INTRODUCTION

The Eustachian Tube (E.T.) is an osteocartilaginous duct which provides the communication between the middle ear and rhinopharynx, covering a posterior-anterior, lateral-medial superior-inferior way between these two points, forming an angle of 45º with the horizontal plan in adults and of 10º in children. Its two anterior-medial thirds have cartilaginous origin and its posterior-lateral has bone origin. Its cartilaginous portion opens in the lateral region of rhinopharynx through the pharyngeal ostium of the Eustachian Tube, while its bone portion has its opening ostium in the anterior region tympanic cavity. The E.T. has three main functions: 1) Ventilation of the middle ear to equalize its pressure with the atmospheric pressure, improving, thus, the hearing; 2) Draining and clearance of the middle ear secretion for rhinopharynx; 3) Protection of the middle ear against microorganisms and refluxes proceeding from rhinopharynx(1,2). Mechanical or functional tube obstructions, alterations of the rheological characteristics of secretions, primary or secondary ciliary dysfunction, mucous blockage, negative pressure and vacuum are some of the factors that harm the draining of mucus and microorganisms excesses of the tympanic cavity, propitiating the development of the Otitis media.

Small blockages of E.T. which create negative pressure in the middle ear can take to secretion aspirations of rhinopharynx to the tympanic cavity. In children, for having the widest, more horizontal and shorter E.T., the protection function is less efficient(3,4)

A healthful middle ear implies in working E.T. Structural, physiological or functional alterations of E.T. cause pathologies in the tympanic cavity, either due to hypoventilation of the middle ear, lack secretions draining due to contiguity of rhinopharynx infections. Consequently, good results of great part of the otologic surgeries depend, among other factors, on the functional state of the Eustachian Tube. There are some people who emphasize its role in the surgical prognosis to be basic when determining pathologies of the middle ear and of the tympanic membrane.

The classification of types of ostiums followed the model adopted by Manrique and Cervera-Paz (5)(1999) taking as base the tubal dysfunction associated to the aeration failure of the middle ear as possible causes for the development of cholesteatoma, carried through a study analyzing the Pharyngeal Ostium of the Eustachian Tube and dividing it in 5 types.

Normal Ostium (Type 1)

Inferiorly triangular base, surrounded by torus, which has a comma shape, with voluminous posterior edge and less prominent anterior edge. The inferior limit is formed by the proeminence of the "elevating muscle" that corresponds to the lump of the elevating muscle of the palate.

During the deglutition or phonation, the posterior edge moves posteriorly and superiorly, being the ostium of elevator muscle more evident due to contraction of this muscle. The mucosa appearance of the tubal orifice is normal and Rosenmüller fossa is pale red and of soft aspect.

Inflammatory Ostium (Type 2)

The mucosa that recovers the tubal orifice is of respiratory type and participates on different conditions of inflammation and infection of the nose and nasopharinx. In acute episodes, the mucosa becomes edematous, generally in morphology distortion of these structures. The color of the mucous changes from pale red to intense, always erythematous red, being common the mucous-purulent secretion presence re-covering the tubal orifice. In chronic conditions, such as allergy, this orifice can also be inflamed. In these conditions, the mucosa is pale, it does not present edema and it does not present distortion of the morphology of the tubal ostium.

Ostium with Adjacent Lymphoid Hyperplasia (Type 3)

The tubal ostium has a lymphoid accumulation of tissue that forms tubal tonsil. The hypertrophy of this tonsil is observed and limited to the tubal ostium, Rosenmüller fossa and the posterior wall of the tubal orifice. It is necessary to remember that in the proximity of tubal tonsil there is a bigger accumulation of lymphoid tissue of the Lymphatic Waldeyer's Ring which corresponds to pharyngeal tonsil (adenoid). The hypertrophy of the lymphoid peritubal tissue can distort the normal morphology of the tubal orifice. The mucosa is edematous, granular and dark red. Sometimes it is difficult to distinguish tubal tonsil, the tubal ostium and the adjacent adenoidal tissue. In some cases, they may also be found in patients affected by chronic nasal inflammation, with isolated hypertrophy of the tonsil peritubal tissue.

During the first years of life, the lymphoid adenoidal tissue shows remarkable size changes. In some cases it can compress the posterior edge of the ostium and exceptionally reaches and recovers the tubal orifice. In the cases of adenoidal hypertrophy, the tubal disfunction can more be reported more as an infectious or inflammatory process of rhinopharynx than as a diminished function, due to the mechanism of compression of the tubal ostium.

Hypoplasic Ostium (Type 4)

In some cases, the bilateral hypoplasia of the tubal ostium can be observed. The anterior edge of the ostium involves more that the posterior one, giving the impression of that the anterior edge is absent, being impossible to visualize it during the deglutition. The hypoplasic ostium morphology does not change as time goes by. When it is associated with illness of the middle ear, its prognosis is favorable and directs to the one chronic otitis media. The etiology of these pathological changes is unknown, being able to be a final level of a chronic inflammatory process of the mucosa.

Cicatricial Ostium (Type 5)

The tubal ostium can show important changes due to total or partial amputation of its components, to loss of the normal configuration for cicatricial retraction or presence of cicatricial adherence which partially sticks it into the nasopharynx wall. This type of ostium is generally found in patients who have been submitted to the surgical or radiotherapy treatment for nasopharyngeal pathologies or of skull base.

It is on the basis of the physiology of the Eustachian Tube and in pathogenesis of the Middle Otitis that this study has the objective to correlate, through nasopharyngeal and endoscopic findings, the alterations found in the pharyngeal Ostium of the Eustachian Tube with illnesses of the Middle Ear, as Chronic Otitis Media (COM), Cholesteatomatous Chronic Otitis Media (CCOM) and the Tympanic Membrane Retraction (TMR).


PATIENTS AND METHOD

Among adults and children, 30 patients with Chronic Otitis media Simples (COM) participated on this study, uni- or bilaterally, corresponding to a total of 42 affected ears and 42 evaluated ostiums; 23 patients carrying Cholesteatomatous Chronic Otitis Media(CCOM), adding up a total of 34 affected ears, with 34 studied ostiums and 20 patients with of the Tympanic Membrane Retraction (TMR), in its most varied degrees, a total of 29 disturbed ears and 29 evaluated ostiums. 10 patients with absence of otologic, nasal or rhinopharyngeal pathologies, including inflammatory, infectious and the obstructive ones were also submitted to the examinations, who were part of the control group, adding up a total of 20 ostiums submitted to the evaluation.

The age of the patients varied between 4 and 65 years, being from 4 to 54 years for COM, from 8 to 61 years for COM and from 8 to 65 for TMR. A etária band among children varied from 4 to 15. We considered children who are older than 16 years old as adults.

In terms of gender, 56.5% of the patients were men and 43.5% women.

All patients were submitted to the otorhinolaryngological, audiological and nasopharyngoscopic evaluation, examined with nasofibroscopy Olympos ENF fibroscopic P3 type, with xenon light for illumination and camcorder for documentation.

The optical fiber was inserted in the nostrils with higher attention for the side corresponding to the one of the otologic alteration: tympanic retraction, tympanic perforation or of cholesteatome. In some cases, the use of topical anesthetic was necessary.

All the patients participanting on the study were assited in the of Otorhinolaryngology Clinic of Faculdade de Medicina de Santo Amaro, in the period between May 2004 and June 2005 and had signed the term of full consent and had register in the CEP-UNISA Nº 027/07.

The qualitative variables were represented by absolute (n) and relative (%) frequency, quantitative by average and maximum and maximum values. The association between the variables type of Otitis media, type of ostium and age (children and adults) was studied through the qui-square test and or through the Fisher Exact Test. The significance level of 0.05 (a= 5%) was adopted and descriptive levels (p) which were lower than such value were considered significant.


RESULTS

Out of the patients with Simple Chronic Otitis Media, 18 (60.0%) had unilateral affection and 12 (40%) had bilateral affection, totalizing 42 evaluated ears and, therefore, 42 ostiums. The age of the patients varied between 4 and 54 years, with average of 22.7 years, being 12 (40.0%) children and 18 (60.0%) adult. Under endoscopic vision, the E.T. pharyngeal ostium was normal in 67.0% of the cases (28 ostiums). Amongst the modified ostiums, 3 (7.0%) were of the inflammatory type, 1 (2.0%) were of the hypoplasic type, 8 (19.0%) with adjacent lymphoid hypertrophy and 2 (5.0%) of the cicatricial type.

Among the patients with Cholesteatomatous Chronic Otitis Media, 12 (52.2%) presented unilateral affection and 11 (47.8%) bilateral affection, adding up a total of 34 ears and ostiums evaluated. The age of the patients varied between 8 and 61 years, with average of 27 years, being 7 (30.4%) children and 16 (69.6%) adult ones. At the Nasofibroscopic study, 21 (61.8%) patient presented E.T. pharyngeal ostiums of normal aspect, while 13 (38.2%) were considered modified, between them: 3 (8.8%) inflammatory ones, 3 (8.8%) hypoplasic ones, 1 (2,9%) with adjacent lymphoid hypertrophy and 6 (17.6%) cicatricial ones.

Amongst the patients with Tympanic Membrane Retraction, 11 (55.0%) presented unilateral alteration and 9 (45.0%) bilateral, totalizing 29 evaluated ears and 29 ostiums. The age of the patients varied between 8 and 65 years, with average of 26.8 years, being 8 (40.0%) children and 12 (60.0%) adult. The evaluation of the ostiums was normal in 16 (55.2%) and modified in 13 (44.8%), being 4 (13.8%) ostiums of inflammatory type, 2 (6.8%) of the hypoplasic type, 7 (24.1%) with adjacent lymphoid hypertrophy and none (0.0%) of the cicatricial type. The comparison between adults and children, according to the type of Otitis media studied and the presence or not of alterations of the pharyngeal ostium of the E.T. did evidence that, among children, the percentages of modified ostiums were significantly more frequent than the one observed in the control group, fact which was not evidenced in relation to adults. (Table 1)

The analysis showed significant association of children in relation to adults, in terms of the presence of ostiums alterations and the occurrence of CCOM and Retraction of TM (2.8 and 2.26) (Table 2).

It is observed that the percentages of types of otologic alterations studied did not significantly differed from one another (p < 0.01).

The distribution of patients with and without Otitis Media, when divided in terms of alterations of E.T. pharyngeal ostium, shows:

1. Preponderance of normal ostiums (68%) in relation to the altered ones (32%);

2. The percentage of ostium alterations in the control group was significantly lower than the ones observed in the COM, CCOM and TM retraction, which did not differ among themselves Table 3.

Table 4 exposes the frequencies of each kind of ostium in the three kinds of Otitis which were studied. When we compare the three Middle Ear diseases in relation to the ostium alterations, the size of the sample did not allow to reject the equality hypothesis among the groups. However, the results suggest that there may be differences among them (x² critical = 15.51 and x² calculated = 15.08).

The following graph shows the relation among the kinds of ostium in the Middle Ear diseases studied. The incidence of type 3 ostium is pointed out in the tympanic perforations and retractions and of type 5 ostium in the cholesteatome (Chart 1).

Chart 1. COM: Chronic Otitis Media CCOM: Choloesteomatous Chronic Otitis media TM RET: Tympanic Membrane Retraction

DISCUSSION

We define Otitis media as an inflammatory, infectious process or not, located of focal or generalized form in the tympanic cavity, which includes the tympanic portion of E.T. and the cellular mastoidal complex(4).

Several risky factors have been searched to explain the development of Otitis Media, among which intrinsic and extrinsic factors. The intrinsic ones are characterized by the presence of craniofacial malformations, mainly the palate anomalies; immunosuppression; ciliary illnesses and of mucus composition; anatomical blockages of E.T., characterized basically by the hypertrophy of pharyngeal tonsils; allergies, among others. The extrinsic factors are composed by the absence of the protection conferred by the maternal breastfeeding and composed by the active or passive tobaccoism. The association between these factors would propitiate pictures of Medium Otitis.

Amongst the innumerable attempts of classification and briefing of Medium Otitides pathogenesis, Paparella et al(4) suggested the "Continuum" hypothesis. Such theory establishes that the initial causing factor would be the functional tubal dysfunction or mechanism. Once the E.T. was not sufficient to balance the atmospheric and intratympanic pressures, there would be the start of a negative pressure cycle in the tympanic cavity. Such fact would try to be compensated, at a first moment, by the tympanic membrane retraction and, secondarily, by the plasma extravasation to the middle ear due to the rise of the intravascular hydrostatic pressure, configuring an Serous Otitis Media. In case that the starting factors were not corrected or clinical therapies were not instituted, the inflammatory process of the Middle ear would lead to chronification.

The Tympanic Membrane would suffer precocious and significant alterations caused by the liquid persistence the adjacencies and by the extreme negative pressure in the tympanic box. Consequently, the membrane could suffer located or diffuse processes of atrophy which, as fragile regions, could easily be broken. As a result we would have tympanic perforations with considerably bigger dimensions and more difficult regeneration than the ones which occurred in previously healthy tympanum(3,4).

In relation to the Chronic Otitis Media (COM), the percentage of cases observed through the rhinopharyngoscopy that showed pharyngeal ostium of the modified E.T. was 33.0%. The observed cases, uni- or bilaterally, can suggest that the E.T. dysfunction or the anatomical alteration of rhinopharynx itself can be the origin of the middle ear pathology. The endoscopic findings presented one high incidence of alterations in patients with otologic illnesses in relation to the control group, mainly among children. Amongst these alterations, hypertrophy of tissue lymphoid is pointed out, which appears in the study of COM in 19.0% of the cases and the inflammatory ostium, which was also considered an important cause of tubal dysfunction, occurring in 7.0% of COM.

In patients carrying Cholesteatomatous Chronic Otitis Media (CCOM), tubal ostiums alterations were found in 38.2% of the cases, with prominence for the cicatricial ostium, which contributed with 17.6% of the cases. We point out that amongst the patients who presented cicatricial ostium, they were submitted to previous otorhinolaryngologic surgery due to pharyngeal tonsil hypertrophy and or due to inferior nasal shells.

According to theory by Bezold (1888) for the genesis of primary cholesteatome, the tubal affection, which generates negative pressures in the tympanic cavity, would provide an aspiration of the tympanic membrane in its limper, more superior portion. Initially a simple, flat and of relatively wide edges aspiration occurs. This characteristic makes the desquamated skin inside this aspiration may still move the canal, propitiating its ventilation. Later, this aspiration goes deep to the superior and mastoidal region, becomes proportionally much wider than its edge and retains skin that cannot move, gets infected and characterizes primary cholesteatome. On the other hand, secondary cholesteatome is called this way for being consequence of a former illness of the tympanic membrane, either a marginal perforation, or an atelectasis, both probably caused by bad functioning of the Eustachian Tube(6).

The nasofibroscopic examination of our patients with tympanic membrane retraction allowed us to evaluate the sample of 29 studied ears and ostiums: 16 (55.2%) ears had the normal E.T. ostium and 13 (44.8%) ears had altered ostium. The results suggest that in ears with tympanic retraction there is an average percentage of approximately 50.0% of tubal pharyngeal ostium alterations. It is interesting to show that the most common types of tubal ostiums found were of the lymphoid hypertrophy (24.1%) and the hypoplasic (6.8%).

According to SADÉ et al.(7), the adhesive otitis media is a sequel caused by a middle ear inflammatory process, with long duration. It is still not perfectly clearly if the several degrees of tympanic retraction are events that occur in different periods of chronic otitis media, or if they are distinct illnesses. The atelectasis is a final developing period of tympanic retraction, which are: Period I: simple retraction; Period II: severe retraction; Period III: more advanced retraction TM on the promontory; Period IV: adhesion of the collapsed TM to the promontory.

The negative pressure of the tympanic cavity caused by tubal dysfunction cause the medial displacement of TM up to certain limits. These limits depend on the total volume of the tympanic cavity and the rapidity with which the tubal blockage is established. The process can tend to progression, so that the membrane start to re-cover the structures of the middle ear, with or without setting of the ossicles, characterizing the Adhesive Otitis media and the Tympanic Atelectasis, respectively. Erosion of long apophysis of the incus and the posterior-superior tympanum segment pexis with the head of the stape are possible developing this process(4,8).

Grimmer and Poe9(2005) defined, in a revision on the Dysfunction of the Eustachian Tube, that the causes of tubal dysfunction can be divided into the following categories: anatomical blockage, functional blockage or patent tube. Real anatomical blockage can occur due to mucous edema, polyps or mass injuries (lymphoid hypertrophy, rhinopharynx tumors). Functional blockage, that is, failure of tube opening in the absence of obstructive visible cause, is generally more frequent and is caused by extreme negative pressure in the middle ear inhibiting the capacity of tubal dilatation. Unfortunately until the present moment, there is not a completely satisfactory test to evaluate the Eustachian Tube's physiology and function. Valsalva maneuver, Politzer Method, Manometry, E.T. Insufflation, Sonometry, Tympanometry and use of radioisotopes substances are possible tests for the E.T. ventilation functions study and draining. These tests can promote useful information, however, asSloth and Lildholdt(10)(1989) affirmed , these studies that demonstrate functioning E.T., can indicate good surgical results, however inadequate tubal function evaluated from functional tests does not predict surgical successes or failures.

According to Marone et al(11)(1995), who carried through a study about the Eustachian Tube functions and its correlation with surgical results of Miringoplasties, the tubal functions play an important role in the middle ear cause and treatment. They concluded that some existing tests of evaluation of E.T. function, when associated, can have prognostic value in the analyzed surgical procedures.

Currently, intratubal endoscopic examination has already been carried out through transpharyngeal or transtympanic way in places which have appropriate material. The use of endoscope directly in the tubal lumen aims to evaluate both anatomy and function of the Eustachian Tube(12,13,14).

Poe et al(15)(2001), carried through a study with 40 patients, totalizing 58 ears with pathologies (cholesteatome, TM retraction, TM perforation, atelectasis, suppurative otitis media) and 22 normal ears. In this work Eustachian Tube was evaluated through intratubal endoscopic examination, demonstrating that all the 58 tubas corresponding to the affected ears presented significant pathological alterations with reduction of the dilatation tubal. The causes of these alterations were: mucous edema, tuba lateral wall movement reduction, polyp or another obstructive illness and reduction of the tubal dilatation. They concluded that the Eustachian Tube dysfunction seems to have some possible etiological factors, including: 1) primary mucous Illness: inflammation, infection and allergy; 2) Reflux proceeding from rhinopharynx (and possibly laryngopharyngeal reflux); 3) primary muscular disorders: hypotony, incoordination; 4) anatomical blockage.

Through the Eustachian Tube pharyngeal ostium endoscopic analysis carried through in our study, we managed to identify some of these factors that would induce to suppose tubal dysfunction, amongst them, peritubal inflammatory, infectious and allergic processes, tubal anatomical blockage of the rhinopharynx region and signals of laryngopharyngeal reflux.

We understand that the pathological endoscopic findings of the tubal ostium can explain the tubal dysfunction role of obstructive cause in the development of the middle ear illnesses. We suggest the routine of this examination in patients with the described otologic pathologies, as relevant study for the election of appropriate treatment and prognostic types of Tympanic Cavity pathologies.


CONCLUSION

- Pharyngeal Ostiums of the Eustachian Tube in children carrying Otitis Media have more morphologic alterations when compared with the ones of the control group;

- Children with Cholesteatomatous Otitis and Tympanic Membrane Retraction have the same pharyngeal ostiums of Eustachian Tube with bigger prevalence of anatomical alterations when compared with the adults with the same type of pathology;

- the 5 types of ostiums analyzed did not show significant difference in terms of its incidences.


BIBLIOGRAPHICAL REFERENCES

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1. Doctor - UNIFESP (Head Professor II in ORL at Faculdade de Medicina -Santo Amaro - UNISA-SP)
2. Resident on ORL at UNISA - SP
3. ORL Head Professor at Faculdade de Medicina UNISA - SP
4. Senior student at Universidade de Nova Iguaçu - RJ

UNIVERSIDADE DE SANTO AMARO - UNISA/SP

José Evandro Andrade Prudente de Aquino
Al. Ribeirão Preto, 410, ap 1106-São Paulo-SP ZIP- 01331-000 e-mail - clinicaorlsp@uol.com.br

This article was submitted to SGP (Sistema de Gestão de Publicações) at R@IO on February 18, 2007 and approved on April 29, 2007 at 17:17:45.