Round Window Approach Research Articles

Surgical considerations during cochlear implantation: the utility of temporal bone computed tomography.

This paper describes the construction of portals for electrode placement during cochlear implantation and emphasises the utility of pre-operative temporal bone three-dimensional computed tomography. Temporal bone three-dimensional computed tomography was used to plan portal creation for electrode insertion. Pre-operative temporal bone three-dimensional computed tomography can be used to determine the orientation of temporal bone structures, which is important for mastoidectomy, posterior tympanotomy and cochleostomy, and when using the round window approach. It is essential to create appropriate portals (from the mastoid cortex to the cochlea) in a step-by-step manner, to ensure the safe insertion of electrodes into the scala tympani. Pre-operative three-dimensional temporal bone computed tomography is invaluable in this respect.

Radiological and surgical aspects of round window visibility during cochlear implantation: a retrospective analysis

PurposeThe round window approach has become the most preferred option for cochlear implant (CI) insertion, however, sometimes it may not be possible due to the (in)visibility of the round window membrane (RWM). We addressed the prevalence, consequences and indicators of difficult detection of the RWM in cochlear implant surgery.MethodsThis study retrospectively analysed the operative reports and preoperative high resolution axial-computed tomography (CT) scans of a consecutive cohort of patients who underwent a CI insertion. The main outcomes were surgical outcomes of the RW approach, and assessment of radiological markers.ResultsThe operative reports showed that RWM insertion was feasible in 151 out of 153 patients. In 18% of the patients the RWM was difficult to visualize. All these patients had at least one intraoperative event. The chorda tympani nerve (CTN) or posterior canal wall was affected in 8% of the 153 patients and the fallopian canal in 6%. These patients had a facial-chorda tympani nerve distance on the CT scan that was considerably smaller than normal patients (1.5 mm vs 2.3 mm). In addition, a prediction line towards the anterolateral side of the RWM was found to be more prevalent in these patients’ CT scans (sensitivity 81%, specificity 63%).ConclusionThe RW approach is feasible in almost all patients undergoing CI surgery. Difficult visualisation of the RWM seems to lead to at least one intraoperative event. Radiological measures showed that these patients had a smaller facial recess and a more anteriorly placed facial nerve, which can be used to better plan a safe insertion approach.

Selection of cochlear electrode array implantation lengths and outcomes in patients with bilateral sensorineural hearing loss

Objective: To perform a comprehensive comparison on the therapeutic effects of unilateral 31.5 mm and 28 mm cochlear implantation (CI) on the post-operative hearing rehabilitation outcomes, including hearing threshold, speech recognition and quality of life, in patients with bilateral sensorineural hearing loss. Methods: A total of 26 patients [12 males, 14 females, aged 19-71 (43±16) years] diagnosed with bilateral severe-to-profound sensorineural hearing loss at Peking Union Medical College Hospital from April 2018 to August 2019 were included. Patients underwent temporal bone high resolution CT (HRCT), based on which the electrode lengths were calculated using OTOPLAN. Eleven and fifteen ears were implanted with MED-EL Flex 31.5 mm and Flex 28 mm electrode arrays respectively, via round window approach under minimally invasive surgery. The patients were followed up regularly for up to 2 years. At each follow-up, aided hearing threshold, speech recognition in quiet and noise, and Nijmegen Cochlear Implantation Questionnaire (NICQ) scores were evaluated and compared. Results: Post-operative hearing thresholds were (46.5±3.4) dB and (48.5±2.2) dB in patients implanted with MED-EL Flex 31.5 mm and Flex 28 mm electrode arrays, respectively, with no statistically significant difference (P=0.074). Both hearing thresholds and speech recognition demonstrated significant post-operative improvement compared with pre-operative results. Hearing thresholds after 1-year post-operation were (32.1±1.2) dB and (32.5±0.9) dB, respectively (P=0.355). Patients implanted with Flex 31.5 mm electrode scored significantly higher at speech recognition under 65 dB sound pressure level (SPL) at most of the follow-ups (All P<0.05). Speech recognition in noise (S/N=10 dB) was also improved in patients implanted with Flex 31.5 mm electrode. All sub-divisions of the NICQ demonstrated significant post-operative improvement, and no significant difference between the 2 groups was observed apart from the"self-confidence"sub-division. Conclusions: Selection of MED-EL Flex 31.5 mm and 28 mm implantation based on pre-operative OTOPLAN evaluation can both bring significant improvements to patients' hearing and quality of life. Flex 31.5 mm electrode can potentially provide better speech recognition within a certain period after surgery.

Vestibular Function After Bilateral Simultaneous Cochlear Implantation.

Thanks to the advantages of hearing-in-noise and spatial orientation, currently bilateral cochlear implantation (CI) became popular for patients with profound hearing loss. The aim of this study was to investigate vestibular function in bilateral simultaneous CI recipients. Retrospective analysis. University hospital. Sixteen patients with profound hearing loss were included. Bilateral simultaneous CI with flexible electrode using round window approach. Vestibular function was evaluated using both objective and subjective measures in the subjects preoperatively and 4 months postoperatively. Differences were analyzed preoperatively and postoperatively. Preoperative vestibular tests revealed that 8 subjects (50%) had abnormal caloric test results, 11 ears (34.4%) had abnormal ocular vestibular-evoked myogenic potential results, 6 ears (18.8%) had abnormal cervical vestibular-evoked myogenic potential results, 7 ears (21.9%) in the anterior semicircular canal, and 6 ears (18.8%) in the posterior semicircular canal had gain loss. However, surgery significantly decreased the sums of the maximal slow-phase velocities evidenced by caloric test (p ‹ 0.05). Cervical vestibular-evoked myogenic potential abnormal rate significantly increased to 53.1% after surgery (p ‹ 0.05). The postoperative changes regarding ocular vestibular-evoked myogenic potential, video head impulse test (vHIT), and Dizziness Handicap Inventory (DHI) were not significant among all the patients. Patients diagnosed as large vestibular aqueduct syndrome showed significantly higher DHI scores than others (p ‹ 0.05). Spearman's correlation analysis revealed that DHI moderately correlated with the dysfunction of semicircular canals evidenced by vHIT (r = 0.702; p < 0.001), weakly correlated with caloric (r = 0.352; p = 0.048). However, no correlation was found between DHI and VEMPs. The monosyllabic and disyllabic word recognition score significantly improved from 0 to 60.4 ± 14.3% (p < 0.05) and from 0 to 63.3 ± 14.5% (p < 0.05) respectively. There was no correlation between the improvement of word recognition score and the change of vestibular tests. The study showed preservation of utricle function, vestibular function at high frequency after bilateral simultaneous CI. However, operation significantly affected vestibular function at low frequency and saccule function. Patients with large vestibular aqueduct syndrome showed dramatically higher DHI scores than others. DHI moderately correlated with vHIT and weakly correlated with caloric.

Force and pressure measurements in temporal bones

PurposeSome cochlear implant (CI) patients lose their residual hearing during surgery. Two factors that might play a role in residual hearing loss are the change in intracochlear hydraulic pressure and force on the cochlear wall during electrode insertion. The aim of this study is to investigate whether a difference in peak hydraulic pressure and peak force on the cochlear wall exists during a CI electrode insertion with different insertion techniques. Materials and methodsTwenty fresh frozen temporal bones were used. Hydraulic pressure and force on the cochlear wall were recorded during straight electrode insertions with 1) slow versus fast insertion speed, 2) manual versus automatic insertion method and 3) round window approach (RWA) versus extended RWA (ERWA). ResultsWhen inserting with a slow compared to a fast insertion speed, the peak hydraulic pressure is 239% (95% CI: 130–399%) higher with a RWA and 58% (95% CI: 6–137%) higher with an ERWA. However, the peak force on the cochlear wall is a factor 29% less (95% CI: 13–43%) with a slow insertion speed. No effect was found of opening and insertion method. ConclusionsAs contradictory findings were found for hydraulic pressure and force on the cochlear wall on insertion speed, it remains unclear which insertion speed (slow versus fast) is less traumatic to inner ear structure.

Assessment of Frequency-Place Mismatch by Flat-Panel CT and Correlation With Cochlear Implant Performance.

To calculate the frequency allocation mismatch in a group of very selected cochlear implant (CI) recipients and to contrast it with the speech perception performances. Cross-sectional observational prospective study. Tertiary Audiological Department, University hospital. Fifteen adults receiving the same CI array by the same surgeon through a posterior tympanotomy, round window approach. 1) High definition flat panel computed tomography (FPCT) control of the intracochlear position of each electrode contact, and computation of the relative frequency allocation mismatch; 2) analysis of speech perception outcomes in relation with the mismatch. Despite a consistent and reproducible surgical procedure with the same intracochlear array, significant deviations from the frequency allocation tables (FAT) assigned by default by the manufacturer were observed in this study.Their influences on speech perception performances were negligible in the simple tasks of words or sentences recognition in quiet (and, to a lesser extent also in noise). The greatest effect of a significant mismatch was observed for the vocal-consonant-vocal (VCV) sequences recognition under noise masking, the emotional and the linguistic prosody recognition, and the phonemes discrimination of the Auditory Speech Sound Evaluation (A§E) test. The greatest frequency-to-place occurred at the high frequencies. The effect was rather irrelevant on simple words and sentences recognition, while it negatively impacted on the more complex perceptual tasks.

Effect of Cochlear Implantation on the Endocochlear Potential and Stria Vascularis

Animals with cochlear implantation-induced hearing loss will have a lower endocochlear potential (EP) and decreased strial vascular density. The cause of residual hearing loss following cochlear implantation remains poorly understood. Recent work from our lab has shown a correlation between vascular changes in the cochlear lateral wall and postimplantation hearing loss, suggesting a role of the stria vascularis and EP. Fourteen young, normal-hearing male albino guinea pigs underwent cochlear implantation using either a cochleostomy (CI-c, n = 9) or an extended round window (CI-eRW, n = 5) approach. Hearing sensitivity was assessed pre- and postoperatively using auditory brainstem response thresholds. Three weeks after implantation, EP measurements were obtained from the first and second turns. Hair cell counts and stria vascularis capillary density measurements were also obtained. The implanted group experienced significant threshold elevations at 8 to 24 kHz (mean threshold shift 9.1 ± 1.1 dB), with a more robust threshold shift observed in the CI-eRW group compared to the CI-c group. Implanted animals had a significantly lower first turn EP (81.4 ± 5.1 mV) compared with controls (87.9 ± 6.1 mV). No differences were observed in the second turn (75.8 ± 12.0 mV for implanted animals compared to 76.5 ± 7.0 mV for controls). There were no significant correlations between turn-specific threshold shifts, EP measurements, or strial blood vessel density. Reliable EP measurements can be obtained in chronically implanted guinea pigs. Hearing loss after implantation is not explained by changes in strial vascular density or reductions in EP.

A New CT Parameter for Predicting Residual Hearing Preservation in Cochlear Implantation: The "Basal Turn-Facial Ridge Angle".

We suggest a simple measurement, called the "basal turn-facial ridge (BT-FR) angle," for determining the electrode insertion axis using preoperative temporal bone computed tomography (CT) to predict hearing preservation (HP) in cochlear implantation (CI). Retrospective chart review. Tertiary referral center. Eighty-two ears that underwent CI between 2010 and 2018 were included. Ears with preoperative thresholds less than or equal to 80 dB HL at 125, 250, and 500 Hz were enrolled and grouped using the criteria of Skarżyński et al.: Group 1, complete or partial HP; Group 2, minimal HP or complete hearing loss. All subjects underwent CI with soft surgery techniques through the round window approach. The BT-FR angle is the angle between the basal turn line (BT-line), which is a straight line passing through the center of the longitudinal axis of the BT, and the facial ridge line, which is a straight line running from the endpoint of the BT-line to a point just above the facial ridge. The BT-FR angle was 2.5 ± 2.9 degrees in Group 1 and -0.3 ± 2.7 degrees in Group 2 (p = 0.003). The angle and hearing loss showed a significant negative correlation (r = -0.401, p = 0.002). In multiple linear regression, "age at operation" (β coefficient 0.260; p = 0.001) and the "BT-FR angle" (-1.967; p = 0.001) were significant variables affecting the degree of residual hearing loss. The BT-FR angle, which can be measured simply, may be useful to predict residual HP after CI.

VESTIBULAR SYMPTOMS AFTER COCHLEAR IMPLANTATION: CLINICAL OVERVIEW AFTER A 2-YEAR FOLLOW-UP

Background Vestibular symptoms and balance disorders are still common complaints reported by the patients after cochlear implantation (CI). Much research has been devoted to assess dizzy patients after cochlear implantation using both self-prepared questionnaires as well as validated life-quality scales. From this work, various approaches to classifying symptoms according to their onset and duration have been recommended. Material and methods We studied 101 patients after round window approach (RWA) cochlear implantation giving them a self-prepared questionnaire asking them to list their major vestibular complaints formulated according to the consensus document of the Barany Society Committee for the classification of vestibular disorders. Those with persistent symptoms (both postoperatively and existing preoperatively) also filled in a DHI questionnaire. Additionally, cVEMP, oVEMP, caloric, and vHIT tests were performed before and after the CI procedure. Results The 101 patients were divided into four groups: with early symptoms (n = 25), with late symptoms (n = 2), with preoperative symptoms (n = 13), and with no symptoms (n = 61). Among the patients with early symptoms, 15 reported spontaneous vertigo attack, 6 only unsteadiness and/or lateropulsion, and 4 had other symptoms such as orthostatic vertigo, positional vertigo, visual tilt, and head-motion vertigo. Conclusions Close to 40% of the CI recipients suffered from vestibular complaints, either in the postoperative period or from already existing preoperative symptoms. The vast majority of postoperative complaints were transient and only rare cases (with preexisting inner ear pathologies and/or comorbidities) evolved into persistent dysfunction.

Electrocochleography Observations in a Series of Cochlear Implant Electrode Tip Fold-Overs.

Tip fold-over is a rare but serious complication of cochlear implant (CI) surgery. The purpose of this study was to present intraoperative electrocochleography (ECochG) observations in a series of CI electrode tip fold-overs. Five pediatric subjects undergoing CI surgery through a round window (RW) approach with a perimodiolar electrode array, who were diagnosed with either auditory neuropathy spectrum disorder or enlarged vestibular aqueduct. Intraoperative RW ECochG during CI surgery: tone burst stimuli were presented from 95 to 110 dB SPL. Magnitude and phase characteristics of ECochG responses obtained intraoperatively before and immediately after electrode insertion were examined for patients with and without tip fold-over. Three subjects presented with tip fold-over and two formed the control group. Among fold-over cases, one participant exhibited an inversion in the starting phase of the cochlear microphonic response and a decrease in spectral magnitude from pre- to postinsertion. Both subjects who did not exhibit a change in phase had an increase in the ECochG-total response (ECochG-TR) magnitude. No case in the control group exhibited a change in starting phase. In regard to the ECochG-TR, all controls showed a decrease in the magnitude. Despite the small number of patients, heterogeneous ECochG response patterns were observed within the fold-over group. Though these results are not conclusive, they can serve as a framework to begin to understand ECochG's utility in detecting intraoperative tip fold-over.

A Case of Cochlear Implantation in a Child with Congenital Aural Atresia and Cochlear and Cochlear Nerve Malformation

Congenital aural atresia (CAA) is usually accompanied by an anomalous course of facial nerves, which may run over the round window niche toward the promontory in some cases of CAA. Very rarely, cochlear malformation might coexist at the same ear which has CAA, in which case cochlear implantation can be difficult due to anomalous facial nerve. Herein we present a case of cochlear implantation performed in a child who had CAA along with cochlear hypoplasia and cochlear nerve aplasia. The mastoid segment of facial nerve was displaced anteriorly, running over the round window niche. The surgery was done successfully using the round window approach without facial nerve injury.

Cochlear implantation under local anesthesia and conscious sedation: an Italian experience.

To report our experience in performing cochlear implantation under local anesthesia in a group of patients who were deemed unfit for general anesthesia. A retrospective chart review was performed to analyze undesirable events and any other discomfort complained by patients during cochlear implantation. Analysis of patient's satisfaction was performed by means of a survey instrument. We have also compared the duration of surgery and hospitalization time with a control group that was implanted under general anesthesia. Twenty-one cochlear implantation in 20 patients were performed under local anesthesia. Age of patients ranged from 38 to 85years. All interventions were successfully completed without any conversions to general anesthesia. Discomfort during surgery was reported in five cases: vertigo triggered by electrode insertion in two patients, pain during the round window approach in two patients and distress during the use of drill in one case; no patient experienced agitation. During the postoperative period, no complications or unpleasant experiences were reported. Only two patients stated that they would not perform cochlear implantation again under local anesthesia. Lower duration surgery and hospitalization time were found in the local anesthesia group. Local anesthesia with conscious sedation is a safe and effective alternative for cochlear implant candidates considered unfit for general anesthesia. Fundamental for a successful procedure are preoperative counselling, accurate selection of the patients and constant intraoperative assistance. Unfeasibility of facial nerve monitoring and minor detrimental effect on training are the principal disadvantages in performing cochlear implantation under local anesthesia.

An analysis of surgical management of difficulties during cochlear implant with inner ear anomalies

Objective:The purpose of this study is to review the difficulties that can occur during cochlear implant surgery in patients with inner ear abnormalities and the management. Method:A retrospective analysis was made on 186 cases of cochlear implant with inner ear malformation, the types of inner ear malformations included 6 cases（3.23%） of isolated semicircular dysplasia, 137 cases（73.66%） of isolated large vestibular aqueducts, 26 cases（13.98%） of Mondini malformations, 6 cases（3.23%） of incomplete septal type Ⅲ, 3 cases（1.61%） of internal auditory stenosis, 7 cases（3.76%） of cochlear dysplasia and 1 case（0.54%） of incomplete septal typeⅠ. Two hundred patients with normal inner ear structures were randomly selected as the control group. The data collected included the types of inner ear abnormalities, intraoperative manifestations, clinical management strategies, and postoperative speech rehabilitation, and the literature was reviewed. Result:148 patients（77.49%） with inner ear malformation underwent successful surgery, electrode insertion was incomplete in 6 patients（3.14%）, and cerebrospinal fluid blowout occurred in 29 patients（15.18%）, it was difficult to locate the window because of the abnormal structure of the window in 8 cases（4.19%）. In 191 patients, the facial recess approach was adopted intraoperatively, and 17.8% of the patients had significant structural abnormalities of the facial nerve, significantly more than the group with normal inner ear structure. Only 1 patient showed delayed facial nerve paralysis 1 week after surgery, and recovered well after treatment. 6.81% of the patients adopted the expanded round window approach, which was significantly lower than that of the group with normal inner ear structure（28%）. There was no significant difference between patients with inner ear malformation and patients with extremely severe deafness with normal inner ear structure who received cochlear implant in speech rehabilitation. Conclusion:Cochlear implant is safe, feasible and effective for patients with inner ear malformation. For patients with inner ear malformation, special attention should be paid to the preoperative imaging reading to predict the possible risks during the operation. The safest surgical plan, including the type of electrode and the manner in which the window is opened, must be prepared before the operation, and the operation must be performed or directed by an experienced surgeon who can adjust the optimal surgical plan according to what is seen during the operation.

Current management of superior semicircular canal dehiscence syndrome.

The current article reviews literature on the contemporary management of superior semicircular canal dehiscence syndrome (SSCDS). Approaches to management and surgical techniques are compared along with a discussion of the use of more standardized, objective outcome measures. Considerable debate still exists as to what approach and technique is most appropriate for patients with SSCDS and how to best measure postoperative outcomes. However, it is increasingly accepted that multiple factors account for outcomes in SSCDS, including presenting symptoms and presence of vestibular comorbidities. Therefore, surgical intervention is best tailored to each individual patient. Data on SSCDS outcomes is heterogenous, and increased emphasis is being placed on validated measures of outcome. Round window approaches remain controversial and their role is still undefined. The treatment strategies for SSCDS continue to diversify. A patient-specific approach with systematic documentation of outcomes will continue to inform how these patients are best managed.

Modiolar Proximity of Slim Modiolar Electrodes and Cochlear Duct Length: Correlation for Potential Basis of Customized Cochlear Implantation With Perimodiolar Electrodes.

Recent studies have shown that cochlear duct length (CDL) varies among individuals and could significantly influence the final position of the electrode and its trajectory in the cochlea. Given this, we hypothesized that the degree of modiolar proximity of novel slim modiolar electrodes, such as CI532 and CI632, can also be affected by CDL. To test this hypothesis, we retrospectively evaluated individual CDL to determine if there is any significant correlation of CDL with degree of modiolar proximity. Fifty-one ears from 38 subjects implanted with slim modiolar electrodes by a single surgeon through the round window approach using the pull-back technique were included. Our cohort was classified according to the deafness onset (congenital versus postlingual) and the degree of modiolar proximity (less versus tight) with reference to the spiral diameter made by the slim modiolar electrodes in situ on transorbital x ray. We then analyzed the CDL and its metrics using a readily available surgical preplanning tool (OTOPLAN) to obtain comparable data. Among 30 ears associated with congenital deafness, 9 ears (30%) showed less modiolar proximity, while none of the 21 ears from 19 subjects with postlingual deafness exhibited "less modiolar proximity" based on our criteria. In this study, CDL showed significant variation among subjects. Importantly, a significant inverse correlation between spiral diameter and CDL (ρ = -0.581, p < 0.001) was found, showing that shorter CDLs have longer spiral diameter and less modiolar proximity. Moreover, further pull-back technique characterized by pulling out the electrode a little bit more in cases with shorter CDL, if not always, exhibited tighter modiolar proximity. A preponderance of less modiolar proximity of the electrode was observed exclusively among congenital deafness cases, demonstrated by a less tight spiral configuration even under the pull-back technique. Our data suggest that shorter CDL is associated with a less tight spiral configuration of slim modiolar electrodes postoperatively. Depending on the insertion technique, the differential degree of modiolar proximity of slim modiolar electrodes can be alleviated in cases with short CDL, which justifies cochlear duct length-based customized insertion of slim modiolar electrodes.

Surgical management of cochlear implant in chronic otitis media patients: safe and sound

Introduction Cochlear implantation (CI) in cases with chronic otitis media (COM) was previously contraindicated but recent advances have made it possible. Objective To review surgical and audiological outcomes of COM patients that underwent CI. Material and methods Retrospective review of patients above 18 years old. Results Ten patients with complete data were included. Patients were aged 24–69 years old. Tympanoplasty and mastoidectomy were performed before CI. Imaging was performed to rule out ossifications. Eight patients underwent a standard canal wall up with either cochleostomy or round window approach. One patient had additional canalplasty and tympanoplasty and another one had blind sac procedure respectively. Analysis of the hearing aided level with CI and hearing aid showed significant benefit provided by the CI (Z = 2.803, p = .005). Discussion Creating a dry and safe ear is important prior to CI. Definite hearing improvement is seen in all our cases that helped them to become independent again in their daily life. Hearing aid usage pre-CI might not be important as the hearing aids may continue to cause discharging ears and the benefits of hearing aids in severe to profound hearing loss are very minimal. Conclusions Cochlear implant is safe and effective in COM patients.

Cochlear implantation and residual hearing preservation long-term follow-up of the first consecutively operated patients using the round window approach in Uppsala, Sweden

Objective: We conducted a long-term follow-up study to investigate the time course of residual hearing in our first 21 consecutively operated cochlear implant (CI) patients using the round window (RW) approach . The study may provide additional information about the influence of a flexible lateral wall electrode array on cochlear function. Methods: Data were available for long-term follow-up (>5 years) in 15 patients. Pure tone audiometry (PTA) was assessed at 0.125–8 kHz preoperatively, and at one, three and >5 years postoperatively. Insertion angle, number of electrodes inside the cochlea, user-time of the processor and stimulation strategy were documented. Results: Twelve out of 15 patients had residual hearing after a follow-up period of five years (mean 86 months, range: 61–103 months). Four out of 15 patients had >75% complete hearing preservation (HP), 8 out of 15 had 25–75% partial HP and 3 out of 15 patients had complete loss of hearing. There was a high correlation between insertion angle and HP. Conclusion: Long-term HP was possible in 12 out of 15 cases. Even patients with complete hearing loss at long-term follow-up showed high performance in speech understanding and were full-time users.

Anatomy of the Round Window Region With Relation to Selection of Entry Site Into the Scala Tympani.

The aim of cochlear implantation is to safely insert an electrode array into the scala tympani (ST) while avoiding damage to surrounding structures. There is disagreement on the optimal way of entering the ST-the round window (RW) approach versus cochleostomy. Regardless of the chosen approach, it is vital to understand the regional anatomy, which is complex, difficult to conceptualize, and rarely dissected in temporal bone courses. The goal of this study was to examine the anatomy of the RW to gain more in-depth knowledge on the local relationships of the anatomical structures and propose an approach for entering the ST in cochlear implant surgery tailored to the encountered anatomy. Cadaveric prevalence study and expert opinion with literature review. Cadaveric temporal bone dissection (n = 13) by the first author assessing the RW anatomy. The round window membrane (RWM) and the osseous spiral lamina (OSL) are curved structures, each with a horizontal and a vertical part. The two horizontal portions are very closely apposed. The relationship between the OSL and the RWM determines the best site for a cochleostomy, which if required is best placed anteroinferiorly to the RWM. The distance between the oval window inferior margin and the RW membrane is less than 2 to 3 mm. The ST initially extends inferiorly and medially to the RW. The findings of our dissection have implications for cochlear implant surgery in aiming to avoid trauma to the OSL and basilar membrane and aid decision making in choosing the safest surgical approach. 5. Laryngoscope, 131:E598-E604, 2021.

Comparison of Hearing Preservation Outcomes Using Extended Versus Single-Dose Steroid Therapy in Cochlear Implantation.

The purpose of this study was to compare the hearing preservation outcomes of patients who received extended versus single-dose steroid therapy in cochlear implant surgery. Case-control. Tertiary referral centers in Taiwan from April 2017 to 2019. A total of 70 patients aged 1 to 78 years old (mean = 18.04, standard deviation [SD] = 21.51) who received cochlear implantation via the round window approach were included in the study. Prospectively, 35 cases were enrolled for cochlear implantation with single-dose therapy. Thirty-five controls who underwent cochlear implantation with extended therapy were retrospectively enrolled after frequency matching. The main outcome measure was the rate of hearing preservation. This was calculated based on the HEARRING Network formula and results were categorized as complete, partial, and minimal. Impedances served as secondary outcomes. There was no significant difference in the complete hearing preservation rates between the extended and single-dose groups at 6 months postoperatively. Impedances were significantly lower in the extended group after 1 month and 6 months of follow up. When the complete and partial hearing preservation groups were compared, the size of round window opening and speed of insertion were found to be statistically significant. Both extended and single-dose therapies result in good hearing preservation in patients who undergo cochlear implantation. However, better impedances can be expected from patients who received extended therapy. A slower speed of insertion and a widely opened round window play a role in hearing preservation.

Which approach is better for the protection of vestibular receptors in cochlear implant surgery: Round window or standard cochleostomy?

Objectives: This study aims to compare electrode insertion techniques in cochlear implantation (CI) as the standard cochleostomy approach (SCA) versus the round window approach (RWA) on five vestibular end-organ functions and vertigo in the pre- and postoperative period. Patients and Methods: In total, 51 patients (22 males, 29 females; mean age 38.2 years; range 16 to 70 years) with normal vestibular function and operated with single-sided CI were included in this study between January 2015 and December 2019. Of the patients, 30 were operated with the RWA and 21 with the SCA. All of the patients were evaluated with the Dizziness Handicap Inventory (DHI) and a complete vestibular test battery including the video head impulse test (vHIT), cervical vestibular-evoked myogenic potential (cVEMP), and ocular vestibular-evoked myogenic potential (oVEMP) at one week preoperatively and one month postoperatively. Results: Patients in the RWA group had a statistically significantly better protected vestibular functions and fewer subjective vertigo symptoms in the postoperative period (p&lt;0.05). Deterioration in at least one of the five vestibular end-organ functions was observed in eight of 21 patients (38.09%) in the SCA group, compared to three of 30 (10%) in the RWA group. A significant correlation was detected between the vestibular tests and DHI in both groups (r=0.686, p=0.001 in the SCA group and r=0.630, p&lt;0.001 in the RWA group). Conclusion: Our study results suggest that RWA for CI may minimize damage to vestibular receptor functions and vertigo symptoms than SCA.