Mastoid pneumatization in secretory otitis. Further support for the environmental theory

A Comparative Study of Computed Tomography Findings versus Intraoperative Findings of Level of Tegmen Plate in Chronic Otitis Media: An Observational Study

OBJECTIVE

To compare the computed tomography findings with intraoperative findings of the level of tegmen plate with respect to the superior most part of the lateral semicircular canal in patients with Chronic Otitis Media. This study was attemptted to provide an objective assessment of the level of tegmen mastoideum.

MATERIALS AND METHODS

The level of tegmen plate with respect to the superior most part of the lateral semi-circular canal was measured preoperatively using HRCT scan of slice thickness of 0.6 mm with a software - RadiAnt DICOM Viewer 64-bit version in sagittal plane. The distance between these two planes was measured intraoperatively using micro ear straight pick and Vernier Calipers.

RESULTS

75 participants (thirty-three male & forty-two female) with chronic otitis media underwent computed tomography preoperatively and surgery. No significant difference was found in the height of tegmen measured preoperatively using HRCT temporal bone and intraoperatively (p value - 0.16). The tegmen plates were classified as low lying (2.0 -2.49 mm), intermediate lying (2.49-2.99 mm) and high lying (3.0 -3.49 mm).

CONCLUSION

Computed tomography findings of tegmen height correlates well with the intraoperative findings. An objective assessment of the level of tegmen mastoideum can provide the surgeon an idea of the severity of low lying level of tegmen to be expected and hence likely surgical problems. Based on this study, a classification system of level of tegmen plate has also been proposed.

Low-Lying Tegmen and Surgical Outcomes Following the Middle Cranial Fossa Repair of Superior Canal Dehiscence

OBJECTIVE

To compare treatment response from the middle cranial fossa repair of superior canal dehiscence (SCD) between cases with and cases without low-lying tegmen (LLT).

STUDY DESIGN

Cohort study.

SETTING

Single tertiary care institution.

METHODS

Two investigators independently reviewed preoperative high-resolution temporal bone computed tomography images and classified the ipsilateral tegmen as either "low-lying" or "control." Patients completed a symptom questionnaire and underwent audiometric testing pre- and post-operatively. Multivariable regression models assessed for symptomatic resolution and audiometric improvement following surgery with tegmen status as the primary predictor. Models controlled for patient age, sex, bilateral SCD disease, dehiscence location, prior ear surgery status, surgery duration, and follow-up duration.

RESULTS

Among a total of 410 cases included, we identified 121 (29.5%) LLT cases. Accounting for all control measures, patients with LLT were significantly less likely to experience overall symptom improvement (adjusted odds ratio: 0.32, 95% confidence interval [CI]: 0.18-0.57, p < .001) and reported a significantly lower proportion of preoperative symptoms that resolved following surgery (adjusted β: -25.6%, 95% CI: -37.0% to -14.3%, p < .001). However, audiometric outcomes following surgery did not differ significantly between patients with and patients without LLT.

CONCLUSION

This is the first investigation on the relationship between LLT and surgical outcomes following the middle fossa repair of SCD. Patients with LLT reported less favorable symptomatic response but exhibited a similar degree of audiometric improvement.

An innovative method to visualise mastoiditis using a hand-held X-ray system

OBJECTIVE

We explore the utility of using a hand-held X-ray system to diagnose mastoiditis in archaeological populations.

MATERIALS

A sample (n = 56) of hunter-fisher-gatherers from the Early Neolithic (8,000-7,000/6,800 cal. BP) Cis-Baikal cemetery of Shamanka II (Russia) were examined.

METHODS

Images were taken medio-laterally, approximately 90° to a sensor temporarily affixed to the lateral surface of the mastoid process. Digital radiographs were analysed for signs of mastoiditis occurring pre- and/or post-puberty.

RESULTS

Two thirds of individuals (39/56) exhibited evidence of mastoiditis. Chronic mastoiditis and chronic sinusitis co-occurred in 61.5% (24/39) of observable individuals.

CONCLUSIONS

This method was found to be an effective, convenient, and versatile non-destructive alternative to sectioning and traditional radiographic imaging.

SIGNIFICANCE

This is the first project to adapt a hand-held X-ray system for imaging and diagnosis of mastoiditis and this approach encourages future analyses of this infection.

LIMITATIONS

The cost of the imaging system is limiting and there are few comparative images taken in the same plane.

SUGGESTIONS FOR FURTHER RESEARCH

Further research should create a larger catalogue of comparative radiographs and assess the diagnostic potential of imaging the mastoid process to rather than imaging the entire pneumatized portion of the temporal bone.

Anatomical Relationship of the Middle Cranial Fossa Dura to Surface Landmarks of the Temporal Bone

HYPOTHESIS

The suprameatal crest and temporal line provides a reliable landmark to the middle fossa dura.

BACKGROUND

Surface anatomy of the temporal bone is used to guide mastoid surgery, but studies investigating these landmarks are limited. The aim of this study was to examine the anatomical relationship of the middle fossa dura to the temporal line.

METHODS

Thirty-two fresh hemicephalic temporal bones were prepared by drawing four lines along the mastoid including the suprameatal crest and temporal line (line 2), one line 5 mm superior to line 2 (line 1), and one 5 mm inferior to line 2 (line 3), and at Reid's base line (line 4). Four points were marked along these lines anterior to posterior 3 mm apart. A 1 mm bur was used to drill perpendicular to these points to examine the relationship to the middle fossa dura.

RESULTS

The dura was found inferior to line 2 in 6.3% at point 1, 6.3% at point 2, 9.4% at point 3, and 18.8% at point 4. The dura in line 1 was found inferior to point 1 in 52.1%, point 2 in 46.9%, point 3 in 56.3%, and point 4 in 62.5%. Only one specimen (3.1%) had dura lying inferior to line 3. No specimens were inferior line 4 at any point.

CONCLUSION

The dura of the middle fossa lies superior the temporal line in >80% of specimens and at least 5 mm superior in nearly half. This indicates the temporal line or a line slightly inferior to this is reliably inferior the middle fossa dura.

Tegmen height: preoperative value of CT on preventing dural complications in chronic otitis media surgery

OBJECTIVE

The objective was to examine tegmen height in patients with iatrogenic dural exposure in chronic otitis media (COM) surgery.

METHODS

Computed tomographic (CT) scans of 50 patients who underwent COM surgery were retrospectively examined. Twelve patients with dural exposure were admitted to the dura group. The control group of 38 patients had no dural exposure. Tegmen heights in both groups were compared.

RESULTS

There was no statistically significant difference between opposite ears (P>.05). Significant difference was found in tegmen height between healthy and operated ears in unilateral COM patients (P=.001).

CONCLUSION

Preoperative CT assessment of tegmen height is an important parameter in assessing risk of exposing dura during surgery.

Mastoid surface area-to-volume ratios in adult brazilian individuals

Computed tomography-based measurements of mastoid surface area and volume have not been described for adult Brazilian individuals. These measurements add to the understanding of middle ear physiology, related diseases, and their impact on mastoid pneumatization.

Objective

To check the ratio between mastoid surface area and volume.

Method

This contemporary cross-sectional cohort study included 28 patients submitted to CT imaging of the mastoid. Measurements of surface area and volume were made based on serial CT scans and produced with the aid of software package Image Pro Plus.

Results

Mastoid volumes ranged from 5.5 to 72.4 cm³. Surface areas ranged from 43.9 to 525.2 cm². Surface areas varied linearly with volumes.

Conclusion

Mastoid surface areas and volumes of adult Brazilian subjects followed a linear correlation, as also described in studies carried out in other countries. Mean surface areas and volumes were higher than previously published, unlike surface area-to-volume ratios, which were lower. Further studies with larger populations will provide evidence as to whether Brazilian subjects have larger surface areas and volumes than other populations.

A cross-sectional study of the change in mastoid geometry with age in children without a history of otitis media

OBJECTIVES/HYPOTHESIS

This study assessed the normal growth and development of mastoid air-cell system (MACS) geometry from infancy through adolescence.

STUDY DESIGN

Cross-sectional study.

METHODS

This cross-sectional study evaluated the change with age in MACS volume, surface area, and surface area/volume ratio in 36 (72 ears) individuals aged 1.6 to 18 years with no history of middle ear disease. The three MACS parameters were reconstructed using computed tomography (CT) scans judged by a radiologist to be normal. Linear regression was used to determine the relationship between the left and right values of each parameter, and between those parameters and age for male and female subjects.

RESULTS

For all three MACS parameters, the right and left values were highly correlated. MACS volume and surface area for male and female subjects showed an increase between 1 and 18 years. The surface area/volume ratio for males was independent of age but showed a shallow increase for females. When averaged across all ages, the ratio was similar to those previously reported.

CONCLUSIONS

The growth trajectory for MACS volume observed in this study was not consistent with other cross-sectional studies employing planimetry or CT of normal subjects that reported inconsistent results. 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 MACS geometry. Additional well-controlled studies of this phenomenon are needed to clarify which of the growth trajectories actually describe the growth process for the three parameters of interest.

Mastoid geometry in a cross-section of humans from infancy through early adulthood with a confirmed history of otitis media

OBJECTIVE

This study describes the changes in mastoid air cell system (MACS) geometry with age in ears with a history of otitis media (OM), without (GR-I) or with (GR-II) middle ear fluid on the CT scan.

METHODS

Thirty-seven (74 MACSs) CT scans were selected to approximate 4 MACSs/year between 1 and 18 years. For each MACS, the volume, surface area and surface area/volume ratio were reconstructed using standard procedures. Correlation analysis was used to define the left-right relatedness for the geometric parameters, and regression analysis was used to determine the effect of age on those parameters for each group.

RESULTS

Twenty scans were from female and 17 from males. Fluid was observed in 12 left, 4 right and 10 bilateral MACSs. The MACS volume and surface area of GR-I increased with age, were significantly greater than those for age-matched MACSs in GR-II, but show large variability. Those measures in GR-II were independent of age and a large percentage of these MACS volumes was <5 ml. The surface-area/volume ratio for MACSs in both groups was independent of age and group assignment. The left-right correlations for the three geometric parameters of the MACS were significant for all MACS in the two groups, and for bilateral MACS concordant for group assignment. The left-right correlations for surface area and volume were not significant for bilateral MACSs discordant for group assignment.

CONCLUSIONS

These results suggest that: the growth of MACS volume and surface area is genetically programmed but that this is disrupted by long-lasting OM; the effect of OM on MACS growth may depend on the duration and timing of the disease, and the MACS surface area/volume ratio does not explain the effect of MACS volume on the rate of gas exchange between middle ear and blood.

Relationship between surface area and volume of the mastoid air cell system in adult humans

INTRODUCTION

The geometry of the adult human mastoid air cell system has not previously been described over a large range of mastoid air cell volumes.

METHODS

Twenty subjects with a wide range of mastoid air cell pneumatised areas, as determined by X-ray, underwent computed tomography scanning of the middle ear. Mastoid air cell surface areas and volumes were then reconstructed from serial imaging sections, using Image J software.

RESULTS

Mastoid air cell volumes varied from 0.7 to 21.4 ml, and were linearly related to the pneumatised area. Right and left mastoid air cell volumes and surface areas were highly correlated. The mastoid air cell surface area was a linear function of volume.

CONCLUSION

The relationship between mastoid air cell surface area and volume is similar over a wide range of volumes. Given that the rate of gas exchange across the mastoid air cell mucosa is related to the mastoid air cell surface area, that rate will thus also be a direct linear function of the mastoid air cell volume.

Physiological gas exchange in the middle ear cavity

OBJECTIVES

Many reports pointed out that gas exchange in and out of the middle ear cavity occurs not only via the Eustachian tube but also across the middle ear mucosa. Our earlier study on children with otitis media with effusion (OME) for which a tympanic ventilation tube (TUBE) had been inserted revealed that the more severe the inflammatory change of the middle ear mucosa, the higher the degree of impairment of the transmucosal gas exchange function and the greater the decrease in the middle ear total pressure (METP). We hypothesized that the change in METP is caused by gas migration, and we conducted the present animal study to test this hypothesis and to determine the importance of METP measurement.

MATERIALS AND METHODS

Using 30 rabbits, ten in a group in which the middle ear cavity gas was replaced with atmospheric air (Group 1, oxygen (O(2)) 20%, carbon dioxide (CO(2)) 0.03% and nitrogen (N(2)) 79.9%), ten in a group replaced with a high CO(2) pressure gas whose partial pressure of CO(2) only was increased to 5% (Group 2, O(2) 20%, CO(2) 5% and balanced with N(2)) and ten in a group replaced with a low O(2) pressure gas (Group 3, O(2) 5%, CO(2) 0.03% and balanced with N(2)), changes in the METP were measured.

RESULTS

Group 1 showed a pressure change (increase, peak and then decrease in the METP) similar to that observed in a clinical cured group of OME with TUBE. In Group 2, no increase in the METP was observed and in Group 3 increase in the METP was observed but no decrease in the METP was observed.

CONCLUSIONS

It was found that the increase in the METP is attributable to diffusion of CO(2). This study elucidated that the change in the METP is a physiological response. Since the METP correlates with the degree of histologic inflammatory change in the middle ear mucosa, which was revealed in our clinical study of OME, it was reconfirmed that measurement of the METP is an important test method for evaluation of the degree of improvement in the pneumatic cavity mucosa.

Cochlear implantation in healthy and otitis-prone children: a prospective study

OBJECTIVE

To evaluate and compare the timing of surgery, intraoperative findings, and otitis media-related outcome of cochlear implantation in children who are otitis-prone with their counterparts who are not otitis-prone.

STUDY DESIGN

Prospective.

METHODS

Children referred for cochlear implantation were assigned to a non-otitis-prone group (group A: normal otoscopy on their first visit after referral) or an otitis-prone group (group B: current or a recent history of otitis media at referral). Group B patients were managed using a structured protocol aimed at preimplantation otitis media control. The study reviewed pre-, intra-, and postoperative data.

RESULTS

Of the 18 children studied, 8 were assigned to group A (mean age at referral, 40.6 mo) and 10 to group B (mean age at referral, 31.6 mo). For otitis media control, all otitis-prone children underwent ventilating tube insertion (various numbers of procedures before implantation). Only one otitis-prone child required cortical mastoidectomy also. Time from referral to implantation was similar in the two groups (mean, 6.6 mo). High-resolution computed tomography data showed mastoid pneumatization to be significantly smaller in the otitis-prone group, but the facial recess was not smaller in this group. During implantation, 10 children had inflamed middle ear mucosa. Seven of these belonged to group B. All of these seven children had a round window niche obliterated by the inflamed mucosa, which had to be removed for round window membrane identification. After implantation, only one child had drainage through the ventilating tube for more than 1 week. Two children in group B developed otitis media (1 year postimplantation) that was overcome within 1 week. There were no otitis media-related complications.

CONCLUSIONS

If a structured protocol is used for the control of otitis media before cochlear implantation, otitis media should not require a delay in implantation. In otitis media-prone children, the round window niche is often obscured by inflamed mucosa. Its removal is mandatory for identification of the round window membrane. After cochlear implantation, otitis media is not a frequent occurrence.

Experimental results do not support a gas reserve function for the mastoid

The mastoid is an aerated extension of the middle ear gas pocket whose state of development was shown to be an indicator of past and future otitis media experience. While the function(s) of the mastoid is not known, a number of hypotheses has been advanced to explain the reported association between mastoid size and middle ear disease. These include the hypotheses that, with respect to the middle ear, the mastoid functions as a pressure buffer, a gas reserve, and/or a pressure regulator. In this paper, a physical model of the mastoid is presented that makes specific predictions against which the validity of the hypothesized gas reserve function could be tested. Data from three published clinical experiments were evaluated for consistency with the predictions of the model, and the hypothesis was rejected. Also, when reinterpreted within the context of the model, the published data do not support a pressure-regulating function for the mastoid.

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.

Pneumatization in otosclerosis

In this study, degrees of mastoid pneumatization in otosclerotic and normal patients were compared on CT scan and plain X-rays. This study was prospective, conducted on inpatients and outpatients at a large community hospital. Patients were consecutively evaluated with no sex or age predilection. Each patient had a CT scan and a Schuller graph. Temporal bone volumetric and planimetric measurements were done respectively on CT scans and Schuller graphs. Statistically no significant variations were observed between groups. No correlation could be established between the degree of pneumatization and otosclerosis. Neither imaging technique is superior to the other when they are compared.

Secretory otitis media in adults: I. The role of mastoid pneumatizationas a risk factor

We analyzed clinically 102 ears with secretory otitis media (SOM) belonging to 72 adult patients who during their adult life had not suffered previously from ear disease. As in children, most of the cases (63%) could be traced directly to an upper respiratory tract infection. The most striking finding was the preponderance of poorly pneumatized mastoids-which were measured planimetrically-among our SOM cohort. This was found in adult SOM ears compared to contralateral healthy ears (4.59 versus 7.88 cm2), as well as when all 102 SOM ears were compared with values of the normal population (5.41 versus 12.9 cm2). This study showed that poorly pneumatized mastoids are a significant risk factor as far as adult SOM is concerned.

Correlation between temporal bone pneumatization, location of lateral sinus and length of the mastoid process

The relationship between temporal bone pneumatization and the location of the lateral sinus and length of the mastoid process was investigated in 60 fresh frozen adult temporal bones, by plain X-rays, computed tomography and surgical dissection including otomicroscopic findings. Temporal bone pneumatization was classified as small, moderate and large. After drilling, the shortest distances between the middle fossa dura and mastoid tip representing the mastoid length and between the sigmoid sinus and posterior border of external auditory canal were measured and compared to the degree of pneumatization. The distances in the specimens with pathological eardrum and adhesions in the middle ear were compared to the ones without gross pathology. The length of mastoid process was significantly shorter in specimens with small pneumatization than those with large (Mann Whitney P less than 0.001). The specimens with a pathological eardrum and middle ear adhesions had a significantly shorter mastoid length than those without gross pathology. There was no significant difference between degree of pneumatization and the shortest distance between sigmoid sinus and external auditory canal (Mann Whitney P greater than 0.05). It is demonstrated that the 'under-developed' mastoid process can be a consequence of hampered pneumatization.

Serous otitis media and paranasopharyngeal extension of nasopharyngeal carcinoma

Two hundred thirty-two patients with nasopharyngeal carcinoma were evaluated for serous otitis media (SOM) at diagnosis. The diagnosis of SOM required the detection of effusion behind the tympanic membrane in association of air-bone gap of 10 dB or more in pure tone audiogram. These patients were also evaluated by computed tomography for the degree of tumor extension. By stepwise logistic regression analysis, the degree of paranasopharyngeal extension of tumor, erosion of petrous temporal bone, and the obliteration of pharyngeal recess were significantly related to the development of SOM, but sex and age were not. The findings of computed tomography may influence the plan of management for SOM in patients with nasopharyngeal carcinoma at diagnosis.

Mastoid surgery in childhood

The presenting features and operative findings in 105 patients aged 16 years or less undergoing mastoid surgery are reviewed. In 94% surgery was for chronic otomastoiditis, usually acquired, and associated with cholesteatoma in 64%. Post-operative otorrhoea persisted beyond 6 months in 44% and contralateral disease required some form of surgical procedure in 20%. Post-operative hearing thresholds were improved or unchanged in the majority of patients, most of whom underwent cortical or modified radical mastoidectomy. An improvement in the therapeutic results of mastoid surgery in childhood is clearly necessary, but requires a greater understanding of the aetiology of chronic middle ear disease.

Pneumatization of the temporal bones in a Greenlandic Inuit anthropological material

The degree of pneumatization of the temporal bones correlates with exposure during childhood and adolescence to infectious middle ear diseases (IMED), both acute and chronic. The pneumatized area as seen on cranial X-rays can be measured. This was applied to an anthropological material in order to develop methods for assessing ancient populations' exposure to IMED. Fifty-six Greenlandic Inuit (Eskimo) crania were examined. The crania were sexed and measured. X-rays were taken bilaterally, using the projection of Runström II, and the pneumatized area was measured planimetrically by computer. In blind trials it was found that the inter- and intraobserver variation was non-significant; that the degree of pneumatization of the temporal ossa did not reflect cranial size or sexual dimorphism; and that the pneumatized areas correlated bilaterally. Asymmetry in the size of the pneumatized areas, an indicator of exposure to IMED, was found in 5 crania (9%).

Effect of middle ear infection on pneumatization and growth of the mastoid process. An experimental study in pigs

The intention of this experiment was to investigate whether anatomical variations of the temporal bone such as low middle fossa dura, anterior position of the sigmoid sinus or small mastoid process, which are often seen at surgery in cholesteatoma patients, are caused by inflammation in early childhood. In 7 pigs, 1.5 ml paraffin liquid were instilled into the left tympanic cavity 2 or 7 days after birth in order to produce inflammation of the middle ear and tubal dysfunction. After six and a half months the length and area of the mastoid process were significantly smaller on the left instilled side than on the right, normal side. In all cases there was remarkable hypocellularity and increased thickness of the cortical bone strongly supporting the environmental theory of pneumatization that inflammation suppresses the pneumatization process and growth of the mastoid process.

Volumetric changes of the aerated middle ear and mastoid after insertion of tympanostomy tubes

Volumetric changes of the middle ear and mastoid were measured monthly by the direct volumetric method in 28 ears from 21 patients (12 children and nine adults) with otitis media with effusion. The mean volumetric increase immediately after the insertion of the tubes was 1.56 ml and was attributed to the volume of effusion aspirated from the tympanic cavity and mastoid antrum. The volume increased significantly for three months (P less than 0.01). The increase was speculated to be due to disappearance of the mucosal edema and of effusion in the tympanic cavity and mastoid. The volumetric changes showed little increase thereafter.

Secretory otitis and pneumatization of the mastoid process: sexual differences in the size of mastoid cell system

Seventy-nine children (41 girls and 38 boys) were subjected to tympanometry nine times from the age of 2 years to the age of 7 years. In addition, otoscopy was performed, and the children's otologic history was recorded. At the age of 7 years, roentgenograms were taken of the mastoid process, and the area of the air cell system was measured by planimetry. The smallest cell systems were found in ears with a history of secretory otitis or chronic tubal dysfunction--a finding which supports the environmental theory of pneumatization. Boys had significantly smaller cell systems (mean, 7.5 cm2; range, 2.75-16.75) than girls (mean, 9.0 cm2; range, 2.5-15.7). The degree of middle ear pathology was significantly higher in boys, as expressed by the total tympanometric score. The more pronounced middle ear pathology in boys was caused by more frequent and severe episodes of upper respiratory tract infections. The analysis of the sex differences provides substantial support of the environmental theory of pneumatization, since upper respiratory tract infections in childhood often cause tubal dysfunction and secretory otitis, conditions that disturb the normal process of pneumatization and result in hypocellularity.