Does Successful Myringoplasty Affect Eustachian Tube Function?

Abstract

Eustachian tube (ET) is a tube connecting the middle ear cavity with the nasopharynx and has an important role in equalization of pressure around TM. Many studies investigated the role of ET function tests on the results of myringoplasty/tympanoplasty. Our aim is to assess the effect of successful myringoplasty on Eustachian tube function. A prospective study included 37 patients admitted to the E.N.T Department at Sohag University Hospital in the period between March 2018 and March 2019 suffering from dry central perforation necessitating myringoplasty. Pre-operative E.T function tests using tympanometry and methylene blue dye test were done. Post-operative follow-up tympanometry was done after 3 months for those with successful myringoplasty and compared to the preoperative assessment. Thirty-one (83%) patients had functioning ET, 6 (17%) had non-functioning ET and 32 patients (86.5%) had successful myringoplasty (taken healthy graft). According to the effect of myringoplasty on ET function test 3 months following surgery, (9%) were affected, either improved (3%) or worsen (6%), while (91%) were not affected by tympanometry in those with taken healthy graft cases. In our study, there was no significant effect of myringoplasty on E.T function.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-021-02534-8.

Introduction

Eustachian tube (ET) is a tube connecting the middle ear cavity with the nasopharynx. It measures about 36 mm in length and, directed downwards and forward in adults. Its lateral third is bony and opens in the anterior wall of the middle ear, while the medial two-thirds is cartilaginous and opens in the superolateral wall of the nasopharynx, about 1 cm behind the posterior end of inferior turbinate. It is lined by respiratory mucosa continuous with that of the middle ear and nasopharynx [1].

It is normally closed at rest and opens actively during yawning and swallowing by the action of the tensor palati and to a lesser extent the levator palati. The main function of the ET is to equalize the air pressure on both sides of the tympanic membrane and to allow drainage of secretions of the middle ear [2]. It performs three primary functions: gas transfer, pressure equalization between the nasopharynx and middle ear, clearance of mucus from the middle ear, and prevention of sound or fluid reflux from the nasopharynx [3].

Although the ET is normally closed in healthy individuals, these actions are permitted when the cartilaginous portion of the tube is momentarily pulled open during swallowing by para tubal muscles. In infants and young children, the tube is wider, shorter, and more horizontal allowing the easier spread of infection into the ME [4].

There are several ET function tests including the Valsalva test, the Politzer test, catheterization, Toynbee's test, tympanometry, radiological test, saccharine, or methylene blue test, and; sonotubometry [5].

Myringoplasty means repair of the tympanic membrane. Graft materials of choice are temporalis fascia or the periosteum taken from the patient. The repair can be done by two techniques, the underlay or the overlay. In the underlay technique, margins of perforation are freshened and the graft placed medial to perforation or tympanic annulus, if large, and is supported by gel foam in the middle ear. In the overlay technique, the graft is placed lateral to the fibrous layer of the tympanic membrane after carefully removing all squamous epithelium from the lateral surface of the tympanic membrane remnant. There are prognostic factors for successful myringoplasty, one of these is Eustachian tube function which may lead to broken graft if it is dysfunctioning; so, it could be done before and after the operation to predicate the success of the operation [6].

Many studies investigated the role of ET function tests on the results of myringoplasty/tympanoplasty [7–10]. Our aim is to document if successful myringoplasty affects the Eustachian tube function or not.

Patients and Methods

We performed a prospective study recruiting patients older than 16 years presented to the ENT outpatient clinic at Sohag University Hospital in the period between march 2018 and march 2019 suffering from dry perforation necessitating myringoplasty. The study protocol was approved by the ethics committee of the Faculty of Medicine, Sohag University. Informed consent was taken from all cases. Exclusion criteria were as follows:

Pediatric age group, patients with a history of previous middle ear surgery, patients with sinonasal or nasopharyngeal pathology that can obstruct Eustachian tube and affect its function and outcome of surgery.

For all patients, full history taking, general and local examination were done, including nasopharyngeal examination. Full audiological assessment and complete laboratory investigations were done.

Those who fulfill the selection criteria were subjected to an E.T function test using tympanometry before surgery. A negative or positive pressure ( − 200 or +200 mm H₂O) is created in the middle ear and the patient is asked to swallow five times in 20 s. The ability to equilibrate the pressure indicates normal tubal function. Sterile methylene blue dye was injected under microscopic control in the middle ear at the tympanic orifice of ET opening through the perforation, and with the use of an endoscope, the nasopharyngeal opening of the ET was focused to look for the dye to test patency and drainage functions and recorded as following: < 10 min as normal, 10–20 min as partial dysfunction, > 20 min as gross dysfunction.

Within one week from these tests, All patients were subjected to myringoplasty using a periosteal graft by underlay technique under general anesthesia. Saline injection into the tympanic orifice of ET during surgery was done in all patients to clear any inspissated discharge in the ET. The graft was placed under the annulus and supported by gel foam in the middle ear to prevent medial displacement. Follow up tympanometric ET function test was done for all patients who have a successful anatomic outcome of myringoplasty with taken healthy graft 3 months after surgery. Those with a broken graft were excluded from the study.

Statistical Analysis

Descriptive statistics were expressed as mean, standard deviation (SD) for quantitative variables and frequency, and percentages for qualitative variables using the Chi test as a statistical test applying to results.

Results

The age range of our cases was from 16 to 45 years, with a mean age $\pm$ SD 25.5 $\pm$ 24. The patients were classified according to age into three groups: (a) < 20 years old, nine patients (24%), (b) from 20 to < 40 years old, twenty-six patients (70%), (c) 40 or above years old, two patients (6%). Among all patients, twelve cases (32%) were males and 25 cases (68%) were females. Thirty of them were from rural areas (81%) while seven (19%) were from urban areas.

Twenty-five patients had unilateral chronic suppurative otitis with dry perforation (68%), while twelve patients (32%) had bilateral dry, central perforations.

Of all patients, 28 cases gave a history of hearing loss (77%). All patients were presented for the first time without previous ear surgery.

Twenty-nine patients (78%) showed mild conductive hearing loss by audiometry, while eight patients (22%) showed moderate conductive hearing loss.

ET Function Test by Tympanometry before the Operation

The study group was classified according to the ET function by tympanometry into two groups: (1) Functioning ET including 31 cases (84%), (2) Non-functioning ET: 6 (16%) of patients (Fig. 1).

Fig. 1.

Distribution of E.T function test before myringoplasty operation by tympanometry

ET Function test by Methylene Blue Dye before the Operation

According to methylene blue test patients were classified into three groups: (i) Good function: twenty (54%) patients, (ii) Partial dysfunction: fifteen (41%) patients, (iii) Gross dysfunction: two (5%) patients as shown in Supplemental Table 1 and Fig. 2.

Fig. 2.

Distribution of passage of dye before myringoplasty

By application of both tests to all patients included in our study before the operation, our patients were classified into four groups: (A) Twenty patients (54%): had functioning ET by both tests, (B) Eleven patients (30%): had functioning ET by tympanometry with partial (9 cases) or gross (2 cases) dysfunction by methylene blue dye, (C) Six patients (16%): had non-functioning ET by tympanometry with partial (4 cases) or gross (2 cases) dysfunction by the dye, (D) No case who was functioning by dye proved to be non-functioning by tympanometry as shown in Fig. 3.

Fig. 3.

Distribution of combination of results of E.T function test by dye and tympanometry before myringoplasty

Five of our cases had broken graft on the follow-up, one of them performed cortical mastoidectomy and tympanoplasty, another one had bilateral persistent aural discharge and the third patient refused to repeat E.T function test and those 3 cases were excluded from the post-operative study of E.T function. ET function tests applied to the remaining two cases with broken graft.

ET Function Test by Tympanometry Three Months after Operation in Cases with taken Graft

The test was conducted on all patients with a taken graft (32 cases) and classified as the following: (1) Functioning ET: in twenty-five (68%) patients, (2) Non-functioning ET: in seven (19%) patients as shown in Fig. 4.

Fig. 4.

Distribution of E.T function test by tympanometry 3 months after myringoplasty, in those with taken graft

By comparing both ET function tests before operation and ET function test by tympanometry post-operatively in those with taken graft (32 cases) we found the following results: one patient (3%) was functioning by both tests preoperatively and non-functioning by tympanometry post-operatively, one patient (3%) was non-functioning by both tests preoperatively and functioning by tympanometry post-operatively, one patient (3%) was non-functioning by both tests preoperatively and still non-functioning by tympanometry post-operatively while sixteen patients (43%) were functioning by both tests preoperatively and still functioning by tympanometry post-operatively, eight patients (21%) were functioning by tympanometry with partial (7 cases) or gross (1 case) dysfunction by dye and still functioning by tympanometry post-operatively while one patient (3%) was functioning by tympanometry with gross dysfunction by dye and non-functioning by tympanometry post-operatively, there were four patients (11%) non-functioning by tympanometry with partial dysfunction by dye and still non-functioning by tympanometry post-operatively as shown in Supplemental Table 1.

Also by comparing the results of ET function tests pre and post-operatively in the two cases with broken graft we found the following: one patient (3%) had a functioning ET by tympanometry with good function by dye preoperatively and functioning by tympanometry with partial dysfunction by dye post-operatively, the other patient (3%) had functioning ET by tympanometry with good function by dye preoperatively and still functioning by both tests post-operatively as shown in Supplemental Table 2.

Discussion

Eustachian tube function tests are one of the important tools in the evaluation and follow-up of prognosis in patients with chronic suppurative otitis media with central perforation [8].

In a study done by Biswas [11], there was a success rate of 85% in a group of patients in whom preoperative tubal function by tympanometric measures was normal, and El-Guindy [12] obtained the same results, with a 95% success rate of myringoplasty in patients with normal preoperative tubal function assessment by tympanometry. In another study by Vartiainen and Nuutinen [13], there was a success rate of 80% in patients with normal preoperative tubal function by inflation-deflation test by tympanometry and by the forced response. In this study, there was a success rate of 86.5% (taken graft cases).

Prasad et al. [9], studied the mucociliary function of E.T in patients with chronic otitis media with tympanic membrane perforation. They concluded that saccharin and methylene blue dye were correlated in evaluating the E.T function; however, it could not be determined whether the failure of dye, saccharine, or radioisotopes to appear in the nasopharynx was due to the presence of middle ear effusion, middle ear mucosal disease, or other failures of E.T function. Injection of E.T by saline was done in all cases during the operation aimed to clear ET lumen off any inspissated discharge to improve its function.

In this study, 54% of preoperative patients were functioning ET by both tympanometry and methylene blue dye, 30% had functioning ET by tympanometry with partial dysfunction or gross dysfunction by the dye, no patient with non-functioning E.T by tympanometry and good function by dye and 16% with non-functioning ET by tympanometry with partial or gross dysfunction by dye test. After 3 months of myringoplasty, five cases had broken graft (11%), and E.T function tests repeated on two of them and showed no change in E.T function by methylene blue dye in one case, and the other partial dysfunction was noticed with no change in function by tympanometry. By comparing both tests before the operation and 3 months postoperatively in these 2 cases, there was no significant difference between the results of both tests. We can say that the E.T function is not related to myringoplasty operation. This might be explained by the fact that many other factors are controlling the function of E.T post-operatively as a type of mastoid, middle ear mucosa, well-aerated tympanic cavity after taken graft in addition to state of the nasopharynx, which should be evaluated well pre and post-operatively.

Various factors have been contributing to the outcome of myringoplasty, of these, ETF can be practically assessed before the operation. ETF tests must be a part of the investigational preparation in managing cases of CSOM. These tests are important in that they have good predictive value. Heermann et al. [14] noticed that besides E.T function, many other factors control the success of myringoplasty as graft material used, size, site of perforation, stage of CSOM either quiescent/ active, condition of middle ear mucosa, age of the patient, tympanosclerosis in the remaining part of TM, the status of the opposite ear, the technique of operation and experience of the operating surgeon. There are possible risk factors for the success of myringoplasty as age, gender, history of perforation, otorrhea, the status of the nose, the type of anesthesia, surgical approach, ossicular status, canal packing, post-operative antibiotic cover, smoking, and alcoholism [8, 15–17].

Adequate function of the E.T undoubtedly remains as one of the prerequisites for re-establishing a closed aerated tympanic cavity in tympanoplasty. E.T function in the successful outcome of myringoplasty remains controversial, some studies had demonstrated a correlation between normal pre-operative tubal function and successful grafting, but other studies had failed to confirm this [2, 7, 18–20]. MacKinnon [21] measured ventilator function of the E.T in 80 cases before myringoplasty with three grades of good, moderate, and poor Eustachian function described depending on the residual negative intratympanic pressure, eighty percent of cases operated on with good and moderate grades of Eustachian function had a healed TM, only 20% of those with poor Eustachian function had a similarly successful result.

Fateen et al. [22], concluded that 95.6% of ears with good post-operative tubal function resulted in successful graft uptake, whereas only 42.8% of ears with poor postoperative tubal function healed well emphasizing the essence of E.T function for successful graft uptake. Holmquist [7], explicitly stated that ears with “poor” pre-operative E.T function had a higher risk for atelectasis with retraction pockets or secretory or adhesive otitis media.

Kurien et al. [23] found that the diseased and edematous mucosa had a graft uptake of 50% when compared with dry middle ear mucosa that showed uptake of 69.5%. They claimed that the preoperative factors, such as dry or wet ear, site of perforation do not affect the graft uptake rate. On the other hand, Niteshore et al. [24], found that all cases with a blocked E.T had a failure rate of 100%, with a significant relationship between non-functioning E.T. and failure of the surgery. The overall success rate in this study was 90%. Raj and Meher [25], reported a success rate of 81% when it was correlated with the function of E.T, all those patients (100%) with a non-functioning E.T failed to take up the graft confirming that a normal functioning E.T is an important determinant in the outcome of the surgery.

Seifert et al. [26] mentioned that a successful surgical repair of drum perforation depends upon a normally functioning E.T. Holmquist [7, 21] found a good correlation between preoperative ETF and the success rate of tympanoplasty.

In our series, myringoplasty affected ET function in only 9% of our cases either improved (3%) or worsen (6%), while 91% showed no effect of the operation in taken graft cases.

Conclusion

In our study, there was no significant effect of successful myringoplasty on E.T function. Graft failure does not significantly affect E.T function.

Supplementary Information

Below is the link to the electronic supplementary material.

Funding

No funding was needed.

Declarations

Conflict of interest

The authors declare that they no conflict of interest.