Does Mastoid Pneumatization Affect Facial Canal Dimensions and Distances of Facial Tympanic Segment-Scutum and Lateral Semicircular Canal-Scutum?

OBJECTIVES: In the present study, we investigated whether mastoid pneumatization affects facial canal dimensions and distances of facial tympanic segment and scutum, and lateral semicircular (LSS) canal and scutum. METHODS: One hundred sixty-one temporal multidetector computed tomography scans were reviewed. Patients with unilateral sclerotic mastoid pneumatization (no aeration) (group 1, n = 81) and unilateral total mastoid pneumatization (100.0% aeration) (group 2, n = 80) were included. Facial canal dimensions at the labrythine, tympanic, and mastoid segments; facial canal dehiscence and length; and facial tympanic segment-scutum and LSS canal-scutum distances were evaluated. RESULTS: In the present study, facial canal dimensions of labyrinthine, tympanic, and mastoid segments in total pneumatized mastoid group were significantly lower than sclerotic mastoids on axial and coronal images (P < 0.05). Facial tympanic segment and scutum distance of the sclerotic mastoid group was significantly lower than those of the total pneumatized mastoid group (P < 0.05). However, LSS canal-scutum distance was not different between both groups (P > 0.05). The LSS canal-scutum distance of the females was lower than those of the males (P < 0.05). Facial canal dehiscence ratio was 11.3% and 11.1% in sclerotic and total pneumatized mastoids, respectively. The mean ± SD length of the dehiscence was 2.46 ± 1.29 mm in pneumatized mastoids and 1.92 ± 0.68 mm in sclerotic mastoids. CONCLUSIONS: In cholesteatoma cases, scutum erosion may occur. Because facial tympanic segment and scutum distance decreased in sclerotic mastoids compared with completely pneumatized ones, maximum care must be taken in the operations for avoiding to damage facial canal and nerve. Revision cases may be more difficult because of distorted anatomy. However, in pneumatized mastoids, the mean length of the facial canal was more than 2 mm, which must be kept in mind during operations.

Spaceflight-Associated Changes in the Opacification of the Paranasal Sinuses and Mastoid Air Cells in Astronauts.

Importance: Head congestion is one of the most common somatic symptoms experienced by astronauts during spaceflight; however, changes in the opacification of the paranasal sinuses or mastoid air cells in astronauts have not been adequately studied. Objectives: To quantify preflight to postflight changes in the opacification of the paranasal sinuses and mastoid air cells in Space Shuttle astronauts and International Space Station (ISS) astronauts and to assess whether there are differences between the 2 groups of astronauts. Design, Setting, and Participants: This cohort study examined preflight and postflight head magnetic resonance images (MRIs) of 35 astronauts who had participated in either a short-duration (≤30 days) Space Shuttle mission or a long-duration (>30 days) ISS mission and had undergone both preflight and postflight MRI. Images were obtained before and after spaceflight. Images were evaluated by 2 neuroradiologists blinded to which mission each astronaut had flown and to which images were preflight or postflight images. Exposure: Spaceflight on the Space Shuttle or the ISS. Main Outcomes and Measures: Measured outcomes included preflight to postflight changes in Lund-Mackay scores for the paranasal sinuses and in scores grading mastoid effusions. Results: Most astronauts in both the Space Shuttle group (n = 17; 15 men; mean [SD] age at launch, 47.7 [3.1] years) and the ISS group (n = 18; 14 men; mean [SD] age at launch, 48.6 [4.7] years) exhibited either no change or a reduction in paranasal sinus opacification as seen on postflight MRI scans (Space Shuttle group: 6 [35.3%] had no sinus opacification before or after spaceflight, 5 [29.4%] had less sinus opacification after spaceflight, 3 [17.6%] had the same amount of sinus opacification before and after spaceflight, and 3 [17.6%] had increased paranasal sinus opacification after spaceflight; ISS group: 8 [44.4%] had no sinus opacification before or after spaceflight, 4 [22.2%] had less sinus opacification after spaceflight, 1 (5.6%) had the same amount of sinus opacification before and after spaceflight, and 5 [27.8%] had scores consistent with increased paranasal sinus opacification after spaceflight). Long-duration spaceflight (ISS group) was associated with an increased risk of mastoid effusion relative to short-duration spaceflight (relative risk, 4.72; 95% CI, 1.2-18.5). Images were obtained a mean (SD) 287.5 (208.6) days (range, 18-627 days) prior to and 6.8 (5.8) days (range, 1-20 days) after spaceflight. Astronauts had undergone either a mean (SD) of 13.6 (1.6) days of spaceflight on the Space Shuttle (17 astronauts) or 164.8 (18.9) days on the ISS (18 astronauts). Conclusions and Relevance: This study found that exposure to spaceflight conditions on the ISS is associated with an increased likelihood for the formation of mastoid effusions. There was no association between exposure to spaceflight conditions and changes in paranasal sinus opacification. The limitations of this study include lack of information concerning medical history and mission-specific operational experience for individual astronauts. Further studies are indicated to determine the cause and composition of the mastoid effusions.

A quantitative study of the suppression of the development of the mastoid air cells by the presence of congenital cholesteatoma.

Background: The mastoid air cells are considered to develop better in children with congenital cholesteatoma but only a few quantitative studies have examined. Aims/objectives: The present study was undertaken in order to clarify the relationships between the development of the mastoid air cells in children with congenital cholesteatoma and clinical factors. Materials and methods: Mastoid air cell development was evaluated in 53 children with congenital cholesteatoma. The sizes of the mastoid air cells were measured on computed tomography scans of the temporal bone, and clinical factors, including age, the extent of invasion, and whether it was located close to the eustachian tube were evaluated. Results: The cross-sectional area of the mastoid air cells was significantly smaller on the affected side than on the unaffected side, especially in the older patients. The cases involving invasion into the mastoid portion also had smaller mastoid cells. Whether the cholesteatoma was located close to the eustachian tube had no effect. Conclusions and significance: The mastoid air cells on the affected side were less well developed. Our findings indicate that a high age and the presence of cholesteatoma in the mastoid region might be associated with suppressed mastoid pneumatization.

Implications for Bone Conduction Mechanisms from Thresholds of Post Radical Mastoidectomy and Subtotal Petrosectomy Patients.

OBJECTIVES: To assess bone conduction (BC) thresholds following radical mastoidectomy and subtotal petrosectomy, in which the tympanic membrane and the ossicular chain, responsible for osseous BC mechanisms, are surgically removed. The removal of the tympanic membrane and the ossicular chain would reduce the contributions to BC threshold of the following four osseous BC mechanisms: the occlusion effect of the external ear, middle ear ossicular chain inertia, inner ear fluid inertia, and distortion (compression-expansion) of the walls of the inner ear. MATERIALS AND METHODS: BC thresholds were determined in 64 patients who underwent radical mastoidectomy and in 248 patients who underwent subtotal petrosectomy. RESULTS: BC thresholds were normal (≤15 dB HL, i.e., better) in 19 (30%) radical mastoidectomy patients and in 19 (8%) subtotal petrosectomy patients at each of the frequencies assessed (0.5, 1.0, 2.0, and 4.0 kHz). CONCLUSION: Normal BC thresholds seen in many patients following mastoidectomy and petrosectomy may be induced by a non-osseous mechanism, and the onset ("threshold") of the classical osseous BC mechanisms may be somewhat higher.

Workflow and simulation of image-to-physical registration of holes inside spongy bone.

PURPOSE: Mastoid cells as well as trabecula provide unique bone structures, which can serve as natural landmarks for registration. Preoperative imaging enables sufficient acquisition of these structures, but registration requires an intraoperative counterpart. Since versatile surgical interventions involve drilling into mastoid cells and trabecula, we propose a registration method based on endoscopy inside of these drill holes. METHODS: Recording of the surface of the inner drill hole yields bone-air patterns that provide intraoperative registration features. In this contribution, we discuss an approach that unrolls the drill hole surface into a two-dimensional image. Intraoperative endoscopic recordings are compared to simulated endoscopic views, which originate from preoperative data like computed tomography. Each simulated view corresponds to a different drill pose. The whole registration procedure and workflow is demonstrated, using high-resolution image data to simulate both preoperative and endoscopic image data. RESULTS: As the driving application is minimally invasive cochlear implantation, in which targets are close to the axis of the drill hole, Target Registration Error (TRE) was measured at points near the axis. TRE at increasing depths along the drill trajectory reveals increasing registration accuracy as more bone-air patterns become available as landmarks with the highest accuracy obtained at the center point. At the facial recess and the cochlea, TREs are ([Formula: see text]) mm and ([Formula: see text]) mm, respectively. CONCLUSION: This contribution demonstrates a new method for registration via endoscopic acquisition of small features like trabecula or mastoid cells for image-guided procedures. It has the potential to revolutionize bone registration because it requires only a preoperative dataset and intraoperative endoscopic exploration. Endoscopic recordings of at least 20 mm length and isotropic voxel sizes of 0.2 mm or smaller of the preoperative image data are recommended.

Acoustical transmission-line model of the middle-ear cavities and mastoid air cells.

An acoustical transmission line model of the middle-ear cavities and mastoid air cell system (MACS) was constructed for the adult human middle ear with normal function. The air-filled cavities comprised the tympanic cavity, aditus, antrum, and MACS. A binary symmetrical airway branching model of the MACS was constructed using an optimization procedure to match the average total volume and surface area of human temporal bones. The acoustical input impedance of the MACS was calculated using a recursive procedure, and used to predict the input impedance of the middle-ear cavities at the location of the tympanic membrane. The model also calculated the ratio of the acoustical pressure in the antrum to the pressure in the middle-ear cavities at the location of the tympanic membrane. The predicted responses were sensitive to the magnitude of the viscothermal losses within the MACS. These predicted input impedance and pressure ratio functions explained the presence of multiple resonances reported in published data, which were not explained by existing MACS models.

Association between atopy, mastoid pneumatization and tympanometric findings.

The purpose of this study was to reveal whether the presence of atopy plays any unfavorable role in the development of a healthy middle ear as evaluated by tympanometry or in the degree of mastoid pneumatization as measured by mastoid volume. 33 atopic patients with positive skin prick test results (atopic group) and 30 healthy subjects (control group) were included in this study. Tympanometric tests were performed in all participants, and the results were classified as type A to C. Mastoid cell volumes were measured by three-dimensional temporal computed tomography. Both the right and left mastoid volumes were significantly lower in the atopic group than in the control group. Tympanogram types among all participants showed that the number of individuals with abnormal tympanograms was significantly higher in the atopic group than in the control group. Moreover, the presence of atopy was found to be associated with an almost 4.5-fold increased risk of having an abnormal tympanogram. Individuals with abnormal tympanograms (type BB or CC) demonstrated significantly lower right and left mastoid volumes than did individuals with normal type A tympanograms. Atopic individuals demonstrated significantly lower right and left mastoid volumes than did subjects in the control group. This study suggests a direct association between atopy and mastoid cell volumes. It was found that the mastoid cell systems of atopic individuals are less pneumatized, and tympanometric measurements are worse in atopic subjects. Therefore, the authors suggest that when a medical or surgical treatment is planned for ear disease in atopic individuals, atopy is an important factor that should be taken into consideration.

Can post-mortem CT reliably distinguish between drowning and non-drowning asphyxiation?

PURPOSE: The aim of this study is to evaluate whether previously reported post-mortem CT findings in drowning can reliably distinguish drowning from asphyxiation by any other manner. MATERIALS AND METHODS: Cases (n = 14) were corpses with cause of death determined as drowning by concordant autopsy findings and physical and circumstantial evidence. Controls (n = 11) were corpses in which the cause of death was defined as asphyxiation by any other manner than submersion in a liquid. Images were evaluated for the presence of fluid in paranasal sinuses, mastoid air cells and lower airways, frothy foam in the upper airways, ground-glass opacity of the lung parenchyma, the height of the right hemi-diaphragm, the interpulmonary distance at the level of the aortic valve, the mean density of intracardiac blood, and gastric and esophageal contents. Descriptive statistics, Fisher's exact test, and Student's t test were used when appropriate. RESULTS: Only the height of the right hemi-diaphragm differed significantly (p = 0.045) between cases (mean 5.4) and controls (mean 4.3). Other findings were not significantly different between both groups. CONCLUSION: Our results indicate that it is not possible to reliably distinguish drowning from non-drowning asphyxiation on CT, because many findings in drowning were also present in non-drowning asphyxiation. CT indicators for drowning as the cause of death should therefore be defined with great caution, keeping in mind that they are not specific to only a single cause of death.

Development of a porous poly(DL-lactic acid-co-glycolic acid)-based scaffold for mastoid air-cell regeneration.

OBJECTIVES/HYPOTHESIS: To develop a porous, biodegradable scaffold for mastoid air-cell regeneration. STUDY DESIGN: In vitro development of a temperature-sensitive poly(DL-lactic acid-co-glycolic acid)/poly(ethylene glycol) (PLGA/PEG) scaffold tailored for this application. METHODS: Human mastoid bone microstructure and porosity were investigated using micro-computed tomography. PLGA/PEG-alginate scaffolds were developed, and scaffold porosity was assessed. Human bone marrow mesenchymal stem cells (hBM-MSCs) were cultured on the scaffolds in vitro. Scaffolds were loaded with ciprofloxacin, and release of ciprofloxacin over time in vitro was assessed. RESULTS: Porosity of human mastoid bone was measured at 83% with an average pore size of 1.3 mm. PLGA/PEG-alginate scaffold porosity ranged from 43% to 78% depending on the alginate bead content. The hBM-MSCs proliferate on the scaffolds in vitro, and release of ciprofloxacin from the scaffolds was demonstrated over 7 to 10 weeks. CONCLUSIONS: The PLGA/PEG-alginate scaffolds developed in this study demonstrate similar structural features to human mastoid bone, support cell growth, and display sustained antibiotic release. These scaffolds may be of potential clinical use in mastoid air-cell regeneration. Further in vivo studies to assess the suitability of PLGA/PEG-alginate scaffolds for this application are required.

When is fluid in the mastoid cells a worrisome finding?

Mastoiditis is a common clinical entity that is technically present in all cases of otitis media; only a minority of cases actually represents the otolaryngologic emergency of acute coalescent mastoiditis. When reviewing an image with a radiologic diagnosis of mastoiditis, looking for key signs such as destruction of bony septa and considering patient presentation can help distinguish mild mastoiditis from acute coalescent mastoiditis.

Improvement of eustachian tube function by tissue-engineered regeneration of mastoid air cells.

OBJECTIVES/HYPOTHESIS: Most cases of chronic otitis media (OMC) are associated with poor development of the mastoid air cells (MACs) and poor Eustachian tube (ET) function. We have previously reported that MAC regeneration can effectively eliminate intractable OMC. In this study, we assessed the ability of regenerated MACs to restore normal gas exchange function and contribute to improved ET function. STUDY DESIGN: Clinical trial with control. SETTING: General hospitals. MATERIALS AND METHODS: Seventy-six patients with OMC, including cholesteatoma and adhesive otitis media, received tympanoplasty and MAC regeneration therapy. At the first-stage of tympanoplasty, artificial pneumatic bones and/or autologous bone fragments were implanted into the opened mastoid cavity. At the 2nd-stage operation, a nitrous oxide (N2O) gas study was performed in 10 patients to measure middle ear pressure (MEP). For the control group, MEP was measured in five patients with good MAC development during cochlear implantation or facial nerve decompression. ET function was measured twice in each patient, once before the 1st operation and 6 months after the second operation. RESULTS: At the 2nd-stage operation, in all cases with regenerated MACs and in the normal control group, MEP changed after administration of N2O. In contrast, no change in MEP was observed in cases with unregenerated MACs. In 70% (n = 37/53) of the regenerated MAC group, ET function was improved, whereas improvement of ET function was observed in only 13% (n = 3/23) of the unregenerated MAC group. CONCLUSIONS: Tissue-engineered regeneration of MACs improves ET function and gas exchange in the middle ear.

Regeneration of mastoid air cells using polycaprolactone/ß-tricalcium phosphate biocomposites: an experimental study.

OBJECTIVES/HYPOTHESIS: The study aimed to regenerate pneumatic air cells in guinea pig bulla using three-dimenisonal (3D) biocomposite scaffolds consisting of polycaprolactone/ß-tricalcium phosphate (PCL/ß-TCP). STUDY DESIGN: Prospective controlled study in experimental animals. METHODS: PCL/ß-TCP composites were implanted into the bulla with mucosa preservation in group A (n = 10). PCL/ß-TCP composites coated with collagen were implanted in group B (n = 10). After 12 weeks, the bullae were extracted and evaluated by micro-computed tomography (micro-CT) and were processed for histological analyses. RESULTS: In group A, micro-CT showed a well-maintained honeycomb appearance of micropores without obstruction. Regeneration of the mucosa was noted inside the pores of the 3D scaffold. However, partial obstruction of the micropores with new bone formation was evident in group B. CONCLUSIONS: Group A showed more satisfactory mucosal regeneration into the micropores. Our results indicate that the 3D scaffold may be amenable for use during mastoidectomy. Further studies for gas exchange in the regenerated mucosa are necessary.

Palatoplasty and growth of the temporal bone mastoid air cells.

OBJECTIVES: The present study was undertaken to analyze the relationship between the method used for manipulation of the levator veli palatini muscle and the area of the mastoid air cells in patients with cleft palate. DESIGN: Retrospective study. PATIENTS: The subjects were 50 patients seen for surgical treatment of cleft palate. INTERVENTIONS: Palatoplasty was carried out using the mucosal flap method in 25 patients and the mucoperiosteal flap method in 25 patients. In the mucosal flap method, the levator veli palatini muscle was overlapped and sutured, followed by posterior movement of the muscle bundle (the posterior relocation group). In the mucoperiosteal flap method (the control group), the mucoperiosteal flap was pushed back, followed by end-to-end suturing of the muscle. The area of the mastoid air cells was measured on X-rays when patients were 5 years old. RESULTS: The mastoid air cell area did not differ significantly between the posterior relocation group (mean, 5.00 cm(2); range, 1.66 to 19.7 cm(2)) and the control group (mean, 5.3 cm(2); range, 2.29 to 15.9 cm(2)). CONCLUSION: No significant growth of mastoid air cells was noted following posterior relocation of the levator veli palatini muscle. Thus, in cases of cleft palate in which significant growth of mastoid air cells is not expected following reconstruction of the levator veli palatini muscle, the results confirm the view that tympanic ventilation tube insertion is the most suitable method for the treatment of otitis media.

Comparative study of the pneumatization of the mastoid air cells and paranasal sinuses using three-dimensional reconstruction of computed tomography scans.

PURPOSE: The purpose of this study was to investigate the relationship between the pneumatization of mastoid air cells and PNS using three-dimensional (3D) reconstruction of computed tomography (CT) scans of the PNS. METHODS: A retrospective review of PNS CT scans from 60 cases was performed. Patients with evidence of sinusitis or mastoiditis, or a history of head trauma, were excluded from the study. Volumes were measured using 3D reconstruction based on axial images of 1 mm thickness. Volumes of the mastoid air cells (right and left), frontal sinus, sphenoid sinus, and maxillary sinuses (right and left) were obtained and compared using statistical analysis. RESULTS: The volume of mastoid air cells and sinuses did change with age, but the volumes of male subjects were larger than those of females. There was a positive correlation between the pneumatization of mastoid air cells and that of the sphenoid sinus; however, no relationship was observed between the volume of mastoid air cells and that of the maxillary sinuses. CONCLUSIONS: This study examined whether a similarity in pneumatization exists between the mastoid air cells and PNS of individuals; these results may be useful in understanding the normal and pathological conditions of both structures.

The growth rate and size of the mastoid air cell system and mastoid bone: a review and reference.

This review suggests a reference to the postnatal growth of mastoid air cells and bone. Information was retrieved from studies having large consecutive age groups, in order to reveal a development pattern. Data regarding origin, gender, and antibiotic treatment was investigated as well. Most measurements were obtained by planimetry. Assessment of the various data sources suggested the antrum to be well developed at birth (1-1.5 cm2), the mastoid cells to be about 3.5-4 cm2 at 1 year, followed by a linear growth till the age of 6 (1-1.2 cm2/year), having a slower increment up to adult size at puberty (approximately 12 cm2). The mastoid bone expansion is about 0.6-0.9 cm/year in length and width and 0.4 cm/year in depth in the first year, followed by half that rate until the age of 6-7. At puberty there was a slower sprout reaching adult size. Different ethnic groups share similar mastoid aeration and bone growth patterns. There were no differences between mastoid aeration measured at the pre-antibiotic era and after its widespread use. In conclusion, there are three distinguishable phases of mastoid pneumatization from birth till reaching final size. Bone and air cell compartments share a similar growth pattern; bone expansion lags behind aeration. Antibiotic treatment for otitis may have no impact upon mastoid aeration.

Experimental studies on a new highly porous hydroxyapatite matrix for obliterating open mastoid cavities.

OBJECTIVE: In an initial preliminary study, the applicability of a new high-porosity hydroxyapatite (HA) ceramic for obliterating large open mastoid cavities was proven and tested in an animal model (bulla of guinea pig). STUDY DESIGN: Experimental study. METHODS: NanoBone, a highly porous matrix consisting of 76% hydroxyl apatite and 24% silicone dioxide fabricated in a sol-gel technique, was administered unilaterally into the opened bullae of 30 guinea pigs. In each animal, the opposite bulla was filled with Bio-Oss, a bone substitute consisting of a portion of mineral bovine bone. Histologic evaluations were performed 1, 2, 3, 4, 5, and 12 weeks after the implantation. RESULTS: After an initial phase in which the ceramic granules were surrounded by inflammatory cells (1-2 wk), there were increasing signs of vascularization. Osteoneogenesis and-at the same time-resorption of the HA ceramic were observed after the third week. No major difference in comparison to the bovine bone material could be found. DISCUSSION: Our results confirm the favorable qualities of the new ceramic reported in association with current maxillofacial literature. Conventional HA granules used for mastoid obliteration to date often showed problems with prolonged inflammatory reactions and, finally, extrusions. In contrast to those ceramics, the new material seems to induce more osteoneogenesis and undergoes early resorption probably due to its high porosity. Overall, it is similar to the bovine bone substance tested on the opposite ear in each animal. Further clinical studies may reveal whether NanoBone can be an adequate material for obliterating open mastoid cavities in patients.

Spontaneous regression of an EBV-associated monoclonal large B cell proliferation in the mastoid of a young child following surgical biopsy.

We report the spontaneous regression of an Epstein-Barr virus-associated monoclonal lymphoid proliferation in an immunocompetent child. A 2-year-old male with acute otitis media presented with a right-sided facial palsy secondary to acute mastoiditis. During mastoid decompression a polypoid mass, a histologically diffuse large B cell lymphoma, was found. Staging revealed localized disease. At surgical re-exploration 5 weeks later the disease had resolved. Retrospective serological testing was consistent with an acute Epstein-Barr viral infection and in situ hybridization of the tumour tissue was positive for Epstein-Barr RNA.

Human periosteum-derived progenitor cells express distinct chemokine receptors and migrate upon stimulation with CCL2, CCL25, CXCL8, CXCL12, and CXCL13.

For bone repair, transplantation of periosteal progenitor cells (PCs), which had been amplified within supportive scaffolds, is applied clinically. More innovative bone tissue engineering approaches focus on the in situ recruitment of stem and progenitor cells to defective sites and their subsequent use for guided tissue repair. Chemokines are known to induce the directed migration of bone marrow CD34(-) mesenchymal stem cells (MSCs). The aim of our study was to determine the chemokine receptor expression profile of human CD34(-) PCs and to demonstrate that these cells migrate upon stimulation with selected chemokines. PCs were isolated from periosteum of the mastoid bone and displayed a homogenous cell population presenting an MSC-related cell-surface antigen profile (ALCAM(+), SH2(+), SH3(+), CD14(-), CD34(-), CD44(+), CD45(-), CD90(+)). The expression profile of chemokine receptors was determined by real-time PCR and immunohistochemistry. Both methods consistently demonstrated that PCs express receptors of all four chemokine subfamilies CC, CXC, CX(3)C, and C. Migration of PCs and a dose-dependent migratory effect of the chemokines CCL2 (MCP1), CCL25 (TECK), CXCL8 (IL8), CXCL12 (SDF1alpha), and CXCL13 (BCA1), but not CCL22 (MDC) were demonstrated using a 96-multiwell chemotaxis assay. In conclusion, for the first time, here we report that human PCs express chemokine receptors, present their profile, and demonstrate a dose-dependent migratory effect of distinct chemokines on these cells. These results are promising towards in situ bone repair therapies based on guiding PCs to bone defects, and encourage further in vivo studies.