Contralateral ear evaluation in chronic otitis media patients with cholesteatoma: a cross-sectional study

¹Department of Otorhinolaryngology, Hanoi Medical University, Hanoi, Vietnam, ²Department of Otorhinolaryngology, University of Medicine and Pharmacy, Vietnam National University, Hanoi, Vietnam, ³School of Preventive Medicine and Public Health, Hanoi Medical University, Hanoi, Vietnam

^&Corresponding author
Hung Ba Do, Department of Otorhinolaryngology, Hanoi Medical University, Hanoi, Vietnam

Introduction    

Chronic otitis media (COM), particularly the cholesteatomatous (squamous) subtype, has increasingly been reported to involve abnormalities in both ears rather than presenting as an exclusively unilateral condition. Although clinical symptoms are often confined to one ear, a growing body of evidence demonstrates that the contralateral ear (CLE) frequently exhibits structural and functional abnormalities. Recent studies report abnormal CLE findings in approximately 70.6% of unilateral COM cases [1], with rates approaching 80% in some cohorts [2], and ranging from 44% to 71% in others [3-6]. Even earlier cholesteatoma-focused series have documented abnormalities in nearly half of cases (46.3-57%) [2].

From an otoscopic standpoint, tympanic membrane (TM) retraction, affecting the pars tensa and/or pars flaccida, is the most frequently observed abnormality in the CLE [1,5-7]. Other findings include TM atrophy, tympanosclerosis, and, less commonly, perforation [1,4,8]. Cholesteatoma may also develop in the contralateral ear, although less frequently than retraction or perforation [1,2,9]. Audiologically, conductive hearing loss is the predominant pattern, with increasing air-conduction thresholds correlating with disease severity in the affected ear [1,7]. Tympanometric abnormalities (type B and C curves) and radiological findings such as reduced mastoid pneumatization, mucosal thickening, or middle ear opacification-observed in 12-62% of CLEs-have been described in previous studies and may indicate subclinical middle ear involvement [1,2,6].

Several hypotheses have been proposed to explain contralateral ear involvement in COM. The continuum theory proposed by Paparella et al. [10] conceptualises middle ear disease as a progressive spectrum driven by shared etiological factors, particularly Eustachian tube dysfunction and nasopharyngeal pathology [2,5,7,11]. Anatomical variations, such as a shorter and more horizontal Eustachian tube, further contribute to impaired middle ear ventilation and disease progression [11]. Moreover, indices of disease severity, such as the Middle Ear Risk Index, have been shown to correlate with contralateral auditory dysfunction, suggesting that more advanced disease in one ear is associated with subclinical impairment in the other [7]. These observations underscore the importance of comprehensive bilateral assessment in patients with COM, particularly those with cholesteatoma. Accordingly, the present study was conducted to systematically evaluate structural and functional alterations of the contralateral ear in patients with chronic otitis media with cholesteatoma.

Methods     

Study design: this study was conducted using a cross-sectional, descriptive design to characterise contralateral ear alterations in patients diagnosed with chronic otitis media with cholesteatoma.

Setting: the study was carried out at the Neurotology and Otology Departments of the National Otorhinolaryngology Hospital, Vietnam, over 12 months from January 2024 to December 2024. All clinical evaluations, imaging procedures, and audiological assessments were performed within this institutional setting following standardised protocols.

Participants: a total of 95 patients diagnosed with chronic otitis media with cholesteatoma were enrolled. The inclusion criterion was the presence of cholesteatoma in at least one middle ear. Patients were excluded if they refused participation, had a history of prior ear surgery, or if adequate ear canal cleaning and videotoscopic documentation could not be achieved. For analytical purposes, participants were categorised into two age groups: children (0-18 years) and adults (≥19 years), consistent with the age classification commonly applied in clinical practice and previous otologic studies.

Variables: the primary study outcome was the prevalence of structural abnormalities in the contralateral ear, including tympanic membrane retraction, perforation, and cholesteatoma. Additional variables included otoscopic and endoscopic findings of both the main ear (ME) and the contralateral ear (CLE), cholesteatoma growth pattern, mastoid pneumatization degree, and audiological parameters. The ME was defined as the ear with cholesteatoma or more severe clinical manifestations. In cases of bilateral cholesteatoma, the ME was determined based on the ear demonstrating more extensive disease on otoscopic and HRCT evaluation, including greater ossicular erosion, wider lesion extension, or more severe hearing impairment. CLE findings were categorised as normal or abnormal. Clinically significant abnormalities included tympanic membrane perforation, moderate to severe retraction (Sade stages II-IV) [12], and presence of cholesteatoma.

Data sources/measurement: all patients underwent comprehensive clinical evaluation, including detailed history and otologic examination. Rigid otoendoscopy using 0° and 2.7mm endoscopes (Karl Storz) was performed bilaterally, with video recording using OBS Studio (version 31.1.1). Pure tone audiometry was conducted using the Audiostar Pro audiometer (Grason-Stadler, USA) with TDH supra-aural headphones (Telephonics Corporation, USA). Air-conduction thresholds were measured at 250-8000 Hz, and bone-conduction thresholds at 500-4000 Hz. Pure tone average (PTA) was calculated from 500, 1000, and 2000 Hz. Tympanometry was also performed. High-resolution computed tomography (HRCT) of the temporal bone was obtained using a Somatom Definition AS scanner (Siemens Healthineers, Germany). Mastoid pneumatization was classified according to Han's criteria [12] into four categories: hypopneumatization, moderate, good, and hyperpneumatization. Cholesteatoma growth patterns were classified based on the system described by Rosito et al. [13] into anterior epitympanic, posterior epitympanic, posterior mesotympanic, combined (dual origin), or undetermined.

Bias: to minimize measurement bias, all examinations were performed following standardised procedures, including thorough cleaning of the external auditory canal before endoscopy. Objective diagnostic tools such as audiometry and HRCT were used to complement clinical assessment. However, as a cross-sectional study conducted at a single tertiary centre, selection bias may be present, and findings may not be fully generalizable.

Study size: the study included 95 consecutive patients meeting the eligibility criteria within the study period. The sample size was determined by the number of eligible cases available during the study timeframe.

Quantitative variables: continuous variables, such as audiometric thresholds and PTA, were expressed as mean ± standard deviation and interquartile range where appropriate. Categorical variables included classification of CLE findings, cholesteatoma growth patterns, and mastoid pneumatization groups.

Statistical methods: all statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS) version 20.0 (IBM, NY, USA). Categorical variables were summarised as frequencies and percentages, and continuous variables were expressed as mean ± standard deviation (SD) or interquartile range, as appropriate. Comparisons between groups were conducted using the Chi-square (Χ²) test for categorical variables. Fisher's exact test was applied when expected cell counts were <5, particularly in subgroup analyses involving the pediatric population. A p-value < 0.05 was considered statistically significant. Given the descriptive cross-sectional design, no multivariable analyses were performed to control for confounding, and results are presented as unadjusted associations. Subgroup analyses were conducted according to age groups (children vs. adults) to explore differences in contralateral ear findings, hearing loss patterns, and radiological characteristics; however, no formal interaction testing was performed due to the limited sample size. Missing data were minimal, and analyses were conducted using complete-case data without imputation. As consecutive sampling was applied in a single-centre setting, no specific adjustments for sampling strategy were required, and no sensitivity analyses were performed.

Ethical consideration statement: the study protocol was reviewed and approved by the Institutional Research and Postgraduate Committee of the National Otorhinolaryngology Hospital and Hanoi Medical University. All participants provided written informed consent for inclusion in the study and for the use of anonymised data for research purposes.

Results     

Participants: a total of 95 patients diagnosed with chronic otitis media with cholesteatoma were included in the analysis. There were 48 males (50.5%) and 47 females (49.5%), with no significant difference in sex distribution. The mean age was 41.2 ± 17.2 years (range: 5-80 years). Adults accounted for the majority of cases (87.4%), while children represented 12.6% (Table 1).

Descriptive data: regarding contralateral ear (CLE) status, 58 patients (61.1%) had normal findings, whereas 37 patients (38.9%) presented with abnormalities (Table 1). The distribution of cholesteatoma growth patterns in the main ear (ME) is shown in Table 2. Posterior epitympanic cholesteatoma was the most common type, observed in 51 cases (53.7%), followed by posterior mesotympanic type in 19 cases (20.0%), while other growth patterns were less frequent (Table 2).

Outcome data: otoscopic evaluation of the contralateral ear revealed abnormalities in 37 patients (38.9%) (Table 3). Tympanic membrane retraction was the most common finding (24.2%), followed by perforation (8.4%) and cholesteatoma (6.3%) (Table 3). Pure-tone audiometry demonstrated that 49 patients (51.6%) had hearing impairment in the CLE, with conductive hearing loss being the most common type (44.9%), followed by sensorineural (38.8%) and mixed hearing loss (16.3%) (Table 4). HRCT findings showed that hypopneumatization was the most common pattern in the CLE (Table 5).

Main results: comparative analysis between adults and children showed no statistically significant differences in the distribution of contralateral ear abnormalities, types of hearing loss, or mastoid pneumatization patterns (p > 0.05 for all comparisons) (Table 3, Table 4 and Table 5).

Other analyses: subgroup analysis by age group did not demonstrate significant differences in otoscopic findings, audiological outcomes, or radiological characteristics of the contralateral ear (p > 0.05) (Table 3, Table 4 and Table 5). No additional analyses or interaction testing were performed.

Discussion     

This study aimed to characterise CLE findings in 95 patients with chronic otitis media with cholesteatoma. A substantial proportion of patients exhibited abnormalities in the CLE, suggesting that contralateral ear involvement may occur in patients with cholesteatoma.

In the present study, clinically significant alterations in the CLE were observed in 38.9% of patients. The most frequent abnormality was TM retraction, particularly in moderate to severe stages. These findings are consistent with previous reports on COM with cholesteatoma [14-16]. Bilateral cholesteatoma was identified in 6.3% of cases, indicating that bilateral manifestations may be present in a subset of patients. Although CLE abnormalities appeared numerically less frequent in children (16.7%) than in adults (42.2%), these differences did not reach statistical significance and should therefore be interpreted cautiously. Adults also demonstrated a higher prevalence of moderate and severe TM retraction. This observation may hypothetically relate to longer disease exposure or cumulative pathological changes over time; however, the cross-sectional design of the present study does not permit conclusions regarding temporal progression or causality. The present findings are compatible with previously proposed concepts, including the continuum theory described by Paparella et al. [10], although the current study design does not allow direct evaluation of pathophysiological mechanisms or disease progression. Within this conceptual framework, the ear with established cholesteatoma may reflect more advanced disease manifestations.

Audiometric evaluation demonstrated that 51.6% of patients had hearing impairment in the CLE. Among patients with hearing impairment, conductive hearing loss was the most common type (44.9%), followed by sensorineural (38.8%) and mixed hearing loss (16.3%). These findings are in agreement with prior studies [17,18]. Conductive hearing loss may be explained by negative middle ear pressure, TM retraction, or subclinical middle ear effusion, while sensorineural components may reflect inner ear damage secondary to chronic inflammatory mediators.

Radiological assessment using HRCT revealed a high prevalence of poor mastoid pneumatization in both ears, particularly in the CLE. In the present study, hypopneumatization was observed in 48.2% of adults and 25.0% of children. These findings are consistent with previous imaging studies. Silva et al. reported contralateral mastoid sclerosis in 28% of cases and radiological signs of chronic otitis media in 54% of patients [19]. Similarly, Chung et al. demonstrated reduced mastoid pneumatization in contralateral ears compared with healthy controls [17]. Additional HRCT abnormalities observed in the present study, including mastoid sclerosis and middle ear opacification, further suggest that radiological alterations may occur even in clinically less symptomatic ears. Although poorer pneumatization appeared more frequent in adults, these subgroup differences were not statistically significant and should be interpreted with caution. Poor mastoid pneumatization is widely considered a predisposing anatomical factor, likely established during early childhood rather than solely resulting from inflammatory processes [17,19]. The coexistence of bilateral radiological abnormalities may reflect shared anatomical or inflammatory predisposition; however, this interpretation remains speculative within the limitations of a descriptive cross-sectional study. To improve methodological rigour, otoscopic and HRCT findings were independently reviewed by experienced otologists and radiologists following standardised institutional protocols. In cases of disagreement, consensus interpretation was achieved through joint review.

Despite these findings, several limitations should be acknowledged. First, the cross-sectional design restricts the ability to evaluate temporal progression or causal relationships. Second, the absence of a healthy control group limits the ability to contextualise the observed abnormalities against baseline population characteristics. Third, as the study was conducted at a single tertiary referral centre, referral bias may have resulted in inclusion of patients with more advanced or complex disease, thereby limiting generalizability. Finally, the relatively small pediatric subgroup reduced statistical power for age-stratified analyses and limited the ability to detect subtle subgroup differences. Future longitudinal studies with appropriate controls are warranted to better elucidate disease evolution and risk factors.

Conclusion     

A considerable proportion of patients with cholesteatoma exhibit abnormalities in the contralateral ear, including structural changes and hearing impairment. These findings suggest that contralateral ear involvement is relatively common in patients with chronic otitis media with cholesteatoma. Comprehensive evaluation of the contralateral ear may be helpful for accurate diagnosis and clinical assessment. Early identification of subclinical abnormalities could potentially support timely monitoring and management in selected patients.

Competing interests     

The authors declare no competing interests.

Authors' contributions     

Giang Hoang Nguyen and Hung Ba Do contributed to data collection and data analysis. Giang Hoang Nguyen, Hung Ba Do, Thanh Nguyen Hoang and Hoa Le Nguyen were responsible for manuscript writing. Giang Hoang Nguyen, Hoa Le Nguyen, and Hung Ba Do contributed to study conception, study design, and manuscript preparation. All authors read and approved the final manuscript.

Acknowledgments     

The authors sincerely thank the leadership, clinicians, and medical staff of the National Otorhinolaryngology Hospital (Vietnam) for their support in patient management, data collection, and study implementation.

Tables     

Table 1: demographic and clinical characteristics of the study population (n = 95)

Table 2: cholesteatoma growth patterns in the main ear (n = 95)

Table 3: otoscopic findings in the contralateral ear by age group (n = 95)

Table 4: hearing loss types in the contralateral ear (n = 49)

Table 5: mastoid pneumatization in the contralateral ear by HRCT (n = 95)

References