Intracochlear Damage Research Articles

Innovative computed tomography based mapping of the surgical posterior tympanotomy: An exploratory study

Robotic devices have recently enhanced cochlear implantation by improving precision resulting in reduced intracochlear damage during electrode insertion. This study aimed to gain first insights into the expected dimensions of the cone-like workspace from the posterior tympanotomy towards the round window membrane.This retrospective chart review analyzed ten postoperative CT scans of adult patients who were implanted with a CI in the past ten years. The dimensions of the cone-like workspace were determined using four landmarks (P1–P4). In the anteroposterior range, P1 and P2 were defined on the edge of the bony layer over the facial nerve and chorda tympani nerve, respectively. In the inferosuperior range, P3 was defined on the bony edge of the incus buttress and P4 was obtained at a distance of 0.45 mm between the facial nerve and the chorda tympani nerve. After selecting the landmarks, the calculations of the dimensions of the surgical access space were done in a standardized coordinate system and presented using descriptive statistics.The cone-like space is limited by two maximal angles, α and β. The average angle α of 19.84 (±3.55) degrees defines the angle towards the round window membrane between P1 and P2. The second average angle β of 53.56 (±10.29) degrees defines the angle towards the round window membrane between P3 and P4. Based on the angles the mean anteroposterior range of 2.25 (±0.42) mm and mean inferosuperior range of 6.73 (±2.42) mm. The distance from the posterior tympanotomy to the round window membrane was estimated at 6.05 (±0.71) mm.These findings present data on the hypothetical maximum workspace in which a future robotically steered insertion tool can be positioned for an optimal automated electrode insertion. A larger sample size is necessary before generalizing these dimensions to a population. Further research including preoperative CT scans is needed for planning robotic-steered cochlear implantation.

Cochlear reimplantation outcomes over 20 years: Expertise in reimplantation surgery and auditory-speech rehabilitation

ObjectivesThe aim of this study was to present an institution's experience with cochlear reimplantation (CRI), to assess surgical challenges and post-operative outcomes and to increase the success rate of CRI. Study designRetrospective single-institution study. SettingTertiary medical center. MethodsWe retrospectively evaluated data from 76 reimplantation cases treated in a tertiary center between 2001 and 2022. Clinical features including etiology of hearing loss, type of failure, surgical issues, and auditory speech performance were analyzed. Categorical Auditory Performance (CAP) and Speech Intelligibility Rating (SIR) scores were used to evaluate pre- and post-CRI outcomes. ResultsThe CRI population comprises of 7 patients from our institute,69 referred patients from other centers. Device failure was the most common reason (68/76, 89.5 %) for CRI; in addition, there were 7 medical failures and 1 had both soft device failure. Medical failures included flap rupture and device extrusion, magnet migration, auditory neuropathy, leukoencephalopathy, foreign-body residue and meningitis. In 21/76 patients, the electrode technology was upgraded. The mean time to failure was 0.58–13 years, with a mean of 4.97 years. The mean (± SD) CAP and SIR scores before and after CRI were 5.2 ± 1.2 versus 5.5 ± 1.1 and 3.4 ± 1.1 versus 3.5 ± 1.1, respectively. Performance was poor in six patients with severe cochlear malformation, auditory nerve dysplasia, leukoencephalopathy, and epilepsy. ConclusionCRI surgery is a challenging but relatively safe procedure, and most reimplanted patients experience favorable postoperative outcomes. Medical complications and intracochlear damage are the main causes of poor postoperative results. Therefore, adequate preoperative preparation and atraumatic CRI should be carried out for optimal results.

Temporal bone histopathology in revision cochlear implantation

An increasing number of young infants, as early as six months of age with congenital hearing loss receive cochlear implantation, and it is probable that many of these patients will require revision surgery later in life. The possibility of explantation of the cochlear electrode and reimplantation may cause damage to the cochlea, compromising the speech perception outcome in revision implant is of concern. There is only one prior temporal bone histopathology study to look at the outcome of revision surgery and no prior study evaluating revision cochlear implantation that used the round window approach. We conducted a histopathological study of four temporal bone specimens from four patients who underwent revision cochlear implantation and when available post-operative speech perception tests were evaluated. In all cases, the reimplanted electrode followed into the same fibrous sheath without evidence of additional intracochlear damage due to revision surgery. The intracochlear damage from the initial cochlear implantation appears to be a more important factor in outcomes rather than changes associated with explantation and reimplantation.

Histological Reaction in the Round Window Membrane after Cochlear Implant Insertion in Nonhuman Primates

Introduction: The primary objective of this article was to determine if any histological alterations occur in the round window (RW) and adjacent anatomical structures of an animal model with normal hearing when a cochlear implant (CI) electrode array is inserted. Furthermore, this article aims to relate these histological alterations to the auditory changes generated. Methods: Cochlear implantation was performed, following the principles of minimally traumatic surgery (MTS), in 15 ears of nonhuman primates (Macaca fascicularis) (Mf) with normal hearing. Auditory brainstem-evoked potentials (ABR) using clicks and tones were used prior to surgery and during a 6-month follow-up period. Histological evaluation was carried out, analyzing the position of the electrode array with respect to the round window membrane (RWM), its percentage of occupation and integrity, the presence of intracochlear damage, and the tissue reaction provoked, the latter of which was quantified in the temporal bones. Results: Surgery was performed on all 15 ears without relevant incidences. Regarding histology, the electrode array in the RW of all ears presented a lateral position with respect to the modiolus. No lesions affecting the integrity of the RW were observed. The mean value of the array’s occupation in the RW was 25%. Tissue reaction, in the form of fibrosis, was observed in all ears and more intensely in the trans-RWM and post-RWM areas. In all ears, the electrodes remained on the scala tympani. No profound hearing impairment was recorded in any ear, being the mean loss of 25.4 dB when comparing presurgical thresholds with those collected 6 months after implantation in ABR click and 24.4 dB in ABR tone burst. Conclusions: The animal model and Hybrid L-14 (HL14) electrode array were optimal for implementing a surgical technique similar to that routinely performed on humans. Mild histological alterations were observed in the round window membrane and adjacent anatomical structures from the insertion of a cochlear implant electrode array. Following the minimally invasive technique, levels of hearing preservation were satisfactory, reaching a pre-post difference of 25.4 dB in the ABR click and 24.4 dB for a high-frequency tone burst. Complete hearing impairment was not observed in either ear. Correlation between the severity of histological alterations and hearing changes recorded in the ABR studies was observed.

Case Report on Rare Otologic Sequelae of Coronavirus Disease-2019

Among multiple etiologies of hearing loss, viral infections often goes unnoticed due to flu like symptoms. Otologic dysfunctions have been reported with COVID – 19 infection as well. however, this case report is unique in terms of otologic dysfunction following the COVID illness. This case report is indicative of the intracochlear damage following COVID - 19 illness. So far, there is no reported case of LO following COVID -19 in the literature. This article brings out the first reported case of SNHL due to labyrithnine ossificans following covid-19 infection.

Otosclerosis under microCT: New insights into the disease and its anatomy.

Otospongiotic plaques can be seen on conventional computed tomography (CT) as focal lesions around the cochlea. However, the resolution remains insufficient to enable evaluation of intracochlear damage. MicroCT technology provides resolution at the single micron level, offering an exceptional amplified view of the otosclerotic cochlea. In this study, a non-decalcified otosclerotic cochlea was analyzed and reconstructed in three dimensions for the first time, using microCT technology. The pre-clinical relevance of this study is the demonstration of extensive pro-inflammatory buildup inside the cochlea which cannot be seen with conventional cone-beam CT (CBCT) investigation. A radiological and a three-dimensional (3D) anatomical study of an otosclerotic cochlea using microCT technology is presented here for the first time. 3D-segmentation of the human cochlea was performed, providing an unprecedented view of the diseased area without the need for decalcification, sectioning, or staining. Using microCT at single micron resolution and geometric reconstructions, it was possible to visualize the disease's effects. These included intensive tissue remodeling and highly vascularized areas with dilated capillaries around the spongiotic foci seen on the pericochlear bone. The cochlea's architecture as a morphological correlate of the otosclerosis was also seen. With a sagittal cut of the 3D mesh, it was possible to visualize intense ossification of the cochlear apex, as well as the internal auditory canal, the modiolus, the spiral ligament, and a large cochleolith over the osseous spiral lamina. In addition, the oval and round windows showed intense fibrotic tissue formation and spongiotic bone with increased vascularization. Given the recently described importance of the osseous spiral lamina in hearing mechanics and that, clinically, one of the signs of otosclerosis is the Carhart notch observed on the audiogram, a tonotopic map using the osseous spiral lamina as region of interest is presented. An additional quantitative study of the porosity and width of the osseous spiral lamina is reported. In this study, structural anatomical alterations of the otosclerotic cochlea were visualized in 3D for the first time. MicroCT suggested that even though the disease may not appear to be advanced in standard clinical CT scans, intense tissue remodeling is already ongoing inside the cochlea. That knowledge will have a great impact on further treatment of patients presenting with sensorineural hearing loss.

Tinnitus

Coronavirus disease-2019 (COVID-19) is a highly infectious respiratory disease caused by the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), which result in plethora of health implications. The COVID-19 epidemic has impacted the lives of millions of people worldwide, wreaking havoc on health-care delivery, economic activity, and social connection. Although the majority of COVID-19 patients have respiratory symptoms, some experience neurological manifestations. The impact of the SARS-CoV-2 infection on the cochlea is a novel presentation which is not explored to date. Because of the risk of COVID-19 infection spreading from person to person, the majority of countries implemented social distancing and suggested people for home isolation. Social distancing and stay home protocol inducing stress and depression because of social isolation. Tinnitus has been documented in COVID-19 infection. However, tinnitus is not properly investigated in COVID-19 patients. Viral infections usually cause intracochlear damage and result in auditory dysfunction. Presently, there is little evidence for the direct relation of novel coronavirus and tinnitus. Tinnitus and hearing loss are important inner ear manifestations are reported in different literature which is considered morbid clinical entity in the present COVID-19 pandemic. This review article discusses details of this epidemiology, etiopathology, assessment, and management of tinnitus among patients with SARS-CoV-2 infection.

Robotic Milling of Electrode Lead Channels During Cochlear Implantation in an ex-vivo Model.

Objective: Robotic cochlear implantation is an emerging surgical technique for patients with sensorineural hearing loss. Access to the middle and inner ear is provided through a small-diameter hole created by a robotic drilling process without a mastoidectomy. Using the same image-guided robotic system, we propose an electrode lead management technique using robotic milling that replaces the standard process of stowing excess electrode lead in the mastoidectomy cavity. Before accessing the middle ear, an electrode channel is milled robotically based on intraoperative planning. The goal is to further standardize cochlear implantation, minimize the risk of iatrogenic intracochlear damage, and to create optimal conditions for a long implant life through protection from external trauma and immobilization in a slight press fit to prevent mechanical fatigue and electrode migrations.Methods: The proposed workflow was executed on 12 ex-vivo temporal bones and evaluated for safety and efficacy. For safety, the difference between planned and resulting channels were measured postoperatively in micro-computed tomography, and the length outside the planned safety margin of 1.0 mm was determined. For efficacy, the channel width and depth were measured to assess the press fit immobilization and the protection from external trauma, respectively.Results: All 12 cases were completed with successful electrode fixations after cochlear insertions. The milled channels stayed within the planned safety margins and the probability of their violation was lower than one in 10,000 patients. Maximal deviations in lateral and depth directions of 0.35 and 0.29 mm were measured, respectively. The channels could be milled with a width that immobilized the electrode leads. The average channel depth was 2.20 mm, while the planned channel depth was 2.30 mm. The shallowest channel depth was 1.82 mm, still deep enough to contain the full 1.30 mm diameter of the electrode used for the experiments.Conclusion: This study proposes a robotic electrode lead management and fixation technique and verified its safety and efficacy in an ex-vivo study. The method of image-guided robotic bone removal presented here with average errors of 0.2 mm and maximal errors below 0.5 mm could be used for a variety of other otologic surgical procedures.

Finite element modelling of the surgical procedure for placement of a straight electrode array: Mechanical and clinical consequences

A cochlear implant is an electronic device implanted into the cochlea to directly stimulate the auditory nerve. Such device is used in patients with severe-to-profound hearing loss. The cochlear implant surgery is safe, but involves some risks, such as infections, device malfunction or damage of the facial nerve and it can result on a poor hearing outcome, due to the destruction of any present residual hearing. Future improvements in cochlear implant surgery will necessarily involve the decrease of the intra-cochlear damage. Several implant related variables, such as materials, geometrical design, processor and surgical techniques can be optimized in order for the patients to partially recover their hearing capacities The straight electrode is a type of cochlear implant that many authors indicate as being the less traumatic.From the finite element analysis conducted in this work, the influence of the insertion speed, the friction coefficient between the cochlear wall and the electrode array, and several configurations of the cochlear implant tip were studied. The numerical simulations of the implantation showed the same pattern of the insertion force against insertion depth, thus indicating the different phases of the insertion. Results demonstrated that lower insertion speeds, friction coefficients and tip stiffness, led to a reduction on the contact pressures and insertion force. It is expected that these improved configurations will allow to preserve the residual hearing while reducing surgical complications.

Predictors of Fibrotic and Bone Tissue Formation With 3-D Reconstructions of Post-implantation Human Temporal Bones.

Years of implantation, surgical insertion approach, and electrode length will impact the volume of new tissue formation secondary to cochlear implantation. New tissue formation, fibrosis, and osteoneogenesis after cochlear implantation have been implicated in increasing impedance and affecting performance of the cochlear implant. 3-D reconstructions of 15 archival human temporal bones from patients with a history of cochlear implantation (CI) were generated from H&E histopathologic slides to study factors which affect volume of tissue formation. Years of implantation was a predictor of osteoneogenesis (r = 0.638, p-value = 0.011) and total new tissue formation (r = 0.588, p-value = 0.021), however not of fibrosis (r = 0.235, p-value = 0.399). Median total tissue formation differed between cochleostomy and round window insertions, 25.98 and 10.34%, respectively (Mann-Whitney U = 7, p = 0.018). No correlations were found between electrode length or angular insertion depth and total new tissue (p = 0.192, p = 0.35), osteoneogenesis (p = 0.193, p = 0.27), and fibrosis (p = 0.498, p = 0.83), respectively. However, the type II error for electrode length and angular insertion depth ranged from 0.73 to 0.90, largely due to small numbers of the shorter electrodes. With numbers of cochlear implant recipients increasing worldwide, an understanding of how to minimize intracochlear changes from implantation is important. The present study demonstrates that increasing years of implantation and inserting electrodes via a cochleostomy compared with a round window approach are associated with significantly greater degree of new tissue volume formation. While previous studies have demonstrated increased intracochlear damage in the setting of translocation with longer electrodes, length, and angular insertion depth of CI electrodes were not associated with increased tissue formation.

Electric-acoustic stimulation with longer electrodes for potential deterioration in low-frequency hearing

Background: Electric-acoustic stimulation (EAS) has emerged as a standard treatment for patients with high-frequency hearing loss. EAS is usually performed with shorter electrodes of 16–24 mm in length. As most EAS recipients gradually lose residual acoustic hearing in the implanted ear over time, EAS with longer electrodes without causing significant intra-cochlear damage might be ideal.Objective: The aim of this study was to investigate hearing preservation (HP) results after EAS surgery with longer electrodes.Methods: Ten patients (11 ears) with partial deafness that met the indications for EAS with a MED-EL FLEX28 electrode were included in this study. Auditory thresholds before and at 6 months after activation were examined.Results: In 100% of cases, HP was comfortably achieved, indicating that all patients could utilize acoustic amplification combined with electric stimulation.Conclusion: EAS with longer electrodes can offer broader cochlear coverage, resulting in natural frequency matching in comparison with shorter electrodes, even in EAS cases. The combination of advanced surgical techniques and flexible, long, straight electrodes permits deep insertion that reaches the apical region with little or no insertion trauma.

Using endoscopy to locate the round window membrane during cochlear implantation: Our experience with 25 patients.

Locating the round window membrane during cochlear implantation surgery is crucial to insert the electrode array correctly and to minimize intracochlear damage. However, it can be difficult to access the round window membrane in certain patients, especially in paediatric patients or patients with inner ear malformations. Recently, it has been demonstrated that endoscopy enables excellent visualization and exploration of the round window niche in ear surgery. This article is protected by copyright. All rights reserved.

Efficiency of Assistant Robots in Cochlear Implant Surgery: A Systematic Review

Introduction: Cochlear implant (CI) surgery is an invasive procedure in order to create hearing sense. This procedure may cause some risks such as cochlear damage. Therefore, it is needed to reduce these risks as much as possible. Future CIs will address three general goals: 1) reducing cochlear damage during surgical insertion, 2) more efficient operation that reduces the load of electrical stimulation required to produce appropriate loudness, and 3) deeper insertion into the scala tympany (ST) cavity in order to access cochlear neurons related to lower frequencies. In order to achieve these goals, we need high degree of precision to which the use of an assistant robot in surgery might be a good solution. The aim of this study was to assess the efficiency of the robotic systems in the cochlear implant surgery. Materials and Methods: Published research was identified by reviewing the scientific databases (Pubmed, ScienceDirect and Google Scholar) from 1980 to 2017 using relevant keywords. The researches were selected based on the input and output criteria. Results: This study focused on three robotic systems. One of the robotic systems acts as a magnetic guide. This system uses a magnetically tipped CI to insert into the cochlea and also rotating manipulator magnet as a magnetic guide that is located near the patient’s head. The other robotic system determines the changes of the insertion angle of the electrode array into the cochlea by controlled electrode arrays insertion. The last robotic system reduces the invasiveness of the surgery by removing the need for mastoidectomy, replacing this with a direct tunnel approach known as direct cochlear access. Conclusion: These systems reduce the energy needed for the insertion of the electrode array, enable a deeper insertion into the cochlea in order to have an improved performance in CI, and reduce intracochlear damage during surgery. Therefore, both speech understanding in noise and sound quality will improve.

An Evaluation of the Surgical Trauma to Intracochlear Structures After Insertion of Cochlear Implant Electrode Arrays: A Comparison by Round Window and Antero-Inferior Cochleostomy Techniques.

To evaluate the extent of intracochlear damage by histologic assessment of cadaveric temporal bones after insertion of cochlear implants by: round window approach and cochleostomy approach. Cochlear implantation was performed by transmastoid facial recess approach in 10 human cadaveric temporal bones. In 5 temporal bones, electrode insertion was acheieved by round window approach and in the remaining 5 bones, by cochleostomy approach. The bones were fixed, decalcified, sectioned and studied histologically. Grading of insertion trauma was assessed. In the round window insertion group, 2 bones had to be excluded from the study: one was damaged during handling with electrode extrusion and another bone did not show any demonstrable identifiable cochlear structure. Out of the 3 temporal bones, a total of 35 sections were examined: 24 demonstrated normal cochlea, 4 had basilar membrane bulging and 7 had fracture of bony spiral lamina. In the cochleostomy group, histology of 2 bones had to be discarded due to lack of any identifiable inner ear structures. Out of the 3 bones studied, 18 sections were examined: only 3 were normal, 4 sections had some bulge in spiral lamina and 11 had fracture of bony spiral lamina. The fracture of spiral lamina and bulge of basement membrane proportion is relatively higher if we perform cochleostomy as compared to round window approach. Therefore, round window insertion is relatively less traumatic as compared to cochleostomy. However, our sample size was very small and a study with a larger sample is required to further validate these findings.

Variability of an ideal insertion vector for cochlear implantation.

Based on a three-dimensional analysis, the orientation of the basal turn of the cochlea, the disposition of the basilar membrane, and the characteristics of the hook region--all of which determine the ideal electrode insertion vector during cochlear implantation--might vary among individuals to a greater degree than previously considered. The aim of this study is to assess the variability of an ideal insertion vector among a sample of surgical candidates from a purely anatomical perspective as well as from a more intraoperative-surgical perspective. During cochlear implantation through a cochleostomy or round window approach, the angle or vector of insertion after the first entry point seems to be related to intracochlear damage, which might correlate with anatomical and functional features. Three-dimensional reconstructions of the temporal bones of 50 cochlear implant candidates (a total of 100 ears) were assessed. The spatial orientation of an ideal insertion vector for a cochleostomy and a round window approach were estimated. A difference as great as 60 degrees was observed for an ideal insertion vector among the subjects. From an intraoperative perspective, this variability involves pushing the electrodes "as near to the buttress" or "as near to the emergence of the corda tympani" as possible, depending on the case. The orientation of the basal turn and the corresponding ideal electrode insertion vector vary widely among subjects. A proper preoperative estimation on a case-to-case scenario for this feature might lead to technique adaptation during insertion, possibly contributing to minimizing electrode insertion trauma and thus optimizing the anatomical and functional results.

Detection of intracochlear damage during cochlear implant electrode insertion using extracochlear measurements in the gerbil

An intraoperative monitoring algorithm during cochlear implant electrode insertion could be used to detect trauma and guide electrode placement relative to surviving hair cells. The aim of this report was to assess the feasibility of using extracochlear recording sites to monitor acoustically evoked responses from surviving hair cells and neural elements during implantation in an animal model. Animal experiments. The normal-hearing gerbil was used. Two recording methods, one using a lock-in amplifier and another using Fourier analysis of recorded signals, were used to obtain frequency-specific information about the responses to tones. Amplitude and threshold determinations were made at the round window and at three extracochlear sites. To induce intracochlear damage, a platinum-iridium wire was inserted through the round window. The wire was advanced, and changes in the potentials were correlated with cochlear contact. Anatomic integrity was assessed using cochlea whole mount preparations. In general, the lock-in amplifier showed greater sensitivity and lower thresholds at higher frequencies relative to the Fourier method. Also, the lock-in amplifier was more resistant to masking effects. Both systems were able to detect loss of cochlear potentials secondary to intracochlear trauma. Histologic damage was seen in all cases and corresponded to electrophysiologic changes. Impact of electrodes on cochlear structures affecting cochlear performance could be detected from several extracochlear sites. The lock-in amplifier demonstrated greater sensitivity and resistance to noise when compared to the fast Fourier transform recording paradigm. The latter showed greater flexibility of detecting and separating hair cell and neural potentials.

Detection of intracochlear damage during cochlear implant electrode insertion using extracochlear measurements in the gerbil

Detection of intracochlear damage during cochlear implant electrode insertion using extracochlear measurements in the gerbil

Detection of Intracochlear Damage With Cochlear Implantation in a Gerbil Model of Hearing Loss

Cochlear trauma due to electrode insertion can be detected in acoustic responses to low frequencies in an animal model with a hearing condition similar to patients using electroacoustic stimulation. Clinical evidence suggests that intracochlear damage during cochlear implantation negatively affects residual hearing. Recently, we demonstrated the usefulness of acoustically evoked potentials to detect cochlear trauma in normal-hearing gerbils. Here, gerbils with noise-induced hearing loss were used to investigate the effects of remote trauma on residual hearing. Gerbils underwent high-pass (4-kHz cutoff) noise exposure to produce sloping hearing loss. After 1 month of recovery, each animal's hearing loss was determined from auditory brainstem responses and baseline intracochlear recording of the cochlear microphonic and compound action potential (CAP) obtained at the round window. Subsequently, electrode insertions were performed to produce basal trauma, whereas the acoustically generated potentials to a 1-kHz tone-burst were recorded after each step of electrode advancement. Hair cell counts were made to characterize the noise damage, and cochlear whole mounts were used to identify cochlear trauma due to the electrode. The noise exposure paradigm produced a pattern of hair cell, auditory brainstem response, and intracochlear potential losses that closely mimicked that of electrical and acoustic stimulation patients. Trauma in the basal turn, in the 15- to 30-kHz portion of the deafened region, remote from preserved hair cells, induced a decline in intracochlear acoustic responses to the hearing preserved frequency of 1 kHz. The results indicate that a recording algorithm based on physiological markers to low-frequency acoustic stimuli can identify cochlear trauma during implantation. Future work will focus on translating these results for use with current cochlear implant technology in humans.

Detection of Intracochlear Damage With Cochlear Implantation in a Gerbil Model of Hearing Loss

Detection of Intracochlear Damage With Cochlear Implantation in a Gerbil Model of Hearing Loss

Scala tympani cochleostomy for cochlear implantation

The use of cochlear implantation to treat sensorineural hearing loss continues to evolve as an increasing number of both adult and pediatric patients undergo this life-changing surgery. As our understanding of electrical stimulation of the auditory system unfolds, the importance of proper cochleostomy placement and intracochlear electrode positioning continues to evolve. Currently, atraumatic intracochlear electrode array implantation into scala tympani appears to optimize performance while providing the opportunity for hearing preservation for the purposes of bimodal stimulation. With these objectives in mind, this article describes the authors' surgical approach to gain access to scala tympani with the intent of minimizing trauma to the underlying structures. This approach is based on the results of multiple clinical and anatomical studies as well as on data from various temporal bone experiments. Based herein, the authors perform either direct round window insertions or create a round window-related cochleostomy either with or without a bony partition. Blind drilling procedures on the convexity of the promontory are avoided because this can result in either scala vestibuli access or substantial intracochlear damage.