Balloon Eustachian Tuboplasty and Grommet Insertion: A Combined Surgical Treatment for Chronic Suppurative Otitis Media with Eustachian Tube Dysfunction

Abstract

Objectives. This study aims to evaluate the effectiveness of Balloon Eustachian tuboplasty (BET) and grommet insertion in patients having chronic suppurative otitis media combined with eustachian tube dysfunction (CSOM-ETD). Methods. We evaluated the data of CSOM-ETD patients (n = 96) from January 2019 to January 2021, who were divided into the following groups: 48 cases underwent BET (BET group) and 48 cases underwent BET plus Grommet insertion (BET + Grommet group). The air-bone gap (ABG), Eustachian Tube Dysfunction Questionnaire (ETDQ‐7) score, Eustachian tube inflammation scale, Chronic Otitis Media Outcome Test 15 (COMOT-15), Valsalva maneuver, and patient satisfaction were evaluated after surgery. Results. The postoperative ABG in the BET + Grommet group was better than that in the BET. In addition, the ABG was improved obviously in the BET + Grommet group at 6 and 12 months after the corresponding surgery. Moreover, the Eustachian tube inflammation scale, ETDQ-7, and COMOT-15 scores were reduced after the treatment with the combination of BET and Grommet insertion at 6 and 12 months. The postoperative ETDQ-7 score, Eustachian tube inflammation scale, and COMOT-15 score were lower in the BET + Grommet group than that in the BET group. The percentage of patients who could perform a positive Valsalva maneuver was significantly higher in the BET + Grommet group than that in the BET group at 6 months and 12 months after surgery with increased patient satisfaction. Conclusion. Our results demonstrate that BET plus Grommet insertion showed better treatment efficacy for patients with CSOM-ETD than BET alone via improving the Eustachian tube function hearing outcome and quality of life with less Eustachian tube inflammation.

This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

1. Introduction

Otitis media (OM), characterized by infection, inflammation, and the production of persistent effusions in the middle ear, mainly includes acute otitis media (AOM), chronic otitis media with effusion (COME; glue ear), and chronic suppurative otitis media (CSOM) [1,2]. CSOM (sometimes referred to chronic OM [3]) is a chronic polymicrobial infection with perforation of the tympanic membrane [4,5], thus being the common and major cause of persistent or intermittent ear discharge, as well as acquired hearing impairment and disability [2,6]. The hearing loss had a negative impact on the quality of life via affecting the speech and language skills, employment prospects, and children’s psychosocial and cognitive development [2]. Moreover, mortality was increased due to complications of CSOM, for instance, the intracranial complications (brain abscess and meningitis) are the most common causes of death in CSOM patients [7]. Worth mentioning, eustachian tube dysfunction (ETD) was reported to impair pressure equilibration in the middle ear and perturb the middle ear aeration, thus resulting in the classic symptoms of CSOM, which is found in 70% of patients undergoing middle ear surgery [8]. Therefore, finding an effective therapy for patients having CSOM combined with ETD (CSOM-ETD) is urgent and necessary.

Balloon Eustachian tuboplasty (BET), as a second-line treatment in cases in which adenoidectomy and paracentesis have failed, is a treatment option used to solve ETD [9,10]. Besides, it has been also widely used as a surgical approach for OM [11,12], which, however, did not achieve significant symptom improvement with an effective rate of only 66% [13]. A previous study showed that simultaneous BET and hearing reconstruction surgery can effectively improve the hearing degree in CSOM-ETD patients with better Eustachian tube function [14]. Moreover, BET could be used as an adjunctive procedure in the treatment of CSOM with obstructive Eustachian tube dysfunction (OETD) [15]. The Grommets insertion (also known as ventilation or tympanostomy tubes) as one of the most common surgical procedures for OM [16,17] cannot directly resolve ETD being associated with several complications, such as infection, persistent perforation, and tympanosclerosis [18]. According to a previous study, the BET combined with grommet insertion could effectively reduce the complications for patients with chronic dilation Eustachian tube dysfunction (CDETD) [19]. Therefore, we performed this retrospective study to determine the combined effectiveness of BET and grommet insertion in CSOM-ETD patients via evaluating the hearing ability, eustachian tube function, Eustachian tube inflammation, quality of life, and patient satisfaction.

2. Materials and Methods

2.1. Demographic Data of Subjects

A total of 96 ears from 96 patients having CSOM combined with ETD (CSOM-ETD) were observed from January 2019 to January 2021 with the age ranged from 23 to 61 years, who were divided into the following groups: 48 cases underwent BET (BET group), and 48 cases underwent BET plus grommet insertion (BET + Grommet group).

2.2. Inclusion and Exclusion Criteria

All CSOM-ETD subjects fulfilled the following inclusion criteria: (1) The patients were diagnosed as CSOM, a perforated tympanic membrane with persistent drainage from the middle ear lasting >6∼12 weeks [20]; (2) Patients were identified as severe ETD according to the Eustachian Tube Dysfunction Questionnaire (ETDQ‐7, a seven‐question survey, Table 1) with the total score of ≥14.5 (mean score ≥2.1) and the symptoms lasting more than 3 months [15,21]. Exclusion criteria: (1) Patients had previously undergone treatment; (2) Patients were due for revision procedure; (3) Patients had a congenital ear anomaly, a history of ear surgery within the past 6 months, a history of head and neck cancer, acute otitis media, refractory chronic rhinosinusitis, recent use of ototoxic medications, or pregnancy.

Table 1

Evaluation of Eustachian tube function by the Eustachian Tube Dysfunction Questionnaire (ETDQ‐7).

Symptom	No problem	Moderate problem	Severe problem
Pressure in the ears?	1∼2	3∼5	6∼7
Pain in the ears?
A feeling that your ears are clogged?
Ear symptoms when you have a cold or sinusitis?
Cracking or popping sounds in the ears?
Ringing in the ears?
A feeling that your hearing is muffled?
Patients with ETD	ETDQ‐7 total score of 14.5 (mean item score 2.1)

2.3. Surgical Procedure

All patients performed BET surgery under general anesthesia. In brief, a balloon catheter (20 mm in length and 3 mm in width) was introduced into the cartilaginous part of the Eustachian tube endoscopically through the nasal cavity, which was inflated with distilled water to achieve a pressure of 10 bars for maintaining 2 minutes. In the BET + Grommet group, the patients also performed bilateral insertion of ventilation tubes in the tympanic membranes. All patients were followed up for 12 months.

2.4. Hearing Test Using Air-Bone Gap (ABG)

Using a Madsen OB922 pure-tone audiometer (Otometrics, Taastrup, Denmark), the air and bone conduction thresholds were measured at frequencies of 500 Hz, 1 kHz, 2 kHz, and 4 kHz, followed by calculating the air-bone gap (ABG). Surgical success was defined as an ABG ≤20 dB [22].

2.5. Chronic Otitis Media Outcome Test 15 (COMOT-15)

The disease-specific quality of life (QoL) was measured using COMOT-15 (total score: 0∼100) [23], which consists of three subscales called ear symptoms, hearing function, and mental health, as well as two other questions: (1) an overall evaluation of the impact of CSOM on QoL and (2) the frequency of doctor visits as a result of CSOM in the previous 6 months. Higher scores in the COMOT-15 overall score correlate with a poorer QoL.

2.6. Eustachian Tube Inflammation Scale

Using nasal endoscopy, the assessment of Eustachian tube inflammation from normal to severely inflamed mucosa (Grade 1–4) was based on mucosal inflammation within the nasopharyngeal orifice and lumen, as well as the Eustachian tube function according to a previous study [24].

2.7. Positive Valsalva Maneuver and Subjective Satisfaction

When performing the Valsalva maneuver, the patient could find the ‘‘pop’’ sound in their ears which indicated positive Valsalva maneuver. At 6 months and 12 months postoperatively, patients were asked for their opinion on the surgery based on the satisfied or dissatisfied [25].

2.8. Statistical Analysis

All two-sided P values are regarded as statistical significance at the 0.05 level. The descriptive statistics presented as means ± SD and categorical variables as counts (n) and percentages (%) were analyzed using SPSS Statistics. The χ² test was performed to compare categorical variables between groups, and the Student’s t-test to compare descriptive statistics. The paired t-test was performed to compare pre and postoperative data.

3. Results

3.1. General Characteristics of the CSOM-ETD Patients in the Two Groups

Demographic data for CSOM-ETD patients in the BET group and the BET + Grommet group are shown in Table 2, which showed no significance of age (42.52 ± 10.90 years vs. 40.27 ± 12.05 years, P = 0.340), gender (P = 0.683), and ear sides (P = 0.100) between the two groups.

Table 2

General characteristics of the CSOM-ETD patients in the two groups.

	BET group	BET + Grommet group	P
Age (years)	42.52 ± 10.90 (25∼60)	40.27 ± 12.05 (23∼61)	0.340
Gender
Male	25	22
Female	23	26	0.683
Ear sides
Left	17	26
Right	31	22	0.100

3.2. Improvement of ABG after the Treatment with the Combination of BET and Grommet Insertion

We determined the postoperative ABG and the improvement in ABG after surgery (Table 3 and Figure 1). The average preoperative ABG was 24.19 ± 12.8 dB in the BET group and 25.50 ± 10.51 dB in the BET + Grommet group with no significant difference ($P=0.584$). Moreover, the postoperative ABG in the BET + Grommet group (6 months: 18.06 ± 10.34 dB; 12 months: 15.40 ± 10.12 dB) was better than that in the BET group (6 months: 23.31 ± 10.56 dB; 12 months: 22.29 ± 10.65 dB, both $P<0.05$). In addition, the ABG was obviously decreased in the BET + Grommet group at 6 and 12 months after the corresponding surgery (both $P<0.05$). A postoperative ABG of ≤20 dB was observed in 43.75% (6 months) and 45.83% (12 months) patients in the BET group and 54.17% (6 months) and 66.67% (12 months) patients in the BET + Grommet group.

Table 3

The preoperative and postoperative air-bone gap (ABG) of the CSOM-ETD patients in the two groups.

Groups	Preoperative	Postoperative
		6 months	12 months
BET group	24.19 ± 12.8	23.31 ± 10.56	22.29 ± 10.65
BET + Grommet group	25.50 ± 10.51	18.06 ± 10.34${}^{\ast }$	15.40 ± 10.12${}^{\ast }$
P	0.584	0.016	0.002

Note: ${}^{\ast }$$P<0.05$, the intragroup comparison with preoperative data.

[figure(s) omitted; refer to PDF]

3.3. Improvement of ETDQ-7, Eustachian Tube Inflammation Scale, and COMOT-15 after the Treatment with the Combination of BET and Grommet Insertion

As illustrated in Table 4 and Figure 2, the preoperative ETDQ-7 scores (BET + Grommet group: 27.19 ± 6.11; BET group: 26.4 ± 5.56) and Eustachian tube inflammation scale (BET + Grommet group: 2.98 ± 0.81; BET group: 3.08 ± 0.74) showed no significant difference between the two groups (both $P>0.05$). The Eustachian tube inflammation scale in the BET + Grommet group (6 months: 1.92 ± 0.87; 12 months: 1.48 ± 0.50) and the BET group (6 months: 2.56 ± 1.17; 12 months: 2.04 ± 0.82) was decreased at 6 and 12 months after surgery (all $P<0.05$). Moreover, the ETDQ-7 scores were reduced after the treatment with the combination of BET and Grommet insertion at 6 months (21.77 ± 6.34) and 12 months (18.04 ± 6.38, both $P<0.05$). The postoperative ETDQ-7 score and Eustachian tube inflammation scale were lower in the BET + Grommet group than the BET group (all $P<0.05$). In addition, 6 and 12 months after surgery, there were only one (2.08%) and three (6.25%) patients in the BET group, but 12.50% (6/48) and 31.25% (15/48) in the BET + Grommet group who achieved a normal ETDQ-7 score of less than or equal to 14.

Table 4

Improvement of ETDQ-7, Eustachian tube inflammation scale, and COMOT-15 after the treatment with the combination of BET and Grommet insertion.

	Preoperative	Postoperative
		6 months	12 months
ETDQ-7 scores
BET group	26.4 ± 5.56	24.75 ± 5.88	22.23 ± 6.34${}^{\ast }$
BET + Grommet group	27.19 ± 6.11	21.77 ± 6.34${}^{\ast }$	18.04 ± 6.38${}^{\ast }$#
P	0.509	0.019	0.002
Eustachian tube inflammation scale
BET group	3.08 ± 0.74	2.56 ± 1.17${}^{\ast }$	2.04 ± 0.82${}^{\ast }$#
BET + Grommet group	2.98 ± 0.81	1.92 ± 0.87${}^{\ast }$	1.48 ± 0.50${}^{\ast }$#
P	0.513	0.003	<0.001
COMOT-15 scores
BET group	40.79 ± 15.49	39.98 ± 15.03${}^{\ast }$	38.38 ± 15.54${}^{\ast }$#
BET + Grommet group	40.60 ± 15.92	33.42 ± 15.58${}^{\ast }$	30.60 ± 15.89${}^{\ast }$#
P	0.954	0.038	0.0173

Note: ${}^{\ast }$$P<0.05$, the intragroup comparison with preoperative data; ^#$P<0.05$, intragroup comparison with the postoperative data at 6 months.

[figure(s) omitted; refer to PDF]

3.4. Improvement of QoL after the Treatment with the Combination of BET and Grommet Insertion

Based on the result of COMOT-15 score (Table 4 and Figure 2), we found no significant difference in preoperative QoL between the BET + Grommet group (40.60 ± 15.92) and the BET group (40.79 ± 15.49, $P=0.954$), which was improved in both groups after the treatments at 6 months (BET + Grommet group: 33.42 ± 15.58; BET group: 39.98 ± 15.03) and 12 months (BET + Grommet group: 30.60 ± 15.89; BET group: 38.38 ± 15.54, all $P<0.05$). Besides, the combination of BET and Grommet insertion had better effect on improving the QoL of CSOM-ETD patients than those receiving BET alone (both $P<0.05$).

3.5. Comparison of Positive Valsalva Maneuver and Patient Satisfaction in the Two Groups

The percentage of patients who could perform a positive Valsalva maneuver was significantly higher in the BET + Grommet group than in the BET group at 6 months (62.50% vs. 37.50%) and 12 months (83.3% vs. 56.25%) after surgery (Figure 3(a)). Additionally, the percentage of satisfactory outcomes in the BET + Grommet group vs the BET group were 58.33% and 77.08% at 6 months after surgery, as well as 68.75% and 89.58% at 12 months after surgery, respectively (Figure 3(b)). Furthermore, only few complications were seen during these the procedures, namely, only two patients in the BET group kept slight tenderness, which was relived at 6 and 12 months postoperatively, indicating there was no difference regarding to the adverse events between the two groups.

[figure(s) omitted; refer to PDF]

4. Discussion

Grommet insertions are traditional treatment for ETD and/or recurrent/chronic otitis media because of the persistent middle ear fluid, frequent ear infections, or ear infections that persist after antibiotic therapy, to re-establish ambient-middle ear pressure, resolving inflammation, clearing effusions, and improve hearing, thus being the most commonly performed ambulatory procedure [26–28]. BET as a minimally invasive intervention first described in 2010 has been successfully investigated by randomized control trials and clinical studies in the past decade [29,30]. Considering BET surgery did not achieve significant symptom improvement of OM, the combination treatment with BET and Grommet insertion has been evaluated in OM [12,31,32] and ETD [19].

As demonstrated by Chen S et al., at 12 months after the operation, the ABG an important indicator of hearing status [33] in children having otitis media with effusion treated with BET combined with myringotomy and Grommet insertion was smaller than those treated with myringotomy alone [34]. Moreover, the average ABG improvement was found in patients with CSOM and OETD treating with the combination of tympanoplasty and BET when compared with the control subjects enrolled for tympanoplasty [15], suggesting both Grommet insertion and BET could improve the hearing ability. In our study, the ABG was decreased obviously in the BET + Grommet group at 6 and 12 months after the surgery, and the postoperative ABG in the BET + Grommet group was better than that in the BET group. Additionally, based on the Japan Clinical Otology Committee criteria [35], a postoperative ABG of ≤20 dB for calculating hearing improvement was observed in 43.75% (6 months) and 45.83% (12 months) patients in the BET group and 54.17% (6 months) and 64.58% (12 months) patients in the BET + Grommet group. All mentioned above indicating the combination of BET and Grommet insertion could significantly increase the hearing function.

It has generally been considered that surgery for improving hearing can be considered only when eustachian tube function becomes normal [36]. COME patients treated with BET and grommet insertion was reported to have an improvement in eustachian tube function and structure [12,32]. In a previous study, the ETDQ-7 score with total score of ≥14.5 (mean score of ≥2.1) showed 100% sensitivity and 100% specificity for categorizing a patient as having ETD [37]. At 6 and 12 months after surgery, there were only 2.08% and 6.25% patients in the BET group who achieved a normal ETDQ-7 score ≤14.5, respectively, but 12.50% and 31.25% in the BET + Grommet group. In addition, ETDQ-7 and COMOT-15 scores were reduced after the treatment with the combination of BET and Grommet insertion at 6 and 12 months with the improvement of Valsalva maneuver. The postoperative ETDQ-7 and COMOT-15 scores were lower in the BET + Grommet group than the BET group accompanied by higher positive Valsalva maneuver, indicating the significant efficacy of this combination for the treatment of ETD. Because mucosal inflammation is the most common cause for ETD [24], a scale for Eustachian tube mucosal inflammation was determined, and the result revealed that the alleviated inflammation in both BET + Grommet group and BET group at 6 and 12 months after surgery, especially in the BET + Grommet group. These results suggested that the combination treatment could alleviate ETD via attenuating the inflammation status, thus improving the HoL of CSOM-ETD patients.

It was considered that BET plus Grommet Insertion can be used as an appropriate approach for the treatment of COME with ETD, which is the main strength of our study. However, this study has several limitations. Firstly, similar to previous studies in this field, this retrospective study did not involve a control group, thus causing lower credibility of our results, which should be verified by the randomized controlled trial. Secondly, follow-up was limited to only 12 months after surgery in the current study, the treatment effect should be compared over a longer time span with a large cohort of patients.

In conclusion, BET plus Grommet insertion showed better treatment efficacy for patients with CSOM-ETD than BET alone via improving the Eustachian tube function and hearing outcome with less Eustachian tube inflammation, as well as increasing patient satisfaction.

References

[1] A. G. M. Schilder, T. Chonmaitree, A. W. Cripps, R. M. Rosenfeld, M. L. Casselbrant, M. P. Haggard, R. P. Venekamp, "Otitis media," Nature Reviews Disease Primers, vol. 2 no. 1,DOI: 10.1038/nrdp.2016.63, 2016.

[2] H. Coates Ao, R. Thornton, J. Langlands, P. Filion, D. K. Anthony, S. Vijayasekaran, P. Richmond, "The role of chronic infection in children with otitis media with effusion: evidence for intracellular persistence of bacteria," Otolaryngology—Head and Neck Surgery, vol. 138 no. 6, pp. 778-781, DOI: 10.1016/j.otohns.2007.02.009, 2008.

[3] C. G. Brennan-Jones, K. Head, L. Y. Chong, M. J. Burton, A. G. Schilder, M. F. Bhutta, "Topical antibiotics for chronic suppurative otitis media," Cochrane Database of Systematic Reviews, vol. 1, 2018.

[4] S. Mahdiani, L. Lasminingrum, D. Anugrah, "Management evaluation of patients with chronic suppurative otitis media: a retrospective study," Annals of Medicine and Surgery, vol. 67,DOI: 10.1016/j.amsu.2021.102492, 2021.

[5] L. Y. Chong, K. Head, K. E. Webster, J. Daw, P. Richmond, T. Snelling, M. F. Bhutta, A. G. Schilder, M. J. Burton, C. G. Brennan-Jones, "Topical versus systemic antibiotics for chronic suppurative otitis media," Cochrane Database of Systematic Reviews, vol. 2,DOI: 10.1002/14651858.CD013053.pub2, 2021.

[6] A. Master, E. Wilkinson, R. Wagner, "Management of chronic suppurative otitis media and otosclerosis in developing countries," Otolaryngologic Clinics of North America, vol. 51 no. 3, pp. 593-605, DOI: 10.1016/j.otc.2018.01.017, 2018.

[7] R. Mittal, C. V. Lisi, R. Gerring, J. Mittal, K. Mathee, G. Narasimhan, R. K. Azad, Q. Yao, M. Grati, D. Yan, A. A. Eshraghi, S. I. Angeli, F. F. Telischi, X. Z. Liu, "Current concepts in the pathogenesis and treatment of chronic suppurative otitis media," Journal of Medical Microbiology, vol. 64 no. 10, pp. 1103-1116, DOI: 10.1099/jmm.0.000155, 2015.

[8] D. C. Rosario, M. D. Mendez, Chronic Suppurative Otitis, 2022.

[9] I. Todt, F. Oppel, H. Sudhoff, "Sensorineural hearing loss after balloon eustachian tube dilatation," Front Surg, vol. 8,DOI: 10.3389/fsurg.2021.615360, 2021.

[10] B. Demir, C. Batman, "Efficacy of balloon Eustachian tuboplasty on the quality of life in children with Eustachian tube dysfunction," Acta Oto-Laryngologica, vol. 140 no. 4, pp. 297-301, DOI: 10.1080/00016489.2020.1714077, 2020.

[11] Q. Li, Z. Jiang, X. Tian, X. Li, M. Li, "Clinical observation of chronic recurrent secretory otitis media in adults treated by balloon dilatation of Eustachian tube combined with myringotomy and catheterization," Lin Chung Er Bi Yan Hou Tou Jing Wai Ke Za Zhi, vol. 35 no. 12, pp. 1073-1077, 1084.

[12] G. Yin, J. Tan, P. Li, "Balloon dilation of Eustachian tube combined with tympanostomy tube insertion and middle ear pressure equalization therapy for recurrent secretory otitis media," Journal of Otology, vol. 14 no. 3, pp. 101-105, DOI: 10.1016/j.joto.2019.05.003, 2019.

[13] S. Schroder, U. Reineke, M. Lehmann, J. Ebmeyer, H. Sudhoff, "Chronic obstructive eustachian tube dysfunction in adults: long-term results of balloon eustachian tuboplasty," HNO, vol. 61 no. 2, pp. 142-151, 2013.

[14] C. Zhang, C. Xu, F. Zheng, W. Ren, M. Zhang, Y. Yan, R. Liu, N. Wu, Z. Hou, S. Yang, H. Zhao, "The discussion on the application of simultaneous balloon Eustachian tuboplasty in the hearing reconstruction in patients with chronic suppurative otitis media," Lin Chung Er Bi Yan Hou Tou Jing Wai Ke Za Zhi, vol. 34 no. 10, pp. 892-895, 2020.

[15] C. Y. Hsieh, C. J. Chang, C. H. Sun, C. Y. Lee, G. L. Gotamco, C. J. Hsu, H. P. Wu, "Tympanoplasty with or without balloon eustachian tuboplasty for chronic suppurative otitis media with obstructive eustachian tube dysfunction," Otology & Neurotology, vol. 41 no. 8, pp. 1077-1083, DOI: 10.1097/mao.0000000000002730, 2020.

[16] L. Vaile, T. Williamson, A. Waddell, G. Taylor, "Interventions for ear discharge associated with grommets (ventilation tubes)," Cochrane Database of Systematic Reviews, vol. 2,DOI: 10.1002/14651858.CD001933.pub2, 2006.

[17] R. P. Venekamp, F. Javed, T. M. van Dongen, A. Waddell, A. G. Schilder, "Interventions for children with ear discharge occurring at least two weeks following grommet (ventilation tube) insertion," Cochrane Database of Systematic Reviews, vol. 11,DOI: 10.1002/14651858.CD011684.pub2, 2016.

[18] S. Y. Hwang, S. Kok, J. Walton, "Balloon dilation for eustachian tube dysfunction: systematic review," Journal of Laryngology & Otology, vol. 130 no. S4, pp. S2-S6, DOI: 10.1017/s0022215116008252, 2016.

[19] H. Qin, J. Yang, "Efficacy of balloon Eustachian tuboplasty combined with grommet insertion in the treatment of chronic dilation Eustachian tube dysfunction," Lin Chung Er Bi Yan Hou Tou Jing Wai Ke Za Zhi, vol. 32 no. 6, pp. 465-469, 2018.

[20] R. Sheikh, H. Haidar, H. Abdulkarim, W. Aslam, A. Larem, A. Alsaadi, A. Alqahtani, "Preoperative predictors in chronic suppurative otitis media for ossicular chain discontinuity: a cross-sectional study," Audiology and Neurotology, vol. 21 no. 4, pp. 231-236, DOI: 10.1159/000447045, 2016.

[21] N. S. Andresen, J. D. Sharon, C. L. Nieman, S. M. Seal, B. K. Ward, "Predictive value of the Eustachian Tube Dysfunction Questionnaire-7 for identifying obstructive Eustachian tube dysfunction: a systematic review," Laryngoscope Investigative Otolaryngology, vol. 6 no. 4, pp. 844-851, DOI: 10.1002/lio2.606, 2021.

[22] K. Mantsopoulos, V. Thimsen, L. Taha, F. Eisenhut, S. K. Muller, M. Sievert, H. Iro, J. Hornung, "Comparative analysis of titanium clip prostheses for partial ossiculoplasty," American Journal of Otolaryngology, vol. 42 no. 5,DOI: 10.1016/j.amjoto.2021.103062, 2021.

[23] I. Baumann, B. Gerendas, P. K. Plinkert, M. Praetorius, "General and disease-specific quality of life in patients with chronic suppurative otitis media—a prospective study," Health and Quality of Life Outcomes, vol. 9 no. 1,DOI: 10.1186/1477-7525-9-48, 2011.

[24] I. Kivekas, L. Poyhonen, A. Aarnisalo, M. Rautiainen, D. Poe, "Eustachian tube mucosal inflammation scale validation based on digital video images," Otology & Neurotology, vol. 36 no. 10, pp. 1748-1752, DOI: 10.1097/mao.0000000000000895, 2015.

[25] M. C. Satmis, M. van der Torn, "Balloon dilatation of the Eustachian tube in adult patients with chronic dilatory tube dysfunction: a retrospective cohort study," European Archives of Oto-Rhino-Laryngology, vol. 275 no. 2, pp. 395-400, DOI: 10.1007/s00405-017-4857-4, 2018.

[26] R. M. Rosenfeld, S. R. Schwartz, M. A. Pynnonen, D. E. Tunkel, H. M. Hussey, J. S. Fichera, A. M. Grimes, J. M. Hackell, M. F. Harrison, H. Haskell, D. S. Haynes, T. W. Kim, D. C. Lafreniere, K. LeBlanc, W. L. Mackey, J. L. Netterville, M. E. Pipan, N. P. Raol, K. G. Schellhase, "Clinical practice guideline: tympanostomy tubes in children," Otolaryngology—Head and Neck Surgery, vol. 149 no. 1, pp. S1-S35, DOI: 10.1177/0194599813487302, 2013.

[27] R. Padia, J. A. Alt, K. Curtin, H. R. Muntz, R. R. Orlandi, J. Berger, J. D Meier, "Familial link of otitis media requiring tympanostomy tubes," The Laryngoscope, vol. 127 no. 4, pp. 962-966, DOI: 10.1002/lary.26360, 2017.

[28] C. M. Alper, M. S. Teixeira, T. J. Rath, D. Hall-Burton, J. D. Swarts, "Change in eustachian tube function with balloon dilation in adults with ventilation tubes," Otology & Neurotology, vol. 41 no. 4, pp. 482-488, DOI: 10.1097/mao.0000000000002559, 2020.

[29] N. Ramakrishnan, P. Kadambi, "The use of balloon eustachian tuboplasty in patients with eustachian tube dysfunction: a retrospective pilot usage experience," Indian Journal of Otolaryngology and Head & Neck Surgery, vol. 72 no. 3, pp. 392-394, DOI: 10.1007/s12070-020-01822-z, 2020.

[30] H. Cheng, A. Saxby, N. Jufas, J. Kong, N. Patel, "Balloon dilation eustachian tuboplasty for dilatory dysfunction: safety and efficacy analysis in an Australian cohort," ANZ Journal of Surgery, vol. 91 no. 7-8, pp. 1480-1484, DOI: 10.1111/ans.16980, 2021.

[31] Y. Q. Li, Y. B. Chen, G. D. Yin, X. L. Zeng, "Effect of balloon dilation eustachian tuboplasty combined with tympanic tube insertion in the treatment of chronic recurrent secretory otitis media," European Archives of Oto-Rhino-Laryngology, vol. 276 no. 10, pp. 2715-2720, DOI: 10.1007/s00405-019-05512-7, 2019.

[32] L. Li, Y. Mao, N. Hu, W. Yan, Y. Lu, Z. Fan, H. Wang, Y. Han, "The effect of balloon dilatation eustachian tuboplasty combined with grommet insertion on the structure and function of the eustachian tube in patients with refractory otitis media with effusion," Annals of Palliative Medicine, vol. 10 no. 7, pp. 7662-7670, DOI: 10.21037/apm-21-1280, 2021.

[33] Y. Zhang, J. Wang, Y. Wang, Q. Fu, Y. Li, "Association between the air-bone gap and vibration of the tympanic membrane after myringoplasty," Ear, Nose, & Throat Journal, vol. 100 no. 4, pp. 241-248, DOI: 10.1177/0145561320983649, 2021.

[34] S. Chen, M. Zhao, W. Zheng, R. Wei, B. Zhang, B. Tong, J. Qiu, "Myringotomy and tube insertion combined with balloon eustachian tuboplasty for the treatment of otitis media with effusion in children," European Archives of Oto-Rhino-Laryngology, vol. 277 no. 5, pp. 1281-1287, DOI: 10.1007/s00405-020-05828-9, 2020.

[35] C. F. Tai, K. Y. Ho, K. H. Juan, "Age and the prognosis of tympanoplasty type I," The Kaohsiung Journal of Medical Sciences, vol. 14 no. 9, pp. 542-547, 1998.

[36] Y. Si, Y. Chen, G. Xu, X. Chen, W. He, Z. Zhang, "Cartilage tympanoplasty combined with eustachian tube balloon dilatation in the treatment of adhesive otitis media," The Laryngoscope, vol. 129 no. 6, pp. 1462-1467, DOI: 10.1002/lary.27603, 2019.

[37] M. S. Teixeira, J. D. Swarts, C. M. Alper, "Accuracy of the ETDQ-7 for identifying persons with eustachian tube dysfunction," Otolaryngology—Head and Neck Surgery, vol. 158 no. 1, pp. 83-89, DOI: 10.1177/0194599817731729, 2018.