Volume Of Pneumatization Research Articles

Positional relationship between the facial nerve and other structures of the temporal bone.

The quantitative relationships between the position of the mastoid segment of the facial nerve, mastoid pneumatization and the positions of neighbouring structures are undetermined. Using high resolution computed tomography (HRCT), the positions of these structures were measured in 66 normal temporal bones. A new method for measuring the volume of pneumatization in the temporal bone based on the serial digital images of CT was designed. The method of partial correlation analysis was used to find the real relationship of the two variables. The results suggest that the factors that influence the position of the mastoid segment of the facial nerve are complicated and multiple. The development of the cranium including the temporal bone, the temporal bone pneumatization and the variable position of the jugular bulb are considered to be important factors.

The relationship between presbycusis and mastoid pneumatization.

Presbycusis is defined as the natural hearing loss accompanying aging, caused by degenerative changes in the inner ear. The etiology of presbycusis is uncertain. However, it would appear that a complex genetic cause is most likely. The determinants of mastoid size continue to be controversial. One of the pneumatization theories is the hereditary theory. In this study, the possible relationship between presbycusis and the extent of mastoid pneumatization was investigated. This study was carried out on 21 patients with presbycusis and 21 normal subjects of similar ages. The pneumatized volume was measured by computerized tomography. The temporal bone was scanned at 2 mm thickness intervals. Exposure (kV 130, mA105). The scan plane was parallel to the orbitomeatal line and the CT images covered the entire mastoid region. The average mastoid pneumatization in presbycusis group was 6.08 +/- 2.52 cm(3) in the right ear and 6.19 +/- 2.93 cm(3) in the left ear. However, in the control group it was 4.69 +/- 3.17 cm(3) in the right ear (p=0.12) and 5.10 +/- 3.49 cm(3) in the left ear (p=0.28). No significant difference was found between the presbycusis patients and normal subjects in terms of the volume of mastoid pneumatization.

Childhood otitis media and electrically elicited stapedius reflexes in adult cochlear implantees.

Electric stapedius reflex thresholds are helpful in programming cochlear implants, but only approximately two-thirds of patients have identifiable reflexes. Childhood otitis media correlates with absent stapedius reflexes or with high electric stimulation needed to elicit a reflex in cochlear implantees. Twenty-five adults with acquired hearing loss who underwent implantation with the MED-EL COMBI 40+ standard electrode array. STUDY PARAMETERS: The extent of temporal bone pneumatization, an indicator of childhood otitis media, was measured from preoperative computed tomographic images. Clinical units (in microamperes) needed to elicit a contralateral stapedius reflex, or maximum stimulation tried, were recorded. No definite association of pneumatization volume with intensity of stimulation was observed. The null hypothesis of no association cannot be rejected. Childhood otitis media does not seem to explain absent electric stapedius reflexes and the wide range of clinical units needed for maximum comfortable loudness level. Remaining potential explanations probably include the wide range of cochlear neurons that can be electrically stimulated, and that the maximum tolerable stimulation is too low to elicit a stapedius reflex.

Computer aided Surface Area Measurement of Temporal Bone Pneumatization Histological Sections

Contention exists on the development of pneumatization of temporal bone. Many techniques to measure the volume of pneumatization have been reported, but no techniques for direct surface area measurement. We measured the surface area and volume of human mastoid air cells. Eight normal temporal bones removed at autopsy were analyzed and fixed in formalin fixative, decalcified, and embedded in celloidin, sectioned at 25 microns and stained with H-E for histological examination. Total surface area and the volume of human mastoid air cells were measured using a personal computer. The surface area of pneumatic spaces for the 8 temporal bone specimens ranged from 36.1 cm2 to 163.0 cm2 (mean +/- SD: 89.1 +/- 34.0 cm2). The volume of pneumatic spaces for the 8 specimens ranged from 1.53 ml to 6.03 ml (mean +/- SD: 4.12 +/- 0.97 ml). The surface area of temporal bone pneumatic spaces we determined could serve as useful basic data for determining the physiology of ventilation for the temporal bone and the function of mastoid cells.

Volume of Mastoid Pneumatization: Three-Dimensional Reconstruction with Ultrahigh-Resolution Computed Tomography

The volume of the mastoid air cell system was measured in 69 patients with normal middle ears. All patients underwent axial ultrahigh-resolution computed tomography. Mastoid pneumatization was marked on each axial slice, and 3-dimensional reconstruction was performed. The volumes were measured with a volumetric algorithm. A polyethylene tubing phantom with a density similar to that of bone on computed tomography was devised. The polyethylene tubing was tied in a particular fashion so as to create interconnecting air spaces with a known volume. The phantom was scanned with the imaging parameters used for scanning the temporal bone. The air in the tubing was marked, and 3-dimensional reconstruction for the marked phantom air was performed. The volume of the interconnecting air spaces was measured and found to be identical to its known volume, thereby verifying the accuracy of the method used. The mean mastoid volume was 6.61 cm3. The smallest volume measured was 1.3 cm3, and the largest was 12.7 cm3. The importance of this technique lies in its high accuracy, ease of use, and ability to directly correlate mastoid size and clinical findings.

Computerized assessment of the mastoid air cell system

There have been many arguments on the development of pneumatization of temporal bone. However, a technique for direct volume measurement from high resolution computed tomography has never been reported. The aim of this paper is to develop a technique by using digital image processing to measure the volume of the mastoid air cell system. Forty three ears of 26 healthy subjects (13 males and 13 females) without a history of chronic or exudative otitis media, clear signs of Meniere's disease, severe sensorineural hearing impairment or malformation of temporal bone were eligible for enrolment in this study. Using a digital image processing technique, only the black air cells and tympanic cavity on the CT films are easily selected. Then, after image processing, only areas of these extracted black pneumatized parts are calculated. Consequently, the volume of pneumatized parts of temporal bone could be calculated separately as total volume and as partial volume that divided by several CT planes. The average volume of pneumatization in 43 temporal bones was 5.97 ml. However, since the volume of pneumatization in the temporal bone has traditionally been estimated by analyzing areas on X-ray films, the new method described in this study is significant for its ability to directly measure the volume of pneumatization in the temporal bone.

Relationship Between Severity of Middle Ear Mucosal Lesion and Middle Ear Pneumatic Space Volume in Patients with Otitis Media with Effusion

If we assume that the state of suppression of pneumatic cells is the result of suppression of pneumatic cell growth by inflammatory stimulation in the middle ear pneumatic space, it is possible to improve the state of suppression by performing sufficient treatment during the growth period of the pneumatic cells. We indwelt a tympanic membrane ventilation tube (hereinafter referred to as tube) for treatment of otitis media with effusion (OME) in child patients aged 3-13 years and investigated the following points: i) relationship between the severity of inflammation of the lamina propria of middle ear mucosal specimens (hereinafter referred to as lamina propria) collected at the time of tube indwelling and the degree of growth of the pneumatic space; and ii) changes in the pneumatic space associated with treatment by tube indwelling, which was studied by comparing the above-described mucosal severity with the pneumatic space area of 2 years after tube indwelling, and with increase in the pneumatic space volume measured periodically after tube indwelling. The results indicated that mastoid cell growth suppression is higher in patients with a higher degree of inflammatory changes in the lamina propria. In association with treatment by tube indwelling, effusion accumulated in the pneumatic space and mucosal swelling disappeared early after the treatment, or 2 months of tube indwelling. After that, in patients with severe mucosal lesion, a long time, 1.5-2 years, was found to be required for repneumatization accompanying regrowth of the temporal bone. We confirmed that the severity of inflammation of the lamina propria is deeply involved in the growth and repneumatization of the pneumatic cells.

Morphological characterization and classification of air cells in temporal bone by digital processing of CT images

We determined the extent of pneumatization in the temporal bone and reconstructed three-dimensional structures of air cells by computer-assisted digital processing of high resolution CT images of the bone. We attempted morphological classification of temporal bone air cells by characterization of the three-dimensional structures obtained. A total of 52 ears in 33 normal subjects (18 males and 15 females; mean age 51 years) was examined. The volume of pneumatization in the temporal bone, as measured by CT, ranged from 2.08 to 20.05 ml (mean 6.40 +/- 4.09). The morphological characteristics of air cells in the three-dimensional images were examined with reference to the volume of air cells and the direct on of their growth. The three-dimensional structures were observed from four directions (lateral, supralateral, anterolateral and supramedial). Large air cells existed plentifully in all directions. Anteriorly, air cells were growing in two directions; laterally and toward the petrous apex. The growth in the latter direction was especially marked, and this contributed to the growth in the medial direction. Air cells that grew anteriorly had two directions of growth (lateral and toward the petrous apex). The directional difference in growth varied with the ear. On examining the suprainferior growth, air cells that grew large in the anterior direction were found to grow large in the suprainferior direction and those that did not grow large in the anterior direction were found contrarily to grow poorly in the suprainferior direction. With the above morphological characteristics taken into consideration, morphological classification of air cells into five types was attempted by the volume of air cells and the direction of their growth.

CT-assisted measurement of total and regional volumes of pneumatization in the temporal bone

The total volume of air cells in the temporal bone and the regional volumes (tympanic cavity, petrous apex and mastoid antrum) were measured by using a system which we developed for the measurement of air cells by computerized digital processing of high-resolution CT images. We examined a total of 41 normal ears in 25 subjects ranging in age from 12 to 82 years (mean age 46.2). The total volume of pneumatization was approximately 4.05 +/- 1.59 ml and the volume of air cells in the tympanic cavity was 0.45 +/- 0.07 ml. Alveolation of the petrous apex was detected in 15 (36.6%) of the 41 ears, and the volume of air cells in the petrous apex was approximately 0.24 +/- 0.26 ml. The volume of air cells in the mastoid antrum was approximately 0.53 +/- 0.20 ml. The ears were divided into two groups, one with petrous alveolation (15 ears) and the other without it (26 ears). The ratios of regional pneumatization to total pneumatization were studied in the two groups. Statistically significant differences were found in the total volume and the volume of air cells in the mastoid antrum between the groups with and without petrous pneumatization (p < 0.05). The total volume of air cells did not correlate to the volumes of air cells in the tympanic cavity, mastoid cavity and petrous apex.

Comparison of measuring an area with a planimeter and by rectangular dimensional methods

We have developed a system that measures the volume of air cells in the temporal bone through computerized digital processing of high-resolution CT images. By using this method, the volume of pneumatization was measured, and the results were compared with the measured area of pneumatization obtained from two conventionally used simple ear X-ray methods (the planimeter and rectangular dimensional methods). A total of 57 ears, from 34 subjects, confirmed as normal by CT were examined. The average volume of pneumatization measured on CT images was 5.97 +/- 4.15ml, and the average areas of pneumatization measured by the planimeter and rectangular methods were 9.08 +/- 5.64 and 17.39 +/- 9.77 cm2, respectively. Graphically, when the volume of pneumatization was plotted on the Y axis and the planimeter-measured area of pneumatization on the X axis, a regression formula of Y = 0.651X + 0.054 was obtained, with a correlation coefficient of 0.89. With the volume of pneumatization plotted on the Y axis and the rectangular-dimensional-measured area of pneumatization on the X axis, the regression formula was Y = 0.375X - 0.559, with a correlation coefficient of 0.88. Both these correlation coefficients were considered high. Furthermore, 3D models of the air cells in the temporal bone were created and compared for patients with high and low correlations. In order to capture the morphological characteristics of these 3D models, they were examined from four different angles (lateral, upper lateral, anterior lateral and upper medial). The results showed that regardless of whether air-cell growth was present in the direction of the apex partise petrosae in patients with a low correlation coefficient, such growth played a major role in the degree of the correlatiton. Future studies will be required to clarify this point, though it can already be said that 3D models are indispensable for studying the air cells in the temporal bone. When we compared the volume and area of pneumatization in the temporal bone at different CT cross-sections, we found correlation coefficients in the vicinity of the canalis semicircularis lateralis of about 0.9 or higher. A statistical comparison of correlation coefficients for the CT, planimeter, and rectangular dimensional methods, made by using the CT cross-section with the highest coefficient, found a significant difference between the CT method and the other two methods (p < 0.05). In other words, the volume of pneumatization can be estimated more accurately with CT images than with simple ear X-rays.

Temporal bone pneumatization in cystic fibrosis patients.

Cystic fibrosis patients commonly have nasal polyps and sinusitis, but surprisingly are spared from an increased occurrence of otitis media. Twenty cystic fibrosis patients whose ages ranged from 13 to 26 years were studied. Only one of these patients had a history of otitis. Minimal temporal bone pneumatization, as determined by computed tomography, was used as an indicator of childhood otitis. The computed tomography had been done as part of the medical evaluation of their symptomatic paranasal sinusitis. On the average, pneumatization volume was larger for the cystic fibrosis patients than for the normal population (p = 0.033, Student's t-test). That is, these data indicate that cystic fibrosis patients had significantly less otitis than the normal population. Assuming that these cystic fibrosis patients are representative, the data may imply that the gene for good musculoskeletal eustachian differentiation is linked with the gene for cystic fibrosis. The data also imply that poor mucociliary transport does not necessarily induce otitis media.

Relationship of eustachian tube bony landmarks and temporal bone pneumatization.

Anatomic and functional differences of the eustachian tube have been suggested as etiologic factors in patients with otitis media. We studied eustachian tube lengths and vectors of the tensor veli palatini muscle in 25 unilateral specimens from adult human cadavers. The extent of temporal bone pneumatization, as determined by computed tomography and plain lateral radiographs, was used as an indicator of prior otitis media. Increased length of the cartilaginous eustachian tube was associated positively (r = .53, p less than .01) with volume of pneumatization. However, neither the length of the bony eustachian tube nor the vector of maximum pull of the tensor veli palatini muscle was associated statistically with the extent of pneumatization. It may be that the longer cartilaginous eustachian tube is more protective of the middle ear.

Association of abnormal appearance of tympanic membrane with minimal temporal bone pneumatization. A cadaver study.

The association of abnormal tympanic membrane appearance with minimal pneumatization of the temporal bone was studied in 28 unilateral formalin-fixed cadaver specimens. The photographic appearance of each tympanic membrane was judged by seven otolaryngologists, and a normalcy score determined. The normalcy score of the tympanic membranes had a weak association (tau = 0.27, p less than 0.05) with pneumatization volume, as determined by computed tomography. The same trend, though not statistically significant, was found with pneumatization area determined by lateral radiographs. For cross-sectional surveys, the otitis media condition is probably best identified by a combination of indicators: bilateral extent of pneumatization as assessed by computed tomography, bilateral appearance of the tympanic membranes, and a history of otitis media.