[Planning tools and indications for "virtual surgery" for the Bonebridge bone conduction system. German version]. / Planungstools und Indikationen zur "virtuellen Chirurgie" beim Knochenleitungssystem Bonebridge.

BACKGROUND: Implantation of the Bonebridge (MED-EL, Innsbruck, Austria), an active semi-implantable transcutaneous bone conduction hearing system, involves the risk of impression or a lesion in intracranial structures, such as the dura or sigmoid sinus. Therefore, determining the optimal implant position requires careful preoperative radiological planning. OBJECTIVE: The aim of this study was to provide an overview of the possibilities for preoperative radiological planning for the Bonebridge implantation and to evaluate their indications and feasibility. MATERIALS AND METHODS: A systematic literature search was conducted in the PubMed/MEDLINE database for all studies with preoperative planning or implant placement as the primary endpoint or that secondarily mention preoperative planning. RESULTS: Of 558 studies, 49 fulfilled the inclusion criteria. In 18 studies, preoperative planning and floating mass transducer (FMT) placement were the primary endpoints, whereas in 31 studies, preoperative planning was described secondarily. CONCLUSION: There are both freely available and commercial tools involving different time commitments for preoperative three-dimensional (3D) planning and intraoperative transfer. Preoperative 3D planning can increase the safety of Bonebridge implantation.

Planning tools and indications for "virtual surgery" for the Bonebridge bone conduction system.

BACKGROUND: Implantation of the Bonebridge (MED-EL, Innsbruck, Austria), an active semi-implantable transcutaneous bone conduction hearing system, involves the risk of impression or a lesion in intracranial structures, such as the dura or sigmoid sinus. Therefore, determining the optimal implant position requires careful preoperative radiological planning. OBJECTIVE: The aim of this study was to provide an overview of the possibilities for preoperative radiological planning for the Bonebridge implantation and to evaluate their indications and feasibility. MATERIALS AND METHODS: A systematic literature search was conducted in the PubMed/MEDLINE database for all studies with preoperative planning or implant placement as the primary endpoint or that secondarily mention preoperative planning. RESULTS: Of 558 studies, 49 fulfilled the inclusion criteria. In 18 studies, preoperative planning and floating mass transducer (FMT) placement were the primary endpoints, whereas in 31 studies, preoperative planning was described secondarily. CONCLUSION: There are both freely available and commercial tools involving different time commitments for preoperative three-dimensional (3D) planning and intraoperative transfer. Preoperative 3D planning can increase the safety of Bonebridge implantation.

[Hearing classification in patients with vestibular schwannoma using German-language test procedures]. / Hörklassen bei Patienten mit Vestibularisschwannom bei Verwendung deutschsprachiger Testverfahren.

BACKGROUND: Hearing function in patients with vestibular schwannoma is often classified according to the Gardner and Robertson (1988) or the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS, 1995) systems. These classification systems are based on English-language test procedures, there is no German-language equivalent. The aim of the study was to investigate the influence of various target parameters on hearing classification and to derive a recommendation for the use of German-language test methods. MATERIALS AND METHODS: The rules for speech audiometry based on English-language test procedures were applied to German speech test materials. In 91 patients with vestibular schwannoma, pure tone hearing thresholds, speech recognition thresholds, and speech discrimination at different sound pressure levels were measured. The patients were categorized according to the Gardner and Robertson and AAO-HNS classifications. RESULTS: In both the Gardner-Robertson and the AAO-HNS classifications, the number of patients in the hearing classes with serviceable hearing function (measured as Pure Tone Average across three (3PTA) or four (4PTA) frequencies) was highest when using the 3PTA0,5;1;2 kHz condition, followed by 4PTA0,5;1;2;3 kHz, 4PTA0,5;1;2;4 kHz, and 4PTA0,5;1;2;"3"kHz. If maximum word recognition score (WRSmax) was used instead of word recognition 40 dB above the sensation level (WRS40SL), more patients were classified into the hearing classes with serviceable hearing function, irrespective of the mean pure tone hearing threshold. CONCLUSION: The Gardner-Robertson and AAO-HNS classifications can be used in German-speaking settings. The Freiburg monosyllabic test can be used to determine speech discrimination scores or maximum word recognition.

Management of transmodiolar and transmacular cochleovestibular schwannomas with and without cochlear implantation.

INTRODUCTION: Hearing rehabilitation with cochlear implants has attracted increasing interest also for patients with cochleovestibular schwannoma. The authors report their experience with the surgical management of tumors with rare transmodiolar or transmacular extension and outcomes after cochlear implantation (CI). METHODS: This retrospective case series included nine patients with either primary intralabyrinthine tumors or secondary invasion of the inner ear from the internal auditory canal. The primary endpoint with CI, performed in six patients, was word recognition score at 65 dB SPL (sound pressure level). Secondary endpoints were intra- and postoperative electrophysiological parameters, impedance measures, the presence of a wave V in the electrically evoked (via the CI) auditory brainstem responses, the specifics of postoperative CI programming, and adverse events. RESULTS: Hearing rehabilitation with CI in cases of transmodiolar tumor growth could be achieved only with incomplete tumor removal, whereas tumors with transmacular growth could be completely removed. All six patients with CI had good word recognition scores for numbers in quiet conditions (80-100% at 65 dB SPL, not later than 6 to 12 months post CI activation). Four of these six patients achieved good to very good results for monosyllabic words within 1-36 months (65-85% at 65 dB SPL). The two other patients, however, had low scores for monosyllables at 6 months (25 and 15% at 65 dB SPL, respectively) with worsening of results thereafter. CONCLUSIONS: Cochleovestibular schwannomas with transmodiolar and transmacular extension represent a rare entity with specific management requirements. Hearing rehabilitation with CI is a principal option in these patients.

Implantation of a new active bone conduction hearing device with optimized geometry.

Here, we describe the surgical technique for implanting a new, active, transcutaneous bone conduction hearing aid. The implant technology is based on a system that has been in use reliably since 2012. The geometry of the new implant has been adapted based on experience with previously introduced implants. The surgery was feasible, standardized, and safe. Due to the optimized geometric design that improved the bone fit, it is not necessary to use specialized, detailed preoperative planning, except in challenging anatomical conditions; e.g., in young children, malformations, poor pneumatization, or after a canal wall down mastoidectomy.

[Implantation of a new active bone conduction hearing device with optimized geometry. German version]. / Implantation eines neuen, aktiven, knochenverankerten elektronischen Hörimplantats mit verkleinerter Geometrie.

Here, we describe the surgical technique for implanting a new, active, transcutaneous bone conduction hearing aid. The implant technology is based on a system that has been in use reliably since 2012. The geometry of the new implant has been adapted based on experience with previously introduced implants. The surgery was feasible, standardized, and safe. Due to the optimized geometric design that improved the bone fit, it is not necessary to use specialized, detailed preoperative planning, except in challenging anatomical conditions; e.g., in young children, malformations, poor pneumatization, or after a canal wall down mastoidectomy.

Postural regulation and stability with acoustic input in normal-hearing subjects.

BACKGROUND: Postural regulation is based on complex interactions among postural subsystems. The auditory system too appears to have an influence on postural control. OBJECTIVE: The aim of this study was to measure the influence of auditory input on postural control and to gain a deeper understanding of the interactions between auditory input and postural subsystems including subjective aspects. MATERIALS AND METHODS: In 30 healthy normal-hearing subjects, postural regulation and stability was measured with the Interactive Balance System (IBS; Inc. neurodata GmbH, Wien, Österreich) in 8 test positions with noise (frontal presentation) and plugged without noise. The IBS is an electrophysiological measurement device that measures postural control at the product level (e.g., stability, weight distribution) and the mechanisms of postural subsystems at the process level based on frequency-oriented fast-Fourier analysis of force-time relation. RESULTS: At the process level, we found a relevant reduction (ηp2 ≥ 0.10) of postural regulation with noise in the frequency bands F1 (visual and nigrostriatal system ηp2 = 0.122) and F2-4 (peripheral vestibular system ηp2 = 0.125). At the product level, the weight distribution index (WDI) parameter showed a relevant increase with noise (ηp2 = 0.159). No difference between the auditory conditions was found for postural stability (parameter: stability indicator, ST). Substantial interindividual variations in the subjective estimation of the influence of auditory inputs on stability were observed. CONCLUSION: In this study, a shift in the activity of postural subsystems was observed with auditory input, while no difference was seen in ST. This leads to new insights into mechanisms of audiovestibular interaction.

[Postural regulation and stability with acoustic input in normal hearing subjects. German version]. / Posturale Regulation und Stabilität unter akustischem Input bei Normalhörenden.

BACKGROUND: Postural regulation is based on complex interactions among postural subsystems. The auditory system too appears to have an influence on postural control. OBJECTIVE: The aim of this study was to measure the influence of auditory input on postural control and to gain a deeper understanding of the interactions between auditory input and postural subsystems including subjective aspects. MATERIALS AND METHODS: In 30 healthy normal-hearing subjects, postural regulation and stability was measured with the Interactive Balance System (IBS; Inc. neurodata GmbH, Wien, Österreich) in 8 test positions with noise (frontal presentation) and plugged without noise. The IBS is an electrophysiological measurement device that measures postural control at the product level (e.g., stability, weight distribution) and the mechanisms of postural subsystems at the process level based on frequency-oriented fast-Fourier analysis of force-time relation. RESULTS: At the process level, we found a relevant reduction (ηp2 ≥ 0.10) of postural regulation with noise in the frequency bands F1 (visual and nigrostriatal system ηp2 = 0.122) and F2-4 (peripheral vestibular system ηp2 = 0.125). At the product level, the weight distribution index (WDI) parameter showed a relevant increase with noise (ηp2 = 0.159). No difference between the auditory conditions was found for postural stability (parameter: stability indicator, ST). Substantial interindividual variations in the subjective estimation of the influence of auditory inputs on stability were observed. CONCLUSION: In this study, a shift in the activity of postural subsystems was observed with auditory input, while no difference was seen in ST. This leads to new insights into mechanisms of audiovestibular interaction.

[Management of transmodiolar and transmacular cochleovestibular schwannomas with and without cochlear implantation. German version]. / Management transmodiolärer und transmakulärer Vestibularis- und Cochlearisschwannome mit und ohne Cochleaimplantation.

INTRODUCTION: Hearing rehabilitation with cochlear implants has attracted increasing interest also for patients with cochleovestibular schwannoma. The authors report their experience with the surgical management of tumors with rare transmodiolar or transmacular extension and outcomes after cochlear implantation (CI). METHODS: This retrospective case series included nine patients with either primary intralabyrinthine tumors or secondary invasion of the inner ear from the internal auditory canal. The primary endpoint with CI, performed in six patients, was word recognition score at 65 dB SPL (sound pressure level). Secondary endpoints were intra- and postoperative electrophysiological parameters, impedance measures, the presence of a wave V in the electrically evoked (via the CI) auditory brainstem responses, the specifics of postoperative CI programming, and adverse events. RESULTS: Hearing rehabilitation with CI in cases of transmodiolar tumor growth could be achieved only with incomplete tumor removal, whereas tumors with transmacular growth could be completely removed. All six patients with CI had good word recognition scores for numbers in quiet conditions (80-100% at 65 dB SPL, not later than 6 to 12 months post CI activation). Four of these six patients achieved good to very good results for monosyllabic words within 1-36 months (65-85% at 65 dB SPL). The two other patients, however, had low scores for monosyllables at 6 months (25 and 15% at 65 dB SPL, respectively) with worsening of results thereafter. CONCLUSIONS: Cochleovestibular schwannomas with transmodiolar and transmacular extension represent a rare entity with specific management requirements. Hearing rehabilitation with CI is a principal option in these patients.

[Processing of interaural time differences in normal-hearing subjects and cochlear implant users with FSP and HDCIS coding strategy]. / Verarbeitung interauraler Zeitdifferenzen bei Normalhörenden und Cochlea-Implantat-Trägern mit FSP- und HDCIS-Kodierungsstrategie.

BACKGROUND: Sound localization is necessary for social interaction and remains challenging for bilateral cochlear implant (CI) users. This study investigated the influence of fine structure processing (FSP) coding strategies on temporal accuracy and source localization. The ability to discriminate between different interaural time differences (ITD) was measured objectively and compared. MATERIALS AND METHODS: Fifteen normal-hearing subjects and five CI users participated in this study. Electrophysiological recording of mismatch negativity (MMN) and psychoacoustic tests with headphones and loudspeakers were conducted to measure and compare the discrimination of ITDs. RESULTS: In normal-hearing subjects the discrimination threshold for ITD was 83-117 µs. Localization ability in a free sound field was below the limit of resolution. A significant MMN was measured. CI users showed a mean angle detection error of more than 30° and a discrimination threshold between 1100 and 2100 µs. Due to artifacts, no clear MMN component could be recorded. CONCLUSION: This study shows that MMN can be used as an objective measure of ITD discrimination in normal-hearing participants. An indication that improvements in directional hearing can be achieved with the transfer of fine structure could not be provided by this study.

Preoperative determination of nerve of origin in patients with vestibular schwannoma.

BACKGROUND: Vestibular schwannoma (VS) is a benign tumor that develops in the internal auditory canal and the cerebellopontine angle, potentially diminishing hearing or balance. Most VS tumors arise from one of two vestibular branches: the superior or inferior vestibular nerve. Determining the specific nerve of origin could improve patient management in terms of preoperative counseling, treatment selection, and surgical decision-making and planning. The aim of this study was to introduce a novel scoring system that was designed to determine the nerve of origin. METHODS: The nerve of origin was predicted based on video head impulse assessments of all semicircular channels, together with cervical/ocular vestibular-evoked myogenic potential tests. The acquired data were entered into a scoring system developed to allocate the tumor origin. Finally, the nerve of origin was definitively determined intraoperatively. RESULTS: The novel scoring system was applied to five consecutive patients undergoing surgical VS treatment. In one case, no determination was possible. In all other cases, the preoperatively predicted tumor origin was the same as the origin determined during surgery. CONCLUSION: The scoring system predicts the nerve of origin and will be evaluated in a larger prospective cohort study of VS patients in the near future.

[Influence of hearing on vestibulospinal control in healthy subjects. German version]. / Einfluss des Hörens auf die vestibulospinale Kontrolle bei gesunden Probanden.

BACKGROUND: Balance control is based on multisensory interaction. In addition to vestibular, proprioceptive and visual information, it seems that auditory input also plays an important role. OBJECTIVES: The aim of the study was to investigate the effect of hearing on vestibulospinal coordination and to obtain deeper knowledge about mechanisms of audiovestibular interaction. MATERIALS AND METHODS: In normal hearing, healthy subjects who performed the Unterberger (Fukuda) stepping test with and without frontal presentation of noise, the distance of displacement, the angle of displacement and the angle of rotation were measured by means of ultrasound based cranio-corpo-graphy (CCG). Additionally, subjective estimation of the effect of auditory input was compared to objective test results. RESULTS: In the noise condition, there was a significant improvement in the distance of displacement (mean with noise 66.9 cm ± 33.5 standard deviation, SD, mean without noise 77.0 cm ± 32.7 SD, p < 0.001) and in the angle of rotation (mean with noise 14.2°â€¯± 10.1 SD, mean without noise 28.3°â€¯± 20.2 SD, p < 0.001), while no difference was found within the conditions regarding the angle of displacement (mean with noise 29.1°â€¯± 33.5 SD, mean without noise 30.0°â€¯± 34.0 SD, p = 0.641). Side-specific analysis revealed a positive correlation between angle of displacement and angle of rotation in the condition without noise (Spearman r = 0.441, p < 0.001). The rate of agreement between subjective estimation of noise influence and objective test results ranged between only 43% and 63%, depending on the question and endpoint. CONCLUSION: Hearing had a clearly beneficial effect of auditory inputs on vestibulospinal coordination, especially for distance of displacement and angle of rotation.

Influence of hearing on vestibulospinal control in healthy subjects.

BACKGROUND: Balance control is based on multisensory interaction. In addition to vestibular, proprioceptive and visual information, it seems that auditory input also plays an important role. OBJECTIVES: The aim of the study was to investigate the effect of hearing on vestibulospinal coordination and to obtain deeper knowledge about mechanisms of audiovestibular interaction. MATERIALS AND METHODS: In normal hearing, healthy subjects who performed the Unterberger (Fukuda) stepping test with and without frontal presentation of noise, the distance of displacement, the angle of displacement and the angle of rotation were measured by means of ultrasound based cranio-corpo-graphy (CCG). Additionally, subjective estimation of the effect of auditory input was compared to objective test results. RESULTS: In the noise condition, there was a significant improvement in the distance of displacement (mean with noise 66.9 cm± 33.5 standard deviation, SD, mean without noise 77.0 cm±32.7 SD, p< 0.001) and in the angle of rotation (mean with noise 14.2°± 10.1 SD, mean without noise 28.3°± 20.2 SD, p< 0.001), while no difference was found within the conditions regarding the angle of displacement (mean with noise 29.1°± 33.5 SD, mean without noise 30.0°± 34.0 SD, p= 0.641). Side-specific analysis revealed a positive correlation between angle of displacement and angle of rotation in the condition without noise (Spearman r = 0.441, p< 0.001). The rate of agreement between subjective estimation of noise influence and objective test results ranged between only 43% and 63%, depending on the question and endpoint. CONCLUSION: Hearing had a clearly beneficial effect of auditory inputs on vestibulospinal coordination, especially for distance of displacement and angle of rotation.

[Speech audiometric outcome parameters in clinical trials on hearing improvement]. / Sprachaudiometrische Zielparameter in klinischen Studien zur Hörverbesserung.

BACKGROUND: When comparing clinical studies nationally and internationally, there is great heterogeneity in the applied audiometric outcome parameters. Beside different frequencies included in pure-tone audiometry and the resulting averages, the word recognition scores are measured at varying sound pressure levels, i.e., either with a fixed sound pressure level or with a fixed sensation level. However, a comparison of studies, e. g., in meta-analysis, requires comparable outcome parameters. OBJECTIVE: In this study, the influence of speech-audiometric outcome parameters on the outcome reporting of hearing therapies is studied. PATIENTS AND METHODS: Before and after a conservative or a surgical treatment aimed at hearing improvement, 25 patients with hearing impairment were tested with the German Freiburg speech intelligibility test with monosyllables and numbers at various levels, and with the German Oldenburg sentence test in quiet. Additionally, 49 subjects with normal hearing were tested. RESULTS: In a comparison of measurement methods (outcome parameters), the hearing improvement measured using constant sound pressure levels for speech audiometry was significantly greater and therefore more sensitive than using constant sensation levels. CONCLUSION: To test changes in hearing in clinical studies, fixed sound pressure levels should be preferred to fixed sensation levels. For the development of standardized outcome parameters for measuring speech intelligibility in quiet, fixed sound pressure levels or measurement of speech reception thresholds should be selected.

[Preoperative determination of nerve of origin in patients with vestibular schwannoma. German version]. / Präoperative Bestimmung des Ursprungsnervs von Vestibularisschwannomen.

BACKGROUND: Vestibular schwannoma (VS) is a benign tumor that develops in the internal auditory canal and the cerebellopontine angle, potentially diminishing hearing or balance. Most VS tumors arise from one of two vestibular branches: the superior or inferior vestibular nerve. Determining the specific nerve of origin could improve patient management in terms of preoperative counseling, treatment selection, and surgical decision-making and planning. The aim of this study was to introduce a novel scoring system that was designed to determine the nerve of origin. METHODS: The nerve of origin was predicted based on video head impulse assessments of all semicircular channels, together with cervical/ocular vestibular-evoked myogenic potential tests. The acquired data were entered into a scoring system developed to allocate the tumor origin. Finally, the nerve of origin was definitively determined intraoperatively. RESULTS: The novel scoring system was applied to 5 consecutive patients undergoing surgical VS treatment. In one case, no determination was possible. In all other cases, the preoperatively predicted tumor origin was the same as the origin determined during surgery. CONCLUSION: The scoring system predicts the nerve of origin and will be evaluated in a larger prospective cohort study of VS patients in the near future.

[Intracochlear schwannoma : Tumor removal via subtotal cochleoectomy and partial cochlear reconstruction with preservation of semicircular canal function. German version]. / Intracochleäres Schwannom : Tumorentfernung über subtotale Cochleoektomie und partielle Rekonstruktion der cochleären Kapsel unter Erhalt der Bogengangsfunktion.

We report about a patient who in 2005, aged 37 years, experienced sudden mild to moderate, mid-frequency sensorineural hearing loss in the right ear along with tinnitus and mild dizziness. MRI of the temporal bone revealed a very small (1 mm) contrast-enhancing lesion in the second turn of the right cochlea. Hearing gradually deteriorated with complete hearing loss in 2015. At this time, an MRI scan showed a lesion completely filling the cochlea.The tumor was removed via transmeatal subtotal cochleoectomy. The cochlea was partially reconstructed with cartilage and fascia. A cochlea implant dummy electrode was inserted as a placeholder in order to prevent complete fibrosis of the "neocochlea" during follow-up MRI examinations.Vestibular function tests 2 months postoperatively showed preserved caloric excitability and a normal vestibulo-ocular reflex (vHIT) in all three planes. The patient is free of vertigo.Intralabyrinthine schwannomas (ILS) are a rare differential diagnosis of sudden hearing loss, which should be specifically checked for in MRI. Surgical removal of an intracochlear ILS through partial or subtotal cochleoectomy with preservation of vestibular function is possible in principle.

Intracochlear schwannoma : Tumor removal via subtotal cochleoectomy and partial cochlear reconstruction with preservation of semicircular canal function.

We report about a patient, who in 2005, as a 37-year-old, experienced a sudden, mild to moderate, mid-frequency sensorineural hearing loss in the right ear, along with tinnitus and mild dizziness. MRI of the temporal bone revealed a very small (1 mm) enhancing lesion in the second turn of the right cochlea after injection of contrast medium. Hearing gradually deteriorated, with complete hearing loss in 2015. At this time, an MRI scan showed a lesion completely filling the cochlea.The tumor was removed through a subtotal cochleoectomy. The cochlea was partially reconstructed with cartilage and fascia. A cochlea implant dummy electrode was inserted as a placeholder in order to try to preserve a channel within the most likely fibrosing "neocochlea" during follow-up MRI examinations.Vestibular function tests 2 months postoperatively showed preserved caloric excitability and a normal vestibulo-ocular reflex (video head impulse test, vHIT) in all three planes. The patient is free of vertigo.Intralabyrinthine schwannomas (ILS) are a rare differential diagnosis of sudden hearing loss. Surgical removal of an intracochlear ILS through partial or subtotal cochleoectomy with preservation of vestibular function is possible.

Intracochlear drug delivery in combination with cochlear implants : Current aspects.

Local drug application to the inner ear offers a number of advantages over systemic delivery. Local drug therapy currently encompasses extracochlear administration (i. e., through intratympanic injection), intracochlear administration (particularly for gene and stem cell therapy), as well as various combinations with auditory neurosensory prostheses, either evaluated in preclinical or clinical studies, or off-label. To improve rehabilitation with cochlear implants (CI), one focus is the development of drug-releasing electrode carriers, e. g., for delivery of glucocorticosteroids, antiapoptotic substances, or neurotrophins to the inner ear. The performance of cochlear implants may thus be improved by protecting neuronal structures from insertion trauma, reducing fibrosis in the inner ear, and by stimulating growth of neuronal structures in the direction of the electrodes. Controlled drug release after extracochlear or intracochlear application in conjunction with a CI can also be achieved by use of a biocompatible, resorbable controlled-release drug-delivery system. Two case reports for intracochlear controlled release drug delivery in combination with cochlear implants are presented. In order to treat progressive reduction in speech discrimination and increased impedance, two cochlear implant patients successfully underwent intracochlear placement of a biocompatible, resorbable drug-delivery system for controlled release of dexamethasone. The drug levels reached in inner ear fluids after different types of local drug application strategies can be calculated using a computer model. The intracochlear drug concentrations calculated in this way were compared for different dexamethasone application strategies.

[Intraoperative monitoring of cochlear nerve function during cerebello-pontine angle surgery]. / Intraoperatives Monitoring des N. cochlearis bei Eingriffen im Kleinhirnbrückenwinkel.

BACKGROUND: Surgical procedures in the cerebello-pontine angle (CPA), e. g. for vestibular schwannoma, have an increased risk for damage to the cochlear nerve. Consequently, hearing deterioration up to complete deafness may result with severe impact on quality of life. Methods for intraoperative monitoring of function may minimize such risks. OBJECTIVE: Review of current methods for intraoperative monitoring of the cochelar nerve and summary of new developments. MATERIALS AND METHODS: Analysis and summary of literature, discussion of new methods. RESULTS: Early auditory evoked potentials using click stimuli remain the standard method for intraoperative monitoring of cochlear nerve function. Amplitude and latency changes indicate a risk of postoperative hearing deterioration; however demonstrate only limited further differentiation of hearing quality. As novel methods, near-field recordings may allow faster feedback and auditory steady state responses potentially enable frequency specific testing. CONCLUSIONS: Intraoperative monitoring of the cochlear nerve is an integral component of CPA surgery. It enables detection of potential nerve damage and thus contributes to avoiding postoperative functional deficits. Development and implementation of novel and additional approaches may further improve its clinical value.