[Facial nerve protection in surgery for rare tumors of the internal auditory canal].

Objective:To explore strategies for preserving facial nerve function during surgeries for rare tumors of the internal auditory canal. Methods:A total of 235 cases of internal auditory canal tumors treated between 2010 and 2023 were included, encompassing vestibular schwannomas, cavernous hemangiomas, meningiomas, and other rare tumors. Various data, including clinical presentations, imaging classifications, and treatment processes, were meticulously analyzed to delineate the characteristics of rare tumors and assess pre-and postoperative facial nerve function. Results:Among all internal auditory canal tumors, vestibular schwannomas accounted for 91.9%. In rare tumors, facial nerve schwannomas constituted 5.3%, cavernous hemangiomas 26.3%, meningiomas 15.8%, and arterial aneurysms 10.5%. Significantly, patients with cavernous hemangiomas displayed pronounced invasion of the facial nerve by the tumor, in contrast to other tumor types where clear boundaries with the facial nerve were maintained. During surgery, individualized approaches and strategies for facial nerve protection were implemented for different tumor types, involving intraoperative dissection, tumor excision, and facial nerve reconstruction. Conclusion:Preservation of the facial nerve is crucial in the surgical management of rare tumors of the internal auditory canal. Accurate preoperative diagnosis, appropriate timing of surgery, selective surgical approaches, and meticulous intraoperative techniques can maximize the protection of facial nerve function. Personalized treatment plans and strategies for facial nerve functional reconstruction are anticipated to enhance surgical success rates, reduce the risk of postoperative facial nerve dysfunction, and ultimately improve the quality of life for patients.

Unilateral Multifocal Inner Ear and Internal Auditory Canal or Cerebellopontine Angle Cochleovestibular Schwannomas-Genetic Analysis and Management by Surgical Resection and Cochlear Implantation.

OBJECTIVE: To describe the genetic characteristics and the management of two very rare cases of unilateral multifocal inner ear and internal auditory canal or cerebellopontine angle cochleovestibular schwannomas not being associated to full neurofibromatosis type 2-related schwannomatosis. PATIENTS: In a 29-year-old man and a 55-year-old woman with single-sided deafness multifocal unilateral cochleovestibular schwannomas were surgically resected, and hearing was rehabilitated with a cochlear implant (CI). Unaffected tissue was analyzed using next generation sequencing of the NF2 gene. Tumor tissue was analyzed using a 340-parallel sequencing gene panel. MAIN OUTCOME MEASURES: Mutations in the NF2 gene, word recognition score for monosyllables at 65 dB SPL (WRS 65 ) with CI. RESULTS: No disease-causing mutation was detected in the examined sequences in blood leucokytes. All tumor samples revealed, among others, somatic pathogenic NF2 mutations. While the anatomically separate tumors in case 1 were likely molecular identical, the tumors in case 2 showed different genetic patterns. WRS 65 was 55% at 6 years of follow-up and 60% at 4.5 years of follow-up, respectively. CONCLUSIONS: The occurrence of multifocal unilateral cochleovestibular schwannomas without pathogenic variants in NF2 in non-affected blood leucocytes can be associated with mosaic NF2 -related schwannomatosis (case 1), or with likely sporadic mutations (case 2) and may be overlooked due to their extreme rarity. Although challenging, successful hearing rehabilitation could be achieved through surgical resection of the tumors and cochlear implantation.

Long-term outcomes and electrophysiological measures of children with inner ear malformations and cochlear implants.

OBJECTIVES: To compared auditory and speech performance outcomes of children with cochlear implants (CI), between those with inner ear malformations (IEMs) and with normal ear anatomy; and to describe differences in electrophysiological measurements. STUDY DESIGN: A retrospective study. SETTING: A tertiary care pediatric medical center. PATIENTS: Forty-one children with IEMs who underwent CI during 2003-2017, and 41 age-matched CI recipients with normal ear anatomy (control group). MAIN OUTCOME MEASURES: Post-CI auditory performance outcomes including educational setting, Categories of Auditory Performance (CAP), and Speech Intelligibility Rating (SIR); and electrophysiological measurements, Including maximal comfortable electrical levels (CLs) and impedances along CI electrodes. RESULTS: The ANOVA on ranks revealed lower CAP scores in the study than control group: H3 = 18.8, P < 0.001. Among children with IEMs, CAP scores were better in children with enlarged vestibular aqueduct (EVA) (P < 0.04). SIR scores of the control group did not differ from those with isolated EVA; however, SIR scores of the IEMs without EVA subgroup were lower than all the other study subgroups (P < 0.01). The proportion of the control group that was integrated with full inclusion educational settings into the regular mainstream schools was higher than for those with IEMs without EVA (47 % vs. 15 %, P < 0.05), but similar to those with isolated EVA. For the study group versus control group, maximal comfortable electrical levels (CLs) were higher)P > 0.03) while impedance measurements were similar. CONCLUSIONS: Outcomes of pediatric recipients with normal anatomy were better than those with IEMs. Among pediatric recipients of CI with IEMs, auditory performance was better and CLs were lower among children with isolated EVA than all other IEM subgroups.

Variability in Manual Segmentation of Temporal Bone Structures in Cone Beam CT Images.

PURPOSE: Manual segmentation of anatomical structures is the accepted "gold standard" for labeling structures in clinical images. However, the variability in manual segmentation of temporal bone structures in CBCT images of the temporal bone has not been systematically evaluated using multiple reviewers. Therefore, we evaluated the intravariability and intervariability of manual segmentation of inner ear structures in CBCT images of the temporal bone. METHODS: Preoperative CBCTs scans of the inner ear were obtained from 10 patients who had undergone cochlear implant surgery. The cochlea, facial nerve, chorda tympani, mid-modiolar (MM) axis, and round window (RW) were manually segmented by five reviewers in two separate sessions that were at least 1 month apart. Interreviewer and intrareviewer variabilities were assessed using the Dice coefficient (DICE), volume similarity, mean Hausdorff Distance metrics, and visual review. RESULTS: Manual segmentation of the cochlea was the most consistent within and across reviewers with a mean DICE of 0.91 (SD = 0.02) and 0.89 (SD = 0.01) respectively, followed by the facial nerve with a mean DICE of 0.83 (SD = 0.02) and 0.80 (SD = 0.03), respectively. The chorda tympani had the greatest amount of reviewer variability due to its thin size, and the location of the centroid of the RW and the MM axis were also quite variable between and within reviewers. CONCLUSIONS: We observed significant variability in manual segmentation of some of the temporal bone structures across reviewers. This variability needs to be considered when interpreting the results in studies using one manual reviewer.

Inner Ear Breaches from Vestibular Schwannoma Surgery: Revisiting the Incidence of Otologic Injury from Retrosigmoid and Middle Cranial Fossa Approaches.

OBJECTIVE: To assess the rate of iatrogenic injury to the inner ear in vestibular schwannoma resections. STUDY DESIGN: Retrospective case review. SETTING: Multiple academic tertiary care hospitals. PATIENTS: Patients who underwent retrosigmoid or middle cranial fossa approaches for vestibular schwannoma resection between 1993 and 2015. INTERVENTION: Diagnostic with therapeutic implications. MAIN OUTCOME MEASURE: Drilling breach of the inner ear as confirmed by operative note or postoperative computed tomography (CT). RESULTS: 21.5% of patients undergoing either retrosigmoid or middle fossa approaches to the internal auditory canal were identified with a breach of the vestibulocochlear system. Because of the lack of postoperative CT imaging in this cohort, this is likely an underestimation of the true incidence of inner ear breaches. Of all postoperative CT scans reviewed, 51.8% had an inner ear breach. As there may be bias in patients undergoing postoperative CT, a middle figure based on sensitivity analyses estimates the incidence of inner ear breaches from lateral skull base surgery to be 34.7%. CONCLUSIONS: A high percentage of vestibular schwannoma surgeries via retrosigmoid and middle cranial fossa approaches result in drilling breaches of the inner ear. This study reinforces the value of preoperative image analysis for determining risk of inner ear breaches during vestibular schwannoma surgery and the importance of acquiring CT studies postoperatively to evaluate the integrity of the inner ear.

Noise-induced hearing loss in the contralateral ear during otologic and neurotologic surgeries.

OBJECTIVE: Noise-induced hearing loss in the non-surgical ear during otologic/neurotologic surgery has not been well studied. The purpose of this study was to evaluate changes in hearing that may occur in the contralateral (i.e., non-surgical) ear after various otologic/neurotologic surgeries due to noise generated by drills. We hypothesized that otologic/neurotologic surgeries, longer in duration, would suggest longer drilling times and result in decreased hearing in the contralateral ear as evidenced by a change post-operative pure tone air conduction thresholds when compared to pre-operative thresholds. METHODS: A retrospective chart review at a tertiary referral center. Adult patients (18-75 years old) who underwent otologic/neurotologic surgeries from May 1, 2016 through May 1, 2021 were considered for inclusion. Surgeries included vestibular schwannoma resection (translabyrinthine, middle cranial fossa, or retrosigmoid approaches), endolymphatic sac/shunt and labyrinthectomy for Meniere's disease, and tympanomastoid surgery for middle ear pathology (e.g., cholesteatoma). Patient characteristics obtained through record review included age, sex, surgical procedure, pre-operative and post-operative audiometric thresholds and word recognition scores (WRS) for the contralateral ear, and duration of surgery. RESULTS: No significant differences were observed for change in audiometric thresholds in the contralateral ear for any surgery when considering individual frequencies. Additionally, no significant change in WRS was observed for any surgical approach. CONCLUSIONS: The risk of hearing loss in the non-surgical ear during various otologic/neurotologic surgeries appears to be minimal when measured via routine clinical tests.

Intracanalicular vestibular schwannomas: facial and hearing outcomes according to the location of the tumor in relation to the nerves of the internal auditory canal.

OBJECTIVE: The objective was to evaluate whether the position of the nerves within the internal auditory canal (IAC) has any effect on preoperative and postoperative cochlear and facial nerve function in patients with intracanalicular vestibular schwannoma (VS) resected through the retrosigmoid transmeatal approach. METHODS: Forty-four patients with sporadic intracanalicular VS, from a series of 710 patients with VS who underwent operations from January 1993 to April 2022, were retrospectively reviewed. The pattern of displacement of the cranial nerves and tumor within the IAC was recorded. Tumors were divided into 2 types: type T1A lesions had only anteriorly displaced nerves, and type T1B had posteriorly displaced vestibular nerves and anteriorly displaced facial and cochlear nerves. Differences in surgical outcomes between groups in terms of facial nerve function and hearing preservation were evaluated. RESULTS: Thirty-five cases (79.5%) were T1A tumors and 9 were T1B (20.5%). Gross-total resection and anatomical preservation of the facial and cochlear nerves were achieved in all patients. Postoperatively, all patients with T1A VS maintained normal facial nerve function; however, among T1B VS patients, 6 (67%) retained House-Brackmann grade I, 2 worsened to grade II, and 1 worsened to grade III at 6 months (p = 0.006). The 27 T1A VS patients with serviceable hearing maintained this status, and an additional patient with nonserviceable hearing improved to serviceable hearing; among T1B VS patients, only 2 of the 5 patients with serviceable hearing remained as such, 2 evolved to nonserviceable hearing, and 1 lost hearing after surgery (p = 0.0022). T1B VS patients had a 24-fold risk of facial nerve deterioration (relative risk [RR] 25.2, 95% CI 1.42-448.57, p = 0.028) and a 32-fold risk of hearing deterioration (RR 32.7, 95% CI 1.93-553, p = 0.016) after surgery. CONCLUSIONS: In intracanalicular VS, postoperative cochlear and facial nerve function are directly related to the location of the tumor in relation to the nerves, with worse outcomes in cases where the tumor is located between the vestibular and facial-cochlear nerves.

Effect of congenital inner ear malformations (IEMs) on electrically evoked compound action potential (ECAP) responses in cochlear implant children.

PURPOSE: The study was designed to assess the electrically evoked compound action potential (ECAP) responses in children with inner ear malformations compared to children with normal inner ear anatomy. METHODS: The study included 235 prelingual deaf children who were implanted in cochlear implant unit in King Fahad University hospital-Imam Abdulrahman Bin Faisel University. Subjects were using either Cochlear Nucleus or Medel cochlear implant devices. We had 171 (64.5%) subjects with normal inner ear anatomy and 94 (35.5%) subjects with inner ear malformations (IEMs) and they were classified into 6 groups according to inner ear anatomy. Fourteen subjects (14.9%) subjects had enlarged vestibular aqueduct (EVA), 30 (32%) subjects had Mondini deformity, 25 (26.6%) subjects had incomplete partition type two (IPII), 9 (9.6%) subjects had incomplete partition type one (IPI) and 16 (17%) subjects had hypoplastic cochlea type III or IV. Intraoperative electrically evoked compound action potential (ECAP) responses were analyzed and compared in all subjects. RESULTS AND CONCLUSIONS: Measurable ECAP responses can be elicited in patients with IEMs in most of the channels. Severe malformations can affect the prevalence of measuring ECAP and getting identifiable waveform morphology. Additionally, increased thresholds and lower slope of AGF was observed in IEMs specially in more severe malformations (e.g. IPI). IPI patients with better word recognition scores tended to show more identifiable ECAP measurements. This could suggest the presence of some correlation between ECAP responses and patients' performance after cochlear implantation.

Does labyrinthectomy have an impact on hearing in the contralateral ear during long-term follow-up?

OBJECTIVE: To quantify contralateral hearing outcomes after labyrinthectomy for unilateral Ménière's disease (MD). STUDY DESIGN: Retrospective case series. SETTING: Tertiary neurotology referral center. PATIENTS: Labyrinth removal for the management of MD or translabyrinthine (TLAB) acoustic neuroma resection between 2008 and 2012. MAIN OUTCOME MEASURE: Long-term hearing changes via pure tone averages (PTA). RESULTS: Upon comparison of low-frequency PTA (250, 500, 1000 Hz), MD patients experienced a greater degree of hearing loss during the follow-up period when compared to the TLAB lab group (7.54 ± 2.11 dB vs 2.39 ± 1.10 dB, p = 0.035). This difference as attributable to 12 (28.6 %) MD patients experiencing a ≥30 dB increase in low-frequency PTA, whereas none (0.0 %) of the TLAB surpassed this threshold. CONCLUSIONS: At 10 years post-labyrinthectomy there is a heightened risk for MD patients to develop low-frequency sensorineural hearing loss. Clinicians should monitor for audiometric changes through regular testing in the decade following labyrinth removal.

Iatrogenic inner ear dehiscence associated with lateral skull base surgery: a systematic analysis of drilling injuries and their causal factors.

PURPOSE: Drilling injuries of the inner ear are an underreported complication of lateral skull base (LSB) surgery. Inner ear breaches can cause hearing loss, vestibular dysfunction, and third window phenomenon. This study aims to elucidate primary factors causing iatrogenic inner ear dehiscences (IED) in 9 patients who presented to a tertiary care center with postoperative symptoms of IED following LSB surgery for vestibular schwannoma, endolymphatic sac tumor, Meniere's disease, paraganglioma jugulare, and vagal schwannoma. METHODS: Utilizing 3D Slicer image processing software, geometric and volumetric analysis was applied to both preoperative and postoperative imaging to identify causal factors iatrogenic inner ear breaches. Segmentation analyses, craniotomy analyses, and drilling trajectory analyses were performed. Cases of retrosigmoid approaches for vestibular schwannoma resection were compared to matched controls. RESULTS: Excessive lateral drilling and breach of a single inner ear structure occurred in 3 cases undergoing transjugular (n=2) and transmastoid (n=1) approaches. Inadequate drilling trajectory breaching ≥1 inner ear structure occurred in 6 cases undergoing retrosigmoid (n=4), transmastoid (n=1), and middle cranial fossa approaches (n=1). In retrosigmoid approaches the 2-cm visualization window and craniotomy limits did not provide drilling angles to the entire tumor without causing IED in comparison to matched controls. CONCLUSIONS: Inappropriate drill depth, errant lateral drilling, inadequate drill trajectory, or a combination of these led to iatrogenic IED. Image-based segmentation, individualized 3D anatomical model generation, and geometric and volumetric analyses can optimize operative plans and possibly reduce inner ear breaches from lateral skull base surgery.

Endoscope-Assisted Visualization of the Internal Auditory Canal Using the Middle Fossa Approach.

HYPOTHESIS: Angled endoscopes have been postulated to increase visualization of the internal auditory canal (IAC); however, few studies have quantified the extent of IAC visualization using endoscopes of varying angles. BACKGROUND: Preservation of the bony labyrinth in middle fossa (MF) vestibular schwannoma surgery may limit visualization of the lateral IAC. We sought to determine the extent to which IAC visualization is increased with endoscopes in these situations. METHODS: Computed tomography (CT) scans were acquired before and after two cadaveric MF bony drill-outs. An atlas-based method was used to localize the IAC in the preprocedure CT and then registered with the postprocedure CT using standard image registration methods. Virtual microscope and endoscope positions and angles of approach were determined in a 3D rendering environment. Using ray casting techniques, the percentage of IAC surface area visible (unobscured by bony structures) with the microscope and 0°, 30°, and 45° endoscopes was calculated. RESULTS: For cadaver 1, the microscope led to visible IAC surface areas of 72%, whereas 0°, 30°, and 45° endoscopes visualized 58%, 79%, and 84%, respectively. For cadaver 2, the microscope led to visible surface areas of 67%, whereas the same endoscopes visualized 66%, 84%, and 84%, respectively. CONCLUSIONS: Using a microscope yields similar proportions of visible IAC surface area to a 0° endoscope in MF bony drill-outs. Increased visualization of the IAC is possible with more angled endoscopes. Using angled endoscopes may facilitate improved tumor dissection in the lateral IAC with neural and vascular preservation in vestibular schwannoma surgery aimed at hearing preservation.

MRI surveillance after translabyrinthine vestibular schwannoma resection and cochlear implantation: is it feasible?

PURPOSE: Cochlear implantation in patients with vestibular schwannomas is of increasing importance and interest. Two remaining challenges are the assessment of conduction of the cochlear nerve and the possibility of postoperative surveillance with magnetic resonance imaging. The aim of the current study was to assess follow-up imaging and determine the visibility of the internal auditory canal after vestibular schwannoma resection and cochlear implantation as well as in patients with persistent vestibular schwannomas and cochlear implants in place. Visibility of the internal auditory canal, cerebellopontine angle, and labyrinth were evaluated and graded. METHODS: For this retrospective study, 15 MR examinations of 13 patients after translabyrinthine vestibular schwannoma resection and ipsilateral cochlear implantation were included. All patients had been implanted with an MED-EL cochlear implant. Magnetic resonance imaging was carried out on a 1.5T device. All patients were prepped according to the manufacturer's recommendations. RESULTS: All 15 examinations were carried out without any adverse event during imaging, such as pain, magnet dislocation, or malfunction. The internal auditory canal and the cerebellopontine angle were sufficiently visible in all cases to allow for vestibular schwannoma follow-up. CONCLUSION: Magnetic resonance imaging surveillance of the internal auditory canal following vestibular schwannoma resection and cochlear implantation is feasible and safe with modern implants with a 1.5T magnetic resonance imaging device using metal artifact reduction sequences. Necessary follow-up imaging should not be a contraindication for cochlear implantation in patients with vestibular schwannomas.

Meningitis Risk in Patients with Inner Ear Malformations after Cochlear Implants: A Systematic Review and Meta-Analysis.

OBJECTIVE: The objective of this study is to determine the rate of postoperative meningitis after cochlear implantation in those with inner ear malformations (IEMs) via meta-analysis. DATA SOURCES: Medline, EMBASE, and the Cochrane Library. METHODS: This study was reported following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) checklist. Proportion meta-analysis was conducted through an inverse variance random-effect model based on arcsin transformation and presented as forest plots. Quality assessment of the included studies was performed through the National Institutes of Health Quality Assessment Tool. RESULTS: Overall, 38 of 2966 studies met the inclusion criteria and were included in the analysis. There were 10 cases of meningitis after cochlear implantation in 1300 malformed ears. The overall rate of meningitis after cochlear implantation in IEMs was 0.12% (95% confidence interval, 0.006-0.380%; I2 = 0%). Cases occurred in incomplete partition (n = 5), Mondini deformity (n = 2), common cavity (n = 2), and enlarged internal auditory canal (n = 1). Six of 10 cases of postoperative meningitis occurred with an intraoperative cerebrospinal fluid leak. CONCLUSION: In those with IEMs, the risk of meningitis after cochlear implantation is very low.

Anatomical Features of Children With Mondini Dysplasia: Influence on Cochlear Implantation Performance.

OBJECTIVE: To analyze the long-term auditory performance after cochlear implantation (CI) and identify anatomical features of Mondini dysplasia associated with post-CI outcomes. STUDY DESIGN: Retrospective study. SETTING: Tertiary care academic center. PATIENTS: We enrolled 49 ears with Mondini dysplasia who underwent CI with more than 7 years of follow-up and age at CI- and sex-matched control group with radiologically normal inner ears. MAIN OUTCOMES AND MEASURES: The development of auditory skills after CI was evaluated using word recognition scores (WRSs). The anatomical features were measured based on temporal bone computed tomography and magnetic resonance imaging, involving the width of the bony cochlear nerve canal (BCNC), cochlear basal turn, enlarged vestibular aqueduct, cochlear height, and diameter of the cochlear nerve (CN). RESULTS: CI in ears with Mondini dysplasia showed comparable benefits and improvement of auditory performance to controls during the 7 years of follow-up. In Mondini dysplasia, four (8.2%) ears showed narrow BCNC (<1.4 mm) with poorer WRS (58 ± 17%) than those with normal-sized BCNC, which had WRS (79 ± 10%) comparable to that of the control group (77 ± 14%). In Mondini dysplasia, the maximum ( r = 0.513, p < 0.001) and minimum ( r = 0.328, p = 0.021) CN diameters had positive correlations with post-CI WRS. The maximum CN diameter ( ß = 48.347, p < 0.001) and BCNC width ( ß = 12.411, p = 0.041) were significant factors that influence the post-CI WRS in multiple regression analysis. CONCLUSIONS: Preoperative anatomical evaluation, especially BCNC status and CN integrity, may serve as predictive markers for post-CI performance.

[Imaging evaluation of cerebrospinal fluid otorrhea associated with inner ear malformation in children].

Objective: To explore the imaging evaluation of cerebrospinal fluid (CSF) otorrhea associated with inner ear malformation (IEM) in children. Methods: The clinical data of 28 children with CSF otorrhea associated with IEM confirmed by surgical exploration in Beijing Children's Hospital, from Nov, 2016 to Jan, 2021, were analyzed retrospectively,including 16 boys and 12 girls, aged from 8-month to 15-year and 8-month old, with a median age of 4-year old. The shapes of stapes were observed during the exploration surgery, and the imaging features of temporal bone high resolution CT(HRCT) and inner ear MRI pre- and post-operation were analyzed. Results: In 28 children with CSF otorrhea, 89.3%(25/28) had stapes footplates defect during exploration. Preoperative CT showed indirect signs such as IEM, tympanic membrane bulging, soft tissue in the tympanum and mastoid cavity. IEM included four kinds: incomplete partition type I (IP-Ⅰ), common cavity (CC), incomplete partition type Ⅱ (IP-Ⅱ), and cochlear aplasia (CA); 100%(28/28) presented with vestibule dilation; 85.7%(24/28) with a defect in the lamina cribrosa of the internal auditory canal. The direct diagnostic sign of CSF otorrrhea could be seen in 73.9%(17/23) pre-operative MRI: two T2-weighted hyperintense signals between vestibule and middle ear cavity were connected by slightly lower or mixed intense T2-weighted signals, and obvious in the coronal-plane; 100%(23/23) hyperintense T2-weighted signals in the tympanum connected with those in the Eustachian tube.In post-operative CT, the soft tissues in the tympanum and mastoid cavity decreased or disappeared as early as one week. In post-operative MRI, the hyperintense T2-weighted signals of tympanum and mastoid decreased or disappeared in 3 days to 1 month,soft tissues tamponade with moderate intense T2-weighted signal were seen in the vestibule in 1-4 months. Conclusions: IP-Ⅰ, CC, IP-Ⅱ and CA with dilated vestibule can lead to CSF otorrhea. Combined with special medical history, T2-weighted signal of inner ear MRI can provide diagnostic basie for most children with IEM and CSF otorrhea.HRCT and MRI of inner ear can also be used to evaluate the effect of surgery.

Transcanal Transpromontorial Approaches to the Internal Auditory Canal: A Systematic Review.

OBJECTIVE: Exclusive endoscopic (EETTA) and expanded (ExpTTA) transcanal transpromontorial approaches have shown promising results for treating internal auditory canal (IAC) lesions. We reviewed the literature to answer the question: "Do EETTA and ExpTTA achieve high rates of complete resection and low rates of complications in treating patients with IAC pathologies?" DATA SOURCES: PubMed, EMBASE, Scopus, Web of Science, and Cochrane were searched. REVIEW METHODS: Studies reporting EETTA/ExpTTA for IAC pathologies were included. Indications and techniques were discussed and meta-analyzed rates of outcomes and complications were obtained with random-effect model meta-analyses. RESULTS: We included 16 studies comprising 173 patients, all with non-serviceable hearing. Baseline FN function was mostly House-Brackmann-I (96.5%; 95% CI: 94.9-98.1%). Most lesions were vestibular/cochlear schwannomas (98.3%; 95% CI: 96.7-99.8%) of Koos-I (45.9%; 95% CI: 41.3-50.3%) or II (47.1%; 95% CI: 43-51.1%). EETTA was performed in 101 patients (58.4%; 95% CI: 52.4-64.3%) and ExpTTA in 72 (41.6%; 95% CI: 35.6-47.6%), achieving gross-total resection in all cases. Transient complications occurred in 30 patients (17.3%; 95% CI: 13.9-20.5%), with meta-analyzed rates of 9% (95% CI: 4-15%), comprising FN palsy with spontaneous resolution (10.4%; 95% CI: 7.7-13.1%). Persistent complications occurred in 34 patients (19.6%; 95% CI: 17.1-22.2%), with meta-analyzed rates of 12% (95% CI: 7-19%), comprising persistent FN palsy in 22 patients (12.7%; 95% CI: 10.2-15.2%). Mean follow-up was 16 months (range, 1-69; 95% CI: 14.7-17.4). Post-surgery FN function was stable in 131 patients (75.8%; 95% CI: 72.1-79.5%), worsened in 38 (21.9%; 95% CI: 18.8-25%), and improved in 4 (2.3%; 95% CI: 0.7-3.9%), with meta-analyzed rates of improved/stable response of 84% (95% CI: 76-90%). CONCLUSION: Transpromontorial approaches offer newer routes for IAC surgery, but their restricted indications and unfavorable FN outcomes currently limit their use. Laryngoscope, 133:2856-2867, 2023.

A proposed classification system for presigmoid approaches: a scoping review.

OBJECTIVE: The "presigmoid corridor" covers a spectrum of approaches using the petrous temporal bone either as a target in treating intracanalicular lesions or as a route to access the internal auditory canal (IAC), jugular foramen, or brainstem. Complex presigmoid approaches have been continuously developed and refined over the years, leading to great heterogeneity in their definitions and descriptions. Owing to the common use of the presigmoid corridor in lateral skull base surgery, a simple anatomy-based and self-explanatory classification is needed to delineate the operative perspective of the different variants of the presigmoid route. Herein, the authors conducted a scoping review of the literature with the aim of proposing a classification system for presigmoid approaches. METHODS: The PubMed, EMBASE, Scopus, and Web of Science databases were searched from inception to December 9, 2022, following the PRISMA Extension for Scoping Reviews guidelines to include clinical studies reporting the use of "stand-alone" presigmoid approaches. Findings were summarized based on the anatomical corridor, trajectory, and target lesions to classify the different variants of the presigmoid approach. RESULTS: Ninety-nine clinical studies were included for analysis, and the most common target lesions were vestibular schwannomas (60/99, 60.6%) and petroclival meningiomas (12/99, 12.1%). All approaches had a common entry pathway (i.e., mastoidectomy) but were differentiated into two main categories based on their relationship to the labyrinth: translabyrinthine or anterior corridor (80/99, 80.8%) and retrolabyrinthine or posterior corridor (20/99, 20.2%). The anterior corridor comprised 5 variations based on the extent of bone resection: 1) partial translabyrinthine (5/99, 5.1%), 2) transcrusal (2/99, 2.0%), 3) translabyrinthine proper (61/99, 61.6%), 4) transotic (5/99, 5.1%), and 5) transcochlear (17/99, 17.2%). The posterior corridor consisted of 4 variations based on the target area and trajectory in relation to the IAC: 6) retrolabyrinthine inframeatal (6/99, 6.1%), 7) retrolabyrinthine transmeatal (19/99, 19.2%), 8) retrolabyrinthine suprameatal (1/99, 1.0%), and 9) retrolabyrinthine trans-Trautman's triangle (2/99, 2.0%). CONCLUSIONS: Presigmoid approaches are becoming increasingly complex with the expansion of minimally invasive techniques. Descriptions of these approaches using the existing nomenclature can be imprecise or confusing. Therefore, the authors propose a comprehensive classification based on the operative anatomy that unequivocally describes presigmoid approaches simply, precisely, and efficiently.

Cochlear implantation in children with congenital inner ear malformations - Our experience.

OBJECTIVE: To share our experience of the surgical challenges faced in cochlear implanted patients with inner ear malformation and to assess the auditory and speech perception outcomes. MATERIAL AND METHOD: Clinical records of 502 cochlear implant procedures were reviewed and data of 122 patients who had inner ear malformations were enrolled in the study. Their auditory and speech performances were evaluated post implantation for 3 years. RESULT: Cerebrospinal fluid gusher was encountered during opening of cochlea in 42 patients (34.4%) and one patient was re-explored within 24 h. In 30.3% of cases facial anomaly was found. Significant improvement in average performance was seen in all malformation types except in cochlear hypoplasia at 12 months postoperatively. CONCLUSION: Surgical challenges can be overcome with expertise and giving special attention to preoperative imaging. Our experience suggests that outcomes are favourable in patients with inner ear malformations too.

Cochlear Implantation: Systematic Approach to Preoperative Radiologic Evaluation.

Sensorineural hearing loss results from abnormalities that affect the hair cells of the membranous labyrinth, inner ear malformations, and conditions affecting the auditory pathway from the cochlear nerve to the processing centers of the brain. Cochlear implantation is increasingly being performed for hearing rehabilitation owing to expanding indications and a growing number of children and adults with sensorineural hearing loss. An adequate understanding of the temporal bone anatomy and diseases that affect the inner ear is paramount for alerting the operating surgeon about variants and imaging findings that can influence the surgical technique, affect the choice of cochlear implant and electrode type, and help avoid inadvertent complications. In this article, imaging protocols for sensorineural hearing loss and the normal inner ear anatomy are reviewed, with a brief description of cochlear implant devices and surgical techniques. In addition, congenital inner ear malformations and acquired causes of sensorineural hearing loss are discussed, with a focus on imaging findings that may affect surgical planning and outcomes. The anatomic factors and variations that are associated with surgical challenges and may predispose patients to periprocedural complications also are highlighted. © RSNA, 2023 Quiz questions for this article are available through the Online Learning Center. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.