ossified cochlea, although rare, represents a challenge for cochlear implantation. While it is no longer considered an absolute contra-indication to implantation, insertion may be technically difficult and the results may be suboptimal. Techniques which have been employed are reviewed. The new Digisonic™ multi-array implant, which was designed specifically for use in the ossified cochlea is described, along with the technique used for its insertion.In the first patient to be implanted with this new implant, all electrodes lie within the cochlea and are functional. The new Digisonic™ multi-array implant may have advantages over other solutions for the ossified cochlea.
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Franz, Burkhard K.-H. G., e Graeme M. Clark. "The surgical anatomy for multiple-electrode extracochlear implant operations". Journal of Laryngology & Otology 102, n. 8 (agosto 1988): 685–88. http://dx.doi.org/10.1017/s0022215100106152.
Testo completoAbstract (sommario):
AbstractDirect access to the whole length of the cochlear turns via endaural middle ear approach for the placement of extracochlear electrodes is severely restricted. Approximately 10 mm. of the cochlear turns are accessible, being less than a third of their length. The middle cranial fossa, the facial nerve, the internal carotid artery and the temporomandibular joint restrict the access. A further restriction is caused by the position of the cochlea and the direction of its axis. The anterior part of the cochlea lies anterior to the tympanic membrane and medial to the temporomandibular joint, thus limiting an endaural approach to a posterolateral direction. Despite this limitation small sections of the basal, middle and apical turns of the cochlea can be reached.
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Vlajkovic, Srdjan M., e Peter R. Thorne. "Purinergic Signalling in the Cochlea". International Journal of Molecular Sciences 23, n. 23 (28 novembre 2022): 14874. http://dx.doi.org/10.3390/ijms232314874.
Testo completoAbstract (sommario):
The mammalian cochlea is the sensory organ of hearing with a delicate, highly organised structure that supports unique operating mechanisms. ATP release from the secretory tissues of the cochlear lateral wall (stria vascularis) triggers numerous physiological responses by activating P2 receptors in sensory, supporting and neural tissues. Two families of P2 receptors, ATP-gated ion channels (P2X receptors) and G protein-coupled P2Y receptors, activate intracellular signalling pathways that regulate cochlear development, homeostasis, sensory transduction, auditory neurotransmission and response to stress. Of particular interest is a purinergic hearing adaptation, which reflects the critical role of the P2X2 receptor in adaptive cochlear response to elevated sound levels. Other P2 receptors are involved in the maturation of neural processes and frequency selectivity refinement in the developing cochlea. Extracellular ATP signalling is regulated by a family of surface-located enzymes collectively known as “ectonucleotidases” that hydrolyse ATP to adenosine. Adenosine is a constitutive cell metabolite with an established role in tissue protection and regeneration. The differential activation of A1 and A2A adenosine receptors defines the cochlear response to injury caused by oxidative stress, inflammation, and activation of apoptotic pathways. A1 receptor agonism, A2A receptor antagonism, and increasing adenosine levels in cochlear fluids all represent promising therapeutic tools for cochlear rescue from injury and prevention of hearing loss.
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Meenderink, Sebastiaan W. F., e Marcel van der Heijden. "Reverse Cochlear Propagation in the Intact Cochlea of the Gerbil: Evidence for Slow Traveling Waves". Journal of Neurophysiology 103, n. 3 (marzo 2010): 1448–55. http://dx.doi.org/10.1152/jn.00899.2009.
Testo completoAbstract (sommario):
The inner ear can produce sounds, but how these otoacoustic emissions back-propagate through the cochlea is currently debated. Two opposing views exist: fast pressure waves in the cochlear fluids and slow traveling waves involving the basilar membrane. Resolving this issue requires measuring the travel times of emissions from their cochlear origin to the ear canal. This is problematic because the exact intracochlear location of emission generation is unknown and because the cochlea is vulnerable to invasive measurements. We employed a multi-tone stimulus optimized to measure reverse travel times. By exploiting the dispersive nature of the cochlea and by combining acoustic measurements in the ear canal with recordings of the cochlear-microphonic potential, we were able to determine the group delay between intracochlear emission-generation and their recording in the ear canal. These delays remained significant after compensating for middle-ear delay. The results contradict the hypothesis that the reverse propagation of emissions is exclusively by direct pressure waves.
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Weddell, Thomas D., Yury M. Yarin, Markus Drexl, Ian J. Russell, Stephen J. Elliott e Andrei N. Lukashkin. "A novel mechanism of cochlear excitation during simultaneous stimulation and pressure relief through the round window". Journal of The Royal Society Interface 11, n. 93 (6 aprile 2014): 20131120. http://dx.doi.org/10.1098/rsif.2013.1120.
Testo completoAbstract (sommario):
The round window (RW) membrane provides pressure relief when the cochlea is excited by sound. Here, we report measurements of cochlear function from guinea pigs when the cochlea was stimulated at acoustic frequencies by movements of a miniature magnet which partially occluded the RW. Maximum cochlear sensitivity, corresponding to subnanometre magnet displacements at neural thresholds, was observed for frequencies around 20 kHz, which is similar to that for acoustic stimulation. Neural response latencies to acoustic and RW stimulation were similar and taken to indicate that both means of stimulation resulted in the generation of conventional travelling waves along the cochlear partition. It was concluded that the relatively high impedance of the ossicles, as seen from the cochlea, enabled the region of the RW not occluded by the magnet, to act as a pressure shunt during RW stimulation. We propose that travelling waves, similar to those owing to acoustic far-field pressure changes, are driven by a jet-like, near-field component of a complex pressure field, which is generated by the magnetically vibrated RW. Outcomes of research described here are theoretical and practical design principles for the development of new types of hearing aids, which use near-field, RW excitation of the cochlea.