Internal Auditory Canal Research Articles (Page 1)

To analyze radiographic characteristics that predict adequate internal auditory canal (IAC) access through retrolabyrinthine corridor for potential removal of vestibular schwannoma (VS). Retrospective imaging analysis of the retrolabyrinthine corridor (RLC) and fundal fluid cap (FC) were measured and multiple linear regression models were used to examine the relationship between RLC width and FC and their impact on extent of IAC access as well as logistic regressions to analyze the likelihood of tumor exposure achievable with both 0 and 30-degree endoscopic views. Single-institution radiology analysis of patients undergoing MRI IAC with diagnosis of VS (ICD-10 D33.3). The predicted IAC exposure was 68.6% and 42.2% with 30 and 0-degree views, respectively (P<0.05, CI: 17.1%-35.6%). For every 1mm increase in RLC width, the 30-degree IAC access increases by ∼1.54mm (P<0.001) and the 0-degree IAC access increases by 1.45mm (P<0.001), while FC did not significantly impact IAC access. When predicting the impact on tumor exposure with a 0-degree view, each 1mm increase in RLC width increases the odds of complete exposure by 153% (OR=2.53, P=0.043), while each 1mm increase in FC corresponds to 109% higher odds (OR=2.09, P=0.012). With a 30-degree view, each 1mm increase in RLC increases the odds of complete exposure by nearly 300% (OR=3.99, P<0.001). FC has less impact on tumor exposure when utilizing a 30-degree view compared with a 0-degree view with each 1mm increase in FC increasing odds of complete exposure by 56% (OR=1.56, P=0.011). In addition, the use of a 30-degree endoscope over a 0-degree endoscope is associated with 4,336% higher odds of achieving complete tumor exposure (OR=44.35, 95% CI: 8.46-232.52, P<0.001), highlighting the importance of angled visualization and exposure in skull base surgery. Greater retrolabyrinthine corridor and fundal cap measurements are correlated with improved IAC access and VS exposure. These radiographic characteristics may be used as tools to predict candidacy for a retrolabyrinthine approach to VS.

The main objective was to evaluate the hearing impairment of patients after hypofractionated stereotactic radiotherapy (HSRT) by CyberKnife® for vestibular schwannoma (VS). Patients treated by HSRT with CyberKnife® for sporadic progressive VS between January 2010 and February 2020 with at least 1 year follow-up were included. Exclusion criteria were pre-treatment cophosis, lack of at least one pre- and post-irradiation hearing test, a history of treatment of the VS. Bilateral pure-tone testing and speech testing, magnetic resonance imaging (MRI) characteristics of the VS (volume, Koos classification, fundus and internal auditory canal invasion), and HSRT characteristics (80% isodose, number of fractions, dose per fraction, mean cochlear dose) were collected before HSRT and at 1, 3, and 5 years follow-up. 71 patients with a 1-year follow-up were included, 55 patients had a 3-year follow-up, and 34 had a 5-year follow-up; the mean follow-up was 43 months (± 24). During the entire follow-up, 89% of the patients (63/71) had hearing impairment, which occurred during the first year for 79% (56/71) of the patients. No risk factor among age, MRI characteristics, and HSRT modalities were found to be associated with hearing impairment in the first year. No relationship was found between tumor volume and hearing impairment. For most patients, HSRT is responsible for hearing impairment within the first year. #20-84 on September the 10th, 2021.

Sudden sensorineural hearing loss (SSNHL) is a dramatic and often frightening condition that benefits from prompt treatment. While most cases of SSNHL are idiopathic, a retrocochlear pathology is expected to account for some presenting cases of SSNHL. This study aims to assess the presence of retrocochlear pathology in SSNHL and ascertain whether clinical features could help determine their presence on MRI. A retrospective cohort study was conducted using a patient data registry from 2015 to 2022. Patients who underwent MRI of the internal auditory canals for SSNHL at a single center were included. MRs were reviewed for relevant positive findings and incidental actionable findings. Clinical features recorded included laterality of hearing loss, tinnitus, dizziness, vertigo, and pure tone average (PTA) thresholds from audiograms. Treatment decisions were documented. Exclusion criteria included previous temporal bone pathology, trauma, surgery, or missed MR appointments. Eight hundred forty-one patients (929 ears; mean age 53.6 years ±15.7 [standard deviation]) were included. MRs showed no retrocochlear pathology in 874 ears (94.1%). Twenty-five ears had relevant tumors (2.7%). Nine patients with tumors underwent surgery or radiation. All tumors were visible on noncontrast cisternographic sequences. Twenty-one ears (2.3%) had findings suggestive of labyrinthitis. Additional relevant findings included enlarged endolymphatic ducts and small cochlear nerves. Patients with a PTA ≥49.5 dB had 5.3 times higher odds of having a tumor or labyrinthitis on MRI (P < .001), and those with tinnitus had 4.2 times higher odds (P = .02). No statistical difference was found in steroid use between patients with or without labyrinthitis features (P = .38). Most patients showed no retrocochlear pathology on MRI, with only 2.7% having relevant tumors. To screen for urgent pathology, a noncontrast MR protocol may be feasible. Clinical features such as high PTA values and tinnitus may increase the odds of finding a treatable retrocochlear condition.

Osteomas of the Internal Auditory Canal: A Systematic Review and Case Report.

Comparison of Clinical Features and Surgical Outcomes of Cystic and Solid Vestibular Schwannoma.

Collagen Matrix Dural Repair for the Internal Auditory Canal in Retrosigmoid Vestibular Schwannoma Surgery.

CT evaluation of the internal acoustic canal and safe drilling triangle morphometry in relation to temporal pneumatization and age for gender determination and hearing preservation in surgery.

Surgical management of large vestibular schwannoma (VS; Koos grades III and IV) requires a balance between the maximum extent of resection and the best functional preservation. The primary objective of this study was to determine the volumetric threshold of the VS residual tumor at risk of progression after incomplete resection. The secondary objective was to identify other risk factors of regrowth after incomplete resection. This retrospective study included patients who underwent incomplete resection of sporadic VS at a single center from January 2008 to December 2018. The inclusion criteria were: adult age, large single sporadic VS, incomplete resection, and follow-up of > 5 years. Quantitative 3D volumetry was assessed on pre- and postoperative contrast-enhanced T1-weighted MRI using semiautomated segmentation. The volumetric criteria for residual tumor were < 250 mm3 for near-total resection (NTR) and < 2 cm3 for subtotal resection (STR). Univariate and multivariate logistic regression analyses were performed to assess predictors of regrowth after incomplete resection. A residual volume cutoff for risk of regrowth was determined using the Youden index via area under the curve analysis. The cohort included 119 patients (60 female, median age 58 years) who were categorized into 3 subgroups based on the residual VS according to 3D volumetry: NTR, STR, and partial resection (PR). NTR achieved the best long-term tumor control. Kaplan-Meier progression-free survival rates at 2, 5, and 10 years were 98%, 97%, and 95% for the NTR group; 69%, 56%, and 56% for the STR group; and 20%, 0%, and 0% for the PR group, respectively (p < 0.0001). The cutoff residual volume at risk of growth was 200 mm3, with sensitivity of 95% (95% CI 74%-99%) and specificity of 77% (95% CI 68%-85%, p < 0.001). Moreover, good facial nerve outcomes (House-Brackmann grades I and II) were best achieved with PR (100%), followed by STR (96%) and NTR (90%). In the univariate analysis, the risk factors for regrowth of residual tumor were cystic morphology, residual volume, and residual location (internal auditory canal, cisternal segment, and brainstem combined). The multivariate model identified the volume and location of residual as risk factors (p < 0.0001). These findings suggest that limited NTR (< 250 mm3) offered an excellent compromise, with long-term tumor control comparable to that of radical resection while preserving superior functional preservation. The authors hope to stimulate discussion toward a unified volumetrically established classification of incomplete resections, allowing for cooperation in future multicenter studies.

Primary culture of inner ear schwannoma.

Malformations of the internal auditory canal (IAC) are rare. They can present as a narrowing of the canal due to aplasia or hypoplasia of the vestibulocochlear nerve, complete atresia, or even a doubling of the IAC. The aim of our study is to provide a comprehensive overview of the different types of IAC anomalies and to provide a classification based on radiological findings and their relation to syndromes and/or inner/middle ear anomalies. In addition, IAC malformations will be explained in a putative phylogenetic context.All patients who underwent pre-interventional imaging between 1995 to 2024 for evaluation of a hearing implant in domo with an inner ear malformation were included in the present retrospective study. The available imaging data, i.e. high resolution computed tomography (HRCT) or cone beam CT (CBCT) of the temporal bone and supplementary MR of the temporal bone, were reviewed independently by two neuroradiologists. Malformations of the IAC and concomitant malformations of the middle and inner ear were recorded. Demographic and clinical data were also collected. Based on the data and information obtained, a radiological classification of the different IAC malformations was provided.A total of 36 patients (55 affected ears) were included in the analysis. The majority of the patients were female (75%). The mean age was 6.3 ± 9.4 years (mean ± std). A syndromic disease was present in 28% of the patients. Due to severe hearing loss, a total of 48% of patients received a hearing system. Based on the radiological findings, we performed the following typing: Type I - Narrow IAC; Type II - Atresia with isolated facial nerve canal; Type III - Double IAC with/without atresia, Type IV - Complete atresia. In descending order, the frequency of these malformations of the IAC in our cohort was distributed as follows: Type III - Double (n= 29, 52.7%), Type I - Narrow (n=15, 27.3%), Type IV - Complete atresia (n=4, 7.3%), Type II - Atresia with isolated facial nerve canal (n=7, 12.7%).Since hypoplastic IAC may be associated with hypoplastic or absent cochlear nerve and sensorineural hearing loss, radiological assessment of the IAC is of critical importance in the evaluation of patients with severe sensorineural hearing loss undergoing cochlear implantation. Accurate analysis of the imaging data and understanding the complexity of the malformations are of great importance in assessing the expected benefits prior to cochlear implantation. · IAC malformations can be classified into four different groups based on recurring patterns.. · IAC malformations are often associated with hypo-/aplasia of the vestibulocochlear nerve.. · The facial nerve is usually present, but may have an aberrant course.. · Döring K, Salcher R, Lanfermann H et al. Radiological Characterization of Malformations of the Internal Auditory Canal. Rofo 2025; DOI 10.1055/a-2699-9904.

ABSTRACTMorphological descriptions of the tympano‐periotic complex (TPC) are fundamental for understanding odontocete auditory adaptations, as well as their relationships with habitat, behavior, and evolutionary processes. This study analyzed the TPC morphology of six Delphinidae species stranded along the northeastern coast of Brazil: Peponocephala electra (n = 4), Pseudorca crassidens (n = 2), Sotalia guianensis (n = 39), Stenella attenuata (n = 4), Stenella longirostris (n = 4), and Tursiops truncatus (n = 4). A total of 57 TPCs were examined, with 24 morphometric measurements taken, including two novel parameters introduced in this study. The results revealed similarities in TPC morphology among species, particularly among S. guianensis, S. attenuata, and S. longirostris, which exhibited more comparable anatomical features in the structures analyzed. Species identification was supported by distinct features: in the tympanic bone, the posterior process, inner and outer prominences, and sigmoid process; and in the periotic bone, the cochlear portion, apertures for the cochlear and vestibular aqueducts, and the transverse crest. A previously undescribed anatomical structure, termed the “mesocochlear opening,” was identified in S. attenuata. No remarkable ontogenetic variations were observed in the TPC of S. guianensis, P. electra, or S. longirostris, supporting the hypothesis that auditory structures reach full development early in life. These findings highlight key morphological features of the tympano‐periotic complex that contribute to species differentiation while providing new insights into the evolutionary and ecological adaptations of odontocetes. Furthermore, this study underscores the value of detailed morphological analyses for elucidating structural taxonomic variation and supporting future studies on the auditory capabilities of odontocetes.

Temporal Bone Anatomy at 0.55T: Comparison to 1.5/3T MR and High-Resolution CT.

Patient: Female, 13-year-oldFinal Diagnosis: Duplication of internal auditory canalSymptoms: Single sided deafnessClinical Procedure: Bone conductive implant as a CROSSpecialty: Audiology • OtolaryngologyObjective: Congenital defects/diseasesBackgroundDuplicated internal auditory canal (dIAC) is a rare congenital temporal bone anomaly associated with ipsilateral sensorineural hearing loss (SNHL). The Bonebridge bone conduction implant has a magnet, an internal transducer, and an external audio processor. This report is of a 14-year-old girl with unilateral SNHL and vestibulocochlear nerve (VIII cranial nerve) aplasia due to dIAC who was treated with a Bonebridge bone conduction implant.Case ReportA 14-year-old girl was diagnosed with unilateral hearing loss during a school health check. Her hearing screening at birth was normal. Pure-tone audiometry revealed unilateral deafness in the right ear. CT scan showed a separate canal for the facial and vestibulocochlear nerves. MRI suggested unilateral aplasia of the right nerve VIII. The patient was implanted with a Bonebridge 602 implant in the right ear as a CROS (contralateral routing of signal). During implant activation in the Matrix test with the Bonebridge implant (in SSD configuration), the patient achieved SRT=−10.3 dB SNR. The results of the APHAB questionnaire indicated improvements in hearing.ConclusionsDuplication of the internal auditory canal is pathognomonic for severe cochlear nerve hypoplasia or aplasia. It is important to perform an imaging study before deciding on implantation, as a hearing screening test at birth may not detect congenital hearing loss (embryogenesis of the inner ear and the internal auditory canal occurs independently). In the case of a unilateral anomaly with no hearing impairment on the opposite side, bone conduction implantation should be considered as a CROS.

Pneumatisation patterns surrounding the internal acoustic meatus.

.PurposeCochlear implants (CIs) are neural prosthetics used to treat patients with severe-to-profound hearing loss. Patient-specific modeling of CI stimulation of the auditory nerve fiber (ANF) can help audiologists improve the CI programming. These models require localization of the ANFs relative to the surrounding anatomy and the CI. Localization is challenging because the ANFs are so small that they are not directly visible in clinical imaging. We hypothesize that the position of the ANFs can be accurately inferred from the location of the internal auditory canal (IAC), which has high contrast in CT because the ANFs pass through this canal between the cochlea and the brain.ApproachInspired by VoxelMorph, we propose a deep atlas-based IAC segmentation network. We create a single atlas in which the IAC and ANFs are pre-localized. Our network is trained to produce deformation fields (DFs) mapping coordinates from the atlas to new target volumes and that accurately segment the IAC. We hypothesize that DFs that accurately segment the IAC in target images will also facilitate accurate atlas-based localization of the ANFs. As opposed to VoxelMorph, which aims to produce DFs that accurately register the entire volume, our contribution is an entirely self-supervised training scheme that aims to produce DFs that accurately segment the target structure. This self-supervision is facilitated using a loss function inspired by the Mumford–Shah functional. We call our method Deep Atlas-Based Segmentation using Mumford-Shah (DABS-MS).ResultsResults show that DABS-MS outperforms VoxelMorph for IAC segmentation. Tests with publicly available datasets for trachea and kidney segmentation also show significant improvement in segmentation accuracy, demonstrating the generalizability of the method.ConclusionsOur proposed DABS-MS method can accurately segment the IAC, which can then facilitate the localization of the ANFs. This patient-specific modeling of CI stimulation of the ANFs can help audiologists improve the CI programming, leading to better outcomes for patients with severe-to-profound hearing loss.

A retrospective observational study in a tertiary otologic referral centre was conducted in to analyse a case series of 33 patients with inner ear schwannoma and cochlear involvement (intracochlear, intravestibulocochlear, or transfundal with modiolar involvement) and report the results of different treatment modalities. We included consecutive patients with inner ear schwannoma and cochlear involvement (intracochlear, intravestibulocochlear, or transfundal with modiolar involvement). Data collectedincluded demographic data, presenting symptoms, audiometric results, radiological characteristics of the tumour at presentation and at follow-up visits, and treatment modalities. We included 33 adults with schwannoma; 17 (51%) were men. The mean age at diagnosis was 55 ± 13.1 years. Twenty-four patients (73%) had intracochlear, 5 (15%) transfundal with modiolar involvement, 2 (6%) intravestibulocochlear schwannoma. Two (6%) schwannomas involved the cerebellopontine angle. Concerning symptoms at diagnosis, 28 on 33 patients audiometric datas were available; in these cases, all patients presented some degree of hearing loss. One patient had spontaneous facial paralysis. Twenty-eight (85%) underwent "wait-and-scan" management, during which hearing worsened to AAO-HNS class D for 6 (21%), 15 (54%) showed some degree of tumour growth, 2 (7%) developed spontaneous facial paralysis. All 3 patients with spontaneous facial paralysis had a tumour involving the internal auditory canal. Eleven of 28 patients (39%) underwent surgery after an initial wait-and-scan management (median follow-up of 50 months). Five patients (15%) elected immediate microsurgery tumour removal. Two patients underwent cochlear implantation: one patient did not use the device and had not achieved satisfactory audiometric results The other one exhibited good audiometric results after 3 months (PTA = 30 dB, Speech Discrimination Score = 100% at 70 dB). Complications were rare and minor; no patients showed residual tumour or recurrence. A wait-and-scan policy is the preferred treatment if patients have serviceable hearing. With AAO-HNS class D hearing, microsurgical removal is advised: tumours extending to the internal auditory canal were associated with risk of spontaneous facial paralysis. Surgery is safe and effective. A simultaneous cochlear implant could be proposed.

Premises: Metastatic carcinoma in the internal auditory canal (IAC) or cerebellopontine angle is extremely rare. The most common primary tumor is lung cancer, being also the primary site with the highest rate of bilateral occurrence of IAC metastasis. Meningeal metastasis occur more frequently in bilateral diseases versus unilateral ones. Clinical and radiological features of bilateral IAC lesions can mimic neurofibromatosis type 2 (NF2), since IAC metastases on MRI appear similar to vestibular schwannomas and bilateral vestibular schwannomas are pathognomonic of this genetic disease, according to Manchester criteria.Description of the Case report: A 64 year old man was admitted to our ward with rapid-onset leg paresthesia, cauda equina syndrome and bilateral hearing loss. The patient was misdiagnosed as having NF2 due to MRI findings of bilateral internal auditory canals nodules, reported as vestibular neurinomas, and numerous foci of pathological contrastographic impregnation on the whole spinal cord’s surface, interpreted as meningiomas. The rapid worsening of the symptoms lead to reconsideration of the diagnosis and it turned out the patient was affected by multimetastatic non-small cell lung carcinoma.Conclusions: Although metastatic tumors in the IAC are rare, clinicians should be aware of this possibility. Patients with rapid-onset hearing loss, tinnitus, vertigo or facial palsy with radiological diagnosis of bilateral schwannomas should be tested in order to rule out IAC metastasis and to achieve an early identification of a possible malignancy and its primary site.

Objective: This study aims to analyze the incidence of high jugular bulb (HJB), an anatomical variation, in patients with otitis media using high-resolution CT imaging in the lateral position.Methods: A retrospective analysis was performed on high-resolution CT scans of the middle ear from 965 patients clinically diagnosed with otitis media between October 2018 and October 2023. The age range was 6 to 81 years, with a mean age of 47.11 years. The cohort included 387 male and 578 female patients. HJB was defined as the superior border of the jugular bulb extending beyond the inferior border of the basal turn of the cochlea. Using the lateral wall of the cochlear basal turn as the reference line, HJB was classified into medial and lateral types. In the lateral type, the jugular bulb was in proximity to the tympanic membrane, ossicular chain, or round window; in the medial type, it was adjacent to the cochlear aqueduct, vestibular aqueduct, or internal auditory canal. The presence of HJB was recorded, and gender and side distribution were analyzed.Results: Among the 965 patients with chronic otitis media, 176 cases exhibited HJB, representing an incidence rate of 18.23%. Of these, 103 were female (58.52%) and 73 were male (41.48%), indicating a higher prevalence in females. Right-sided HJB occurred in 115 cases (65.34%), compared to 61 cases on the left (34.66%), suggesting a predominance on the right side. Lateral HJB was observed in 125 cases (71.02%), including five cases with direct exposure, whereas medial HJB was found in 51 cases (28.98%), demonstrating a significantly higher frequency of the lateral variant.Conclusions: The findings indicate that HJB is more prevalent in females than males and more common on the right side than the left. Additionally, the lateral type occurs more frequently than the medial type. Given its anatomical significance, lateral HJB must be carefully evaluated during otoscopic tympanic surgery to prevent potentially serious complications. Special attention should be paid to identifying this variation preoperatively.

In this study, we aimed to provide our initial experience with a novel combined approach resection of chondrosarcomas of the skull base and petrous apex (ChPA) and posterior cranial fossa by employing middle cranial fossa and retrosigmoid (RS) approaches with an augmented reality and virtual reality (AR/VR) system. A 66-year-old female patient was referred to our department owing to the growth of a left petrous apex lesion noted in computed tomography (CT) and magnetic resonance imaging (MRI) scans 10 years earlier. Her symptoms included headache, imbalance, and left-sided hearing loss. The lesion was resected via a combined extended middle cranial fossa (xMCF) and RS approach, gross total resection (GTR) and preservation of hearing and facial nerve function. The tumor was World Health Organization (WHO) Grade II, extending from the left petrous apex (PA) to the posterior fossa, cerebellopontine angle (CPA), and internal auditory canal (IAC). We also performed a systematic literature review of chondrosarcomas involving the skull base. The patient tolerated the procedure well and was discharged without complications or neurological deficits on postoperative day 6 with normal facial nerve function and stable hearing as observed prior to surgery. Preoperative planning for the surgical approach must be carefully evaluated and individualized for each patient while considering the experience of the surgical team. GTR remains the preferred treatment for ChPA, preferably via an approach capable of preserving the facial nerve and hearing function. The xMCF approach, along with the RS approach for petrous apex lesions extending to the posterior cranial fossa/CPA with reconstruction of the skull base, appears to be a safe approach.

SummaryObjectivesPartial or complete loss of function of the 7th and 8th nerves is a common occurrence in surgery of the cerebello-pontine angle, with the causal mechanism being considered the mechanical insult on nerves and the critical loss of blood supply to nerves and labyrinth. Preventing a vascular loss requires both soft surgery and knowledge of hitherto disregarded details of vascular anatomy. The goal of this paper is to provide the missing picture of descriptive and surgical anatomy.MethodsData of vascular anatomy were obtained from: (i) a group of 100 injected temporal bones submitted to microdissection; (ii) a group of 30 sectioned temporal bones; (iii) a group of 30 cases who underwent surgery for small vestibular schwannoma.ResultsA detailed picture was obtained concerning position and course of the anterior inferior cerebellar artery, origin and course of internal auditory artery (IAA) and its branches. Handling and cleavage of IAA from nerves was also explored.ConclusionsThe role of blood supply in function preservation of 7th-8th nerves comes from preclinical studies on animals as well as anatomical studies and clinical-surgical observations in humans. Updated knowledge of vascular anatomy is expected to provide surgeons with hitherto disregarded details and contribute to function preservation.