Advanced Arab Academy of Audio-Vestibulogy Journal

ORIGINAL ARTICLE
Year
: 2017  |  Volume : 4  |  Issue : 1  |  Page : 14--18

Tympanometric assessment of Eustachian tube function as a prognostic indicator in myringoplasty


Suresh Babu Undavalli1, Narayan Hanumanth Rao Kulkarni2, Sukrit Bose2, Anuradha Ananthaneni3,  
1 Department of ENT, Dr Pinnamaneni Siddhartha Institute of Medical Sciences and Research Foundation, Vijayawada, Andhra Pradesh, India
2 Department of ENT, BLDE Medical College, Bijapur, Karnataka, India
3 Department of Oral and Maxillofacial Pathology, St Joseph Dental College & Hospital, Duggirala, Andhra Pradesh, India

Correspondence Address:
Anuradha Ananthaneni
D/No 10/200, Anuradha ENT Hospital, Eluru Road, Gudivada, Krishna District - 521 301, Andhra Pradesh
India

Abstract

Aim To determine eustachian tube function in tubo-tympanic type of chronic ear disease and correlate it with pathological changes in middle ear. Objective To ascertain whether eustachian tube function had any demeanor upon the outcome of myringoplasty. Backgound The prevailing interest in the patho-physiology of the eustachian tube has been stimulated by the persistent incidence of middle ear effusion and chronic otitis media. The ongoing sophistication in current middle ear reconstructive surgery has added more dimensions to the study of eustachian tube and its effects in the course of reconstructive middle ear surgery. One of the prime elements accountable for failure of reconstructive middle ear surgery has been tubal dysfunction. Method In the present study eustachian tube function was evaluated in in 30 patients who were undergoing myringoplasty for tubo-tympanic type of chronic suppurative otitis media having central perforation by tuning fork tests, microscopic evaluation of the middle ear mucosa and Impedance audiometry. Results 70% of the myringoplasty cases had good surgical outcome and of the 24 cases that had good eustation tube function 87.5% had successful surgical outcome remaining cases had recurrence of otorrhea. Conclusion The results were validating good eustachain tube function as a criterion for electing cases under middle ear reconstructive surgery and Impedance audiometer assures a superlative means of appraising Eustachain tube function.



How to cite this article:
Undavalli SB, Kulkarni NH, Bose S, Ananthaneni A. Tympanometric assessment of Eustachian tube function as a prognostic indicator in myringoplasty.Adv Arab Acad Audio-Vestibul J 2017;4:14-18


How to cite this URL:
Undavalli SB, Kulkarni NH, Bose S, Ananthaneni A. Tympanometric assessment of Eustachian tube function as a prognostic indicator in myringoplasty. Adv Arab Acad Audio-Vestibul J [serial online] 2017 [cited 2018 Feb 23 ];4:14-18
Available from: http://www.aaj.eg.net/text.asp?2017/4/1/14/213892


Full Text

 Introduction



Reconstructive ear surgery is one of the most common surgeries performed by otologists ensuing improvement in hearing and nonpersistence of symptoms. The success of the surgery depends on proper functioning of the Eustachian tube. Eustachian tube function can be evaluated using computed tomography and manometric testing such as aspiration and deflation testing, tympanometry, and sonotubometry. Eustachian tube function test is performed to assess its physiological profile because it is the physiological functioning that is required for maintaining the normal functions of the middle ear. The modern impedance audiometer offers us the facility to ascertain physiological functioning of the Eustachian tube not only when the tympanic membrane is intact but also in the presence of a perforation. Hence, discerning Eustachian tube function preoperatively would help in increasing the success rate of reconstructive middle ear surgery [1],[2],[3].

 Aim and objectives



The present study was undertaken to determine Eustachian tube function in tubotympanic type of chronic ear disease and correlate it with pathological changes in middle ear mucosa and furthermore to ascertain whether Eustachian tube function had any demeanor upon the outcome of myringoplasty.

 Patients and methods



Thirty adult patients with tubotympanic type of chronic suppurative otitis media having central perforation, hearing loss of less than 40 db, good cochlear reserve on pure-tone audiometry, and who are undergoing myringoplasty at Shri B.M. Patil Medical College and Research Center were subjected to the study. Exclusion criteria were as follows: age younger than 16 years of age, hearing loss more than 40 db with atticoantral type of chronic suppurative otitis media, persistent purulent otorrhea despite adequate medical line of treatment, and presence of general diseases that could affect the outcome of the surgery or any other ENT disorders. Tuning fork tests including Rinnes, Weber’s, and Absolute bone conduction tests were performed with 256, 512, and 1024 Hz tuning forks. The ears were then subjected to microscopic evaluation to assess the condition of the middle ear mucosa, and based on these findings middle ear mucosa was classified into dry, moist, and boggy status. Pure-tone audiometry evaluation for hearing loss followed by impedance audiometry for Eustachian tube function was carried out in all the cases preoperatively.

 Observations and results



Preoperative observations

Out of the 30 patients studied, 22 (73.33%) were male and eight (26.66%) were female with an age range of 16–55 years and a mean age of 25.4 years. The chief complaint of all patients was discharge from the ear with a duration of 6 months to 3 years for which they were treated and at present otorrhea was absent. Laboratory investigations such as blood hemoglobin, total and differential white cell count, bleeding time, clotting time, and urine examination for albumin, microscopy, and sugar were within normal limits in all 30 selected patients.

Twenty (66.66%) cases had dry middle ear mucosa, four (13.33%) cases had boggy middle ear mucosa, and six (20%) cases had moist middle ear mucosa. Pure-tone audiometry revealed mild-to-moderate hearing loss in all cases. The mean hearing loss was 35.66 dB. Impedance audiometry revealed that 24 (80%) cases had good Eustachian tube function and six (20%) cases had poor Eustachian tube function. In all 24 cases having good Eustachian tube function, the range of opening pressure was 258–373 daPa. The mean pressure was 328.5 daPa. The range of residual pressure was 2–45 daPa. The mean residual pressure was 23.458 daPa. In all six cases having poor Eustachian tube function the range of opening pressure was 371–450 daPa with a mean pressure of 415.833 daPa. The range of residual pressure was 60–165 daPa and the mean pressure was 102.5 daPa.

Twenty-one (70%) cases of 30 cases that underwent myringoplasty had good surgical outcome and nine (30%) cases were unsuccessful. Of 24 cases of good Eustachian tube function, 21 (87.5%) cases had successful surgical outcome, and in the remaining three (12.5%) cases there was recurrence of otorrhea. All six cases with poor Eustachian tube function had surgical failure.

Postoperative results

After 6 weeks of myringoplasty, the nine cases of surgical failure had opening pressures between 360–444 daPa. The mean pressure was 406.55 daPa. The range of residual pressure was 20–150 daPa. The mean pressure was 71.11 daPa. The mean middle ear pressure was −8.030 daPa. None of the cases having the successful myringoplasty showed negative middle ear pressure postoperatively. The range of normal middle ear pressure was taken as +50 to −100 daPa ([Table 1]).{Table 1}

After 12 weeks, among the cases that had surgical failure the range of opening pressure was 358–417 daPa. The mean pressure was 394.11 daPa. The range of residual pressure was 30–135 daPa. The mean pressure was 80.66 daPa. The mean middle ear pressure was −7.8557 daPa. None of the cases of successful myringoplasty showed negative middle ear pressure postoperatively. The range of normal middle ear pressure was taken as +50 to −100 daPa.

 Discussion



The tubal dysfunction is one of the most important factors responsible for failure of reconstructive middle ear surgery [4],[5],[6],[7]. Even recently the importance of Eustachian tube function in middle ear surgery has been emphasized [8],[9]. Adequate functioning of the Eustachian tube is considered as one of the prerequisite for re-establishing a closed aerated tympanic cavity in tympanoplasty. The Eustachian tube function has been implicated in tympanoplasty failure both primarily via middle ear pressure dynamics and secondarily via recurrent otitis [10],[11]. Zollner [4] pioneered a qualitative and quantitative test, which measured the tubal opening pressure including an air stream of constant pressure into the nasopharynx through the nose. A reduction in the intratympanic pressure to indicate Eustachian tube patency in experimental animals was used by few researchers [12],[13],[14]. Miller [15] presented a technique for measuring the reduction of artificially produced intratympanic pressure, which occurs when the Eustachian tube opens during swallowing.

Tubal function was assessed by observing the middle ear clearance of a radio opaque fluid into the nasopharynx [16], using fluorescent solution [17],[18], water-soluble contrast substance under pressure through the external auditory meatus [19], the valsalva response [19], and acoustic impedance bridge [19],[20] to estimate tubal function with an intact drum.

The three functions of the Eustachian tube warrants separate testing procedure for individual functions. Eustachian tube function can also thus be evaluated by means of radiographic investigation, particularly computerized tomography, manometric testing such as aspiration and deflation testing, tympanometry, and sonotubometry.

Now many otologists routinely carry out tests for anatomical patency of Eustachian tube before surgery by passing some dye into the middle ear or a nylon thread. Nevertheless, these tests only tell us whether the Eustachian tube is anatomically patent or not. The purpose of undertaking the Eustachian tube function test is to access its physiological profile. For maintaining normal function of the middle ear the physiological functioning and not anatomical patency of the Eustachian tube is required. A modern impedance audiometer offers us the facility of ascertaining the physiological function of the Eustachian tube not only when the tympanic membrane is intact but also in the presence of a perforation.

In our study we have used a modern impedance audiometry bearing in mind its advantages: it can be used in perforated membrane, it is quick and noninvasive, patient compliance not required, it is accurate and inexpensive. Although according to published literature there are reports of over 90% success in the middle ear reconstructive surgery, the general experience is not exactly so. The average results are usually in the range of 75–80% [21],[22].

After ruling out infection and poor surgical technique, the common factor inherent in all failures is poor Eustachian tube function [23]. The conflicting reports mentioned above have much to do with the procedure involved in testing the Eustachian tube. We believe that the modern impedance audiometer offers the best procedure for evaluating Eustachian tube functions. On comparing the data by Munjal et al. [24] ([Table 2]), it is evident that, the lower the opening and higher the pressure, higher is the success rate of surgery. In our study in cases with good Eustachian tube function the mean opening pressure was 382.5 daPa and in cases having poor Eustachian tube function the mean opening pressure were 415.8 daPa. Follow-up after 6 and 8 weeks revealed mean opening pressure values of 406.55 and 394.11 daPa, respectively.{Table 2}

The opening pressure value is an important parameter in predicting the surgical outcome for myringoplasty. Sato et al. [25] studied Eustachian tube function in tympanoplasty using the positive and negative pressure equalization and the clearance tests. The study states that the positive pressure equalization and the clearance tests correlate with the outcome of the middle ear surgery. These data are also consistent with previous studies. On comparing the above data it reveals the same percentage of unsuccessful surgical outcome in good Eustachian tube function as ours. Our study revealed 100% surgical failure in poor Eustachian tube function ([Table 3]). This discrepancy can be attributed to different methods used in measuring Eustachian tube function but the conclusions are pretty much the same.{Table 3}

Good Eustachian tube function always carries better prognosis in the surgical outcome of myringoplasty and vice versa. This fact was more apparent when all six cases having poor Eustachian tube function preoperatively had a surgical failure. All cases of bilateral chronic suppurative otitis media in our study had surgical failures. This includes cases even with good Eustachian tube function. We attribute this to the prolonged state of the existing disease. Adkins et al. [27] had shown similar failure rate with bilateral perforations and they attributed this to a more severe and prolonged etiology of the otitis in these patients. In contrast, Packer et al. [28] did not find the correlation between bilateral perforation and the success. Most others do not comment on the presence of perforation in the opposite ear.

In the same study by Packer et al. [28] the successful closer rate obtained was 89% − that is, 63 of 71 cases. Seven of the eight failures occurred in patients with total or near-total perforations and they attributed this to the increased technical difficulty and the increased area to be vascularized and epithelialized in large perforations. However, contrary to these observations, there was no much correlation in our study.

The state of the middle ear mucosa also did influence the results of surgical outcome. In all failed cases the state of middle ear mucosa was not dry and all cases showing poor Eustachian tube function had diseased middle ear mucosa. The study by Adkins et al. [27] shows that the condition of the middle ear mucosa preoperatively will not have any bearing on the outcome of the surgery. However, in our study it is evident that preoperative middle ear status is having significant bearing on the outcome of the surgery.

In a study by Biswas [9] there was a success rate of 85.29% in a group of patients in whom preoperative tubal function was normal. In another study by El-Guindy [29],[30], they reported 95% success rate of myringoplasty in patients in whom preoperative tubal function was normal. In another study by Virtanen et al. [26], there was a success rate of 80% in patients in whom there is normal preoperative tubal function.

It can thus be emphatically stated that good Eustachian tube function is a prerequisite for successful middle ear reconstructive surgery. An elaborate assessment of Eustachian tube function can be obtained using modern impedance audiometry and it should be a routine investigation in all cases planned for surgical reconstruction of the middle ear.

 Conclusion



Impedance audiometer offers the best means of assessing Eustachian tube functions. The prognosis of the middle ear reconstructive surgery has a direct correlation with Eustachian tube functions. Bilateral disease does not carry a good prognosis in the operated ear despite the ear having good Eustachian tube functions. The status of the middle ear mucosa has a direct correlation with the outcome of surgery. A dry perforation carries good surgical prognosis as well as good Eustachian tube functions. Although the assessment of Eustachian tube function has not been popularized as much as it warrants it is of paramount importance not only before undertaking any surgery for suppurative otitis media but also for establishing its etiological basis. Thereby, it should be carried out as a routine investigation in all cases planned for surgical reconstruction of the middle ear.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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