High-throughput screening of the effects of 90 xenobiotics on the simplified human gut microbiota model (SIHUMIx): a metaproteomic and metabolomic study.

The human gut microbiota is a complex microbial community with critical functions for the host, including the transformation of various chemicals. While effects on microorganisms has been evaluated using single-species models, their functional effects within more complex microbial communities remain unclear. In this study, we investigated the response of a simplified human gut microbiota model (SIHUMIx) cultivated in an in vitro bioreactor system in combination with 96 deep-well plates after exposure to 90 different xenobiotics, comprising 54 plant protection products and 36 food additives and dyes, at environmentally relevant concentrations. We employed metaproteomics and metabolomics to evaluate changes in bacterial abundances, the production of Short Chain Fatty Acids (SCFAs), and the regulation of metabolic pathways. Our findings unveiled significant changes induced by 23 out of 54 plant protection products and 28 out of 36 food additives across all three categories assessed. Notable highlights include azoxystrobin, fluroxypyr, and ethoxyquin causing a substantial reduction (log2FC < -0.5) in the concentrations of the primary SCFAs: acetate, butyrate, and propionate. Several food additives had significant effects on the relative abundances of bacterial species; for example, acid orange 7 and saccharin led to a 75% decrease in Clostridium butyricum, with saccharin causing an additional 2.5-fold increase in E. coli compared to the control. Furthermore, both groups exhibited up- and down-regulation of various pathways, including those related to the metabolism of amino acids such as histidine, valine, leucine, and isoleucine, as well as bacterial secretion systems and energy pathways like starch, sucrose, butanoate, and pyruvate metabolism. This research introduces an efficient in vitro technique that enables high-throughput screening of the structure and function of a simplified and well-defined human gut microbiota model against 90 chemicals using metaproteomics and metabolomics. We believe this approach will be instrumental in characterizing chemical-microbiota interactions especially important for regulatory chemical risk assessments.

[Practical instructions for recording vestibular evoked myogenic potentials]. / Praktische Hinweise zur Messung vestibulär evozierter myogener Potenziale.

Recording of vestibular evoked myogenic potentials (VEMPs) is a well-established method for functional diagnostics of the otolith organs. VEMPs are vestibular reflexes of the sacculus und utriculus to acoustic stimulation by air-conducted sound or bone-conducted vibration and are recorded by surface electrodes from the cervical (cVEMP) and ocular (oVEMP) muscles. The results of VEMP recordings are part of the neuro-otologic test battery and enable diagnosis of various vestibular disorders or differentiation between non-vestibular and peripheral vestibular vertigo. However, the methods for recording VEMPs vary substantially, although recording and stimulation parameters as well as methods of data analysis have a significant influence on the results. This article provides an overview of recommended parameters as well as practical instructions for the recording, analysis, and interpretation of VEMPs.

Influence of Hearing Rehabilitation With Active Middle Ear and Bone Conduction Implants on Postural Control.

Background: As audition also seems to contribute to balance control, additionally to visual, proprioceptive, and vestibular information, we hypothesize that hearing rehabilitation with active middle ear and bone conduction implants can influence postural control. Methods: In a prospective explorative study, the impact of hearing rehabilitation with active middle ear [Vibrant Soundbrige (VSB), MED-EL, Innsbruck, Austria] and bone conduction implants [Bonebridge (BB), MED-EL, Innsbruck, Austria] on postural control in adults was examined in three experiments. Vestibulospinal control was measured by cranio-corpography (CCG), trunk sway velocity (°/s) by the Standard Balance Deficit Test (SBDT), and postural stability with a force plate system, each time in best aided (BA) and unaided (UA) condition with frontal-noise presentation (Fastl noise, 65 dB SPL), followed by subjective evaluation, respectively. Results: In 26 subjects [age 55.0 ± 12.8 years; unilateral VSB/BB: n = 15; bilateral VSB/BB: n = 3, bimodal (VSB/BB + hearing aid): n = 8], CCG-analysis showed no difference between BA and UA conditions for the means of distance, angle of displacement, and angle of rotation, respectively. Trunk sway measurements revealed a relevant increase of sway in standing on foam (p = 0.01, r = 0.51) and a relevant sway reduction in walking (p = 0.026, r = 0.44, roll plane) in BA condition. Selective postural subsystem analysis revealed a relevant increase of the vestibular component in BA condition (p = 0.017, r = 0.47). As measured with the Interactive Balance System (IBS), 42% of the subjects improved stability (ST) in BA condition, 31% showed no difference, and 27% deteriorated, while no difference was seen in comparison of means. Subjectively, 4-7% of participants felt that noise improved their balance, 73-85% felt no difference, and 7-23% reported deterioration by noise. Furthermore, 46-50% reported a better task performance in BA condition; 35-46% felt no difference and 4-15% found the UA situation more helpful. Conclusions: Subjectively, approximately half of the participants reported a benefit in task performance in BA condition. Objectively, this could only be shown in one mobile SBDT-task. Subsystem analysis of trunk sway provided insights in multisensory reweighting mechanisms.

Speech perception and hearing effort using a new active middle ear implant audio processor.

PURPOSE: The Vibrant Soundbridge (VSB) was introduced in 1996, and the fourth generation of the audio processor recently released. This clinical study evaluates the audiological performance and subjective satisfaction of the new SAMBA 2 audio processor compared to its predecessor, SAMBA. METHOD: Fifteen VSB users tested both audio processors for approximately 3 weeks. Air conduction and bone conduction thresholds and unaided and aided sound field thresholds were measured with both devices. Speech performance in quiet (Freiburg monosyllables) and noise (OLSA) was evaluated as well as subjective listening effort (ACALES) and questionnaire outcomes (SSQ12 and APSQ). In addition, data from 16 subjects with normal hearing were gathered on sound field tests and ACALES. RESULTS: Both audio processors showed substantial improvement compared to the unaided condition. The SAMBA and SAMBA 2 had comparable performance in sound filed thresholds, while the SAMBA 2 was significantly better in speech in quiet, speech in noise, reduced listening effort, and improved subjective satisfaction compared with the SAMBA. CONCLUSION: The SAMBA 2 audio processor, compared to its predecessor SAMBA, offers improved performance throughout the parameters investigated in this study. Patients with a VSB implant would benefit from an upgrade to SAMBA 2.

Clinical and functional results after implantation of the bonebridge, a semi-implantable, active transcutaneous bone conduction device, in children and adults.

PURPOSE: Aim of the study was to evaluate the surgical, clinical and audiological outcome of 32 implantations of the Bonebridge, a semi-implantable transcutaneous active bone conduction implant. METHODS: In a retrospective cohort study, we analyzed data for 32 implantations in 31 patients (one bilateral case; seven age < 16 years) with conductive or mixed hearing loss, malformations, after multiple ear surgery, or with single-sided deafness as contralateral routing of signal (CROS). RESULTS: Four implantations were done as CROS. Five cases were simultaneously planned with ear prosthesis anchors, and 23 implantations (72%) were planned through three-dimensional (3D) "virtual surgery." In all 3D-planned cases, the implant could be placed as expected. For implant-related complications, rates were 12.5% for minor and 3.1% for major complications. Implantation significantly improved mean sound field thresholds from a preoperative 60 dB HL (SD 12) to 33 dB HL (SD 6) at 3 postoperative months and 34 dB HL (SD 6) at > 11 postoperative months (p < 0.0001). Word recognition score in quiet at 65 dB SPL improved from 11% (SD 20) preoperatively to 74% (SD 19) at 3 months and 83% (SD 15) at > 11 months (p < 0.0001). The speech reception threshold in noise improved from - 1.01 dB unaided to - 2.69 dB best-aided (p = 0.0018). CONCLUSION: We found a clinically relevant audiological benefit with Bonebridge. To overcome anatomical challenges, we recommend preoperative 3D planning in small and hypoplastic mastoids, children, ear malformation, and simultaneous implantation of ear prosthesis anchors and after multiple ear surgery.

Similarities and Differences Between Vestibular and Cochlear Systems - A Review of Clinical and Physiological Evidence.

The evoked response to repeated brief stimuli, such as clicks or short tone bursts, is used for clinical evaluation of the function of both the auditory and vestibular systems. One auditory response is a neural potential - the Auditory Brainstem Response (ABR) - recorded by surface electrodes on the head. The clinical analogue for testing the otolithic response to abrupt sounds and vibration is the myogenic potential recorded from tensed muscles - the vestibular evoked myogenic potential (VEMP). VEMPs have provided clinicians with a long sought-after tool - a simple, clinically realistic indicator of the function of each of the 4 otolithic sensory regions. We review the basic neural evidence for VEMPs and discuss the similarities and differences between otolithic and cochlear receptors and afferents. VEMPs are probably initiated by sound or vibration selectively activating afferent neurons with irregular resting discharge originating from the unique type I receptors at a specialized region of the otolithic maculae (the striola). We review how changes in VEMP responses indicate the functional state of peripheral vestibular function and the likely transduction mechanisms allowing otolithic receptors and afferents to trigger such very short latency responses. In section "ELECTROPHYSIOLOGY" we show how cochlear and vestibular receptors and afferents have many similar electrophysiological characteristics [e.g., both generate microphonics, summating potentials, and compound action potentials (the vestibular evoked potential, VsEP)]. Recent electrophysiological evidence shows that the hydrodynamic changes in the labyrinth caused by increased fluid volume (endolymphatic hydrops), change the responses of utricular receptors and afferents in a way which mimics the changes in vestibular function attributed to endolymphatic hydrops in human patients. In section "MECHANICS OF OTOLITHS IN VEMPS TESTING" we show how the major VEMP results (latency and frequency response) follow from modeling the physical characteristics of the macula (dimensions, stiffness etc.). In particular, the structure and mechanical operation of the utricular macula explains the very fast response of the type I receptors and irregular afferents which is the very basis of VEMPs and these structural changes of the macula in Menière's Disease (MD) predict the upward shift of VEMP tuning in these patients.

Fatty acid and oxylipin concentration differ markedly between different fetal bovine serums: A cautionary note.

Fetal bovine serum (FBS) has been used as a universal supplement in cell culture for more than six decades. This includes the investigation of lipid and lipid mediator formation and biology. Little is known about the (polyunsaturated) fatty acid composition and their oxidation products in FBS. Therefore, we analyzed six different FBS purchased from three different companies regarding their fatty acid and oxylipin concentrations. We found pronounced differences in the fatty acid concentrations. Even two batches of "standardized" FBS batches from one company showed drastic differences (e.g., for eicosapentaenoic acid 5 ± 1 µM vs. 11 ± 1 µM). Oxylipin concentrations also markedly differ between the FBS lots. The highest differences were found for 12-lipoxygenase products (e.g., 12-hydroxyeicosatetraenoic acid free 21-87 nM and total 58-108 nM), probably due to inconsistent serum generation procedures. Our results indicate that for cell culture studies dealing with lipid metabolism, researchers should carefully characterize their used FBS to ensure reliability and reproducibility of study outcomes.

Influence of surgical and N95 face masks on speech perception and listening effort in noise.

Daily-life conversation relies on speech perception in quiet and noise. Because of the COVID-19 pandemic, face masks have become mandatory in many situations. Acoustic attenuation of sound pressure by the mask tissue reduces speech perception ability, especially in noisy situations. Masks also can impede the process of speech comprehension by concealing the movements of the mouth, interfering with lip reading. In this prospective observational, cross-sectional study including 17 participants with normal hearing, we measured the influence of acoustic attenuation caused by medical face masks (mouth and nose protection) according to EN 14683 and of N95 masks according to EN 1149 (EN 14683) on the speech recognition threshold and listening effort in various types of background noise. Averaged over all noise signals, a surgical mask significantly reduced the speech perception threshold in noise was by 1.6 dB (95% confidence interval [CI], 1.0, 2.1) and an N95 mask reduced it significantly by 2.7 dB (95% CI, 2.2, 3.2). Use of a surgical mask did not significantly increase the 50% listening effort signal-to-noise ratio (increase of 0.58 dB; 95% CI, 0.4, 1.5), but use of an N95 mask did so significantly, by 2.2 dB (95% CI, 1.2, 3.1). In acoustic measures, mask tissue reduced amplitudes by up to 8 dB at frequencies above 1 kHz, whereas no reduction was observed below 1 kHz. We conclude that face masks reduce speech perception and increase listening effort in different noise signals. Together with additional interference because of impeded lip reading, the compound effect of face masks could have a relevant impact on daily life communication even in those with normal hearing.

Optimized preoperative determination of nerve of origin in patients with vestibular schwannoma.

In vestibular schwannoma (VS) patients hearing outcome and surgery related risks can vary and depend on the nerve of origin. Preoperative origin differentiation between inferior or superior vestibular nerve may influence the decision on treatment, and the selection of optimal treatment and counselling modalities. A novel scoring system based on functional tests was designed to predict the nerve of origin for VS and was applied to a large number of consecutive patients. A prospective, double blind, cohort study including 93 patients with suspected unilateral VS was conducted at a tertiary referral centre. Preoperatively before tumor resection a functional test battery [video head-impulse test (vHIT) of all semicircular canals (SCC)], air-conducted cervical/ocular vestibular evoked myogenic potential tests (cVEMP, oVEMP), pure-tone audiometry, and speech discrimination was applied. Sensitivity and specificity of prediction of intraoperative finding by a preoperative score based on vHIT gain, cVEMP and oVEMP amplitudes and asymmetry ratios was calculated. For the prediction of inferior vestibular nerve origin, sensitivity was 73% and specificity was 80%. For the prediction of superior vestibular nerve origin, sensitivity was 60% and specificity was 90%. Based on the trade-off between sensitivity and specificity, optimized cut-off values of - 0.32 for cVEMP and - 0.11 for oVEMP asymmetry ratios and vHIT gain thresholds of 0.77 (anterior SCC), 0.84 (lateral SCC) and 0.80 (posterior SCC) were identified by receiver operator characteristic curves. The scoring system based on preoperative functional tests improves prediction of nerve of origin and can be applied in clinical routine.

Influence of bone conduction transducer type and placement on ocular and cervical vestibular evoked myogenic potentials.

Evaluating the effectiveness of different bone conduction (BC) transducers with controlled coupling force to elicit cervical and ocular vestibular evoked myogenic potentials (cVEMPs, oVEMPs) in healthy subjects by comparing response rates, amplitudes, latencies, thresholds and asymmetry ratios. Prospective experimental study including healthy participants. VEMPs were measured to different stimulation modes; the BC transducer coupling force was controlled to 5.4 (± 0.5) Newton. cVEMPs: to bone conducted vibration (BCV) with the B81 transducer on the mastoid; oVEMPs: to BCV with the B81 on the mastoid, BCV with the B81 on the forehead, and BCV with the Mini-Shaker 4810 on the forehead. Air conducted sound (ACS) with insert earphones was used as reference. Data of 24 normal subjects (mean age 25.3 (± 3.0) years) were analyzed. ACS and BCV with the B81on the mastoid evoked cVEMPs in 100% of ears. The highest oVEMP response rates were obtained with the B81 on the mastoid (83-92%), the lowest with the B81 on the forehead (17-22%). The Mini-Shaker elicited lower response rates (65%) compared to results from the literature without coupling force control and compared to ACS (78-87%). Amplitudes were higher for BCV than ACS. ACS and BCV on the mastoid caused higher asymmetry compared to BCV forehead stimulation. The B81 was feasible to elicit VEMPs with mastoid placement and can be used as an approved medical device to measure BCV VEMPs in a clinical set-up. Normative asymmetry values have to be established due to higher variability for mastoid stimulation.

A case series shows independent vestibular labyrinthine function after major surgical trauma to the human cochlea.

Background: The receptors for hearing and balance are housed together in the labyrinth of the inner ear and share the same fluids. Surgical damage to either receptor system was widely believed to cause certain permanent loss of the receptor function of the other. That principle, however, has been called into question because there have been anecdotal reports in individual patients of at least partial preservation of cochlear function after major surgical damage to the vestibular division and vice versa. Methods: We performed specific objective vestibular function tests before and after surgical trauma (partial or subtotal cochlear removal) for treatment of intracochlear tumors in 27 consecutive patients in a tertiary referral center. Vestibular function was assessed by calorics (low-frequency response of the lateral semicircular canal), vestibulo-ocular reflex by video head impulse test (vHIT) of the three semicircular canals, cervical and ocular vestibular evoked myogenic potentials (cVEMP, saccule and oVEMP, utricle). Preoperative and postoperative distributions were compared with paired t-tests. Results: Here we show that there was no significant difference between pre- and post-operative measures for all tests of the five vestibular organs, and that after major surgical cochlear trauma, the vestibular receptors continue to function independently. Conclusions: These surprising observations have important implications for our understanding of the function and the surgery of the peripheral auditory and vestibular system in general and open up new possibilities for the development, construction and evaluation of neural interfaces for electrical or optical stimulation of the peripheral auditory and vestibular nervous system.

Hearing rehabilitation after subtotal cochleoectomy using a new, perimodiolar malleable cochlear implant electrode array: a preliminary report.

PURPOSE: We here report about the first surgical experience and audiological outcome using a new, perimodiolar malleable cochlear implant electrode array for hearing rehabilitation after subtotal cochleoectomy for intralabyrinthine schwannoma (ILS). METHOD: Based on a cochlear implant with MRI compatibility of the magnet in the receiver coil up to 3 T, a cochlear implant electrode array was developed that is malleable and can be placed perimodiolar after tumor removal from the cochlea via subtotal cochleoectomy. Malleability was reached by incorporating a nitinol wire into the silicone of the electrode array lateral to the electrode contacts. The custom-made device was implanted in four patients with intracochlear, intravestibulocochlear or transmodiolar schwannomas. Outcome was assessed by evaluating the feasibility of the surgical procedure and by measuring sound field thresholds and word recognition scores. RESULTS: After complete or partial tumor removal via subtotal cochleoectomy with or without labyrinthectomy, the new, perimodiolar malleable electrode array could successfully be implanted in all four patients. Six months after surgery, the averaged sound field thresholds to pulsed narrowband noise in the four patients were 36, 28, 41, and 35 dB HL, and the word recognitions scores for monosyllables at 65 dB SPL were 65, 80, 70, and 25% (one patient non-German speaking). CONCLUSION: The surgical evaluation demonstrated the feasibility of cochlear implantation with the new, perimodiolar malleable electrode array after subtotal cochleoectomy. The audiological results were comparable to those achieved with another commercially available type of perimodiolar electrode array from a different manufacturer applied in patients with ILS.

Intraoperative quantification of floating mass transducer coupling quality in active middle ear implants: a multicenter study.

PURPOSE: Evaluating the effectiveness of intraoperative auditory brainstem responses (ABRs) to stimulation by the Vibrant Soundbridge (VSB) active middle ear implant for quantifying the implant's floating mass transducer (FMT) coupling quality. METHODS: In a diagnostic multicentric study, patients (> 18 years) who received a VSB with different coupling modalities were included. Pre- and postoperative bone conduction thresholds, intraoperative VSB-evoked ABR thresholds (VSB-ABR) using a modified audio processor programmed to preoperative bone conduction thresholds, postoperative vibrogram thresholds, and postoperative VSB-ABR thresholds were measured. Coupling quality was calculated from the difference between the pure tone average at 1000, 2000, and 4000 Hz (3PTA) vibrogram and postoperative 3PTA bone conduction thresholds. RESULTS: Twenty-three patients (13 males, 10 females, mean age 56.6 (± 12.5) years) were included in the study. Intraoperative VSB-ABR response thresholds could be obtained in all except one patient where the threshold was > 30 dB nHL. Postoperatively, an insufficient coupling of 36.7 dB was confirmed in this patient. In a Bland-Altman analysis of the intraoperative VSB-ABRs and coupling quality, the limits of agreement exceeded ± 10 dB, i.e., the maximum allowed difference considered as not clinically important but the variation was within the general precision of auditory brainstem responses to predict behavioral thresholds. Five outliers were identified. In two patients, the postoperative VSB-ABR thresholds were in agreement with the coupling quality, indicating a change of coupling before the postoperative testing. CONCLUSION: The response thresholds recorded in this set-up have the potential to predict the VSB coupling quality and optimize postoperative audiological results.

Active Middle Ear Implant Evoked Auditory Brainstem Response Intensity-Latency Characteristics.

OBJECTIVE: To analyze intensity-latency functions of intraoperative auditory evoked brainstem responses (ABRs) to stimulation by the Vibrant Soundbridge (VSB) active middle ear implant with respect to coupling efficiency, VSB evoked ABR thresholds, and coupling modality [oval window (OW) placement vs. Incus placement and vs. round window (RW) placement]. STUDY DESIGN: Exploratory study. SETTING: Bi-centric study at tertiary referral centers. PATIENTS: Twenty-four patients (10 female, 14 male, mean age: 58 years) who received a VSB. OUTCOME MEASURES: Wave-V intensity-latency functions of intraoperative VSB evoked ABRs using a modified audio processor programmed to preoperative bone conduction thresholds for stimulation. Threshold level correction to coupling efficiency and ABR thresholds. Individual plots and exponential function fits. RESULTS: After ABR threshold level correction, the latency functions could be aligned. A large variance of latencies was observed at individual threshold level. Wave-V latency was longest in the Incus placement subgroup (9.73 ms, SD: 1.04) as compared to OW placement subgroup (9.47 ms, SD: 1.05), with the shortest latency in the RW placement subgroup (8.99 ms, SD: 0.68). For increasing stimulation levels, the variance decreased with intensity-latency function slopes converging toward a steady-state (saturation) latency caused by saturation of audio processor (stimulation) gain. Latency saturation was reached at a stimulation level of 50 dB nHL for the OW placement subgroup, 35 dB nHL for the Incus placement subgroup, and 30 dB nHL for the RW placement subgroup. The latency and saturation results indicated decreased dynamic range for RW placement, i.e., reverse stimulation. CONCLUSIONS: VSB evoked ABR wave-V intensity-latency function slopes were similar to acoustic stimulation at high stimulation levels with a shift toward longer latencies caused by audio processor signal delay. Saturation of latencies occurred for higher stimulation levels due to saturation of audio processor gain. Thus, the analysis of VSB evoked intensity-latency functions appears to allow for the objective assessment of a patient's individual dynamic range. This can further improve diagnostics as well as intraoperative and postoperative quality control.

Cervical and Ocular Vestibular-Evoked Myogenic Potentials in Patients With Intracochlear Schwannomas.

Objective: To evaluate ocular and cervical vestibular evoked myogenic potentials (oVEMPs and cVEMPs) in patients with solely intracochlear localization of an intralabyrinthine schwannoma (ILS). Study Design: Retrospective analysis of a series of cases. Setting: Monocentric study at a tertiary referral center. Patients: Patients with intracochlear schwannoma (ICS) and VEMP measurements. Outcome Measures: Signed asymmetry ratio (AR) of cVEMPs and oVEMPs to air conducted sound with AR cut-offs considered to be asymmetrical when exceeding ±30% for cVEMPs and ±40% for oVEMPs with respect to the side affected by the tumor (reduced amplitudes on the affected side indicated by negative values, enhanced amplitudes by positive values); VEMP amplitudes and latencies; tumor localization in the cochlear turn and scala. Results: Nineteen patients with a solely intracochlear tumor (ICS patients) [10 males, 9 females, mean age 57.1 (SD: 13.4) years] were included in the study. On the affected side, cVEMPs were absent or reduced in 47% of the patients, normal in 32%, and enhanced in 21%. Ocular VEMPs on the affected side were absent or reduced in 53% of the patients, normal in 32% and enhanced in 15%. Latencies for cVEMPs and oVEMPs were not significantly different between the affected and non-affected side. In all patients with enhanced VEMPs, the tumor was located in the scala tympani and scala vestibuli. Conclusions: As a new and unexpected finding, VEMP amplitudes can be enhanced in patients with intracochlear schwannoma, mimicking the third window syndrome.

A Quantitative Approach for the Objective Assessment of Coupling Efficiency for an Active Middle Ear Implant by Recording Auditory Steady-state Responses.

OBJECTIVE: The coupling efficiency of a semi-implantable active middle ear implant with an electromagnetically driven floating mass transducer coupled to a middle ear ossicle or the round window can only be quantified postoperatively in cooperative patients by measuring behavioral vibroplasty in situ thresholds in comparison with bone conduction thresholds. The objective of the study was to develop a method to objectively determine the vibroplasty in situ thresholds by determining calibration factors from the relation between the objective and behavioral vibroplasty in situ thresholds. STUDY DESIGN: Prospective experimental study. PATIENTS: Fifteen patients, implanted with an active middle ear implant for at least 6 months. INTERVENTION: Diagnostic. MAIN OUTCOME MEASURES: Vibroplasty in situ thresholds measured objectively by auditory steady state responses (floating mass transducer [FMT]ASSR). Subjective vibroplasty in situ thresholds were measured in this experimental ASSR set-up (FMTsubj.) and behaviorally by pure-tone audiometry (vibrogram). All thresholds were obtained at 500, 1000, 2000, and 4000 Hz. RESULTS: Thresholds could be objectively measured by ASSR in all patients. Differences between the FMTASSR and FMTsubj. were statistically significant but small. A significant correlation was found between the FMTASSR and the vibrogram thresholds at 4000 Hz but not for the other test frequencies. CONCLUSION: The method is feasible to measure objective vibroplasty in situ thresholds in active middle ear implant users. Since calibration factors could not be determined for all frequencies, the method is only applicable to comparatively determine the coupling efficiency of the floating mass transducer.

How Much Cochlea Do You Need for Cochlear Implantation?

OBJECTIVE: To assess the efficacy of cochlear implantation (CI) after surgical removal of sporadic intracochlear or intravestibulocochlear schwannomas. STUDY DESIGN: Nonconcurrent cohort study. SETTING: Monocentric study at a tertiary referral center. PATIENTS: Patients with tumor resection and CI between 2011 and 2018 and a historic control group of CI patients matched by age, CI electrode type, and follow-up. INTERVENTIONS: Partial or subtotal cochleoectomy for tumor removal and single-stage CI. OUTCOME MEASURES: Main outcome measure: word recognition score for monosyllables in quiet at 65 dB SPL. RESULTS: Sixteen patients with tumor removal and CI (6 female, 10 male; mean age 55 ±â€Š14 years) and 16 control patients (6 female, 10 male; mean age 55 ±â€Š15 years) were identified. In the tumor group, surprisingly good word recognition scores were reached even after substantial structural defects in the cochlear capsule. While 12 months after cochlear implantation mean word recognition score for monosyllables in quiet was 58% (SD: 26) and 41% (SD: 26) in the control groups, it was 75% (SD: 19%) in the tumor group. CONCLUSIONS: In patients with intracochlear schwannomas, despite substantial structural damage to the cochlear capsule by partial or subtotal cochleoectomy, a tendency toward better performance with respect to word recognition with CI was observed as compared with other CI patients. The surprisingly good functional results despite substantial cochlear trauma may change clinical thinking with respect to cochlear implantation also beyond this special indication.

Reduced Spread of Electric Field After Surgical Removal of Intracochlear Schwannoma and Cochlear Implantation.

OBJECTIVE: The primary aim of the study was to explore whether reduced spread of electrical field is observed after partial or subtotal cochleoectomy and cochlear implantation compared with standard cochlear implantation. Secondarily, the influence on speech perception was explored comparing both groups. STUDY DESIGN: Nonconcurrent cohort study. SETTING: Monocentric study at a tertiary referral center. PATIENTS: Twenty adult cochlear implant (CI) users after tumor resection with cochleoectomy of varying extent and 20 electrode-matched CI users with standard electrode insertion. INTERVENTIONS: Partial and subtotal cochleoectomy for tumor removal and CI. OUTCOME MEASURES: Trans-impedance, electrically evoked compound action potentials, and word recognition were measured. Relative impedance was computed as a function of distance between the stimulation and recording electrode. RESULTS: Trans-impedance was smaller and more homogeneous in patients with partial or subtotal cochleoectomy than in the control group. In the tumor group, the mean relative impedance decreased to 0.20 (standard deviation [SD] = 0.03) at a distance of 1 electrode and to 0.25 (SD = 0.04) in the control group. After excluding seven patients with a second tumor in the internal auditory canal or cerebellopontine angle, with transmodiolar tumors, after near total cochleoectomy, or only extended cochleostomy, word recognition was 61% (SD = 19%) at 3 months and 75% (SD = 19%) at 12 months after activation of the audio processor in the tumor group. At 12 months, it was significantly (p < 0.05) better than in the control group (3 mo: 45%, SD = 25%; 12 mo: 53%, SD = 26%). A smaller trans-impedance is associated with a better word recognition. CONCLUSION: We conclude that the surgical technique used for CI surgery after subtotal cochleoectomy reduces the spread of the electric field and overcomes the potential drawbacks in structure preservation associated with that technique.