Audiology and Neuro-Otology最新文献

Background: Auditory neuropathy (AN) is a nosological entity of unknown etiology, which is associated with fluctuations in rates of speech discrimination. Its diagnosis is based on presence of otoacoustic emissions and lack of, or abnormal, brainstem auditory evoked potential. With respect to treatment, we have variable results in the literature about development of speech perception and skills, in children with AN and cochlear implant (CI) rehabilitation.

Objectives: Comparatively assessing results recorded for the development of auditory and speech skills in children with auditory neuropathy spectrum disorder (ANSD), who were subjected to cochlear implantation, in comparison to results recorded for children with sensorineural hearing loss associated with other causes was the objective of this study.

Method: A systematic literature review with meta-analysis was performed, with studies published from 1975 to 2023.

Results: Nineteen studies were included in the systematic review, and eight were selected for the meta-analysis, which showed there was no evidence allowing the conclusion that the two groups were different from each other about results in speech performance after 1 year of CI placement.

Conclusion: Therefore, this study shows that CI provides the comparable benefit to children with ANSD in comparison to children with neurosensory hearing loss associated with other causes in their speech development.

Introduction: Optimal cochlear implant (CI) outcomes are due to, at least in part, appropriate device programming. Objective measures, such as electrically evoked stapedial reflex thresholds (ESRTs), can be used to more accurately set programming levels. However, underlying factors that contribute to ESRT levels are not well understood. The objective of the current study was to analyze how demographic variables of patient sex and age, along with CI electrode location, influence ESRTs in adult CI recipients.

Methods: A single institution retrospective review was performed. Electronic medical records, CI programming records, and clinic database of postoperative computerized tomography were reviewed to gather information regarding patient demographics, ESRTs, and electrode array metrics including medial-lateral distance and scalar location. Linear mixed models were constructed to determine how demographic variables and electrode position influence ESRTs recorded in 138 adult CI recipients.

Results: ESRTs were significantly affected by recipient age, with older listeners demonstrating higher ESRT levels. On average, males had higher ESRT levels when compared to females. In a subset of the study sample, ESRT levels increased with increasing medial-lateral distance; however, there was not a statistically significant effect of electrode type (lateral/straight arrays compared to perimodiolar arrays). ESRTs were not affected by scalar location.

Discussion/conclusions: The results suggest that key demographic and electrode position characteristics influence the level of ESRTs in adult CI recipients. While ESRTs are widely used to assist with CI programming, underlying factors are not well understood. The significant factors of aging and sex could be due to middle ear mechanics or neural health differences. However, further data are needed to better understand these associations.

Introduction: Mefloquine is an antimalarial medicine used to prevent and treat malaria. This medicine has some side effects, including ototoxicity. This study, which was designed in two phases, aimed to investigate the side effects of mefloquine and evaluate the preventive effects of electrical stimulation on these side effects.

Methods: In the first phase, two doses of mefloquine (50 and 200 μM) were injected into male rats, and after 7 days, they were evaluated by an auditory brainstem response (ABR) test. In the second phase, electrical stimulation was applied for 10 days, and then a toxic dose of mefloquine was injected. Similar to the first phase of the study, the animals were evaluated by an ABR test after 7 days.

Results: In the first phase, the results showed that a high dose of mefloquine increased the ABR threshold and wave I latency; however, these changes were not observed in the second phase.

Conclusion: Application of electrical stimulation could prevent the ototoxic effects of mefloquine. According to the findings of the present study, electrical stimulation can be used as a preconditioner to prevent the ototoxic effects of mefloquine.

Introduction: The prevalence of hearing loss in Canada is high, with many patients requiring implantable hearing devices (IHDs) as treatment for their disease severity. Despite this need, many eligible patients do not pursue these interventions. The objective of this study was to examine rates of IHD based on geographic location to understand locoregional variation in access to care.

Study design: This was a retrospective population-based cohort study.

Setting: All hospitals in the Canadian province of Ontario.

Methods: Of all patients with IHD between April 1, 1992, and March 31, 2021, cochlear implants (CIs) (4,720) and bone-anchored hearing aids (BAHA) (1,125) cohorts were constructed. Place of residence was categorized based on Local Health Integrated Network (LHIN). Summary statistics for place of surgical institution based on LHIN at first surgery, name of institution of first surgery and "as the crow flies" distance (in km) between place of residence and surgical institution were calculated. Rate of implantations was calculated for LHIN regions based on number of surgeries per 1,000,000 persons/years.

Results: Toronto Central, Central, Central East, and Champlain regions had >10% of patients undergoing BAHA and CI. 1,019 (90.6%) and 4,232 (89.7%) of patients receiving BAHA and CI, respectively, resided in urban/suburban regions and 94 patients (8.4%) and 436 (9.2%) resided in rural regions. The median distance between residential location and the institution was 46.4 km (interquartile range [IQR], 18.9-103.6) and 44.7 km (IQR, 15.7-96.9) for BAHA and CI, respectively. From 1992 to 2021, the number of CI and BAHA performed across Ontario increased by 17 folds and 6 folds, respectively.

Conclusion: This large comprehensive population study provides longitudinal insight into the access to care of IHD based on geographic factors. Our findings of the present population-based study indicate an overall increase in access to devices with disproportionate access to care based on geographic locations. Further work is needed to characterize barriers to IHD access to align with demands.

Objective: The purpose of this study was to compare the originally applied frequency allocation of cochlear implant electrodes assigned by default at the time of activation with a more recent frequency allocation that is anatomy-based by a software called OTOPLAN®. Based on a computed tomography scan of the temporal bone, this software calculates the position of each electrode in the cochlea and its corresponding tonotopic frequency. We also evaluated whether patients with a significant mismatch between these two allocations present poorer speech intelligibility.

Materials and methods: Patients who underwent cochlear implantation from 2016 to 2021 at the University Hospital of Liege were included in this retrospective study. We used OTOPLAN® to calculate the tonotopic frequency allocation of each electrode according to its exact position in the cochlear duct. This anatomical frequency mapping was compared with the default frequency mapping at the time of cochlear implant activation. Finally, we compared the mismatch with the patients' auditory performance, represented by the Auditory Capacity Index (ACI).

Results: Thirteen patients were included in the study. All patients had a mismatch between the two frequency maps, to a variable extent (200 Hz-1,100 Hz). Frequency shift was significantly inversely correlated with ACI and with the time needed to improve speech intelligibility.

Conclusion: Our primary results show that patients with a larger mismatch between default frequency mapping and anatomically assigned frequency mapping experience poorer hearing performance and slower adaptation to a cochlear implant.

Introduction: Assessing cochlear implantation's impact on cell loss and preventing post-implant cochlear damage are key areas of focus for hearing preservation research. The preservation of auditory neuronal and sensory neural hearing cells has a positive impact on auditory perception after implantation. This study aimed to provide details on a semi-automated spiral ganglion neuronal cell counting method, developed using whole implanted gerbil cochlea acquisitions with light-sheet microscopy.

Methods: Mongolian gerbils underwent right cochlear implantation with an electrode array whose silicone was loaded with dexamethasone or not and were euthanized 10 weeks after implantation. The cochleae were prepared according to a 29-day protocol, with the electrode array in place. Light-sheet microscopy was used for acquisition, and Imaris software was employed for three-dimensional analysis of the cochleas and semi-automatic quantification of spiral ganglion cells. The imaJ software was used for the manual quantification of these cells.

Results: Six cochleae were acquired by light-sheet microscopy, allowing good identification of cells. There was no significant difference between the mean number of spiral ganglion cells obtained by manual and semi-automatic counting (p = 0.25).

Conclusion: Light-sheet microscopy provided complete visualization of the spiral ganglion and cell identification. The semi-automated counting method developed using Imaris software tools proved reliable and efficient and could be applied to a larger sample to assess post-cochlear implant cell damage and the efficacy of protective drugs delivered to the inner ear.

Introduction: Mild therapeutic hypothermia (MTH) is an exciting nonpharmaceutical otoprotection strategy. In this study, we applied simple irrigation of the tympanic and mastoid cavities to understand the timing of both achieving MTH and recovery back to euthermic temperatures for application in the clinical setting.

Methods: Three human temporal bones were used in this study in the temporal bone laboratory. A standard mastoidectomy was performed on each followed by the insertion of temperature probes into the basal turn of the cochlea via a middle cranial fossa approach. The temporal bones were warmed in heated bead baths to 37°C. The tympanic and mastoid cavities were then irrigated with room temperature water, and intracochlear temperature readings were recorded every minute. After 15 min, irrigation was stopped, and temperature readings were collected until temporal bones returned to euthermic levels.

Results: Intracochlear MTH was achieved within the first minute of irrigating the tympanic and mastoid cavities. Intracochlear temperatures plateaued after 5 min around 30°C. Discontinuation of irrigation resulted in the temperature rising logarithmically above the MTH levels after 9-10 min.

Conclusion: Intracochlear MTH can be achieved via irrigation of the tympanic and mastoid cavities with room temperature irrigation within 60 s. After irrigation for 5 min, hypothermic temperatures will remain therapeutic for 10 min following cessation of irrigation.

Background: Many studies have shown increased academic problems in children with unilateral hearing loss (UHL). However, whether hearing devices can ameliorate the educational difficulties associated with UHL is not well studied. Therefore, the objective of the current systematic review was to answer the question: do nonsurgical amplification devices, bone-anchored hearing aids, and/or cochlear implants improve academic outcomes in school-aged children and adolescents with UHL?

Methods: Embase, MEDLINE, Scopus, CINAHL, APA PsycInfo, ClinicalTrials.gov, and Cochrane databases were searched from inception to December 21, 2022. Published, peer-reviewed studies comparing academic outcomes in patients with UHL aged ≥5 and ≤19 years with and without hearing devices (nonsurgical amplification devices, bone-anchored hearing aids, or cochlear implants) were included. Results of studies were qualitatively synthesized, and the risk of bias was evaluated with the Effective Public Health Practice Project (EPHPP) Quality Assessment Tool.

Results: A total of 5,644 non-duplicate publications were identified by the search, and four studies were included for synthesis, every one of which was investigating nonsurgical amplification. One small, single-arm study demonstrated significant improvement in subjective classroom listening difficulties after a 3- to 4-month trial with a behind-the-ear hearing aid. The other three studies of nonsurgical amplification devices showed no benefit across multiple academic outcomes with FM systems and conventional and CROS-style hearing aids.

Discussion: The small sample sizes, heterogeneous and/or ill-defined study samples, and overall low quality of the available literature ultimately make it hard to draw definitive conclusions regarding nonsurgical amplification devices' effectiveness in improving academic outcomes in children with UHL. No articles were identified that studied cochlear implants or bone-anchored hearing aids. Further studies with high-quality study design, large sample sizes, and long-term follow-up are needed to answer this clinically important question.

Background: Correct individual tonotopic frequency stimulation of the cochlea plays an important role in the further development of anatomy-based cochlear implantation. In this context, frequency-specific fitting of the basal electrode contact with a normal insertion depth can be difficult since it is often placed in a frequency range higher than 10 kHz, and current audio processors only stimulate for frequencies up to 8.5 kHz due to microphone characteristics. This results in a mismatch of the high frequencies. Therefore, this study represents a proof of concept for a tonotopic correct insertion and aims to develop an algorithm for a placement of the basal electrode below 8.5 kHz in an experimental setting.

Methods: Pre- and postoperative flat-panel volume CT scans with secondary reconstructions were performed on 10 human temporal bone specimens. The desired frequency location for the most basal electrode contact was set at 8.25 kHz. The distance from the round window to the position where the basal electrode contact was intended to be located was calculated preoperatively using 3D-curved multiplanar reconstruction and a newly developed mathematical approach. A specially designed cochlear implant electrode array with customized markers imprinted on the silicone of the electrode array was inserted in all specimens based on the individually calculated insertion depths. All postoperative measurements were additionally validated using otological planning software.

Results: Positioning of the basal electrode contact was reached with only a small mean deviation of 37 ± 399 Hz and 0.06 ± 0.37 mm from the planned frequency of 8.25 kHz. The mean rotation angle up to the basal electrode contact was 51 ± 5°. In addition, the inserted electrode array adequately covered the apical regions of the cochleae.

Conclusion: Using this algorithm, it was possible to position the basal electrode array contact in an area of the cochlea that could be correctly stimulated by the existing speech processors in the context of tonotopic correct fitting.

Introduction: Gap detection tests are crucial clinical tools for identifying auditory processing disorders that result from abnormalities in the central auditory nervous system. These tests assess the ability to resolve temporal information in sounds, which aids in the diagnosis of auditory temporal processing issues. This study explores the directional effects of marker frequencies on gap detection tasks with respect to the conditions of long and short frequency disparity (separation).

Methods: We measured the gap detection thresholds (GDTs) using four across-channel narrowband noise conditions (1-2, 2-1, 1-4, and 4-1 kHz). A within-subject study design involved 29 healthy individuals with normal hearing. Stimuli were presented monaurally using headphones routed via a calibrated audiometer.

Results: The condition with long frequency disparity and a low leading frequency (1-4 kHz) exhibited higher GDTs compared to the other across-channel conditions. However, we did not observe this effect in the other condition with long frequency disparity and a high leading frequency (4-1 kHz), which did not show significant differences from the two conditions with short frequency disparity.

Conclusion: The study findings suggest that the combined effects of the spectral characteristics of the gap markers, including frequency disparity and order of presentation, influence the temporal resolution ability of auditory gap detection. Clinicians evaluating a patient suspected to have central auditory disorders should recognize that the across-channel GDTs may not consistently increase as the frequency separation between the markers increases.