Abstract
Middle ear aeration is a predictive indicator of myringoplasty’s successful outcome and tympanometric ear canal volume is a novel investigation that can estimate the volume of middle ear cleft and mastoid air cells. Our aim of this study is to determine the role of tympanometric ear canal volume on myringoplasty outcome in Chronic Suppurative Otitis Media Patients. Prospective analysis involving 50 patients of CSOM was performed on patients undergoing myringoplasty from April 2022 to December 2023. Smokers, Patients with squamosal COM, Bilateral COM, Otitis Externa, and Revision surgery were excluded from the study. The successful outcome of surgery was defined as no tympanic membrane perforation on postoperative follow-up. Analysis was carried out using SPSS. V. 25 and P-value less than 0.05 was considered significant. A total of 50 patients were included in the study with a mean age of 24.4 ± 8.965 and male predominance. Overall graft uptake was 64%. Graft uptake had no significant statistical correlation with age, gender, type, location, or size of perforation. However, there is a significant effect of tympanometric ear canal volume of pathological ear and interaural tympanometric ear canal volume difference on graft uptake with p-values of 0.023 and 0.033 respectively. Tympanometric ear canal volume can predict middle ear aeration and the higher the interaural tympanometric canal difference more are the chances of successful graft uptake.
Keywords: Chronic Suppurative Otitis Media, Myringoplasty, Tympanometry, Ear Canal Volume
Introduction
Chronic suppurative otitis media is a prolonged inflammation of middle ear mucosa and mastoid air cells [1] characterized by long-standing ear discharge through tympanic membrane perforation. This disease causes a significant health challenge and if left untreated can lead to hearing impairment [2].
Myringoplasty is a reconstructive surgical procedure performed by ENT specialists on a routine basis in mucosal COM patients. In this procedure, the perforated tympanic membrane is repaired with the help of a graft to restore the function of the middle ear [3]. It improves the quality of life of patients by decreasing recurrent infections and improvement in hearing. The success rate of myringoplasty varies between 52 to 91.9% [4] Poor surgical results are associated with Eustachian tube dysfunction, chronic mastoiditis, and smoking. Adequate aeration of the contralateral ear, a few ear discharge episodes, and normal mucosa of the middle ear are some of the factors indicative of good middle ear function [5] Moreover, for successful graft uptake adequate middle ear ventilation is an important determinant [6].
Thus preoperative middle ear ventilation assessment is necessary to predict the surgical outcomes in patients undergoing surgical procedures. This study focuses on the role of tympanometric ear canal volume as a contributing factor while controlling for other potential variables.
Tympanometry is a noninvasive procedure routinely performed to assess the status of middle ear function [7]. It is performed by placing a probe in the ear canal and an air-tight seal is created. Air pressure is changed via a manometer and single frequency pure tone introduced by the speaker [8] The amount of acoustic energy reflected from the eardrum is measured. In addition to providing pressure and compliance, it also estimates middle ear volume and Eustachian tube function. Theoretically, the volume measured by tympanometry in a patient with COM is the volume of the external auditory canal, middle ear cleft, and possibly mastoid cavity. So in a patient with unilateral COM if the ECV (External canal volume) of the normal ear is subtracted from the ECV of the diseased ear we can estimate the middle ear and mastoid cell volume which is > 2 ml in the aerated ear [9].
Merenda et al. in research concluded that large tympanometric volume is associated with higher success rates in tympanoplasty. In his study success rate was 89% in patients with large tympanometric canal volume and 34% in patients with small ECV volume [10].
Tympanometry is a procedure routinely performed for diagnosis of OME but its role in detection of mastoid aeration and predicting graft uptake in myringoplasty has not yet been studied. This study was designed to determine whether, preoperative ECV and interaural ECV differences in patients with unilateral COM, can predict successful graft uptake in myringoplasty.
Materials and Methods
We performed a prospective analysis of all patients who underwent myringoplasty procedures in the ENT Department of Benazir Bhutto Hospital with a diagnosis of COM (Mucosal) disease and had no episode of otorrhea in the past 3 months between April 2022 to December 2023. After approval from the ethical review board, 58 patients were enrolled in the study after taking written informed consent.8 patients lost follow-up during the study and were excluded from the results.
Study Population
Smokers, Patients with squamosal COM, Bilateral COM, Otitis Externa, and Revision surgery and patients with Chronic Suppurative Otitis Media (CSOM) who had episodes of otorrhea in the past three months were excluded from the study. This selection criterion was intended to minimize the influence of active infection and inflammatory changes on middle ear volume. Additionally, patients with active granulations or significant polypoidal mucosa were excluded from the study to ensure a more accurate assessment of the role of tympanometric ear canal volume in predicting myringoplasty outcomes. After a complete history and examination of the patients preoperative PTA and tympanometry were performed in all patients. The external canal volume of both ears was calculated by tympanometry. While assuming the canal volume to be equal in both ears interaural tympanometric volume difference was calculated by subtracting the volume of the normal ear from the diseased ear canal volume giving us the volume of the middle ear and mastoid air cells. Using a cutoff value of 2 cm3 interaural tympanometric volume difference we divided patients into patent and obstructive groups.
All procedures were performed by experienced surgeon of > 5years experience using a standardized technique to reduce variability related to surgical skill. A preoperative evaluation of all patients was done. All procedures were done with General anesthesia. Temporalis fascia graft was used in all patients. Underlay technique via post-aural approach was performed in all patients. Gelfoam and a BIPP pack were placed in the external auditory canal at the end of surgery. Patients were called for follow-up after 1 and 3 months. Postop follow-up of the patient was done after 1 and 3 months. Graft uptake was assessed via postop otoscopy of the patient.
Statistical Analysis
The analysis was carried out by using SPSS. V. 25 and P-value of less than 0.05 was taken as significant. The Qualitative variables were expressed in the form of Frequencies and percentages, similarly, the quantitative variables were expressed as mean and standard deviation. Correlation of perforation characteristics and ear canal volume of pathological ear was analyzed by applying Kruskal-Wallis H test. However diseased ear canal volume and interaural tympanometric ear canal volume were correlated with graft uptake and reperforation by applying Mann-Whitney U test. The correlation between qualitative variables and outcomes variables was expressed using Chi-square analysis and for quantitative variables Student Sample t-test was used.
Results
The total patients included in the study were 50 with a mean age of 24.4 ± 8.965 and there was a male predominance (60%). The tympanometric ear canal volume in the diseased ear ranged from 1.9 to 6.2 with a mean of 3.720. The most common presenting symptom in our study was hearing loss 28(56%) followed by recurrent ear discharge in 22 patients (44%) patients. In our study, the most frequent cause of Tympanic membrane perforation was an infection in 25 (50%) followed by an unknown cause in 18(36%) patients, and trauma in 7 (14%) patients. The most common type of perforation was central perforation as shown in Fig. 1.
Fig. 1.
Frequency of perforation type showing the most frequent type being central perforation
In our study 26 patients had central perforation while 11 had posterior, 10 had anterior and 3 had inferior quadrant perforation. The overall success rate of graft uptake in our study is 64%. Correlation of perforation characteristics and ear canal volume of pathological ear was analyzed by applying Kruskal-Wallis H test. The most common size of perforation was more than 75% in 23 patients as shown in Fig. 2.
Fig. 2.
Frequency of size of perforation showing the most frequent size being > 75%
Tympanometric ear canal volume does not correlate with the size of perforation and location of perforation and type of perforation with p values statistically non significant (Table 1).
Table 1.
Correlation between perforation characteristics with ear canal volume of diseased ear
| Variables | p-value |
|---|---|
| Perforation Type | 0.603 |
| Size of perforation | 0.630 |
| Location of Perforation | 0.796 |
No statistically significant correlation was observed between graft uptake and gender of the patient, age of the patient, perforation type, location of perforation, size of perforation, and history of allergic rhinitis. Analysis was done by apply chi square test on all variables except age (student t test was applied) and p value mentioned in (Table 2).
Table 2.
Correlation between successful surgical outcome and other variables
| Variables | Graft Intact | Reperforation | p-value |
|---|---|---|---|
| Gender | |||
|
Male Female |
13 19 |
7 11 |
0.904 |
| Perforation type | |||
| Central | 18 | 7 | |
| Subtotal | 10 | 8 | 0.384 |
| Total | 4 | 2 | |
| Marginal | 0 | 1 | |
| Location of Perforation | |||
| Anterior | 7 | 3 | 0.612 |
| Posterior | 8 | 3 | |
| Inferior | 1 | 2 | |
| Central | 16 | 10 | |
| Size of Perforation | |||
| < 25% | 6 | 1 | 0.523 |
| 25–50% | 8 | 4 | |
| 50–75% | 4 | 4 | |
| > 75% | 14 | 9 | |
| Allergic Rhinitis | |||
| Yes | 12 | 4 | 0.266 |
| No | 20 | 14 | |
| Age | 24.47 ± 8.512 | 24.39 ± 9.977 | 0.977 |
Graft uptake was assessed via otoscopy after 1 month and 3 months postoperatively and graft uptake was 74.07% in patent group as shown in Fig. 3.
Fig. 3.
Graft uptake after 3 months showing patent group with better graft uptake
Tympanometric ear canal volume in the normal ear shows no statistically significant correlation with the graft uptake. However diseased ear canal volume and interaural tympanometric ear canal volume difference show statistically siginifcant correlation with graft uptake and reperforation with p value of 0.023 and 0.033 respectively after applying Mann-Whitney U test (Table 3).
Table 3.
Correlation between tympanometric ear canal volume and graft uptake
| Variables | Graft Intact | Reperforation | p-value |
|---|---|---|---|
| Tympanometric ear canal volume of normal ear | Mean = 1.131 ± 0.145 | Mean = 1.067 ± 0.161 | 0.245 |
| Tympanometric ear canal volume of Diseased ear | Mean = 4.106 ± 1.557 | Mean = 3.033 ± 1.161 | 0.023 |
| Interaural Tympanometric ear canal volume difference | Mean = 2.975 ± 1.554 | Mean = 1.967 ± 1.136 | 0.033 |
Discussion
Myringoplasty is the procedure in which repair of tympanic membrane perforation is done using different graft materials. [10] It is one of the most common surgical procedure done by ENT Specialist. Graft uptake depends on various patient related factors other than surgeon’s expertise. This study supports using interaural tympanometric volume difference as a predictor for graft uptake, reinforcing the importance of a multifactorial approach.
The overall graft uptake rate in our study was 64%, which is within the lower range of reported success rates in the literature (52–91.9%). This rate reflects the real-world challenges and variability in surgical outcomes, influenced by numerous patient-related and procedural factors. Our study specifically aimed to isolate and examine the role of tympanometric ear canal volume, acknowledging that multiple variables contribute to graft success.
We recognize that factors such as Eustachian tube dysfunction, chronic mastoiditis, smoking, and overall health status can significantly impact graft uptake rates. Our exclusion criteria aimed to minimize the influence of these factors. However, the multifactorial nature of myringoplasty outcomes necessitates comprehensive evaluation. Our study’s findings underscore the importance of middle ear aeration, as indicated by tympanometric measurements, as one of the contributing factors to surgical success.
Preoperative evaluation of middle ear aeration, eustachian tube function and condition of contralateral ear is important before performing myringoplasty to predict surgical outcome. Good aeration of middle ear is an important factor for graft uptake in patients undergoing myringoplasty. For assessing aeration of middle ear preoperatively middle ear volume including mastoid air cells and eustachian tube functionality status is required.
3-dimensional Temporal bone CT with volume reconstruction was used previously for calculating middle ear volume. But as CT scan has the associated risk of radiation exposure and is expensive so a cost-effective method was required. Recent work by Epprecht et al. suggested that there is good correlation between middle ear and mastoid cell volume calculated with interaural tympanometric volume difference [8]. As tympanometry is safe, simple and cost-effective investigation so in our study we utilized interaural tympanometric ear canal volume for estimating the aeration of middle ear cleft. As both external auditory canals have equal volume interaural tympanometric ear canal volumes difference will help us assess volume of middle ear and aeration of mastoid air cells.
By assuming that higher tympanometric ear canal volume is associated with better graft uptake we used the cutoff value of 2 cm3 interaural tympanometric canal volume difference and analyzed the successful surgical outcome in both groups.
A study conducted by Kim et al. suggested that if tympanometric ECV of diseased ear is > 2.5 ml or interaural tympanometry ECV difference is > 1.5 ml middle ear and mastoid air cells were considered as patent [11]. In our study we used 2 cm3 cutoff value of interaural tympanometric ear canal volume difference and found statistically significant effect on graft uptake postoperatively in patients included in patent group. Thus our analysis of statistically significant results suggests a correlation between TECV profiles and myringoplasty success rates in CSOM patients.
As mentioned earlier good aeration of middle ear is important predictor of graft uptake in myringoplasty [12] and tympanometry is an effective tool for assessing it. A greater likelihood of surgical success was anticipated with an increased measurement of ear canal volume in tympanometry.
Condition of contralateral ear is also a prognostic indicator of graft uptake. Darouassi et al. worked on prognostic factors of myringoplasty and concluded that out of 140 patients 89.05% had graft uptake in case of normal contralateral ear and only 62% patients had graft uptake in diseased contralateral ear [13]. In our study we included the patients with normal contralateral ear and post procedure graft uptake was 74.07% in patent group and only 52.2% in obstructed group.
Another important factor involved in the graft uptake is normal eustachian tube function which can also be assessed by tympanometry. A study conducted by Undavalli et al. used tympanometry for assessment of eustachian tube function and its role in graft uptake in myringoplasty and concluded that out of 30 patients 24 had good eustachian tube function and good surgical outcome [14]. In our study we assessed the eustachian tube function via tympanometry of contralateral ear and patients with type C curve in nondiseased ear were excluded from the study to minimize the effect of eustachian tube dysfunction on graft uptake.
Other confounding factors that can affect the graft uptake like smoking history, associated ear infections, revision surgery were excluded from this research.
Performing mastoid exploration with tympanoplasty in case of mucosal COM with no evidence of cholesteatoma is controversial and shows no improvement in graft.
uptake. Eliades et al. concluded that mastoid exploration adds no significant benefit in mucosal CSOM but its role in complicated disease is not established. In another study by doesn’t seem to add significant benefit for uncomplicated tympanic membrane perforations, however, it may have a role in patients with complicated disease but, due to lack of evidence, there isn’t a formal recommendation for this population [15]. Another study conducted by Tawab et al. concluded that mastoidectomy performed in safe CSOM provides no statistically significant benefit to the patient regarding graft uptake [16]. So we did not perform cortical mastoidectomy in our obstructed group patients in this study.
Thus the integration of Tympanometric ear volume assessment into the preoperative protocol holds important clinical implication. Surgeons can stratify patients on the basis of their tympanometric ear canal volumes identifying high risk cases. and it can guide regarding postoperative care, risk of complications overall helping in improvement of patient outcomes.
Limitations
The sample size was relatively small, and the follow-up period was limited to three months. Additionally, we used temporalis fascia as the graft material for all patients, which may not represent outcomes with different graft materials. Future studies with larger sample sizes, extended follow-up periods, and varied graft materials are needed to validate our findings. Moreover, while we controlled for several confounding factors, the multifactorial nature of myringoplasty outcomes necessitates further investigation into other potential influences such as patient comorbidities and eustachian tube function.
Conclusion
In conclusion, interaural tympanometric ear canal volume is helpful in determining the aeration of middle ear. Thus patients with higher interaural tympanometric ear canal volume difference have better graft uptake in Chronic Suppurative Otitis Media patients. As tympanometry is simple, cost effective and noninvasive procedure as compared to CT Scan so it should be included in preoperative evaluation of patients undergoing myringoplasty. However, it is essential to recognize Ear canal volume as one of several factors, including patient age, condition of contralateral ear and surgical technique which collectively influence the success of the procedure. Future research should aim to further elucidate the interplay between these variables to refine surgical strategies.
Acknowledgements
N/A.
Author Contributions
Concept: ZS; design: ZS; definition of intellectual content: ZS, AHA; literature search: ZS; data acquisition: ZS, HS; manuscript preparation ZS, JA, SM, AR; manuscript editing: ZS, SM; manuscript review: ZS, AHA, MA, NR, SM.
Funding
We verily state that this study is not funded by any source(s).
Declarations
Conflict of Interest
All authors have declared that they have no conflict of interest to disclose.
Informed Consent
All patients were informed about the nature of the project and their verbally and written consent was taken for participation in our study.
Human and Animal Participants
Humans were involved in this particular research.
Conflict of Interest
There exists no conflict of interest among all authors. The manuscript has been read and approved by all the authors, the requirements for authorship as stated earlier in this document have been met, and each author believes that the manuscript represents honest work.
Declaration of Patient Consent
The authors certify that they have obtained all appropriate consents from the patients and patients know that the information will be reported in a medical journal. The patients understand that their name and initials will not be published and due efforts will be made to conceal the identity.
Footnotes
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