Internal Auditory Canal Research Articles

Erosion of the temporal bone by vestibular schwannoma: morphometrics and predictive modeling.

To perform a comprehensive morphometric analysis of vestibular schwannomas (VS) using multimodal imaging, focusing on the relationship between tumor characteristics and internal acoustic canal (IAC) changes. We analyzed a cohort of patients undergoing radiosurgery for VS, utilizing high-definition MRI and bone CT for detailed anatomical assessment. Image co-registration and fusion techniques were employed to examine VS and IAC dimensions. Advanced statistical methods, including logistic regression, were applied to identify patterns of IAC dilation and establish predictive indicators for these morphological changes. The study included 659 patients (51.1% female, mean age 56.37years) with evenly distributed tumor lateralization. Koos grades were I (22.9%), II (29.9%), III (38.2%), IVa (8.9%), and IVb (0.3%). Most tumors (90.9%) extended both inside and outside the IAC. Ipsilateral IAC (IIAC) dimensions were significantly larger than contralateral, with IIAC volume 49% greater (p < .0001). Higher Koos grades correlated with increased intra-canalicular lesion volume (icLV), which was strongly associated with IIAC size. Logistic regression identified icLV as the strongest predictor of IIAC dilation (AUC = 0.7674, threshold = 137.52 mm3). The icLV appears central to the pathophysiological development of VS and its impact on IAC anatomy. While limited by a selective patient base and static imaging data, these findings enhance the understanding of VS-IAC interactions, offering insights for improved clinical management and further research.

Impairment of Internal Auditory Canal Barrier in Meniere'sDisease.

The aim of this investigation was to explore the potential correlation between the signal intensity ratio (SIR) at the internal auditory canal (IAC) fundus and hearing impairment in Meniere's disease (MD), thereby providing a foundation to further understand the mechanisms underlying hearing loss. Fifty patients diagnosed with unilateral definite MD were enrolled in the study. 3D-FLAIR MRI was conducted 4 h after intravenous administration of gadobutrol to determine the SIR of the bilateral IAC fundus. The difference in the SIR of the IAC fundus between the affected and unaffected sides was assessed, followed by an analysis of its correlation with low-, middle-, and high-tone hearing thresholds. Correlation analysis was also conducted between the degree of endolymphatic hydrops (EH) in the vestibule and cochlea and the SIR on the affected side. The degree of EH in MD can be clearly visualised using 3D-FLAIR MRI. The SIR on the affected side was significantly higher than that on the unaffected side (p = 0.000). Furthermore, a positive correlation was observed between the SIR at the affected and low (r = 0.692, p = 0.000), middle (r = 0.615, p = 0.000) and high-tone (r = 0.440, p = 0.001) hearing thresholds, while the SIR showed no significant correlation with cochlear (r = 0.315, p = 0.088) or vestibular hydrops (r = 0.215, p = 0.244). The IAC fundus barrier may be damaged in patients with MD, representing one of the factors affecting the level of hearing.

Morphometric evaluation of facial and vestibulocochlear nerves using magnetic resonance imaging in patients with Menière's disease.

Menière's disease (MD) is a condition of unknown etiology, involving genetic predisposition, autoimmune processes, viral infections, cellular apoptosis, and oxidative stress. This study aimed to investigate potential differences in the VIIth and VIIIth cranial nerves in MD patients using Hydrops-MRI (FLAIR) for morphometric evaluations. Using a 3T MRI scanner, constructive-interference-in-steady-state (CISS) and 3D-FLAIR-inversionrecovery (FLAIR) sequences were acquired. We evaluated the morphometrics of the VIIth and VIIIth cranial nerves from the cerebellopontine angle to the internal auditory canal fundus, comparing the non-affected and affected sides. Furthermore, we examined the findings in relation to symptom duration and evaluated feasibility of FLAIR-imaging in morphometry of cranial nerves. A total of 53 MD patients with unilateral symptoms were included. After statistical analysis, no significant differences were found regarding morphometric changes in the affected side compared to the non-affected side of the VIIth and VIIIth cranial nerves. There was also no significant difference between morphometric evaluations of patients with different symptom durations. The morphometric evaluation using Hydrops-MRI-Sequences (FLAIR) showed no significant difference compared to established morphometric highly T2-weighted imaging (CISS). Our data found no differences in nerve morphometry between clinically non-affected and affected sides in unilateral MD patients, nor any correlation with symptom duration. This contrasts with previous findings of correlations between clinical features and endolymphatic hydrops. A disease process starting before clinical symptom onset could be a possible explanation. Morphometric evaluation of brain nerves using Hydrops-MRI-Sequences is practical and provides similar results to T2-weighted imaging, improving patient comfort and reducing MRI scan time. CN = cochlear nerve; CPA = cerebellopontine angle; CSA = cross-sectional area; FN = facial nerve; IAC = internal auditory canal; IVN = inferior vestibular nerve; LD = long diameter; MD = Menière's disease; SD = short diameter; SVN = superior vestibular nerve.

Predictors of Abnormal MRI Findings in Patients with Asymmetrical Sensorineural Hearing Loss.

This study aimed to determine the predictive factors of abnormal MRI findings in patients with asymmetrical sensorineural hearing loss (ASNHL). A retrospective review of medical records. A tertiary care hospital. Patients with asymmetries of ≥10 dB in at least 1 frequency, who underwent an MRI study of the temporal bone or brain during 2019-2021, were included. Age, sex, clinical symptoms, past medical history, and audiometric parameters, including pure tone thresholds, speech reception thresholds, and speech discrimination scores, were retrieved from the electronic database. The MRI findings reported by radiologists were reviewed and extracted. Of 390 patients, 50 (12.8%) patients had relevant abnormal MRI findings that could explain ASNHL. The most prevalent abnormal MRI finding was an internal acoustic canal (IAC) or cerebellopontine angle (CPA) tumor (n = 38; 76.0%), with other notable abnormalities including labyrinthitis, stroke, mucocele, and epidermoid. Multiple logistic regression analysis highlighted that hearing asymmetry of 15 dB at 1000 Hz (OR = 4.8; 95% CI 2.2-10.5) was a significant variable. The proposed predictor demonstrated 84% sensitivity and 48% specificity in detecting abnormal MRI findings. A hearing asymmetry of 15 dB at 1000 Hz was an important clinical predictor of abnormal MRI findings in patients with ASNHL. This finding has the potential to serve as a referral guide for further MRI investigations. Level 3 Laryngoscope, 2024.

Clinico-Radiological Manifestations of Cochlear Schwannomas

Background and Objectives: Cochlear schwannomas, which are categorized into intracochlear and intravestibulocochlear schwannomas (ICs and IVCs, respectively) are rare and may cause hearing loss (HL). The affected region is invariably correlated with tumor location, which can be detected on magnetic resonance imaging (MRI). We describe the cochleovestibular manifestations of ICs and IVCs. Subjects and Methods: The study included 31 patients with ICs or IVCs. Tumor extent and exact locations were delineated using MRI. Types of HL were subcategorized into the low-to-mid frequency (250 Hz to 1 kHz), mid-to-high frequency (&gt;1 kHz), and all-frequency (universal) HL groups. Results: The tumors involved the entire cochlear turn (two ICs) or extended beyond the cochleae (nine IVCs) in 11 patients, and 20 ICs were located in specific locations as follows: 14 in the basal, 3 in the middle, and 3 in the middle and apical turns. No patient showed tumor invasion of the internal auditory canal or middle ear. The pattern of HL usually reflects the location or extent of a tumor. We observed HL at all frequencies, at low-to-mid frequencies, and at mid-to-high frequencies in 13, 4, and 14 patients, respectively. Dizziness or tinnitus was observed in &gt;50% of patients. Surgical tumor removal was performed in 10 patients, and the remaining patients are undergoing annual monitoring. Conclusions: Cochlear schwannomas may be associated with HL, which may worsen over time and reflect tumor location. Therefore, these lesions should be considered in the differential diagnosis in patients who present with idiopathic, fluctuating, progressive or sudden HL.

Vestibular schwannoma-related increased labyrinthine post-gadolinium 3D-FLAIR signal intensity and association with hearing impairment.

Vestibular schwannomas (VSs) are benign neurogenic tumors commonly associated with progressive unilateral hearing loss, tinnitus, and vestibular symptoms. Growing evidence links signal changes in the VS-adjacent labyrinth with sensorineural hearing loss. This study seeks to quantify the association of labyrinthine signal on post-gadolinium 3D-FLAIR imaging correlates with hearing loss and to evaluate potential longitudinal changes over time. Selected patients were identified from a prospectively maintained VS registry. Mean signal intensity ratios of the bilateral labyrinth and pons were measured on 3D-FLAIR post-gadolinium MRI. Correlations with paired audiometric data including pure tone average (PTA), word recognition score (WRS), and AAO-HNS hearing class within one year were evaluated. 125 studies obtained from 2015 to 2022 among 66 patients undergoing observational management for sporadic VS were analyzed. Increased signal intensity was noted of the VS-affected labyrinth/contralateral labyrinth (mean ratio 1.56, SD 0.58). Increased signal intensity was associated with increased PTA on both labyrinthine (correlation coefficient [CC] 0.20, p=0.03) and pontine comparisons (CC 0.24, p=0.006), and with decreased WRS on pontine comparisons (CC -0.18, p=0.04). Increased signal intensity was significantly associated with non-serviceable AAO-HNS C/D hearing when intensities were compared to the pons (p=0.01) but not the contralateral labyrinth (p=0.1). Among 44 patients with available follow-up, no statistically significant associations were identified between audiometric data and signal changes over the same interval. Increased 3D-FLAIR post-gadolinium labyrinthine signal is associated with sensorineural hearing loss; however, its relationship with hearing trajectory remains unclear. Overall findings suggest that while post-gadolinium 3D-FLAIR techniques are sensitive to inner ear involvement associated with VS, the driving mechanism and their temporal relationships with labyrinthine signal intensity and hearing impairment remain unknown. AAO-HNS =American Academy of Otolaryngology -Head and Neck Surgery. BLB =blood-labyrinth barrier. CPA = cerebellopontine angle. IAC = internal auditory canal. PTA = pure tone average; SIR = signal intensity ratio. VS = vestibular schwannoma. WRS = word recognition score.

Characterizing Hearing Outcomes Following Treatment of Cerebellopontine Angle Meningiomas

Abstract Objectives To characterize treatment and hearing outcomes for cerebellopontine angle (CPA) meningiomas with inherent risks of hearing loss and identify predictors of hearing loss for surgically treated lesions. Design Retrospective chart review. Setting Tertiary care medical center. Participants Adult patients with CPA meningiomas impinging upon cranial nerve VIII and/or pretreatment hearing loss managed with microsurgery or stereotactic radiosurgery (SRS) with Gamma Knife at our center between 2012 and 2023. Main Outcome Measures Hearing preservation rate was determined from analysis of patients with pretreatment serviceable hearing for whom hearing-preserving treatment was attempted. Surgical patients were further analyzed using multivariable Cox proportional hazards regression models to identify factors predictive of postoperative hearing loss. Results We identified 80 patients with CPA meningiomas meeting inclusion criteria who were managed with either microsurgery (43, 54%) or radiosurgery (37, 46%). Following SRS, hearing was preserved in 88% of cases. Following microsurgery, hearing was preserved in 71% of patients—all patients who lost hearing had tumors involving the internal auditory canal (IAC). Among surgical patients only, multivariable analysis accounting for preoperative hearing, recurrence status, lesion size, and patient age, the preoperative imaging finding that the CPA meningioma surrounded the vestibulocochlear nerve was significantly associated with hearing loss (hazard ratio: 10.3, 95% confidence interval: 1.3–81.4, p = 0.02). Conclusion Most patients with meningiomas of the CPA can experience preservation of hearing, even when there is risk of hearing loss based on pretreatment evaluation. IAC invasion and surrounding of eighth nerve by tumor may portend poorer hearing outcomes in surgically managed patients.

Long-Term Follow-Up After Translabyrinthine IAC Tumor Removal With Simultaneous Cochlear Implantation.

To evaluate the long-term hearing outcome after translabyrinthine resection of tumors within the internal auditory canal (IAC) with simultaneous cochlear implantation (CI). Prospective study. Tertiary referral center. Thirty-seven patients with tumors of the IAC undergoing translabyrinthine tumor surgery as a first-line therapy. Intraoperatively, electrically evoked auditory brainstem response audiometry (eABR) was performed in all patients to assess cochlear nerve (CN) integrity. In case of preserved CN function after tumor removal, CI was subsequently performed. Postoperatively, patients were regularly followed up to evaluate pure-tone hearing as well as speech recognition with a monosyllabic word comprehension test. Postoperative hearing thresholds and word recognition scores. Of 37 included patients, 22 (59.46%) had positive eABR responses after tumor removal. Twenty-one of these underwent simultaneous CI directly after tumor surgery and were followed-up for 24.24 ± 19.83 months after surgery. Hearing of these patients significantly improved from 73.87 ± 21.40 dB preoperatively to a mean pure-tone average of 41.56 ± 18.87 dB 1 year (p = 0.0008) and 34.58 ± 2.92 dB 3 years after surgery (p = 0.0157). Speech recognition significantly recovered from 13.33 ± 25.41% to 58.93 ± 27.61% 1 year (p = 0.0012) and 51.67 ± 28.58% 3 years postoperatively (p = 0.0164). Regardless of tumor histopathology, CI is an effective option to restore patients' hearing after translabyrinthine tumor surgery. After CI, patients hearing can be restored over a long-term period of a minimum of 3 years post-surgery. Furthermore, eABR proves to be a practical tool to evaluate CN function and screen for patients eligible for CI.

A postmortem high-resolution MRI study of the development of cochlear nerve-related structures in the second and third trimesters of pregnancy.

Magnetic resonance imaging (MRI) is used to determine whether cochlear nerve development is normal in infants and adults, but it has not yet been used to evaluate cochlear nerve development or measure cochlear nerve-related structures in the fetus. This study sought to provide imaging data for clinical evaluations concerning cochlear nerve development in the fetus using MRI. Postmortem 3.0-Tesla MRI of inner ear was performed in 51 fetuses with normal temporal bones at 25 to 40 weeks of gestation. The continuous scanning protocol incorporated axial three-dimensional (3D) sampling perfection with application-specific contrasts using different flip angle evolution sequences. The images were evaluated to measure the structures of the cochlear aperture (CA), internal auditory canal (IAC), and vestibulocochlear and facial nerves in the cerebellopontine angle (CPA), which have been reported to be associated with cochlear nerve development. We also calculated the ratio between the diameters of the vestibulocochlear and facial nerves. The measurable parameters were compared between the right and left sides. The threshold for statistical significance was set at P<0.05. The inner ear anatomy was discernible on MRI in all the fetal specimens, and growth of the CA, IAC, vestibulocochlear nerve, and facial nerve in the CPA was observed as fetal age increased. There was no significant difference in the measurements of these structures between the right and left sides (all P>0.05). MRI can be used to help evaluate the anatomy and development of the cochlear nerve in the fetus. These normative measurements could be valuable for clinical evaluations of the cochlear nerve.

Bilateral Internal Auditory Canal Metastasis From Lung Cancer on FDG PET/CT.

The occurrence of metastatic tumor in the internal auditory canal is very rare. Thus, we report FDG PET/CT findings of bilateral Internal auditory canal metastasis from lung cancer in a 67-year-old man. FDG PET/CT and MRI showed nodules in the bilateral internal auditory canal with an SUVmax of 5.2. This case hints us that bilateral metastasis should be considered as differential diagnosis when we encounter bilateral nodule in the internal auditory.

Exposure of the facial nerve within the facial canal: A technical report

BackgroundThe facial canal lies in the petrous part of the temporal bone and contains the facial nerve. The facial canal and nerve are divided into three segments: the labyrinthine, tympanic and mastoid segments, which travel in different planes. These segments are closely related to the structures of the middle- and inner-ear, so pathology of the intracranial facial nerve is often evident in cochlear implant users. The facial canal and nerve are of great concern to otologists during electrode placement for a cochlear implant, as any damage to the nerve may result in untreatable facial paralysis. Few studies have been conducted on a cadaveric population, with most carried out on CT images of the cochlea and facial nerve. Thus, there is no standard or straightforward methodology to visualise the facial canal and nerve directly. We propose a detailed dissection technique to bridge this gap in research. MethodFour cadavers were used, and both the left and right facial canals were dissected. After the exposure of the cranial floor, the internal acoustic meatus and the facial canal were dissected out using drilling tools to remove the surrounding temporal bone and expose the facial nerve within the facial canal. ResultsThis technique allowed for morphometric analyses and observations of the facial canal in relation to the middle- and inner-ear. ConclusionKnowledge of the facial canal may assist otosurgeons in safely dissecting the region without injuring vital structures within this area.

Surgical Outcomes in Patients with Endolymphatic Sac Tumors: A Single-Center Experience of 29 Patients.

To analyze the clinical features and surgical outcomes of patients with endolymphatic sac tumors (ELSTs). Single institution retrospective cohort study. The clinical data of 29 patients with 30 ELSTs who underwent surgery were retrospectively reviewed. Information on patient demographics, tumor size and grade, intraoperative blood loss volume, hearing and facial nerve outcomes, and follow-up data was collected and analyzed. The main symptoms were hearing loss in 26 ELSTs (86.7%) and tinnitus in 17 (56.7%). Twenty-four (80%) ELSTs were in advanced stages (Grade III). The median tumor volume was 6.35 cm3. The median intraoperative blood loss volume was 300 mL. Facial nerve function was well preserved in 21 patients. Among all patients with Grade III tumors, 12 patients underwent tension-free anterior facial nerve rerouting, and 11 patients (91.7%) maintained good facial nerve function postoperatively (HB I and HB II). Only one patient exhibited permanent vocal cord paralysis, and no patients experienced cerebrospinal fluid (CSF) leakage postoperatively. Gross total resection was achieved in 22 patients (73.3%), 5 patients (16.7%) experienced tumor recurrence, and 3 (10%) had residual tumors. Most ELSTs tend to be diagnosed in the advanced stage. Tension-free anterior facial nerve rerouting could maximally preserve facial nerve function. The intraoperative blood loss volume was associated with tumor size and stage. Tumor recurrence tends to occur at the posterior edge of the petrosal bone, internal auditory canal, and surface of the posterior fossa. Given the relatively high recurrence rate of ELSTs, long-term follow-up is recommended. 4 Laryngoscope, 2024.

Species designation requires new name for Gulf of Mexico marsh crab, restricting Sesarma reticulatum (Say, 1817) to the Atlantic seaboard of North America (Decapoda, Sesarmidae)

Abstract Long regarded to represent an undescribed species related to Sesarma reticulatum, warm-temperate populations of a common marsh crab from the Gulf of Mexico are herewith formally named Sesarma schubarti sp. nov. Records of S. reticulatum s. s. are restricted to the U.S. Atlantic seaboard from the Woods Hole region of Massachusetts to the Indian River region on the east coast of Florida. A diverse body of supportive evidence to underpin this separation has accrued over three decades, including previous observations based on physiology, ecology, reproduction, blood hemocyanin proteins, isozymes, and mtDNA sequences. Comparative morphological studies provide only minor structural characters to distinguish the new species from its Atlantic seaboard counterpart, including differences in the shape of the mature male first gonopod tip and positioning of a transverse crest on the male first pleonite. However, in fresh specimens colouration also differs, often strikingly so. Body surfaces that are variously purplish in mature specimens of S. reticulatum s. s., yielding the common name “purple marsh crab”, are instead more commonly reddish to orange in S. schubarti sp. nov. Our analysis of new 16S and COI gene sequences, along with existing genetic data, clarifies relationships of the new species to both S. reticulatum s. s. and S. curacaoense. The new species is formally named in honor of the late Christoph D. Schubart, a cherished colleague who contributed extensively to knowledge of sesarmid and other brachyuran crabs over his unfortunately abbreviated career.

The imaging appearances of stapical footplate fistula related to inner ear malformation

Objective: To summarize the HRCT and MRI appearances of stapical footplate fistula related to inner ear malformation (SFF-Re-IEM). Methods: The HRCT and MRI materials of 48 cases (53 ears) SFF-Re-IEM were retrospectively analyzed. Among them, 25 SFF-Re-IEM ears were confirmed by surgery. Their CT and MRI findings including associated IEM type, internal auditory canal (IAC) malformation, tympanic fluid, its density and signal features, and accompanied labyrinthitis were recorded. Results: Among 48 cases (53 ears) with SFF-Re-IEM, 17 ears with incomplete partition type Ⅰ, accounting for 32.1%, 13 ears with common cavity for 24.5%, 13 ears with cochlear aplasia for 24.5%, 7 ears with cochlear dysplasia Ⅱ for 13.2%, and 3 ears with Mondini for 5.7%,were found respectively. 94.3% of them were associated with a defect or dysplasia in the found of the IAC. They were divided into 4 types according to the intact of the stapical footplate and accompanied CSF otorrhea: 22 ears were diagnosed as the stapical footplate leaking, of them, 2 ears might come from the stapical footplate bony defect, 6 ears were from the stapical footplate hernia. 1 ear belonged to the peristapical footplate leaking. 30 ears with the isolated the stapical footplate hernia were another found. The bony defect in 2 ears with the stapical footplate bony defect were not presented on CT and MRI.The focal bony defect of the affected stapical footplate of 36 ears with the stapical footplate hernia were demonstrated, which presented the hemispherical protruding into the tympana, the soft-tissue density on CT, and CSF-like signal on the MR heaved-T2WI images. Among 22 ears with the stapical footplate leaking, their imaging appearances varied from the different amount of the leaking CSF. Besides the focal bony defects of the affected stapical footplates, there were much more CSF-like density or signal in the ipsilateral tympanic cavity in 17 affected ears connecting with the vestibule through the defect area. In the CSF leaking ears with less CSF leaking in 5 ears, the CSF-like cysts like SFH were shown on the stapical footplate defect area, but their outer edges were irregular, and the CSF-like signal scattering in the tympanic cavity did not connect with the protruding cysts at the stapical area. Conclusion: The variable appearances of the SFF-Re-IEM ears based on the different subtypes are its characteristic HRCT and MRI appearances. This is helpful for the SFF-Re-IEM diagnosing to grasp its imaging features.

Simultaneous cochlear implantation with early endoscopic surgery in small acoustic neuroma.

The exclusive endoscopic transcanal transpromontorial approach (EETTA) has recently been developed for the removal of small-sized acoustic neuromas in the labyrinth (intralabyrinthine schwannoma [ILS]) or internal auditory canal (IAC). Although small tumors that meet the indications for EETTA are also good candidates for cochlear implantation (CI), there are few reports on CI after schwannoma removal using EETTA. Here we present an outcome of patients who underwent simultaneous EETTA and CI. Five patients (two with IAC fundus tumors and three with ILS) who underwent simultaneous EETTA and CI between 2020 and 2022 were retrospectively enrolled. Their medical charts and test results were reviewed. After at least 12 months of follow-up, there were no severe surgical complications such as meningitis, infection, or skin necrosis. Four of the five patients responded to auditory stimulation. Three out of four auditory-responsive patients scored >80% on sentence recognition. Simultaneous EETTA and CI are feasible for the treatment of ILS and IAC fundus tumors. Preservation of the cochlear nerve and modiolus is important for favorable CI outcomes. Therefore, ILS and IAC fundus tumors in patients with nonserviceable hearing should be surgically removed as early as possible to enable proper hearing rehabilitation with CI. Level 4.

Clinical and Radiological Findings in Children with Anomalous Pontine Cranial Nerves.

We retrospectively reviewed the clinical and radiologic findings in 17 children with an aberrant cisternal CN7 and found that these patients had additional anomalies involving other pontine cranial nerves. The hallmark imaging feature identified in all patients was aberrant cisternal segment of an enlarged appearing CN7. The abnormal nerve coursed anteriorly towards the Gasserian ganglion where it fanned out towards the internal auditory canal, Meckel's cave or both. This finding was accompanied by a small cisternal CN5 which often had a lateral bowed appearance. CN5 and CN7 were abnormally close to each other. Meckel's cave appeared widened posteriorly and often was close to or merged with the internal auditory canal. Other abnormalities in the pontine cranial nerves included CN8 deficiency in the majority of children and variable CN6 deficiency. This constellation of findings was most often discovered in children having MR evaluation for sensorineural hearing loss and the majority of patients had preserved facial nerve function. In patients with available genetic testing, no pathogenic variants were observed. Interestingly, in 13 children with available birth history, 9 were notable for maternal or gestational diabetes (69%), suggesting a possible early intrauterine insult to the developing nerves.ABBREVIATIONS: CN= cranial nerve; OAVS= Oculo-Auriculo-Vertebral Spectrum; IAC= Internal Auditory Canal; PTCD= Pontine Tegmental Cap Dysplasia; EMR= Electronic Medical Record; SNHL= sensorineural hearing loss.

Comprehensive Review of Inner Ear Anatomy on Photon Counting CT.

The inner ear contains many fissures and canals which can mimic pathology. Photon counting CT allows greater spatial and contrast resolution of these structures over traditional energy integrating CT detectors. Small channels containing nerves, arteries, and normal anatomy such as the cochlear cleft, cochlear and vestibular aqueducts are commonly encountered on temporal bone imaging. The improved visualization of these structures poses challenges for radiologists who are new photon counting CT. This manuscript updates the existing temporal bone anatomy literature with a detailed anatomical review of the inner ear and major nerves frequently encountered when reviewing temporal bone imaging.ABBREVIATIONS: EID = energy-integrating detector; PCT = photon-counting computed tomography, CPA = cerebellopontine angle; IAC = internal auditory canal.

Cochlear implantation in patients with inner ear schwannomas: a systematic review and meta-analysis of audiological outcomes.

In patients with inner ear schwannomas (IES), reports on hearing rehabilitation with cochlear implants (CI) have increased over the past decade, most of which are case reports or small case series. The aim of this study is to systematically review the reported hearing results with CI in patients with IES considering thedifferent audiologic outcome measures used in different countries. According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline, a search of published literature was conducted. We included patients with IES (primary or with secondary extension from the internal auditory canal (IAC) to the inner ear, sporadic or NF2 related) undergoing cochlear implantation with or without tumour removal. The audiological results were divided into the categories "monosyllables", "disyllables", "multisyllabic words or numbers", and "sentences". Predefined audiological outcome measures were available from 110 patients and 111 ears in 27 reports. The mean recognition scores for monosyllabic words with CI were 55% (SD:24), for bisyllabic words 61% (SD:36), for multisyllabic words and numbers 87% (SD:25), and 71% (SD:30) for sentences. Results from for multisyllabic words and numbers in general showed a tendency towards a ceiling effect. Possible risk factors for performance below average were higher complexity tumours (inner ear plus IAC/CPA), NF2, CI without tumour removal ("CI through tumour"), and sequential cochlear implantation after tumour removal (staged surgery). Hearing loss in patients with inner ear schwannomas can be successfully rehabilitated with CI with above average speech performance in most cases. Cochlear implantation thus represents a valuable option for hearing rehabilitation also in patients with IES while at the same time maintaining the possibility of MRI follow-up. Further studies should investigate possible risk factors for poor performance. Audiological tests and outcome parameters should be reported in detail and ideally be harmonized to allow better comparison between languages.

Prestin in Human Perilymph, Cerebrospinal Fluid, and Blood as a Biomarker for Hearing Loss.

Determining the concentration of prestin in human blood, cerebrospinal fluid (CSF), and perilymph (PL), and evaluating its suitability as a clinical biomarker for sensori-neural hearing loss (SNHL). Human blood, CSF, and PL samples were intraoperatively collected from 42 patients with tumors of the internal auditory canal or with intracochlear tumors undergoing translabyrinthine or middle fossa tumor removal. Prestin concentration was measured using enzyme-linked immunosorbent assay and linear regression analyses were performed to investigate its associations with audiological as well as vestibular test results. Tertiary referral center. The median prestin concentration in blood samples of the 42 study participants (26 women, mean ± standard deviation age, 52.7 ± 12.5 years) was 1.32 (interquartile range, IQR, 0.71-1.99) ng/mL. CSF prestin levels were significantly higher with 4.73 (IQR, 2.45-14.03) ng/mL (P = .005). With 84.74 (IQR, 38.95-122.00) ng/mL, PL prestin concentration was significantly higher compared to blood (P = .01) and CSF (P = .03) levels. Linear regression analyses showed significant associations of CSF prestin concentration with preoperative hearing levels (pure-tone average and word recognition; P = .008, R2 = 0.1894; P = .03, R2 = 0.1857), but no correlations with blood or PL levels. This study's findings highlight the volatile nature of prestin levels and provide the first insights into this potential biomarker's concentrations in body fluids apart from blood. Future investigations should comprehensively assess human prestin levels with different etiologies of SNHL, prestin's natural homeostasis and systemic circulation, and its temporal dynamics after cochlear trauma. Finally, clinically approved detection kits for prestin are urgently required prior to considering a potential translational implementation of this diagnostic technique.

Changes in paranasal sinus volumes, temporal bone pneumatization, internal acoustic canal and olfactory cleft dimensions over the centuries: a comparison of skulls from different epochs in Anatolia

ObjectivesInvestigating changes in temporal bone pneumatization (TBP) and paranasal sinus volumes (PSV) across different eras may help understanding not only changes in skull anatomy but also pathophysiology of chronic otitis media and sinusitis, respectively, which are common health problems.MethodsEight skulls from the second century AD, 20 skulls were from the 10th–11th centuries AD, 20 skulls from the 16th–19th centuries AD, and 60 contemporary skulls were included in this cross-sectional observational study. Using computerized tomography (CT) scans, the PSV were calculated by multiplying the height, width, and antero-posterior distance of the sinuses. TBP was divided into three types. Internal acoustic canal (IAC) length and width, and olfactory cleft (OC) width were measured.ResultsNo statistically significant differences were found between the paranasal sinus (frontal, maxillary, and sphenoid) volumes between the groups. However, TBP decreased statistically significantly over time on both sides of the skulls (p = 0.001). The contemporary IAC and OC measures were found to be significantly lower on both sides compared to the skulls from the other three eras (p < 0.001 for both).ConclusionsAlthough no significant change was observed in PSV, decreases were evident in TBP, OC width and IAC length and width over time. It appears a fair inference that changes in size of OC and IAC might be another indication of the fact that olfaction and hearing were more vital for survival in old eras. Since we do not know incidence of chronic ear problems in old eras, we cannot speculate outcome of increased TBP in terms of developing chronic ear diseases. On the contrary, increased TBP was likely to play a protective role in traumas in old ears. Additionally, the environmental influences may be crucial role in the development of paranasal sinuses.