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Temporal-bone milling is a delicate process commonly performed during otologic surgery to gain access to the middle and inner ear structures. Because of the numerous at-risk structures of this anatomic area, extensive surgeon training is required. Artificial temporal bones offer an interesting alternative to cadaveric training. However, the evaluation of such simulators has not been systematic, with an absence of objective validation of their milling response, especially in a surgical context. By measuring the milling forces obtained during the classical steps of otologic surgery on six 3D-printed and three cadaveric temporal bones, this work aims at evaluating the ability of the OTOtwin® synthetic temporal bone to reproduce human bone behavior. A better repeatability was obtained for artificial bones than for cadaveric ones. However, the level of forces recorded during artificial bone milling was close to the one measured with cadaveric samples. The effects of both surgical phase and irrigation on milling force levels were also quantified. The experiments conducted in this study confirmed the suitability of OTOtwin® temporal bone model for both otologic surgery training and research purposes. Valuable insights were also gained from this study regarding the understanding of the otologic milling process.

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BACKGROUND: Skull base surgery requires anatomical knowledge and appropriate surgical technique in bone drilling. We developed a newly modified three-dimensional (3D) model of the posterior cranial fossa as a learning tool that improves knowledge of skull base anatomy and surgical approaches, including skull base drilling techniques. METHODS: This bone model of the posterior cranial fossa was created based on computed tomography data using a 3D printer, and incorporates artificial cranial nerves, cerebral vessels, bony structures, dura mater, and cerebellar tentorial dura. These anatomical components are differentiated with various colors. In addition, the atlanto-occipital junction can be mobilized to fully expose the surface of the cartilage between the C1 condyle and occipital condyle to allow drilling to open the hypoglossal canal under a wide surgical field. The usefulness of the model for practicing skull base surgical approaches was evaluated. RESULTS: Experience of bone drilling, dural dissection, and 3D positioning of important structures, including cranial nerves and blood vessels, was identical to that in actual surgery. CONCLUSIONS: This model is designed to facilitate teaching anatomical knowledge and essential epidural procedure-related skills, and is useful for teaching the essential elements of posterior skull base surgery.

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Head and neck paragangliomas (HNPGLs), rare neuroendocrine tumors that mainly arise from parasympathetic ganglia along the cranial nerves, are challenging due to anatomic origin, tendency to aggressive neurovascular and skull base infiltration, unpredictable metastatic potential, radio-chemoresistance, and risk of multiplicity. Symptoms range from mild to life threatening depending on location/size, but rarely relate to catecholamine excess. Risk factors include female sex and pathogenic germline variants in genes affecting hypoxia signaling (foremost succinate dehydrogenase genes). Diagnostic work-up relies on imaging, measurements of plasma free metanephrines/methoxytyramine, genetic testing, and pathology/immunohistochemistry. Management is tailored to patient/tumor characteristics and encompasses wait-scan, upfront surgery, debulking surgery, and radiotherapy. Presurgical embolization is recommended, except for small tympanic and tympanomasoid tumors. Presurgical stenting is required for internal carotid artery involvement, and two-stage surgery for intradural extension. Current treatments for metastatic/inoperable HNPGL are non-curative, and long-term follow-up should be recommended for all patients to monitor local recurrence and new tumors.

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The cochlear aqueduct (CA) is a bony canal located at the base of the scala tympani of the cochlea. It connects the inner ear perilymph fluid to the cerebrospinal fluid of the posterior cerebral fossa. Its function is not well understood, as it seems to be patent in only a fraction of adult patients. Indirect observations argue in favor of the CA being more patent in children. To study the CA morphology in children, we performed a retrospective single-center study of 85 high-resolution temporal bone computed tomography (hrCT) scans of children with a mean age of 3.23 ± 3.07 years (13 days of life up to 18 years), and compared them with a group of 22 adult hrCT (mean age of 24.01 ± 3.58 years). The CA morphology measurements included its total length, its funnel (wider intracranial portion) length and width and its type (indicating its radiological patency), according to a previously published classification. The dimensions of the CA were significantly smaller in children compared with adults for the axial length (10.37 ± 2.58 versus 14.63 ± 2.40 mm, respectively, p < 0,001) and the funnel length (3.94 ± 1.59 versus 6.01 ± 1.77 mm, respectively, p < 0,001). The funnel width tended to be smaller but the difference was not significant: 3.49 ± 1,33 versus 3.89 ± 1.07 mm, p = 0,22. The repartition of types of CA was also statistically different. The CA appeared to be more identifiable in the children population. Type 1 (CA visible along its entire course) accounted for 42% (36/85) of children and only 5% (1/22) of adults, type 2 (visible in the medial two thirds) for 30% (25/85) versus 31% (7/22), type 3 (not visible completely along the medial two thirds) for 27% (23/85) versus 50% (11/22). Finally, type 4 (undetectable) was found in only 1% (1/85) of children and 14% (3/22) of adults (p < 0,001). Our study showed significant postnatal growth of the length of the CA, which was more rapid before the age of 2, and slowed after 6 years of age. Its width increased less, with children older than 2 years presenting a similar width to adults. The CA was more identifiable in hrCT in children, arguing for a more permeable tract. The number of completely ossified CA was significantly lower in the children population. These findings highlight the differences between the CA morphology in adults and children and raise the question of differences in function. Moreover, these differences may impact the pharmacodynamics of drugs or vectors delivered into the pediatric inner ear. Further studies are required, both on the anatomy of temporal bones and on the function of the CA in children.

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Introduction: Medication-related osteonecrosis of the temporal bone is rare and has been reported to be associated with the use of anti-resorptive and biologic agents. Here, we present the first case of tyrosine-kinase inhibitor-related external auditory canal (EAC) osteonecrosis as well as two cases related to anti-resorptive therapies. Methods: A retrospective case series. Results: Case one: an 84-year-old female presented with chronic otitis externa and osteonecrosis of EACs bilaterally. She had a history of osteoporosis treated with denosumab and risedronic acid. She successfully underwent left EAC reconstruction using an inferiorly-based pedicle periosteal flap while the right ear canal was managed conservatively. Case two: a 69-year-old male presented with osteonecrosis of the right EAC. He had a history of osteoporosis treated with alendronic acid and zoledronic acid. His osteonecrosis is conservatively managed with local debridement and antibiotic application. Case three: a 60-year-old male presented with osteonecrosis of the right inferior EAC. He had a history of chronic myelogenous leukemia treated with a tyrosine-kinase inhibitor, imatinib. After failing conservative therapy, he underwent right ear canal reconstruction using a periosteal vascular pedicle flap without complication and experienced complete resolution to his symptoms. Conclusion: Anti-resorptive agents and/or tyrosine kinase inhibitors may lead to dysregulation of bone remodeling and result in rare cases of temporal bone osteonecrosis. When a local debridement and antibiotic therapy fail, definitive surgical excision of necrotic bone with subsequent reconstruction of the EAC may offer patients a possible resolution in symptoms.

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BACKGROUND: The anatomy of the retrotympanum is highly variable, and surgical access is challenging. In the medial retrotympanum, a descending series of recesses are found: the posterior tympanic sinus, the sinus tympani (ST), and the subtympanic sinus (STS). Most of the previous anatomical studies of the ST evaluated it as a single depression of variable width and depth, without recesses, just on axial sections. METHOD: The ST was evaluated bilaterally in all the anatomical planes on a lot of 100 cases. Two sagittal anatomical types of the ST were defined and counted: type 0 (saccular ST), with absent postero-inferior recess (PIR) of the ST, and type 1, ST with PIR (bowl-shaped ST). RESULTS: In 200 sides, 144 type 0 ST (72 %) and 56 types 1 (PIRs) of the ST were found (28 %). On the right/left sides the type 0 ST was found in 74 %/70 % and the type 1, with PIR, in 26 %/30 %. There were no significant correlations between sex and the ST types on both sides. In the general lot, bilaterally symmetrical types 0 were found in 68 %, bilaterally symmetrical types 1 in 24 %, and the bilaterally asymmetrical combination 0+1 in just 8 %. CONCLUSIONS: The PIR of the ST is not a scarce anatomical variation in the retrotympanum. It is hidden deep to the ST and difficult to access through the middle ear. It also could retain residual cholesteatoma. A retrofacial approach could access the PIR of the ST if no other anatomical limitations occur.

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Necrotizing otitis externa (NOE) is a severe infection primarily affecting the external auditory canal, seen mainly in immunocompromised individuals as patients with diabetes mellitus (DM). This case report highlights unusual complications of NOE: temporal bone and nasopharyngeal abscesses. These complications underscore the severity of NOE, particularly when caused by rare pathogens such as Klebsiella species. We detail the case of a 70-year-old male with uncontrolled DM who presented with severe right ear pain, purulent discharge, and significant postauricular swelling. Laboratory investigations revealed elevated inflammatory markers and poorly controlled diabetes. Cultures confirmed Klebsiella pneumoniae, and imaging showed diffuse edema and abscess formation in the temporal bone and nasopharynx. The patient was treated with intravenous Ceftazidime and ciprofloxacin for 6 weeks, followed by oral ciprofloxacin. Effective management of NOE necessitates a comprehensive, multidisciplinary approach. Early intervention, regular monitoring, and imaging are critical for promptly detecting and managing complications.

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OBJECTIVE: To distinguish the patterns of inner ear changes between meningogenic and otogenic routes in meningitis cases. Our hypothesis is that pinpointing distinct patterns linked to each route could aid in the development of diagnostic strategies and targeted therapies. METHODS: Temporal bones (TBs) from patients with a history of meningitis and histopathological evidence of labyrinthitis were divided into two groups (otogenic and meningogenic). Inner ear histopathological examination was performed to identify qualitative and semi-quantitative changes. This assessment encompassed inflammation patterns, indications of early ossification, hair cell loss, and alterations in the lateral wall, round window membrane, cochlear aqueduct and vestibular aqueduct. RESULTS: Thirty-six TBs were included in the study (otogenic, 21; meningogenic, 15). Generalized labyrinthitis was more common in otogenic cases (100% vs. 53%, p < 0.001). Early signs of cochlear ossification were exclusively observed in otogenic cases (9 TBs). The spiral ligament of otogenic cases has shown a uniform loss of fibrocytes across all cochlear turns, while meningogenic cases showed more severe loss in the apical turn. Otogenic cases exhibited a higher prevalence of severe inflammation of the cochlear aqueduct and endolymphatic sac. Meningogenic cases showed more severe loss of vestibular hair cells in the otolithic organs. CONCLUSION: Otogenic cases displayed a higher prevalence of changes in the spiral ligament and signs of early ossification, whereas meningogenic cases were associated with a higher degree of vestibular damage. Our findings emphasize the importance of considering the infection route and its implications for timely diagnosis and development of pathology-oriented treatment strategies. LEVEL OF EVIDENCE: NA Laryngoscope, 2024.

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PURPOSE: To investigate the impact of 3D-printed temporal bone models with two different material transparencies on trainees' mastoidectomy performance. METHODS: Eleven ORL residents performed two anatomical mastoidectomies with posterior tympanotomy on two 3D-printed models with different transparency and VR simulation training. Participants where divided into two groups based on their experience. Within each group participants were randomized to start with the model printed in a completely opaque material or in a material featuring some degree of transparency. After drilling on 3D-printed models, the participants performed two similar mastoidectomies on human cadavers: one on the left side of one cadaver and one on the right side of another cadaver. After drilling 3D-printed models and cadavers, the final-product performances were evaluated by two experienced raters using the 26-item modified Welling Scale. Participants also evaluated the models using a questionnaire. RESULTS: Overall, the participants performed 25 % better on the 3D-printed models featuring transparency compared to the opaque models (18.6 points vs 14.9 points, mean difference = 3.7, 95 % CI 2.0-5.3, P < 0.001)). This difference in performance was independent of which material the participants had drilled first. In addition, the residents also subjectively rated the transparent model to be closer to cadaver dissection. The experienced group starting with the 3D-printed models scored 21.5 points (95 % CI 20.0-23.1), while the group starting with VR simulation training score 18.4 points (95 % CI 16.6-20.3). CONCLUSION: We propose that material used for 3D-printing temporal bone models should feature some degree of transparency, like natural bone, for trainees to learn and exploit key visual cues during drilling.

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BACKGROUND: Temporal bone dissection is overwide recognized as an ideal training method for otologic surgeons. The knowledge of temporal bone anatomy and especially of the course of infratemporal facial nerve is pivotal in practice. The 3D exoscope is an innovative and promising tool, that was recently introduced in ear surgery. METHODS: A high-definition 3D exoscope (3D VITOM®) mounted on the VERSACRANETM holding system (Karl Storz) was used to perform two temporal bone dissection, with the aim to study the anatomy of infratemporal facial nerve. The 3D endoscope (TIPCAM®1 S 3D ORL, Karl Storz) was used in combination to provide a close-up high-quality view and to provide a different angle of view on fine anatomical relationships. RESULTS: The high-definition 3D exoscope allowed to conduct the dissection with high quality visualization and to share the same surgical field with trainees. Moreover, it showed a high interchangeability with the 3D endoscope. CONCLUSIONS: 3D 4 K Exo-endoscopic temporal bone dissection seems to have benefits in terms of educational purpose, especially concerning anatomy understanding. The superiority in teaching value of this tool should be further investigated in cohort studies.

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Background Cochlear implant surgery is a complex procedure influenced by the anatomical structures of the temporal bone. Preoperative imaging using CT and MRI can provide critical insights into the surgical challenges that may be encountered. This study aims to evaluate the role of CT and MRI in preoperative assessment to predict the difficulty of cochlear implant surgery in terms of surgical time. Materials and methods A retrospective observational study was conducted at Saveetha Medical College and Hospital, Chennai, from April 2022 to September 2023. Ninety patients with severe to profound sensorineural hearing loss who underwent cochlear implantation were included. Preoperative high-resolution CT (HRCT) and MRI of the temporal bone were performed to assess various anatomical parameters. Surgical difficulty was evaluated intraoperatively and correlated with preoperative imaging findings. Data were analyzed using IBM SPSS Statistics for Windows, V. 21.0 (IBM Corp., Armonk, NY). Results The mean age of participants was 7.4±10.9 years, with the majority (66.7%) in the 1-5-year age group. Out of 90 participants, 50 were male and 40 were female. HRCT and MRI revealed that 35.6% of participants had hypo-/non-pneumatized mastoids, 3.3% had narrow facial recesses, and 3.3% had high-riding jugular bulbs. Significant correlations were found between surgical time and associated congenital (p=0.006) and acquired (p=0.0001) anomalies of the temporal bone, as well as the total difficulty score (p=0.0001). The mean surgical time was 103.97±25.2 minutes, with a range from 45 to 220 minutes. Conclusion Preoperative HRCT and MRI are valuable tools in predicting the degree of difficulty in cochlear implant surgery. Specific anatomical features identified in imaging studies can significantly influence the surgical approach and duration. These findings underscore the importance of detailed preoperative imaging to enhance surgical planning and outcomes in cochlear implant procedures.

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Congenital cholesteatoma (CC) is a non-neoplastic lesion of keratin debris lined by epithelium found in the temporal bone. It is the lesser-known sibling of the acquired cholesteatoma and may be classified as congenital middle ear cholesteatoma and congenital petrous bone cholesteatoma. The incidence is rising, probably owing to increased recognition and advances in imaging modalities. Cone beam CT provides detailed anatomical information, highlighting quadrant location, ossicular involvement, and mastoid extension. MRI aids in lesion characterization and detection of complications. The classification systems for congenital middle ear and petrous bone cholesteatoma are helpful in the preoperative workup and have a role in predicting postoperative recurrence rates. Management almost invariably involves surgical intervention aimed at preserving middle and inner ear function. Follow-up of CC is mainly based on MRI together with otoscopic examination. Non-echo planar diffusion-weighted imaging, especially, has proven essential for detecting residual disease. This review article emphasizes the significance of imaging in the timely diagnosis and management of CCs. CLINICAL RELEVANCE STATEMENT: This article underscores the crucial role of imaging for prompt detection, preoperative assessment, and postoperative follow-up of CCs, a condition with rising incidence associated with potentially severe complications. KEY POINTS: Timely diagnosis of CCs is imperative for avoiding complications. Imaging is key in detection, preoperative evaluation, and postoperative management. Cone Beam CT and non-echo planar DWI represent state-of-the-art imaging techniques.

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Acute Myeloid Leukemia (AML) is the most common leukemia observed in the adult population, accounting for 80% of all leukemia cases. Extramedullary involvement in AML, where leukemic cells are found in organs or tissues outside the blood or bone marrow, is a rare occurrence [1]. The most frequent sites of extramedullary disease include the skin, central nervous system (CNS), and lymph nodes [2, 3]. In this case report, we present an instance of extramedullary AML in the temporal bone, which initially presented with symptoms such as earache, discharge, and facial asymmetry, mimicking acute suppurative otitis media with facial palsy. The patient underwent mastoid exploration and facial nerve decompression. A post-operative bone marrow biopsy confirmed the diagnosis of AML, leading to the initiation of chemotherapy. The patient is currently under follow-up care.

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Congenital facial nerve (FN) malformations are uncommon. Our aim is to determine the clinical and radiological features of FN malformations along with the associated cochlear and vestibular malformations. We conducted a retrospective study including children with a profound sensorineural hearing loss who were candidates for cochlear implantation. We evaluated the presence of FN malformations through temporal bone computed tomography scan and magnetic resonance imaging. We recorded an aberrant FN course in five out of 165 patients in a total of 9 ears. They consisted of a bifurcation of the mastoid segment, an anterior or posterior displacement of the labyrinthine segment and a hypoplasia of the geniculate ganglion. Associated inner ear malformations included vestibular aqueduct dilation, cochlear hypoplasia and total labyrinthine aplasia. We noted a bilateral agenesis of the cochlear nerve in three patients. Facial nerve malformations should be suspected in patients presenting a congenital hearing loss especially in association with other temporal bone malformations. Their pre-operative discovery is helpful in planning the surgical procedure.

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Purpose: To compare image quality and radiation exposure between super- and ultra-high-resolution helical and super-high-resolution volumetric CT of the temporal bone. Methods: Six cadaveric temporal bone specimens were used to evaluate key temporal bone structures using the following CT reconstruction and acquisition modes: helical and single-volume acquisition modes in super-high resolution (0.25-mm slice thickness, 10242 matrix), and helical mode in ultra-high resolution (0.25-mm slice thickness, 20482 matrix). Two observers performed 5 previously described preoperative measurements, measured noise and signal-to-noise ratios for air, and noise for bone, and rated the visualization of 5 anatomical structures on a 4-point scale, for each reconstruction mode. Radiation dose exposure was recorded for each examination. Results: There was no significant difference between any of the quantitative or qualitative measurements in any of the reconstruction and acquisition modes. There was a slight increase in noise and a decrease in signal-to-noise ratio in the air using the single-volume mode (115 ± 13.1 HU and 8.37 ± 0.91, respectively) compared to the helicoidal super-high-resolution (92.4 ± 11.8 HU and 10.8 ± 1.26, respectively) and helicoidal ultra-high-resolution (91.1 ± 10.7 HU and 10.9 ± 1.39, respectively) modes (P < .002). The volumic CT dose index was 50.9 mGy with helical acquisition and 29.8 mGy with single-volume acquisition mode (P < .0001). Conclusion: The single-volume super-high-resolution acquisition mode allows a reduction in radiation dose exposure without compromising image quality compared to helical scanning, but with a slightly lower signal-to-noise ratio in air with the single-volume mode, while there was no difference in image quality between the helical super- and ultra-high-resolution modes.

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BACKGROUND: Meningoencephaloceles can originate through any defect in the cranial bones, including the skull base. They can be completely asymptomatic or present with typical symptoms such as headaches, seizures, or meningitis. OBSERVATIONS: The authors present the case of a 54-year-old female who presented with right-sided ear and temporomandibular joint (TMJ) pain. Computed tomography showed a large lytic lesion of the squamous part of the temporal bone with cortical bone destruction, extending to the mandibular fossa. Magnetic resonance imaging demonstrated a temporal bone meningoencephalocele. The patient underwent resection, dural repair, and multilayer reconstruction with a patient-specific three-dimensional-printed titanium combined craniofossa prosthesis. LESSONS: To the authors' knowledge, this is the first case report of TMJ pain associated with a temporal meningoencephalocele. The exact location and extension of the lesion determine the surgical approach and need for reconstruction in temporal bone meningoencephaloceles. In cases of destruction of the mandibular fossa, a patient-specific combined craniofossa prosthesis is recommended to reconstruct the bone defect. https://thejns.org/doi/10.3171/CASE24132.

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PURPOSE: Chronic otitis media with cholesteatoma is a frequent disease entity in otology, requiring surgery in overwhelming majority of cases. Despite the huge burden there is no established grading system available to assess the severity and extent of disease preoperatively until date. Aim of our study is to assess the applicability of ChOLE staging to preoperative HRCT temporal bone in Chronic otitis media with cholesteatoma. METHODOLOGY: Patients clinically diagnosed as COM with cholesteatoma, who underwent preoperative HRCT temporal bone imaging and mastoid exploration at our tertiary care centre were included. Preoperative radiology was assessed and a radiological ChOLE (r-ChOLE) was given by radiologist. This was then compared with the postop ChOLE. RESULTS: 21 patients were included in the study. Data was linear and normally distributed (Shapiro wilk test). Pearson's product-moment correlation used to see relationship between radiological and postop Total score showed strong statistically significant positive correlation with correlation coefficient (r) of 0.977. Paired t test showed p value was 0.329 (p > 0.05) suggesting no significant difference between radiological and postop Total scores. Cohen kappa test of agreement was applied. It revealed an overall strong agreement (p < 0.001). CONCLUSION: ChOLE staging may be extended to preoperative HRCT of temporal bone in COM with cholesteatoma (rCHOLE). A preoperative radiological staging will help in better prioritizing, planning and execution of tympanomastoid surgeries.

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This case report aims to describe the clinical presentation, imaging findings, diagnostic challenges, and management of a patient with a cerebellopontine angle lesion. A 63-year-old woman presented with progressive headaches, tinnitus, right ear pressure, and dizziness. Initial imaging studies (computed tomography and magnetic resonance imaging) suggested either a thrombosed aneurysm or a lipoma. However, advanced imaging with cone beam computed tomography provided a definitive diagnosis of temporal bone exostosis. This case highlights the importance of cone beam computed tomography in diagnosing complex intracranial lesions due to its superior spatial resolution and lower radiation dose.

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BACKGROUND: Temporal bone computed tomography (CT) helps diagnose chronic otitis media (COM). However, its interpretation requires training and expertise. Artificial intelligence (AI) can help clinicians evaluate COM through CT scans, but existing models lack transparency and may not fully leverage multidimensional diagnostic information. OBJECTIVE: We aimed to develop an explainable AI system based on 3D convolutional neural networks (CNNs) for automatic CT-based evaluation of COM. METHODS: Temporal bone CT scans were retrospectively obtained from patients operated for COM between December 2015 and July 2021 at 2 independent institutes. A region of interest encompassing the middle ear was automatically segmented, and 3D CNNs were subsequently trained to identify pathological ears and cholesteatoma. An ablation study was performed to refine model architecture. Benchmark tests were conducted against a baseline 2D model and 7 clinical experts. Model performance was measured through cross-validation and external validation. Heat maps, generated using Gradient-Weighted Class Activation Mapping, were used to highlight critical decision-making regions. Finally, the AI system was assessed with a prospective cohort to aid clinicians in preoperative COM assessment. RESULTS: Internal and external data sets contained 1661 and 108 patients (3153 and 211 eligible ears), respectively. The 3D model exhibited decent performance with mean areas under the receiver operating characteristic curves of 0.96 (SD 0.01) and 0.93 (SD 0.01), and mean accuracies of 0.878 (SD 0.017) and 0.843 (SD 0.015), respectively, for detecting pathological ears on the 2 data sets. Similar outcomes were observed for cholesteatoma identification (mean area under the receiver operating characteristic curve 0.85, SD 0.03 and 0.83, SD 0.05; mean accuracies 0.783, SD 0.04 and 0.813, SD 0.033, respectively). The proposed 3D model achieved a commendable balance between performance and network size relative to alternative models. It significantly outperformed the 2D approach in detecting COM (P≤.05) and exhibited a substantial gain in identifying cholesteatoma (P<.001). The model also demonstrated superior diagnostic capabilities over resident fellows and the attending otologist (P<.05), rivaling all senior clinicians in both tasks. The generated heat maps properly highlighted the middle ear and mastoid regions, aligning with human knowledge in interpreting temporal bone CT. The resulting AI system achieved an accuracy of 81.8% in generating preoperative diagnoses for 121 patients and contributed to clinical decision-making in 90.1% cases. CONCLUSIONS: We present a 3D CNN model trained to detect pathological changes and identify cholesteatoma via temporal bone CT scans. In both tasks, this model significantly outperforms the baseline 2D approach, achieving levels comparable with or surpassing those of human experts. The model also exhibits decent generalizability and enhanced comprehensibility. This AI system facilitates automatic COM assessment and shows promising viability in real-world clinical settings. These findings underscore AI's potential as a valuable aid for clinicians in COM evaluation. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR2000036300; https://www.chictr.org.cn/showprojEN.html?proj=58685.

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PURPOSE: This study investigated the internal carotid artery (ICA) and jugular bulb (JB) structures in terms of lateral temporal bone resection using 3D computed tomography (CT). METHODS: We retrospectively investigated 80 ears of 40 patients using 3D reconstruction data from normal temporal bone CT. Ten critical points (P) in the temporal bone were marked in the 3D object with reference to the axial, coronal, and sagittal images of the CT scans. An imaginary plane of the facial nerve (PLf) course was also reconstructed in relation to the three points of the chorda-facial junction, P5 (second genu), and P3 (cochleariform) process. RESULTS: The distances (mean ± SD; mm) from points P3 to P1 (the highest level of the JB) and P2 (the posterior wall of the ascending petrous IAC at the level of the Eustachian tube) were 12.03 ± 2.56 and 9.79 ± 1.78, respectively. The distances from point P4 (chorda-facial junction) to P1 and P2 were 10.98 ± 2.70 and 17.66 ± 2.26, respectively. The angles (mean ± SD; degree) between the PLf to the line from Pa (point of the anterior bony canal) to P3 and P4 were 17.80 ± 10.05º and 8.93 ± 5.37º, respectively. The angles between the PLf to the line from P3 to P1 and P2 were - 36.35 ± 13.28º and - 24.78 ± 13.91º, respectively. The angles between the PLf to the line from P4 to P1 and P2 respectively were - 40.35 ± 15.37º and - 13.34 ± 7.63º. CONCLUSIONS: Understanding the anatomical relationships of P1 and P2 at P3 and P4 can be helpful in preventing iatrogenic trauma of the ICA and JB.