Determination of the mastoid surface area and volume based on micro-CT scanning of human temporal bones. Geometrical parameters depend on scanning resolutions

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.

The association between high jugular bulb and mastoid pneumatization in adults

Purpose

The purpose of this study was to analyze the relationship between the degree of high jugular bulb (HJB) and mastoid pneumatization using high-resolution computed tomography (HRCT).

Methods

Between April 2019 and June 2022, HRCT of the temporal bone was retrospectively analyzed in 1,025 patients. By excluding the other coexistent pathologies, 113 patients with HJBs were recruited for the study. The degree of the HJBs were defined as follows: Grade I, JB situated between inferior annulus of tympanic membrane and cochlear basal turn (CBT). Grade II, JB situated between CBT and lateral semicircular canal (LSC). Grade III, JB situated above LSC. The volume of mastoid pneumatization was based on HRCT images using a 3D reconstruction.

Results

There were 32 male and 81 female subjects (mean age, 41.2 ± 14.0 years; age range, 18-80 years). The male group included 16 Grade I, 28 Grade II and 6 Group III HJB subjects. The female group included 38 Grade I, 62 Grade II and 31 Group III HJB cases. In the different groups of HJB, the mastoid cell volume differences were also not statistically significant (p = 0.165). In the classification, Grade II was most common (90/181, 49.7%).

Conclusion

This study found no correlation between mastoid air cell volume and HJB, suggesting that HJB may not affect the mastoid air cell development and disease occurrence. These data must be considered exploratory, requiring more extensive cross-sectional studies.

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 Effect of Anteriorly Located Sigmoid Sinus on Postoperative Hearing Gains: A Case-Control Study

There are many studies on the effects of temporal bone anatomical variations on a mastoid pneumatization. Considering the effects of the anatomic variations on mastoid pneumatization, it is considered that many anatomic variations may affect graft success rates and postoperative hearing threshold gains. We aimed to evaluate the effects of various anatomic variations on postoperative hearing gains among patients undergoing tympanoplasty. This retrospective cohort study conducted in a tertiary-care university hospital. This study enrolled 57 patients who underwent primary type 1 tympanoplasty operation using the temporal muscle fascia. The patients were divided into two groups as those with an anteriorly located sigmoid sinus (group 1), and no anatomic variation (group 2). Airway gain values at the frequency range of 250 Hz-8000 Hz and pure tone average (PTA) value were calculated preoperatively and at postoperative sixth month. The gains attained by the patient groups with anatomic variations were compared with group 2. There were significant differences between Group 1 and Group 2 in terms of the airway frequencies of 250, 500, 2000, 4000 Hz, and PTA value. We detected a lesser postoperative hearing gain in patients with an anteriorly located SS. We believe that anatomic variations that may affect middle ear and mastoid cavity may also affect postoperative hearing gain.

Congenital cholesteatoma: Clinical features and surgical outcomes

OBJECTIVES

A typical presentation of congenital cholesteatoma (CC) is asymmetric conductive hearing loss (CHL). As CHL is usually associated with middle ear effusion, diagnosis of CC is frequently delayed. This study aimed to describe the clinical characteristics, treatment and outcomes of children with CC.

METHODS

The medical files of children diagnosed with CC at a large tertiary pediatric medical center during 2000-2019 were reviewed. The primary outcome measures were: presenting symptoms, surgical findings, stage of disease, recurrence rate and hearing outcome. Imaging findings and the size of mastoid air cells were assessed in CT scans.

RESULTS

Thirty-nine children were diagnosed with CC. The presenting symptom was unilateral CHL in 85%, with an average speech reception threshold of 41.5 ± 13.7 dB in the affected ear. The mean time from first symptoms to diagnosis was 1.3 years. The surgical approach was exploratory tympanotomy in 25% and canal wall up mastoidectomy in 69%. Seventy percent of the children presented with Potsic stage III-IV. The mean postoperative speech reception threshold was 26.4 ± 12.2 dB (P = 0.002). Recurrence of cholesteatoma occurred in 38% of the patients, mostly in stage III-IV. Mastoid air cell size was significantly smaller on the affected than the unaffected side.

CONCLUSIONS

In children with persistent unilateral or asymmetric conductive hearing loss, CC should be suspected. Late diagnosis of CC is associated with a high recurrence rate. This highlights the need to promote awareness to the disease among primary physicians in the community health care system.

Geometric Atlas of the Middle Ear and Paranasal Sinuses for Robotic Applications

In otolaryngologic surgery, more and more robots are being studied to meet the clinical needs of operating rooms. However, to help design and optimize these robots, the workspace must be precisely defined taking into account patient variability. The aim of this work is to define a geometric atlas of the middle ear and paranasal sinuses for endoscopic robotic applications. Scans of several patients of different ages and sexes were used to determine the average size of these workspaces, which are linked by the similar use of endoscopes in surgery.

Correlation between tympanometry volume and three-dimensional computed tomography mastoid volumetry in tympanoplasty candidates

OBJECTIVE

Ventilation of the middle ear and mastoid air cells is believed to play an important role in the pathogenesis of chronic ear disease. Traditionally, ventilation is assessed by computed tomography. However, this exposes patients to cumulative radiation injury. In cases with a perforation in the tympanic membrane, tympanometry potentially presents a non-invasive alternative to measure the ventilated middle-ear and mastoid air cell volume. This study hypothesised that total tympanometry volume correlates with ventilated middle-ear and mastoid air cell volume.

METHOD

Total tympanometry volume was compared with ventilated middle-ear and mastoid air cell volume on computed tomography scans in 20 tympanic membrane perforations.

RESULTS

There was a high correlation between tympanometry and computed tomography volumes (r = 0.78; p < 0.001). A tympanometry volume more than 2 ml predicted good ventilation on computed tomography.

CONCLUSION

These results may help reduce the need for pre-operative computed tomography in uncomplicated cases with tympanic membrane perforations.

Postauricular injection of methylprednisolone sodium succinate as a salvage treatment for refractory sudden sensorineural hearing loss

BACKGROUND

Postauricular steroid administration has been popular for treating sudden sensorineural hearing loss. However, there are few reports on its use in patients with refractory sudden sensorineural hearing loss (RSSNHL).

AIMS

The objective of this study was to investigate the therapeutic efficacy of postauricular steroid injection as a salvage treatment for RSSNHL patients.

METHODS

This retrospective study enrolled 63 RSSNHL patients between January 2016 and January 2019. Thirty-three patients of them who have been divided into the treatment group received postauricular methylprednisolone sodium succinate injection. The remaining 30 patients who formed the control group did not receive any steroid as a salvage therapy. Improvements in hearing were evaluated between pre-salvage therapy and 3 months follow-up after salvage therapy.

RESULTS

The median hearing gain in PTA was 9.88 dB HL (quartile range 7.58, 18.65) in the treatment group and 0.90 dB HL (quartile range 0.00, 4.90) in the control group (P<0.01). According to the criteria of Furuhashi, the total percentage for effective prognosis was 48.48% (16/33) in the treatment group and 10.00% (3/30) in the control group (P<0.01). The time interval from onset to study entry was significantly and independently associated with the prognosis for RSSNHL patients (P< 0.01).

CONCLUSIONS

The present findings suggest that postauricular corticosteroid administration as a salvage treatment demonstrated better results than no treatment for RSSNHL patients. The time interval from onset to study entry was mainly the prognostic factor for RSSNHL patients. It is therefore considered that postauricular corticosteroid administration may be used as a salvage therapy for RSSNHL patients.

Stereologic Investigation of Mastoid Air Cell Geometry: Volume, Surface Area, and Anisotropy

OBJECTIVE

To assess mastoid geometry using computed tomography (CT) scans and design-based stereological methods.

BACKGROUND

The anatomical organization of the mastoid air cell system (MACS) remains debated. Geometrical parameters have previously been determined by automated image-analysis algorithms. Stereology is an alternative approach, which has previously been applied to estimate the volume of the MACS, but has not previously been used to estimate surface area or study anisotropy.

METHODS

Twenty-three clinical CT scans of aerated temporal bones obtained from various ENT patients were studied. The structural orientation and anisotropy of the MACS was investigated by test-grid rotation and rose plots. Volume, surface area, and surface area-to-volume ratio were estimated with design-based stereology.

RESULTS

Anisotropy of the mastoid air cells was demonstrated by a significant difference in surface area estimates between the axial and coronal planes (p = 0.0065). Rose plots illustrated variances in surface area estimates with different grid rotations, and a minimum value in the craniocaudal direction was shown. Sampling in the axial plane provided the least variance due to anisotropy. The mean (±SD) volume and surface area estimates were 5.71 ± 2.98 cm and 117 cm ± 60 cm, respectively. A large biological variation was noted. The mean (±SD) surface-to-volume ratio was 20.6 ± 2.8 cm.

CONCLUSIONS

The stereological technique proved to be a robust method for volume and surface area estimation in clinical CT scans. The mastoid air cells constitute an anisotropic cell-system that seems to have a predominant orientation in the craniocaudal direction.

On the functional compartmentalization of the normal middle ear. Morpho-histological modelling parameters of its mucosa

BACKGROUND

Middle ear physiology includes both sound pressure transmission and homeostasis of its static air pressure. Pressure gradients are continuously created by gas exchange over the middle ear mucosa as well as by ambient pressure variations. Gas exchange models require actual values for regional mucosa thickness, blood vessel density, and diffusion distance. Such quantitative data have been scarce and limited to few histological samples from the tympanic cavity (TC) and the antrum. However, a detailed regional description of the morphological differences of the TC and mastoid air cell system (MACS) mucosa has not been available. The aim of the present study was to provide such parameters.

METHODS

The study included sets of three histological H&E-slides from 15 archived healthy temporal bones. We performed a comparison of the mucosa morphology among the following regions: (1) anterior TC; (2) inferior TC; (3) posterior TC; (4) superior TC; (5) MACS antrum; (6) superior MACS; (7) central MACS; (8) inferior MACS.

RESULTS

Regions (1)-(3), situated below the inter-attico-tympanic diaphragm, had the largest proportion of high respiratory epithelium, cilia and loose lamina propria within the mucosa, as well as the thickest mucosa and the largest diffusion distance. Regions (6)-(8), situated above the diaphragm, had the thinnest mucosa, the shortest distance to the blood vessels, together with the largest proportion of flat epithelium and very few cilia. Regions (4)-(5), still supradiaphragmatic, had intermediary values for these parameters, but generally closer to regions (6)-(8). The blood vessel density and the proportion of active mucosa were not significantly different among the regions.

CONCLUSION

Mucosa of regions (1), (2) and (3) represented a predominantly clearance-specific morphology, whereas in regions (4)-(8) it seemed adapted to gas exchange. However, the lack of statistically significant differences in blood vessel density and proportion of active mucosa indicated that all regions could be involved in gas exchange with the highest adaptation in the superior MACS. This pattern divides the middle ear functionally along the inter-attico-tympanic diaphragm rather than the anatomical division into TC and MACS.

Growth pattern of temporal bone pneumatization: a computed tomography study with consecutive age groups

PURPOSE

To investigate the growth pattern of temporal bone pneumatization (TBP) in consecutive age groups from birth to 18 years old using 3D air-density reconstruction of high-resolution CT (HRCT).

METHODS

A total of 570 patients under 18 years old who performed temporal bone HRCT and with no structural abnormalities on both sides were included. Nineteen groups were created to represent consecutive ages, with 15 males and 15 females in each group. Volume rendering of air density was performed using a segmentation threshold of - 200 HU to obtain TBP volume of each side. The differences in TBP between the sides, sexes, and ages were statistically analyzed.

RESULTS

The mean volume of TBP was measured as 1.17 ± 0.44 ml in patients less than 1 year old and 6.81 ± 1.93 ml as adult size. High consistencies of TBP volume between different sides or sexes were found in most of age groups. Significant differences were shown between sides only in 9- and 11-year-old female groups (p₉ = 0.031, p₁₁ = 0.016) while between sexes only in 6- and 16-year-old groups (p₆ = 0.001, p₁₆ = 0.043), although the volume was larger in all the male groups older than 6 years. The curve drawn by the mean volume in consecutive age groups showed that TBP continued to grow linearly in both males and females until they reached 14 years old. The corresponding linear regression equations were as follows: y_m = 1.553 + 0.370x, (x ≤ 14 years, R² = 0.596); y_f = 1.561 + 0.304x, (x ≤ 14 years, R² = 0.565).

CONCLUSION

The TBP volume shows a linear growth pattern from birth until reaching adult size after 14 years old.

A comparison of systemic and local dexamethasone administration: From perilymph/cochlea concentration to cochlear distribution

Different types of inner ear diseases can damage different cochlear subsites by different mechanisms. Steroids administered by different methods are commonly used for treating inner ear diseases. There is reason to believe that dexamethasone (Dex) may reach cochlear subsite targets via different pathways after administration by different methods: Intratympanic (IT), postaural (PA), and intraperitoneal (IP). The purpose of this study was to explore the cochlear concentration and distribution of Dex after administration by different methods. High-performance liquid chromatography-mass spectrometry and immunofluorescence technology were employed to measure and compare the Dex concentration in the perilymph and cochlear tissue and the cochlear distribution of Dex. IT administration resulted in higher Dex concentrations in the perilymph and cochlear tissues than those with the other administration methods. Intratympanic and postaural administration could result in higher Dex concentrations in the organ of Corti than systemic administration, but systemic administration could result in higher Dex concentrations in the stria vascularis than the other administration methods. A decreasing basal-apical gradient of Dex uptake was present in the cochlea after IT but not IP or PA administration. These results indicate that different administration methods result in different Dex distributions, which can be attributed to features of the cochlear vascular system and intracochlear diffusion. Our results provide clinicians with an experimental basis for the use of different steroid injection routes to optimize the effects on inner ear diseases with different target organs.

Tympanic membrane pressure buffering function at quasi-static and low-frequency pressure variations

Deformation of the tympanic membrane is known to contribute to the pressure regulation processes in the middle ear cleft. In this paper we investigated pressure variations in the rabbit middle ear in response to sinusoidal varying pressures applied to the ear canal, with frequencies ranging from 0.5 Hz to 50 Hz and pressure amplitudes ranging between 0.25 kPa and 1 kPa. The transtympanic pressure difference was found to be smallest in the quasi-static range, and quickly increased as a function of frequency. The response curves showed asymmetry, with larger transtympanic pressures when positive pressures were applied in the ear canal. Normalized transtympanic pressure amplitudes remained fairly constant as a function of input pressure, with values in the range of 60%-70% relative to the applied pressure. The total harmonic distortion of the middle ear pressure signal was calculated and was found to be very small (≤2%) for low-pressure amplitudes and low frequencies. For pressure amplitudes in the order of 0.25 kPa-0.5 kPa, it increased to about 10% at 50 Hz. When a 1 kPa pressure amplitude was applied, variation between animals became large and distortion values up to 30% at 50 Hz were observed. The results showed that pressure buffering due to tympanic membrane displacement was most effective for compensating small transtympanic pressure loads at low frequencies.

Temporal bone anatomy characteristics in superior semicircular canal dehiscence

Introduction

Superior semicircular canal dehiscence (SCD) remains difficult to diagnose despite advances in high-resolution computed tomography (HRCT) imaging. We hypothesize possible associations between gross temporal bone anatomy and sub-millimeter pathology of the semicircular canals, which may supplement imaging and clinical suspicion. This pilot study investigates differences in gross temporal bone anatomic parameters between temporal bones with and without SCD.

Methods

Records were reviewed for 18 patients referred to an otology clinic complaining of dizziness with normal caloric stimulation results indicative of non-vestibular findings. Eleven patients had normal temporal bone anatomy while seven had SCD. Three-dimensional reconstruction of every patient's temporal bone anatomy was created from patient-specific computational tomography images. Surface area (SA), volume (V), and SA to V ratios (SA:V) were computed across temporal bone anatomical parameters.

Results

SCD temporal bones have significantly smaller V, and larger temporal bone SA. Mean (±SD) V was 21,484 ± 3,921 mm³ in temporal bones without SCD and 16,343 ± 34,471 mm³ for those with SCD. Their respective SA were 13,733 ± 1,603 mm² and 18,073 ± 3,002 mm². Temporal bone airspaces and lateral semicircular canals did not demonstrate significant differences where SCD was and was not present. Plots of MV_warm response against computed SCD temporal bone anatomic parameters (SA, V and SA:V) showed moderate to strong correlations: temporal bone SA:V (r = 0.64), temporal bone airspace V (r = 0.60), temporal bone airspace SA (r = 0.55), LSCC SA (r = 0.51), and LSCC-to-TM Distance (r = 0.65).

Conclusions

This analysis demonstrated that SCD is associated with decreased temporal bone volume and density. The defect in SCD does not appear to influence caloric responses.

Tubotympanic system functioning

The Eustachian (auditory) tube and tympanomastoid cavities form an anatomic and functional whole that cannot easily be divided, and is therefore known as the "tubotympanic system". The system has been the focus of several studies, with complex and sometimes contradictory results, making an overview of its functioning difficult to obtain. The objective of the present article is to review the current state of knowledge, as an indispensable preliminary to understanding tubotympanic system dysfunction, and notably the development of chronic otitis. The system as a whole is covered by mucosa, which provides continuity, although with certain particularities from one area to another, and plays a primordial role. Thus, under physiological conditions, gas diffusion across the tympanomastoid mucosa largely ensures the equilibrium of pressure between the middle ear and outside environment, the tube orifice being very little involved. Under large rapid change in atmospheric pressure, the aeration function of the Eustachian tube comes into play, governed by a reflex mechanism. The system also has other functions that are essential to good middle-ear functioning: protection against nasopharyngeal secretions and pathogens and against certain physiological noises; middle-ear cavity clearance by mucociliary transport of pathogens, partly related to submucosal gland secretion; and immune defense.