Effect of middle ear infection upon the pneumatization of the mastoid: an experimental study in pigs

Clinical characteristics of atelectatic eardrums and adhesive otitis media in children

OBJECTIVES

Atelectatic eardrum and adhesive otitis media in children are related to persistent otitis media with effusion (OME) and eustachian tube dysfunction in infancy. However, the pathogenesis of these diseases is not fully understood, and some cases even progress to pars tensa cholesteatoma. This study analyzed the clinical characteristics of children with atelectatic eardrum and adhesive otitis media to clarify associated causes of and risk factors for progression of these middle ear pathologies in children.

PATIENTS AND METHODS

This retroactive study included 38 ears of 31 children with atelectatic eardrums (atelectasis group), and 19 ears of 17 children with adhesive otitis media (adhesive OM group). Thirty-two contralateral non-cholesteatoma ears of 32 children with congenital cholesteatoma were also examined as a control group. Participants were aged 15 or younger. Life history (obtained via questionnaire), associated diseases, hearing acuity, aeration and development of the temporal bone were investigated.

RESULTS

All children in the atelectasis and adhesive OM groups had a history of recurrent acute otitis media (rAOM) and/or OME. The prevalence of perennial allergic rhinitis was 18 cases (58%) in the atelectasis group and 16 cases (94%) in the adhesive OM group. The prevalence of perennial allergic rhinitis was significantly higher in the adhesive OM group compared to the control group (P < 0.01). The development of mastoid air cells, categorized by MC classification, showed MC0 + MC1 (poor pneumatization) in 19 ears (50.0%) with atelectatic eardrums and 12 ears (63.2%) with adhesive OM. Poor pneumatized mastoid was more frequently observed in the ears of the atelectasis and adhesive OM groups compared to the control group (P < 0.01). No significant difference was found in regards to aeration of the middle ear between the two groups; however, aeration was significantly poorer in both groups compared to the control group (P < 0.01). Three characteristics were analyzed using multivariate logistic regression: perennial allergic rhinitis (odds ratio [OR] 4.319, P = 0.013), poor mastoid pneumatization (OR 8.457, P = 0.012), and pars flaccida retraction pocket (OR 20.897, P = 0.006). These characteristics were shown to be significant risk factors for atelectatic eardrums and adhesive OM. In addition, the predisposition to perennial allergic rhinitis was shown to be the most important factor in the progression from atelectatic eardrum to adhesive otitis media (OR 16.615, P = 0.012).

CONCLUSION

Children with perennial allergic rhinitis, poor development of mastoid air cells, poor aeration of the temporal bone, and with pars flaccida retraction pocket were at an increased risk of developing an atelectatic eardrum and adhesive OM. In particular, perennial allergic rhinitis was shown to be a significant risk factor in the progression from atelectatic eardrum to adhesive otitis media. Allergic inflammation may affect not only the nasal passages but also the eustachian tube, resulting in persistent middle ear dysfunction. Therefore, children with rAOM/OME who have these risk factors should be carefully monitored and treat over time in effort to prevent progression of pathology.

Radiological differences between HIV-positive and HIV-negative children with cholesteatoma

INTRODUCTION

HIV-positive children are possibly more prone to developing cholesteatoma. Chronic inflammation of the middle ear cleft may be more common in patients with HIV and this may predispose HIV-positive children to developing cholesteatoma. There are no studies that describe the radiological morphology of the middle ear cleft in HIV-positive compared to HIV-negative children with cholesteatoma.

OBJECTIVES

Compare the radiological differences of the middle ear cleft in HIV-positive and HIV-negative children with cholesteatoma.

METHODS

A retrospective, cross-sectional, observational analytical review of patients with cholesteatoma at our institute over a 6 year period.

RESULTS

Forty patients were included in the study, 11 of whom had bilateral cholesteatoma and therefore 51 ears were eligible for our evaluation. HIV-positive patients had smaller (p=0.02) mastoid air cell systems (MACS). Forty percent of HIV-positive patients had sclerotic mastoids, whereas the rate was 3% in HIV-negative ears (p<0.02). Eighty-two percent of the HIV-positive patients had bilateral cholesteatoma compared to 7% of the control group (p<0.02). There was no difference between the 2 groups with regards to opacification of the middle ear cleft, bony erosion of middle ear structures, Eustachian tube obstruction or soft tissue occlusion of the post-nasal space.

CONCLUSION

HIV-positive paediatric patients with cholesteatoma are more likely to have smaller, sclerotic mastoids compared to HIV-negative patients. They are significantly more likely to have bilateral cholesteatoma. This may have implications in terms of surveillance of HIV-positive children, as well as, an approach to management, recurrence and follow-up. HIV infection should be flagged as a risk factor for developing cholesteatoma.

Middle ear atelectasis: what causes it and how is it corrected?

Many options are available to manage a patient who has atelectatic ears. Establishing normal middle ear ventilation and aeration is the cornerstone to successful control of these ears. Often, medical management with nasal steroids and decongestants is all that is needed. If recurrent infections have weakened the tympanic membrane progressively, or the middle ear environment is so severe that medical management does not correct the problem, then surgical correction is often necessary. This article explores the pathogenesis of middle ear atelectasis and explains a classification system to help the clinician determine the best course of management.

Acute otitis media and mastoid growth

CONCLUSIONS

This study implies that the hypothesis that acute otitis media (AOM) in infancy inhibits the growth of the mastoid system cannot be accepted.

OBJECTIVE

To establish a relationship between AOM in children and their mastoid pneumatization development.

PATIENTS AND METHODS

Lateral Schüller mastoid radiographs (LMRs) were measured in two groups of children at ages 2-11 years. Group A (n=116) had a history of recurrent AOM; group B (n=108) had no such history. Patients were treated in a private clinic. Data were analysed at Tel Aviv University. The patients had their LMR taken and measured planimetrically. LMR areas on left and right sides were compared in each group and age and were tested for possible differences using the paired Student's t test. When no left/right difference was detected, the values were averaged. Groups A and B were compared at different ages using two-tailed two-sample unequal variance and correlation coefficients.

RESULTS

The analyses show that the LMR area became gradually and significantly larger with age in group A (R2=0.858; p<0.05). It did not develop significantly in group B.

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.

Mastoid pneumatization of the patulous eustachian tube

The pathophysiology of the patulous eustachian tube (PET) remains unclear. The degree of mastoid cell pneumatization is considered an indicator of chronic inflammation of the middle ear. We used the mastoid cell area to investigate the relationship between past chronic inflammation of the middle ear cavity and a PET in 84 patients (20 to 83 years old). The mastoid cell size was calculated from radiographs and analyzed relative to the history of otitis media (OM). The controls were 100 normal ears. The patients' mastoid cell size was significantly suppressed versus that of the controls, in both 31 PET cases with and 53 PET cases without past OM. We surmise the possibility that the PET ears had experienced inflammation even when the patients had no history of OM and the tympanic membrane showed no OM sequelae. This study indicates the existence of some relationship between a history of chronic inflammation of the middle ear cavity and a PET.

Cholesteatoma in children

Cholesteatoma in children is generally considered to be more aggressive and destructive than in adults. Each otologic surgeon has experienced widely extended cholesteatomas in children with large pneumatized mastoid processes. In this paper, we want to present clinical and experimental observations which imply that the destructive potential in children is similar to that in adults. Factors and observations that have led to the assumption that cholesteatoma in children is more aggressive will be discussed. Based on our experience and the literature, we tried to distill the current and leading thoughts concerning this intriguing entity.

Relationship between middle ear pressure, mucosal lesion, and mastoid pneumatization

OBJECTIVES

The inflammatory changes of pneumatic space mucosa are thought to affect the development of pneumatic space and the function of transmucosal gas exchange. So, it is assumed that the mucosal change is deeply involved in the onset and healing process of otitis media with effusion (OME). The objective of this study is to investigate whether the growth of the mastoid cells and the middle ear transmucosal gas exchange function in patients with OME are affected by the histopathologic changes in middle ear mucosa, and whether these two factors are changed by the treatment of OME.

MATERIALS AND METHODS

From 65 children with OME, middle ear mucosal specimens were collected during indwelling of a tympanic tube, and their histopathologic changes were compared with cell growth area measured on radiographic films and with the change in the middle ear total pressure (METP).

RESULTS

Suppression of the cell growth area was stronger and the METP stayed lower in cases with a higher degree of mucosal lesion. Significant expansion of pneumatic area was observed after 2 years of tube indwelling, and the peak METP showed a significant increase after 1.5 years. This increase in the METP was caused by diffusion/absorption of CO2 and O2 and indicated recovery of the transmucosal gas exchange function.

CONCLUSIONS

The growth of the mastoid cells and the middle ear transmucosal gas exchange function are closely affected by the subepithelial histopathologic changes in middle ear mucosa, and these two factors recover by the treatment of OME.

Secretory otitis media and mastoid air cell development

Controversy continues over the factors involved in the development of the mastoid air cell system (MACS). This study examines the effect of persistent secretory otitis media with effusion (SOME) on the development of the MACS. Thirty-one children, aged 4, were drawn from a cohort of cleft palate children in a multi-centre, prospective otological study set up in 1984. The initial presence of SOME was assessed by otoscopy, tympanometry and bilateral myringotomy, performed under the same anaesthetic as surgical repair of the cleft lip or palate. Only one ear in each child was ventilated with a tube and the other, the control ear, was assessed by regular follow-up otoscopy and tympanometry. The persistence of SOME after palate repair in over 70% of the non-ventilated ears in 4 years olds and the presence of a contralateral ventilated middle ear provides the perfect model for assessing the effect of SOME on MACS development. Plain, lateral mastoid X-rays were assessed by planimetry to give a well accepted measurement of mastoid pneumatization. Nine children were excluded from analysis as they did not meet the strict criteria of one persistently ventilated middle ear and one with persistent SOME. 22 children (44 ears) were available for analysis, 9 children were tubed at 3 months and 13 were tubed at 12 to 16 months. In 19 of the 22 ears the mastoid air cell system was larger on the tubed side.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

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.

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.

Anthropological study of the mastoid air cell system in Pakistani races

This is an anthropological study of the development of the mastoid process in the four ethnic groups of Pakistani races: Turko-Iranian, Indo-Aryan, Scytho-Dravidian, and Aryo-Dravidian. Cephalometric studies have established that the majority of Pakistanis are brachio to ultra-brachiocephalic (Cephalic Index 82-x). Radiological evaluation of normal mastoids and their planimetric measurements show that the mastoid process is smaller (Av: 10.24 sq.cm. +/- 0.8) than the Caucasian Western races (Av: 12-15 sq.cm.). Neither combined approach tympanoplasty, nor mastoid obliteration technique may be required, nor technically possible in a small mastoid. Natural epithelization of a small 'peanut size' mastoidectomy cavity does not justify these procedures. A modified radical mastoidectomy and tympanoplasty reconstruction provides a satisfactory result in chronic discharging ears.

Mastoid pneumatization in otosclerosis

The extent of mastoid pneumatization in 150 otosclerotic ears was compared with that of 150 healthy control ears. The size of mastoid pneumatization was measured by use of the Schüller lateral x-ray projection with the help of computed planimetry. The measurements showed the average pneumatized area in otosclerotic ears to be 17.4 +/- 5 cm2, in contrast to 12.9 +/- 4 cm2 for the healthy control ears. The difference between the two groups was highly significant (p less than .0001). While both groups showed a bell-shaped distribution of the measured pneumatized area, the curve of the otosclerotic ears was shifted significantly to the right. Our findings indicate a link between otosclerosis on the one hand and highly pneumatized mastoids on the other. This link between a hereditary disease and a specific type of pneumatization points to the likelihood that heredity also plays some role in determining the final type of pneumatization.

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.

The effect of chronic middle ear inflammation on the pneumatization of the tympanic bulla in pigs

The effect of chronic middle ear inflammation on the pneumatization of the tympanic bulla was investigated in piglets. The pig tympanic bulla has an air cell system which is divided by trabeculae and closely resembles the human mastoid air cell system. The tympanic bulla and its air cell system in normal ears were well developed because of the bone formation and the bone resorption inside the cortex, whereas the tympanic bulla affected by chronic otitis media in the early stages of life exhibited retardation of pneumatization arising from the disturbed bone resorption by inflammatory stimulus. It was concluded that affliction with chronic middle ear inflammation in the early stages of life causes inhibition of pneumatization by hindering the development of the air cell system.