Superior Canal Dehiscence and the Risk of Additional Dehiscences: A Retrospective CT Cohort Study.

OBJECTIVE: Determine if superior canal dehiscence (SCD) found on flat-panel CT increases the risk for other defects in the otic capsule. STUDY DESIGN: Retrospective cohort study. SETTING: Tertiary care center. PATIENTS: One hundred ears (50 with SCD and 50 matched controls without SCD). INTERVENTIONS: Flat-panel CT imaging. MAIN OUTCOME MEASURES: (1) Prevalence of other dehiscences in SCD ears, (2) dehiscences in controls, and (3) otic capsule thickness in other reported dehiscence locations (cochlea-carotid, lateral semicircular canal [SCC] and mastoid, facial nerve-lateral SCC, vestibular aqueduct, posterior SCC-jugular bulb, posterior SCC-posterior fossa). Between-group comparisons were considered significant at p < 0.007 after applying the Bonferroni correction for multiple comparisons. RESULTS: Not including the SCD, there was a mean of 0.04 additional dehiscences in the SCD group (n = 2/50, 4%) and 0.04 non-SCD dehiscences in the controls (n = 2/50, 4%, p > 0.007). In the SCD group, there was one dehiscence between the cochlea and carotid artery and one between the posterior SCC and posterior fossa. The control group had one enlarged vestibular aqueduct and one dehiscence between the facial nerve and lateral SCC. As a group, SCD ears had wider vestibular aqueducts (0.68 ± 0.20 vs 0.51 ± 0.30 mm, p < 0.007) and thinner bone between the posterior SCC and posterior fossa (3.12 ± 1.43 vs 4.34 ± 1.67 mm, p < 0.007). The bone between the facial nerve and lateral SCC was thicker in SCD ears (0.77 ± 0.23 vs 0.55 ± 0.27 mm, p < 0.007) and no different for cochlea-carotid, and lateral SCC and mastoid (p > 0.007). CONCLUSIONS: SCD does not increase the likelihood of a second dehiscence in the same otic capsule. SCD patients may have congenitally thinner otic capsule bones compared to controls, particularly near the posterior SCC, where the vestibular aqueduct may be enlarged.

Tuberculous mastoiditis - a case series.

SUMMARY: Tuberculous mastoiditis (TBM) is a rare form of extrapulmonary tuberculosis (TB), which may result in catastrophic complications, including mastoid and ossicle destruction, hearing loss and intracranial spread if untreated. Diagnosis is challenging due to the paucibacillary nature of extrapulmonary TB, compounded by limited theatre access for specimen retrieval, resulting in delayed diagnosis and treatment initiation. In this case series, we discuss three cases of TBM (one paediatric and two adults) who presented to the public and private healthcare sectors in the Eastern Cape in 2022, underscoring that TB does not respect socioeconomic status.

A novel method for evaluating mastoid defect regrowth after cochlear implantation.

This retrospective study examined mastoid defects resulting from cochlear implant (CI) surgery and their potential for spontaneous regrowth across different age groups. Spontaneous closure of mastoid defects has been observed in certain CI patients during revision surgery or through post-operative temporal bone computer tomography (TB-CT). The analysis encompassed 123 CI recipients, comprising 81.3% children and 18.7% adults, who underwent post-operative TB-CT scans. Using image adjustment software, the study measured mastoid defect areas and found a significant reduction in children's defects between the initial and subsequent scans. Notably, mastoid defect areas differed significantly between children and adults at both time points. Furthermore, the analysis revealed significant correlations between mastoid defect areas and the age at implantation as well as the time elapsed since the CI surgery and the first CT scan. This study provides valuable insights for evaluating CI patients scheduled for revision surgery by assessing potential surgical challenges and duration. Furthermore, it may have a pivotal role in evaluating patients who experience postauricular swelling subsequent to CI surgery.

Diagnostic and Imaging Findings in Inflammatory Opacifications of the Middle Ear: A Review of the Literature.

Opacification in the middle ear and mastoid region can stem from a wide range of factors. In terms of diagnostic imaging, CT is the primary tool due to its exceptional spatial resolution, particularly for examining the temporal bone and ossicles. MRI complements this by offering detailed soft tissue lesion characterization and assessing involvement in the inner ear and cranial nerves. This study focuses on inflammatory causes of opacification in the middle ear and mastoid, with an emphasis on the utility of CT and MRI. This comprehensive review aimed to provide a practical framework for considering potential differential diagnoses.

Trans-mastoid plugging of superior semicircular canal dehiscence: long-term follow-up.

OBJECTIVE: To evaluate the long-term outcomes of trans-mastoid plugging of superior semicircular canal dehiscence (SSCD), focusing on complicated cases. METHODS: In this cohort study, we included all patients who underwent trans-mastoid plugging of SSCD between 2009 and 2019. We evaluated the symptoms (autophony, sound-/pressure-induced vertigo, disequilibrium, aural fullness and pulsatile tinnitus) before and 1 year after surgery in the medical records. We systematically assessed the current symptoms 6.2 ± 3 years postoperative (range 2.2-12.3 years) using questionnaires sent by post and validated by telephone interviews. We also documented any complications and the need for further procedures. We compared pure tone and speech audiometry before and 1 year after surgery. Finally, the degree of mastoid pneumatisation and mastoid tegmen anatomy were reviewed on preoperative CT scans. RESULTS: We included 24 ears in 23 patients. No complications were recorded, and none required a second procedure for SSCD. Following surgery, oscillopsia and Tullio phenomena resolved in all patients. Hyperacusis, autophony, and aural fullness were also settled in all patients except one. Balance impairment persisted to some degree in 35% of patients. No deterioration over the years was reported regarding the above symptoms. On average, bone conduction pure tone average pre- and 1 year postoperative were 13.7 ± 17 and 20.5 ± 18 dB, respectively (P = 0.002). Air bone gaps were reduced from 12.7 ± 8 to 5.9 ± 6 (P = 0.001). Two patients had a significant sclerotic mastoid, three had a prominent low-lying mastoid tegmen, and two had both. Anatomy had no effect on outcome. CONCLUSION: Trans-mastoid plugging of SSCD is a reliable and effective technique which achieves long-lasting symptom control, even in cases with sclerotic mastoid or low-lying mastoid tegmen.

Quantification of Mastoid Air Cells and Opacification of the Middle Ear in Primary Ciliary Dyskinesia.

OBJECTIVE: To evaluate pneumatization and opacification of the temporal bone on computed tomography (CT) images in patients with primary ciliary dyskinesia (PCD). STUDY DESIGN: Retrospective case-control study. SETTING: Tertiary referral center. PATIENTS: Fifteen patients with PCD (30 ears) and 45 age-matched individuals without PCD (90 ears) as controls. INTERVENTION: Diagnostic only. MAIN OUTCOME MEASURES: Quantification of mastoid air cells in the PCD and control groups and comparison between them. Degree of middle ear opacification on CT images of the temporal bone in the PCD group. RESULTS: The volume of the mastoid air cells was 30% smaller in the PCD group than in the control group ( p < 0.05). The suppression ratio, which is defined to indicate how much the average volume of mastoid air cells in the PCD group is suppressed relative to the control group, was 64% lower in the PCD group ( p < 0.05). Opacification was noted in 47% of the mastoid air cells and 63% of the tympanic cavity on CT images of the temporal bone in the PCD group, which were significantly higher frequencies than in the control group (1.1% and 1.1%, respectively). CONCLUSIONS: Compared with individuals without PCD, those with PCD showed a significantly smaller volume of mastoid air cells and a significantly higher frequency of opacification of mastoid air cells and tympanic cavity on temporal bone CT. Otitis media raises suspicion for PCD, and the otological manifestations of PCD reported here could help to narrow the differential diagnosis and facilitate early treatment.

Sex Estimation From Measurements of the Mastoid Triangle and Volume of the Mastoid Air Cell System Using Classical and Machine Learning Methods: A Comparative Analysis.

ABSTRACT: Previous studies on the sexual dimorphism of the mastoid triangle have typically focused on linear and area measurements. No studies in the literature have used mastoid air cell system volume measurements for direct anthropological or forensic sex determination. The aims of this study were to investigate the applicability of mastoid air cell system volume measurements and mastoid triangle measurements separately and combined for sex estimation, and to determine the accuracy of sex estimation rates using machine learning algorithms and discriminant function analysis of these data. On 200 computed tomography images, the distances constituting the edges of the mastoid triangle were measured, and the area was calculated using these measurements. A region-growing algorithm was used to determine the volume of the mastoid air cell system. The univariate sex determination accuracy was calculated for all parameters. Stepwise discriminant function analysis was performed for sex estimation. Multiple machine learning methods have also been used. All measurements of the mastoid triangle and volumes of the mastoid air cell system were higher in males than in females. The accurate sex estimation rate was determined to be 79.5% using stepwise discriminant function analysis and 88.5% using machine learning methods.

Congenital Retrosigmoid Cholesteatoma: Case Series and Literature Review.

BACKGROUND: This study aimed to discuss 3 cases of congenital cholesteatoma located posterior to the sigmoid sinus, with no/minimal involvement of mastoid, and compare them with cases presented in the literature to better define this rare entity. METHODS: Retrospective chart analysis of 3 congenital cholesteatomas located posterior to the sigmoid sinus treated surgically in 2 skull-base centers and literature review. Though congenital cholesteatoma can arise outside the middle ear, only a few cases presenting in the retrosigmoid occipital bone have been described earlier. RESULTS: In all 3 patients, there was a delay in the presentation, as symptoms were nonspecific or lacking, leading in 1 case to severe complications. Computed tomography and magnetic resonance imaging, especially diffusion-weighted imaging scans, allowed accurate diagnosis and surgical planning. Surgery happened to be challenging due to the tight adherence of the cholesteatoma to the thinned dural surface. Complete excision was achieved in all the cases. CONCLUSION: Congenital cholesteatoma located posterior to the sigmoid sinus is a rare entity and is even more exceptional after a critical review of the literature. Complete excision is quintessential to prevent intradural extension or infection. The most important surgical issue is the management of the posterior fossa dura and the sigmoid sinus. We recommend meticulous dissection with slow peeling of the epithelial lining from the dura. Bipolar coagulation of the dura may help in avoiding recidivism. Moreover, cerebrospinal fluid (CSF) leak during dissection has to be avoided as long as possible, because the loss of tension of the already thinned dura makes its peeling particularly difficult.

Comparison of tympanometric volume measurement with temporal bone CT findings in the assessment of mastoid bone pneumatization in chronic otitis media patients.

OBJECTIVE: Since mastoid bone aeration is a pressure buffer for the middle ear, it can be accepted as a prognostic factor for tympanoplasty. Temporal bone computed tomography (TBCT) is a primary method for estimating mastoid aeration. However, due to the risk of radiation and its high cost, there is a need for a more straightforward, faster, and more reliable method in non-complicated chronic otitis media cases (COM). Tympanometric volume measurement might be used for this purpose. This study investigated tympanometric volume measurement's reliability in showing mastoid bone aeration by comparing tympanometric volume measurement with TBCT aeration grading. PATIENTS AND METHODS: Preoperative tympanometric volume measurements were performed in patients who underwent audiological examination and temporal computerized tomography (CT) with the diagnosis of COM and sequela of COM without discharge for the last three months and were indicated for surgery. CT was classified into six grades: grade 0: there is no aeration, sclerotic mastoid; grade 1: pneumatization only in the mastoid antrum; grade 2: <25% pneumatization; grade 3: 25-50% pneumatization; grade 4: >50 pneumatization, grade 5: full pneumatization. Averages of tympanometric volume values were determined according to CT degrees. RESULTS: 48 left and 52 right ears (n: 100) of 81 patients, 24 females and 57 males, were included in the study. The mean age was 37.69±13.38. Mastoid pneumatization grades of patients were 32 grade 0, 23 grade 1, 16 grade 2, 14 grade 3, 11 grade 4, and 4 grade 5, respectively. Each grade's mean tympanometric volume (mL) was grade 0: 1.1594, grade 1: 1.6991, grade 2: 2.2250, grade 3: 3.0471, grade 4: 4.0327, and grade 5: 2.9775. CONCLUSIONS: There is a statistically significant relationship between tympanometrically measured ear volume and mastoid degrees of pneumatization on temporal bone tomography. As the degree of mastoid aeration increases, the tympanometric volume also increases. According to the results of this study, tympanometric air volume can be used reliably in the preoperative evaluation of mastoid bone aeration in cases of simple COM without ear drainage.

Analysis of mastoid portion of facial nerve course in temporal bone using computed tomography.

<b>Introduction:</b> The facial nerve (FN) follows a complex route in the temporal bone. Successful temporal bone surgery requires knowledge of its course which can be achieved using imaging methods such as computed tomography. This investigation aims to analyze the FN course in its mastoid portion and second genu and the frequency of its atypical course.</br></br> <b>Material and methods:</b> This is a retrospective study that enrolled 104 CT scans of temporal bones of patients followed up in the outpatient clinic of the Otorhinolaryngology Department of Dentistry Faculty of the Medical University of Warsaw between 2020 and 2022. FN courses were classified as straight, bulging, or letter "S"-like. Other parameters estimated: </br> • position of the second genu according to the prominence of the lateral semicircular canal (classified as lateral, medial, or middle) and its distance from a line adjacent to the lateral semicircular canal was measured;</br> • the distance between the short process of the incus and the outermost point of the second genu;</br> • the course of the mastoid portion of FN and the location of SG in comparison to the tympanic portion of n. VII. The course was later classified as lateral, medial, or middle.</br></br> <b>Results:</b> Among the 104 assessed temporal bones, the course of the mastoid portion of FN was classified as bulging in 47 cases (45.2%). Straight and letter "S"-like courses were present in 41 (39.4%) and 16 (15.4%) cases, respectively. Deviation of the second genu according to the prominence of the lateral semicircular canal was medial in 86 cases (82.7%), and middle in 4 cases (3.8%). In the rest, second genu was paramedian to the prominence of the later circular canal. The mean distance between the short process of the incus and the outermost point of SG was 4.9 mm (0.73 mm). The mastoid portion was located laterally, medially, and in the middle of the tympanic portion plane in, respectively, 4.8%, 83.7%, and 11.5%. The second genu was located laterally, medially, and in the middle of the tympanic portion plane in 1.9%, 73.1%, and 25%, respectively. In conclusion, seven temporal bones (6.7%) of five patients presented with a lateral displacement of FN in relation to the established anatomical landmarks.</br></br> <b>Conclusions:</b> Although the atypical course of FN, including the lateral displacement of the mastoid portion, is rare, screening for it is crucial before surgical exploration.

Mastoid fluid signal in acute cerebral venous thrombosis is is associated with increased clot burden.

PURPOSE: Mastoid air cell abnormalities in the form of hyperintense T2 fluid signal have been reported in cases of acute Cerebral Venous Thrombosis (CVT) without otologic infection and have been hypothesized to be a result of venous congestion rather than infectious mastoiditis. The aim of this study was to investigate a link between the spectrum of mastoid abnormalities and clot burden in patients with acute CVT. METHODS: A retrospective study of adult patients admitted to the National Institute of Mental Health and Neurosciences between 2016 and 2023 who were diagnosed with acute CVT and had no clinical evidence of active or recent ear infections was conducted. Pre- and post-contrast MR Images were analyzed to identify the dural sinuses and/or cerebral veins involved and the presence of fluid signal in the mastoid. Fluid signal in the mastoid was graded from 0 to 3 as described by Shah et al- no fluid signal (grade 0), thin curvilinear hyperintensities (grade 1), thick crescenteric hyperintensities (grade 2), and complete hyperintensity (grade 3). Clot Burden Score (CBS) was calculated by assigning one point for each sinus involved, one point for extension of thrombus into the intracranial Internal Jugular Vein (IJV), one point for thrombosis of cortical veins and one point for thrombosis of deep cerebral veins. RESULTS: A total of 89 patients with acute CVT were included in the final analysis. Median time from presentation to MRI was 2 days (range 0-13). 51 patients (57.3%) had fluid signal in the mastoid air cells on T2-weighted images, of whom 33 showed mucosal contrast enhancement. Higher grade of fluid signal in the mastoid was present ipsilateral to the side of venous thrombosis in 59 out of 60 patients with posterior fossa CVT. CBS was significantly different between patients with different grades of fluid signal (p = 0.002). Grade 2-3 fluid signal was associated with higher clot burden (CBS > 3) in both the entire study population (n = 89) - OR = 8.281, 95 %CI: 2.758-24.866 (p < 0.001) and among patients with posterior fossa CVT - OR = 4.375, 95 %CI: 1.320-14.504 (p = 0.016). Among patients with posterior fossa CVT, grade 2-3 fluid signal was associated with left sided transverse and/or sigmoid sinus thrombosis - OR = 5.600, 95 %CI: 1.413-22.188 (p = 0.014), and extension of thrombosis into the IJV - OR = 4.606, 95 %CI: 1.162-18.262 (p = 0.030). CONCLUSION: T2 fluid signal in the mastoid is associated with venous congestion in adults with acute CVT without evidence of otologic infection. Moderate-to-severe T2 fluid signal in the mastoid air cells is associated with increased clot burden.

Temporal bone CT-based anatomical parameters associated with the development of cholesteatoma.

BACKGROUND: Cholesteatoma is caused by disorders of the middle ear ventilation that trigger a progressive series of events responsible for its formation. The aim of this study was to identify possible radiological CT-derived parameters predisposing to ventilation disorders and cholesteatoma. METHODS: In this retrospective study, patients diagnosed with cholesteatomatous chronic otitis media who underwent temporal bone CT and open tympanoplasty surgery have been included, as well as control patients with clinical examination negative for organic otological pathology who underwent temporal bone CT for other reasons. For each patient, the following parameters have been extracted from CT volumes: degree of mastoid pneumatization, prominence of the cog, patency of the Eustachian tube, antrum width, aditus width, anterior and posterior epitympanic widths, and epitympanic height. RESULTS: Sixty patients have been included, thirty of whom belonged to the group of patients with cholesteatoma and the remaining part to the group of patients without organic otological pathology. The prevalence of a low degree of mastoid pneumatization was significantly higher among patients with cholesteatoma, as well as for the prevalence of cog prominence (p < 0.001). All the continuous variables were found to have statistical significance (p < 0.05) in the comparison between groups except for the width of the antrum. CONCLUSION: Mastoid pneumatization degree, prominence of the cog and epitympanic measures based on temporal bone CT could be good radiological correlates of the ventilatory capabilities of the epitympanum which, if compromised, can facilitate the development of cholesteatoma.

The Age-Related Growth of Mastoid Air Cells in Infancy: A Retrospective Cross-Sectional Study.

OBJECTIVES: To investigate the normal growth and development of mastoid pneumatization volume from 5 to 12 months for pediatric otosurgeons. STUDY DESIGN: Retrospective chart review. SETTING: A tertiary referral center. PATIENTS: This study evaluated age-dependent changes in mastoid air cell volume in 94 (188 ears) patients aged 5 to 12 months without a history of middle ear disease. MAIN OUTCOME MEASURES: Volume reconstruction was based on high-resolution computed tomography images using a three-dimensional reconstruction that is considered normal by radiologists. One-way analysis of variance and linear regression were used to determine the relationship between the volume and age in male and female subjects. RESULTS: Forty-eight scans were from male and 46 from female patients. In the age group from 5 to 12 months, the mastoid pneumatization was independent of age ( p > 0.05). There were no significant volume differences found between the age groups. Neither male/female nor right/left significant differences were observed in relation to the algebraic data of the mastoid air cells volume ( p > 0.05). CONCLUSIONS: Based on this analytic study, we are the first to use three-dimensional volume quantification based on high-resolution computed tomography in such large samples of early infancy. Because of its potential role as a susceptibility factor for otitis media and other otologic problems, it is important to describe the growth and development of mastoid pneumatization. More extensive clinical studies are needed to give a comprehensive insight into the air cell volume across age groups in different populations.

The growth of the mastoid volume in children with a cochlear implant.

The aim of this study was to understand the mastoid volume development in children who undergo cochlear implantation surgery. Cochlear implant (CI) database of our clinic (Kuopio University Hospital) was reviewed for computed tomography (CT) images of CI patients (age under 12 years at the time of implantation) with a minimum time interval of twelve months between their pre- and postoperative CT. Eight patients (nine ears) were found eligible for inclusion. Three linear measurements were taken by using picture archiving and communication systems (PACS) software and the volume of the MACS was measured with Seg 3D software. The mastoid volume increased on average 817.5 mm3 between the pre- and the postoperative imaging time point. The linear distances measured between anatomical points like the round window (RW)- bony ear canal (BEC), the RW-sigmoid sinus (SS), the BEC-SS, and the mastoid tip (MT)-superior semicircular canal (SSC) increased significantly with the age of the patient at both the pre-op and post-op time points. The linear measurements between key anatomical points and mastoid volume showed a positive linear correlation. The correlation between linear measurement and volume were significant between the MT-SSC (r = 0.706, p = 0.002), RW-SS (r = 0.646, p = 0.005) and RW-BEC (r = 0.646, p = 0.005). Based on our findings from the CI implanted patients and comparing it with the previous literature findings from non-CI implanted patients, we could say that the CI surgery seem to have no effect on the development of mastoid volume in children.

A Computer Vision Algorithm to Classify Pneumatization of the Mastoid Process on Temporal Bone Computed Tomography Scans.

BACKGROUND: Pneumatization of the mastoid process is variable and of significance to the operative surgeon. Surgical approaches to the temporal bone require an understanding of pneumatization and its implications for surgical access. This study aims to determine the feasibility of using deep learning convolutional neural network algorithms to classify pneumatization of the mastoid process. METHODS: De-identified petrous temporal bone images were acquired from a tertiary hospital radiology picture archiving and communication system. A binary classification mode in the pretrained convolutional neural network was used to investigate the utility of convolutional neural networks in temporal bone imaging. False positive and negative images were reanalyzed by the investigators and qualitatively assessed to consider reasons for inaccuracy. RESULTS: The overall accuracy of the model was 0.954. At a probability threshold of 65%, the sensitivity of the model was 0.860 (95% CI 0.783-0.934) and the specificity was 0.989 (95% CI 0.960-0.999). The positive predictive value was 0.973 (95% CI 0.904-0.993) and the negative predictive value was 0.935 (95% CI 0.901-0.965). The false positive rate was 0.006. The F1 number was 0.926 demonstrating a high accuracy for the model. CONCLUSION: The temporal bone is a complex anatomical region of interest to otolaryngologists. Surgical planning requires high-resolution computed tomography scans, the interpretation of which can be augmented with machine learning. This initial study demonstrates the feasibility of utilizing machine learning algorithms to discriminate anatomical variation with a high degree of accuracy. It is hoped this will lead to further investigation regarding more complex anatomical structures in the temporal bone.

Morphometric and morphological evaluation of mastoid emissary canal using cone-beam computed tomography.

OBJECTIVES: This study aimed to determine mastoid emissary canal's (MEC) and mastoid foramen (MF) prevalence and morphometric characteristics on cone-beam computed tomography (CBCT) images to underline its clinical significance and discuss its surgical consequences. METHODS: In the retrospective analysis, two oral and maxillofacial radiologists analyzed the CBCT images of 135 patients (270 sides). The biggest MF and MEC were measured in the images evaluated in MultiPlanar Reconstruction (MPR) views. The MF and MEC mean diameters were calculated. The mastoid foramina number was recorded. The prevalence of MF was studied according to gender and side of the patient. RESULTS: The overall prevalence of MEC and MF was 119 (88.1%). The prevalence of MEC and MF is 55.5% in females and 44.5% in males. MEC and MF were identified as bilateral in 80 patients (67.20%) and unilateral in 39 patients (32.80%). The mean diameter of MF was 2.4 ± 0.9 mm. The mean height of MF was 2.3 ± 0.9. The mean diameter of the MEC was 2.1 ± 0.8, and the mean height of the MEC was 2.1 ± 0.8. There is a statistical difference between the genders (p = 0.043) in foramen diameter. Males had a significantly larger mean diameter of MF in comparison to females. CONCLUSION: MEC and MF must be evaluated thoroughly if the surgery is contemplated. Radiologists and surgeons should be aware of mastoid emissary canal morphology, variations, clinical relevance, and surgical consequences while operating in the suboccipital and mastoid areas to avoid unexpected and catastrophic complications. CBCT may be a reliable imaging diagnostic technique.

Anatomical and Clinical Evaluation of Tympanic Tegmen and Mastoid Bone with Multidetector Computed Tomography / Evaluación Anatómica y Clínica del Tegmen Timpánico y Hueso Mastoideo con Tomografía Computarizada Multidetector

SUMMARY: Tegmen level and mastoid bone thickness are important parameters of surgical risk in middle ear and mastoid region surgeries. This retrospective cohort study was conducted to provide a risk classification for the mastoid and middle ear regions. The study population comprised of 300 patients who underwent multidetector computed tomography (MDCT) for various indications. Patients with no pathology that disrupted the structure of the temporal region were included in the study. A risk classification was generated by analyzing the data obtained from mastoid and tympanic tegmen depths and the mastoid bone thickness by MDCT. The mastoid and tympanic tegmen were lower on the right side than on the left. In women, the right-sided mastoid bone thickness and mastoid tegmen were lower, and low-level tympanic and mastoid tegmen on the left and thin right mastoid bones were more common. According to the risk classifications for mastoid and middle ear region surgeries, women demonstrated a higher risk than men. In addition, as the thickness of the mastoid bone increased, the levels of the mastoid and tympanic tegmen increased. The present study provides a proper risk classification that may be helpful for preoperative risk assessment prior to middle ear and mastoid region surgery.

El nivel del tegmen y el grosor del hueso mastoideo son parámetros importantes del riesgo quirúrgico en las cirugías del oído medio y la región mastoidea. Este estudio de cohorte retrospectivo se llevó a cabo para proporcionar una clasificación del riesgo en las regiones mastoidea y del oído medio. La población de estudio estuvo compuesta por 300 pacientes que se sometieron a una tomografía computarizada multidetector (MDCT) por diversas indicaciones. Se incluyeron en el estudio pacientes sin patología que alterase la estructura de la región temporal. Se generó una clasificación de riesgo analizando los datos obtenidos de las profundidades del tegmen mastoideo y timpánico y el grosor del hueso mastoideo por TCMD. El tegmen mastoideo y timpánico estaban más bajos en el lado derecho que en el izquierdo. En las mujeres, el grosor del hueso mastoideo del lado derecho y el tegmen mastoideo eran más bajos, y eran más frecuente la presencia de tegmen timpánico y mastoideo de bajo nivel en los huesos mastoideos izquierdo y delgados en el lado derecho. Según las clasificaciones de riesgo de las cirugías de la región mastoidea y del oído medio, las mujeres presentaban un mayor riesgo que los hombres. Además, a medida que aumentaba el grosor del hueso mastoides, aumentaban los niveles del tegmen mastoideo y timpánico. El presente estudio proporciona una clasificación de adecuada de riesgo que puede ser útil para la evaluación preoperatoria del riesgo antes de la cirugía del oído medio y la región mastoidea.

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

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