The Role of Tympanic Membrane Retractions in Cholesteatoma Pathogenesis

Experimental cholesteatoma: a comparison between spontaneous and induced models

OBJECTIVE

To compare the incidence and the histopathological aspect of spontaneous and two induced Mongolian gerbils' models of cholesteatoma: External Auditory Canal (EAC) obliteration model and the Auditory Tube (AT) cauterization model.

METHODS

Fifty-four ears of 27 animals were divided into EAC obliteration, AT cauterization, and control groups and histologically assessed for cholesteatoma incidence and classification at intervals of 2, 4, 8, and 16 weeks.

RESULTS

Cholesteatoma was diagnosed in 30 of the 53 ears evaluated with a significantly higher incidence in groups that received some type of intervention (p<0.0001). It was not possible to histologically distinguish cholesteatomas of the same stage between the study groups.

CONCLUSION

Although we observed a significant increase in cholesteatoma incidence with the two methods used when compared to the control group, all developed cholesteatomas were apparently identical from a histological point of view.

Tympanic membrane perforations: a critical analysis of 1003 ears and proposal of a new classification based on pathogenesis

PURPOSE

To present a large series ears with tympanic membrane perforations (TMP), to describe their characteristics, and to propose a new classification system based on the pathogenesis of TMP.

METHODS

This cross-sectional study was conducted at a tertiary university hospital with 1003 ears (792 consecutive patients with TMP in at least 1 ear). Otoendoscopy and audiometry were performed. Perforation measurements and their locations were digitally assessed. TMP with no suggestive signs of previous retraction were classified as Group 1, and those with possible previous retraction were classified as Group 2. Signs of retraction previous to the TMP, symptom length, perforation size and location, status of the contralateral ear, and hearing status were compared.

RESULTS

Group 1 comprised 63.5% of the included ears. Compared to Group 2, Group 1 presented a higher rate of central perforations (99% vs. 53%), a shorter duration of symptoms, smaller perforations (mean area: 18.5% vs. 41.4%), a higher rate of perforations in the anterior quadrants, better hearing levels (mean tritonal gap: 23.9 dB vs. 29.2 dB), and a lower rate of abnormal contralateral ears (28% vs. 66%).

CONCLUSION

The classification of TMP into two groups based on signs of previous retractions is feasible and indicates two different levels of disease severity. While the group without previous signs of retraction comprises ears with more limited disease, membranes with previous retraction seem to show more severe disease and, consequently, a less functional middle ear.

Central versus marginal tympanic membrane perforations: does it matter? An analysis of 792 patients

BACKGROUND

There is a lack of studies concerning chronic otitis media without cholesteatoma.

OBJECTIVES

To perform an analysis of tympanic membrane perforations (TMP), compare the parameters of central and marginal TMP, combining both the traditional and more recent technologies available.

MATERIAL AND METHODS

792 consecutive patients. The TMP subgroups were divided by central and marginal locations and compared based on signs suggestive of previous tympanic retraction, namely, medialized malleus, tympanic remnants over the promontory, tympanic remnants over the ossicular chain, and incus/stapes erosion. Analysis of the status of the contralateral ear (CLE).

RESULTS

Central TMP was diagnosed in 79.8%. Compared with the central group, the marginal group had more reported hearing loss (95.6%), greater conductive hearing loss (pure tone average for air-conduction 43.3 dB and average air-bone gap of 28.7 dB), a larger perforated area (46.45%), more posteroinferior quadrant involvement, a greater number retraction signs prior to the TMP, and more changes in the CLE (71%).

CONCLUSION

The differences between TMP subgroups are highlighted when we use all technologies available to compare them. Marginal TMPs have more altered parameters than central TMPs.

SIGNIFICANCE

There is a great possibility to enhance the knowledge of TMPs and to improve the pathogenesis-based treatment.