Changes in Quality of Life Among Patients With Far-Advanced Otosclerosis After Stapes Surgery

Introduction

Otosclerosis is a progressive disease of heterogeneous etiology that occurs exclusively in humans and involves a unique process of bony tissue remodeling at the base of the stapes and/or within the otic capsule of the cochlea. The remodeling process of the otic capsule may begin when specific molecular factors initiate pathologic changes in patients with genetic and/or environmental predispositions [1]. The development of otosclerotic foci around the oval window causes immobilization of the stapes, producing conductive hearing loss. The presence of otosclerotic foci within the otic capsule leads to sensorineural hearing loss. The coexistence of disease processes around the oval window and within the inner ear results in mixed hearing loss. In addition to hearing loss, patients with otosclerosis may experience tinnitus and dizziness [2,3].

The diagnosis of otosclerosis is established based on medical history, otolaryngologic examination, and audiometric testing, which reveal hearing loss, absence of the stapedius muscle reflex, and tympanometry type As characteristic of otosclerosis. Due to the progressive nature of the condition, symptoms worsen over time and can lead to profound hearing loss or deafness – referred to as far-advanced otosclerosis (FAO). Radiologic examinations play an important role in the diagnosis of FAO. Several methods for assessing otosclerotic changes via high-resolution computed tomography have been described; in 80% to 90% of cases, these methods enable detection of abnormalities in the oval window, as well as other structures within the bony capsule of the inner ear. In radiologic diagnosis of otosclerosis, the most frequently used criteria are those proposed by Rotteveel et al, Marshal et al, Valvassori, and Shin et al [4–7].

FAO was first described in 1962 by House and Sheehy as a rare clinical condition characterized by an air conduction threshold (AC) of at least 85 decibels hearing level (dB HL) and a bone conduction threshold (BC) exceeding the audiometer’s capacity (ie, effectively immeasurable) [8]. The remaining criteria for establishing a diagnosis of FAO include confirmed otosclerosis and a speech reception threshold (SRT) in speech audiometry of less than 100%. Tympanometry and the stapedius reflex do not constitute diagnostic criteria for FAO. In 1992, Iurato et al reported a case of very far-advanced otosclerosis that combined clinical suspicion of the disease with the absence of measurable BC and AC using audiometers available at that time. In the era of cochlear implants, speech audiometry, along with the aforementioned criteria, began to be used in the diagnosis of FAO [9].

There is no general consensus regarding optimal treatment for patients with profound hearing loss secondary to otosclerosis. Treatment algorithms include stapedotomy with appropriate hearing aid amplification; in cases of very profound sensorineural hearing loss, patients may meet clinical criteria for cochlear implant insertion [10] (Figure 1). Cochlear implantation in patients with FAO is considered an effective and safe treatment method that should be recommended when stapedotomy and hearing aid use are no longer effective. In 2011, Merkus et al proposed a management algorithm for patients with FAO based on speech audiometry SRT results. The authors suggested that, for patients with an SRT above 50%, stapedotomy and hearing aid fitting should be considered; for SRT of 30% to 50%, treatment with stapedotomy and hearing aids or cochlear implantation should be considered; and for SRT below 30%, cochlear implantation should be recommended [11]. The literature indicates that cochlear implantation in patients with otosclerosis represents approximately 10% to 12% of all operated cases [12].

Previous studies of patients with FAO have analyzed changes in audiometric parameters after treatment by comparing 2 surgical methods: stapedotomy and cochlear implantation. Some studies have shown improvements in patient quality of life after these treatments; they have not reported correlations with changes in audiometric parameters, such as word recognition score (WRS). The present study complements prior observations by linking changes in audiometric parameters with improvements in patient quality of life. The Glasgow Benefit Inventory (GBI) scale used in this study assesses multiple domains of human activity. Before conducting the analysis, we did not assume a direct relationship between improvements in WRS and improvements in total GBI score or its individual subscales. Therefore, this study included 20 patients with profound hearing loss due to FAO and aimed to evaluate improvement in quality of life after stapedotomy according to audiometric test results.

Material and Methods

ETHICS STATEMENT:

Approval for this study was obtained from the local Bioethics Committee (No. 1072.6120.116.2021). All patients included in the analysis provided written informed consent to participate in the study.

MATERIALS:

A retrospective analysis of audiometric results was conducted regarding 588 consecutive patients who had been diagnosed with and treated for otosclerosis between 2005 and 2020. The study group comprised 20 patients diagnosed with FAO, selected from this cohort: 14 women (aged 53–61 years; mean age, 58 years) and 6 men (aged 57–64 years; mean age, 59 years). Despite the small sample size, it was possible to establish a statistically significant cohort. To determine a reasonable sample size, we considered research objectives, resource availability, and the assumed level of statistical significance. The study is preliminary in nature; continuation as a prospective study will allow further analysis of a larger FAO population over a longer follow-up period.

PATIENTS:

A group of 20 patients meeting FAO diagnostic criteria was selected (in addition to criteria required for otosclerosis diagnosis):

Patients were excluded if they:

The study included patients diagnosed with FAO who were qualified for stapedotomy, regardless of the presence or extent of the otosclerotic process in the contralateral ear. The aim of this research was to assess changes in quality of life after surgery, irrespective of the degree of hearing loss in the opposite ear. All patients with FAO included in the study had previously used air conduction hearing aids. Due to disease progression, the effectiveness of this intervention became insufficient, and these patients subsequently underwent stapedotomy. The characteristics of the study group are presented in Table 1.

METHODS:

Pre- and postoperative diagnostics were performed in all patients and included the following:

All patients provided consent to participate in the study and completed all preoperative examinations and postoperative follow-up assessments according to the adopted schedule (1, 3, 6, and 12 months after surgery).

Audiometric testing was conducted using a MIDIMATE 622 audiometer (Madsen, Budapest, Hungary) that met International Organization for Standardization (ISO) standards for air conduction measurements (ISO 0389-1985) and bone conduction (ISO 7566-1987). The device was calibrated twice annually. TDK 39 headphones (TDH, Tokyo, Japan) were used. Average preoperative and postoperative AC values, average postoperative BC values, and average ABG values obtained from pure tone audiometry were calculated in accordance with the guidelines of the American Academy of Otolaryngology–Head and Neck Surgery, Committee on Hearing and Equilibrium; they were averaged across frequencies of 500, 1000, 2000, and 3000 Hz [13]. In the preoperative assessment, BC values were not included because profound hearing loss placed these thresholds beyond the limits of vibrotactile perception.

Speech audiometry in the free acoustic field was performed using a speaker positioned more than 1 m from the patient. The examination was conducted using phonetically balanced monosyllabic word tests. The speech material was presented through the speaker at an intensity level of 60 dB HL. The outcome measure was the percentage of correctly repeated words (ie, WRS). Speech audiometry results were presented as articulation curves across individual speech signal intensity levels. Audiometric testing was performed preoperatively (AC, WRS) and at 3, 6, and 12 months after surgery (AC, BC, ABG, WRS).

GBI questionnaires were administered to all patients at 3, 6, and 12 months after surgical treatment. The GBI, together with audiometric data, enabled assessment of quality-of-life improvement following stapedotomy in patients with FAO.

The GBI questionnaire consists of 18 items:

Questionnaire responses were analyzed on the basis of 4 subscales, according to the themes of the questions:

Responses were provided using a 5-point Likert scale (1–5):

Domain scores were subsequently converted to a scale ranging from −100 to +100. A higher score indicated greater benefit from the surgical procedure within the given domain. A score of zero indicated a subjective lack of benefit, whereas a negative score reflected an adverse impact of the surgery on the patient’s quality of life [14,15].

GBI Total results obtained 12 months after the procedure are presented graphically. Changes in GBI Total were illustrated by dividing the −100 to +100 range into the following score intervals:

All participants completed the GBI questionnaire at each analyzed time point. All 20 patients underwent primary stapedotomy in the worse-hearing ear under general anesthesia. No patient underwent bilateral surgery. Surgical procedures were performed by different surgeons with comparable experience in middle ear surgery; therefore, the group may be considered homogeneous in this respect. Cochlear implantation data were not analyzed because no patients with FAO undergoing this procedure were treated at our center.

STATISTICAL ANALYSIS:

Data obtained during the study were subjected to statistical analysis. Descriptive statistics were used to characterize the study population, including mean, median, standard deviation (SD), first and third quartiles, and range. Distribution normality for the analyzed parameters was assessed using the Shapiro-Wilk test. To obtain an initial understanding of data structure and quality, the measurements were evaluated by exploratory data analysis. This approach enabled examination of results without imposing predetermined assumptions. The statistical analysis facilitated formulation of preliminary research hypotheses, which were subsequently tested.

In analyzing relationships between WRS and GBI variables, as well as relationships among GBI, AC, and BC parameters, the Spearman rank correlation coefficient was used. Correlation strength was interpreted according to the classification proposed by Guilford [16]. The correlation coefficient ranges from −1 to 1. A positive coefficient indicates that as 1 variable increases, the other also increases; a negative coefficient indicates that as 1 variable increases, the other decreases.

Assessment of the statistical results of the GBI questionnaire utilized Cronbach’s α coefficient for the entire scale and for each subscale, as well as test-retest analysis. The test-retest analysis was conducted by asking patients to complete the GBI questionnaire again at scheduled time intervals (ie, intervals sufficiently long to prevent recall of prior responses but sufficiently short to avoid meaningful changes in outcomes). Retest reliability was measured using Lin’s concordance correlation coefficient; the relationship between baseline scores and scores obtained 4 weeks later was examined. All statistical analyses were conducted using R statistical software, version 3.5.1. The statistical significance threshold was set at P<0.05.

Results

AC, BC, AND WRS VALUES BEFORE AND AFTER STAPEDOTOMY ACROSS ANALYZED TIME INTERVALS:

Statistical analysis of the obtained audiometric results included values for BC, AC, and ABG in pure tone audiometry, as well as WRS values in speech audiometry. Audiometric testing was performed preoperatively (AC, WRS) and at 3, 6, and 12 months after surgery (AC, BC, ABG, WRS).

Evaluation of pure tone audiometry results was performed according to the guidelines of the American Academy of Otolaryngology–Head and Neck Surgery, Committee on Hearing and Equilibrium, as indicated in the Materials and Methods. As previously noted, preoperative BC values were not recorded. The analysis therefore included mean preoperative AC values and mean postoperative BC, AC, and ABG values obtained at 3, 6, and 12 months after stapedotomy. Stapedotomy effectiveness was assessed based on the degree of ABG closure and the recording (change) of BC values, which reflected restoration of sound transmission through the middle ear to the inner ear.

When evaluating improvement relative to preoperative parameters, changes in AC values observed during scheduled follow-up visits were used. Because preoperative BC values were unavailable, assessments of BC and ABG could only be performed postoperatively, without reference to baseline values (Table 2).

During postoperative follow-up after stapedotomy, improvements in AC values were observed compared with preoperative measurements (Table 3). No variability was noted among AC measurements obtained at 3, 6, and 12 months postoperatively. The mean change in AC value at 3 months was −11.87 dB (range: −22.7 to +8.4; median: −13.4), indicating improvement. Subsequent mean improvement values were −9.29 dB (range: −22.7 to +7.4; median: −8.4) at 6 months and −8.06 dB (range: −22.7 to +10.4; median: −7.7) at 12 months, relative to preoperative AC values.

Three months after surgery, BC curves were established in 18 patients and remained stable over time (Table 4). Mean BC values at 3 months after stapedotomy were 74.8 dB (range: 63.8–89.4; median: 75.1); they improved by 1.1 dB and 1.01 dB at 6 and 12 months, respectively. As a result of the described AC and BC patterns, postoperative ABG values remained stable throughout follow-up (Table 4).

Concurrently with tonal audiometry changes, improvement was also observed in speech audiometry, reflected by higher WRS results. Improvement in WRS was noted after surgery and remained stable during follow-up. Compared with preoperative values, mean WRS improvement was 21.9% (range: −30.0% to +49.0%; median: 24.5%) at 3 months, 20.8% (range: −30.0% to +46.0%; median: 24.5%) at 6 months, and 21.3% (range: −30.0% to +43.0%; median: 22.5%) at 12 months (Tables 5, 6).

GBI QUESTIONNAIRE SCORES AFTER STAPEDOTOMY ACROSS ANALYZED TIME INTERVALS:

The mean GBI Total score at 3 months after surgery ranged from −45.0 to +67.9 points (mean [SD]: 54 [17.8]). At 6 months, scores ranged from −68.0 to +60.0 points (mean [SD]: 50 [16.1]), and at 12 months, from −77.0 to +55.0 points (mean [SD]: 48 [14.3]).

For the GBI General subscale, scores ranged from −58.8 to +44.7 points (mean [SD]: 46 [13.8]) at 3 months, −80.0 to +42.0 points (mean [SD]: 42 [12.4]) at 6 months, and −80.0 to +50.0 points (mean [SD]: 44 [13.7]) at 12 months postoperatively.

For the GBI Social subscale, scores ranged from −42.6 to +56.0 points (mean [SD]: 52 [16.2]) at 3 months, from −68.0 to +56.8 points (mean [SD]: 49 [15.0]) at 6 months, and from −70.0 to +68.0 points (mean [SD]: 50 [16.1]) at 12 months after surgery.

In the GBI Physical Health domain, scores ranged from −50.0 to +45.0 points (mean [SD]: 49 [14.9]) at 3 months, from −65.0 to +51.6 points (mean [SD]: 46 [14.4]) at 6 months, and from −60.0 to +55.9 points (mean [SD]: 48 [15.3]) at 12 months (Table 7).

One year after surgery, 11 patients (55%) demonstrated improvement in GBI Total and moved to Group 3 (scores 21–40), 3 patients (15%) improved to Group 2 (scores 1–20), and 4 patients (20%) achieved scores within Group 4 (41–60 points). Declining scores were observed in 2 patients (10%), corresponding to Group 1. In these 2 cases, postoperative AC and BC values were not recorded; the patients were subsequently qualified for cochlear implantation.

Next, a statistical assessment of the correlation between changes in WRS and results obtained from the GBI questionnaire was conducted. Speech audiometry performed after stapedotomy demonstrated improvement in WRS, which remained stable during subsequent follow-up visits. This sustained improvement in speech audiometry parameters was associated with better perceived quality of life among operated patients. Although no statistically significant differences in WRS were observed across follow-up time points, a subjective increase in quality of life (expressed by GBI scores) was observed over time. This relationship was reflected by a directly proportional correlation, indicating that higher WRS values were associated with higher GBI scores in domains describing social and mental function, as well as overall treatment assessment. Twelve months after stapedotomy, based on results from 18 patients, positive correlations between changes in WRS and changes in GBI score were observed across all GBI subscales, most strongly for GBI Total: GBI Total (r=0.65; P=0.03), GBI General (r=0.58; P=0.012), GBI Social (r=0.55; P=0.019), and GBI Physical Health (r=0.45; P=0.061) (Table 8).

Subsequently, statistical analyses were performed to assess correlations between changes in GBI and postoperative changes in mean BC values, as well as changes in mean AC values (Table 9).

No statistically significant correlations were identified between changes in GBI scores and postoperative changes in either mean BC or mean AC values.

Discussion

This study assessed hearing improvement and quality of life in 20 patients with advanced otosclerosis after stapedotomy, all of whom met diagnostic criteria for FAO.

In 18 patients who underwent surgery (90% of the analyzed group), previously absent preoperative BC curves were established after stapedotomy. The mean postoperative BC value at 3 months was 74.8 dB (range: 63.8–89.4 dB). At 6 and 12 months, further improvements in BC were observed, with mean ΔBC changes of 1.1 dB at 6 months and 1.01 dB at 12 months. Improvements in AC were observed at all analyzed time intervals relative to preoperative values, with mean ΔAC changes of 11.87 dB at 3 months, 9.29 dB at 6 months, and 8.06 dB at 12 months. Changes in both AC and BC values were statistically significant at each follow-up interval. In 2 patients (10% of the cohort), postoperative AC and BC valueswere not recorded. Surgical procedures and perioperative care in these cases were uneventful; however, these patients were subsequently qualified for cochlear implantation.

Audiometric improvement after surgery in the 18 patients – expressed by statistically significant changes in AC and BC values – was accompanied by satisfactory speech audiometry outcomes. To evaluate the impact of stapedotomy on hearing improvement in the context of interpersonal communication, speech audiometry results were subjected to statistical analysis, with detailed assessment of WRS changes. Improvements in WRS were statistically significant at each analyzed time interval. These results confirm prior observations regarding the beneficial effect of stapedotomy on audiometric outcomes in patients with FAO.

The primary goal of any treatment is to eliminate disease and improve patient quality of life. Concerning otosclerosis, despite numerous studies and advances in research, disease progression cannot yet be halted; management is limited to interventions aimed at improving hearing despite the advancing condition. Adequate hearing in social, professional, and personal contexts is associated with better quality of life; quality-of-life measures are increasingly used to evaluate surgical procedures, including those in otolaryngology [17]. Currently, there is no broad consensus regarding the optimal management of profound hearing loss secondary to otosclerosis. The primary objectives of treating patients with FAO are to prevent deprivation processes within central auditory pathways and to improve hearing, thereby enhancing quality of life across social, mental, and physical domains.

Therapeutic guidelines for patients with FAO have evolved along with advances in hearing aid technology and the development of cochlear implants. In recent decades, multiple authors have proposed stapedotomy as first-line treatment for patients with FAO [18,19]. Lachance et al reported outcomes of stapedotomy in a cohort of 16 cochlear implant candidates; 87% achieved satisfactory postoperative results and did not require cochlear implantation [20]. Conversely, some researchers advocate cochlear implantation as the initial treatment approach for patients with FAO [21,22]. A literature review of FAO revealed excellent outcomes after cochlear implantation. Cochlear implant use was associated with improved hearing in 100% of patients and postoperative speech perception ranging from 45% to 98%, depending on the assessment method, compared with hearing improvement of approximately 70% after stapedotomy; WRS values ranged from 38% to 75% [10].

Our previous clinical experience treating patients with FAO is based on stapedotomy followed by the use of air-conduction hearing aids. Observations from other centers regarding cochlear implant use in FAO support consideration of this therapeutic option. Treatment for patients with FAO should be individualized. The final treatment choice depends on overall patient condition, hearing status in the contralateral ear, patient age, and the experience of the treating center. In selected cases, stapedotomy may serve as an alternative to cochlear implantation in patients with FAO, even when there is limited expectation of improvement in understanding speech. Importantly, lack of satisfactory benefit after stapedotomy does not preclude subsequent cochlear implantation.In a study by Glasscock et al, stapedotomy was effective in 60% of patients with FAO. Postoperative hearing aid use was beneficial in 9 of 11 patients who had not experienced hearing improvement with hearing aids before surgery [23].

Proper functioning of the middle ear sound transmission system is responsible for transmitting sound to the inner ear;it also represents a key component influencing BC values. Disruption of middle ear mechanical influence on the inner ear contributes to pseudoperceptive hearing loss. Stapedotomy restores ossicular chain transmission to the inner ear (Carhart effect), thereby improving postoperative BC values. In the present study, among patients with bilateral hearing loss, improvements in quality of life after treatment and the ability to effectively use air-conduction hearing aids were associated with enhanced interpersonal communication. Among patients who showed mild hearing loss in the contralateral ear, treatment combined with hearing aid use enabled directional hearing and improved comfort in daily functioning. van Loon et al emphasized that treatment success in patients with otosclerosis should be measured primarily by speech understanding in the free acoustic field, whereas postoperative AC and BC values alone do not reflect functional hearing performance in everyday life [10].

We highlight improvement in WRS values after stapedotomy in FAO as a parameter correlated with subjective increases in quality of life, as measured by the GBI scale. Improvement in quality of life after surgical intervention represents a crucial therapeutic outcome. Although the concept of “quality of life” is difficult to define, it constitutes an essential component of an individual’s real-world experience. Quality of life may be assessed using various methodologies. The GBI questionnaire used in this study enables detailed analysis of the impact of stapedotomy on multiple domains of patients’ lives. Previous research has demonstrated that, for many patients with profound hearing loss, stapedotomy represents an appropriate primary surgical procedure that significantly improves quality of life.

In the present analysis assessing the relationship between changes in WRS and changes in subjective surgical benefits captured by the GBI questionnaire, a positive correlation was identified. However, no statistically significant correlations were observed between postoperative changes in GBI scores and changes in BC and AC values. Given the central role of interpersonal communication in improving quality of life among patients with FAO after otologic surgery, inclusion of the WRS parameter in the diagnostic evaluation appears essential. Our statistical analysis of changes in GBI score and WRS demonstrated a positive correlation, indicating that increases in WRS were associated with higher GBI scores and, consequently, better quality of life. To determine the value of WRS as a qualifying parameter for selecting the most appropriate surgical intervention in FAO, further analyses of WRS, AC, BC, and GBI outcomes are needed in patient groups undergoing cochlear implantation or stapedotomy.

The role of the WRS parameter in assessing hearing improvement after surgical treatment has also been examined by other researchers. Lippy et al conducted audiometric analysis in a cohort of 73 patients with FAO [24]. After stapedotomy, AC improvements exceeding 20 dB were observed in 77% of patients. Moreover, average WRS improvement of 15% was achieved in 54% of cases, and nearly 75% of patients described subjective postoperative improvement in hearing aid use. A detailed analysis of the impact of stapedotomy on speech discrimination among patients with FAO was also performed by Lippy et al [25]. Their findings indicated WRS improvement by 16.5% at 1 month after surgery. Over a 2-year postoperative period, mean WRS improvement increased by an additional 16.2%, resulting in a total improvement of 32.7%. In the present study, no further statistically significant changes in WRS were observed at 6 and 12 months postoperatively compared with values obtained at 3 months after stapedotomy. Frattali and Sataloff demonstrated that 70% of patients with FAO achieved postoperative hearing levels associated with improved quality of life based on standardized assessments. In their study, 78% of patients who had not benefited from hearing aids preoperatively achieved sufficient postoperative improvements in BC and AC values to enable effective hearing aid use [26].

The present study confirms prior reports that, for many patients with FAO, stapedotomy is an appropriate first-line intervention producing significant improvement in quality of life, as measured by the GBI scale. In addition to yielding satisfactory outcomes, stapedotomy offers several advantages: it is a minimally invasive procedure and may be performed under local anesthesia, which is beneficial when treating older patients and those with comorbidities. The prosthesis used in this procedure is less costly than a cochlear implant and enables more natural sound perception through acoustic rather than electrical stimulation. Rehabilitation time after stapedotomy is also shorter than the time required following cochlear implantation. Additionally, cochlear implant placement may be technically challenging in FAO due to cochlear bone changes caused by otosclerotic processes. Rotteveel et al. reported electrode insertion difficulties in 10 of 53 patients undergoing cochlear implantation (18.8%) [4]. They also noted that a key postoperative complication of cochlear implantation in FAO was facial nerve stimulation; the estimated incidence was 38%. Importantly, prior stapedotomy does not adversely affect outcomes of subsequent cochlear implantation.

According to a meta-analysis of treatment outcomes in patients with FAO, cochlear implantation demonstrated a significantly higher patient satisfaction rate (86.3%) compared with stapedotomy (69.5%) [27]. Appropriate qualification of patients with FAO for treatment requires comprehensive counseling regarding all of the above factors; treatment decisions should be made collaboratively by surgeons and well-informed patients. The present results underscore the importance of assessing the impact of ongoing therapy on quality of life among patients with FAO. Evaluation of the relationship between WRS and GBI appears to be a valuable approach in this context.

Given the small and heterogeneous patient cohort, the following study limitations were identified – confounding and model specification:

Conclusions

The observed significant improvement in WRS after stapedotomy confirms the usefulness of this surgical procedure in the treatment of patients with FAO. Assessment of the correlation between WRS and GBI among patients with FAO after stapedotomy may be used to evaluate changes in quality of life following treatment.