|Year : 2021 | Volume
| Issue : 1 | Page : 18-23
A prospective cohort study on ossicular reconstruction using autologous incus or cartilage in chronic otitis media
SM Joy, P Karthikeyan, DT Pulimootil
Department of Otorhinolaryngology, Mahatma Gandhi Medical College and Research Institute, Sri Balaji Vidiyapeeth (Deemed to be University), Puducherry, India
|Date of Submission||18-Jul-2020|
|Date of Acceptance||05-Feb-2021|
|Date of Web Publication||03-Jul-2021|
Prof. P Karthikeyan
Department of Otorhinolaryngology, Mahatma Gandhi Medical College and Research Institute, Sri Balaji Vidiyapeeth (Deemed To Be University), Puducherry
Source of Support: None, Conflict of Interest: None
Background: Loss of hearing resulting from ossicular discontinuity is prevalent, with chronic otitis media being the primary causative factor. Aim and Objectives: The study aimed at evaluating the potential of autologous incus and cartilage in restoring hearing as well as identifying predictors of ossiculoplasty outcomes. Methodology: Patients with autologous incus constituted Group I (n = 52) and patients with autologous cartilage constituted Group II (n = 48). Reliability of pre-operative predictors such as pure-tone average, air-bone gap, and middle ear risk index (MERI) scores in anticipating hearing associated outcomes of ossiculoplasty was investigated. Inferential statistics were employed. Results: Group I patients displayed better postoperative outcomes in terms of pure-tone audiometry than Group II counterparts (P = 0.0035). Age (P = 0.044), MERI (P = 0.021) and gender (P = 0.046) proved to be reliable indicators. Conclusion: Autologous incus can be explored as a competent ossiculoplasty material in developing countries.
Keywords: Cartilage, incus, otitis media, pure-tone audiometry
|How to cite this article:|
Joy S M, Karthikeyan P, Pulimootil D T. A prospective cohort study on ossicular reconstruction using autologous incus or cartilage in chronic otitis media. Ann Indian Acad Otorhinolaryngol Head Neck Surg 2021;5:18-23
|How to cite this URL:|
Joy S M, Karthikeyan P, Pulimootil D T. A prospective cohort study on ossicular reconstruction using autologous incus or cartilage in chronic otitis media. Ann Indian Acad Otorhinolaryngol Head Neck Surg [serial online] 2021 [cited 2021 Nov 29];5:18-23. Available from: https://www.aiaohns.in/text.asp?2021/5/1/18/320568
| Introduction|| |
Chronic otitis media presents as a set of irreversible changes occurring in the middle ear mucosa due to inflammation., Among a gross estimate of 65 million to 330 million people affected by chronic otitis media, about 60% of patients are said to experience impaired hearing. Ossicular damage is one of the most prominent impacts of chronic otitis media., In accordance with the classification of ossicular defects given by Austin, eroded long process of the incus with intact malleus and stapes fall under group A and are the most frequently occurring defect., The ear ossicles play a crucial role in the transmission and amplification of sound from the outer ear to the inner ear, hence reconstruction of the damaged or disrupted ossicular chain in the middle ear with grafts becomes necessary for the restoration of hearing.
Homografts were widely used initially but were later abandoned due to the heightened possibility of infections, prion transmission, and resorption., Following the primogenial use of autografts by Hall and Rytzner in 1957, the use of autologous incus for ossicular reconstruction gained substantial popularity. The success of an ossicular reconstruction procedure is determined by pure-tone average (PTA) and air-bone gap (ABG) which are also considered to be useful predictors of ossicular discontinuity in chronic otitis media affected patients.,
At present, various treatment options exist for ossiculoplasty, but many remain beyond the reach of the economically challenged patients, a scenario frequently faced by developing nations. In this subset of patients, the application of autologous materials appears to be the obvious choice for cost-effective and audiologically efficient ossiculoplasty. However, there persists a dearth in literature upon the suitability of autografts in ossicular reconstruction. These factors have inspired the current study to compare the efficiency of various autologous grafts for ossiculoplasty in patients with chronic otitis media.
Aim and objective
This study aimed at comparing the results of ossiculoplasty using autologous incus and autologous conchal/tragal cartilage adjudged by the improvement in audiological outcomes postoperatively. This study also strived to identify the predictors of ossicular erosion in patients with chronic otitis media which would direct preoperative surgical planning. In addition, histopathological signs for the ubiquity of micro-deposits of squamous epithelium in autologous incus among the patients with chronic otitis media with cholesteatoma were also evaluated.
| Methodology|| |
This prospective cohort study was based in the Department of Otorhinolaryngology of a tertiary care center. An inclusion criterion of patients >18 years of age with Chronic Otitis Media refractory to medical therapy and requiring surgical intervention was applied. The exclusion criteria consisted of patients with intracranial complications of Chronic Otitis Media, otosclerosis, any uncontrolled systemic disease, unwilling or unable to comply with regular postoperative visits, contraindications to surgery or anesthesia, having mixed and sensorineural hearing loss or previously operated ears. Prior approval from the Institutional Ethics Committee along with written informed consent from patients was obtained. A time-dependent sample selection procedure was opted for in this study. Analysis of the archived patient records indicated that 68 patients visited the center annually, a sample size of 100 patients was deemed to be appropriate.
Pure-tone audiograms of the patients were analyzed, and the relevance of PTA as a potential indicator of incudostapedial joint necrosis was subsequently evaluated. Preoperative and postoperative audiograms representative of pure-tone averages, ABGs, and closure of ABGs were juxtaposed. The American Academy of Otolaryngology-Head and Neck Surgery guidelines define a postoperative ABG of 20 dB or less as a successful hearing result. Preliminary preoperative blood investigations were carried out. Radiographic evaluations of the mastoid (Law's view) to determine the gross anatomical deformities or pathologies and Water's view to rule out any focus of infection in the nose or paranasal sinuses were done using an 800 mA Siemens machine. This was followed by nasal endoscopy, where a 4 mm Hopkins rod nasal endoscope was employed to eliminate any focus of localized infection. High resolution computed tomography (HRCT) of both the temporal bones was done when indicated. The examination of the ear was done using a higher and lower magnification of a Carl Zeiss operating microscope to confirm the diagnosis. The type of perforation, the status of middle ear ossicles, mucosa, and the presence of any granulation or polyps were thoroughly investigated. The success rate of middle ear reconstruction procedures and their associated surgical outcomes were predicted using the middle ear risk index (MERI), for which the status of the middle ear and its ossicles were ascertained.
Ossiculoplasty was done under general anesthesia by postaural route in all cases. The ossicular continuity was assessed in the following ways; if the incudostapedial joint was discontinuous, the incus was removed and examined and if the incus was in adequate condition, it was refashioned and placed over the stapes head or footplate. On the other hand, if the incus was severely eroded, autologous conchal or tragal cartilage was harvested and was refashioned and positioned over the stapes head or footplate. The eroded incus was sent for histopathological examination to look for the presence of microdeposits of squamous epithelium. Therefore, based on the intraoperative findings, patients fell into two cohorts/groups, wherein Group I patients (n = 52) were fitted with autologous incus and Group II (n = 48) patients were fitted with autologous tragal cartilage. A 0.6 mm diamond burr was used for drilling the grafts. The interposition of incus was done as described by Pulec and Sheehy. After placement of the ossicular or cartilage graft, it was temporarily supported by gel foam soaked in antibiotic eardrops. Along with this, the patients received adequate analgesia, oral antihistamines, and topical nasal decongestants. Patients were discharged on the 7th postoperative day after the suture removal. Following discharge, review at 2, 4, and 6 weeks looked for the closure of tympanic membrane perforation, graft takes up, and the presence of retraction pockets in patients. Post-operative pure-tone audiometry was done at 3 and 6 months follow-up.
Data were collected using a Proforma sheet and tabulated using Microsoft Excel. Statistical analysis was performed using SPSS statistical software, version 16.0. Descriptive statistics such as mean, frequency, and standard deviation of quantitative parameters were used to express their distribution patterns. Wilcoxon Signed-rank test, Student's t-test (both paired and unpaired), and multiple logistic regression were used to calculate the statistical significance across the two groups (I and II). Chi-square test was used to find the association between the qualitative variables and the respective groups. A value of P < 0.05 was considered statistically significant.
| Results|| |
The study included a total of 100 patients suffering from chronic otitis media, ranging between 18 and 55 years, with the mean age of patients being 32.5 years. A majority of patients undergoing autologous incus ossiculoplasty belonged to the 31–40 years age group, while most patients who underwent autologous cartilage reconstruction were aged between 21–30 years. Overall, there was a consistent distribution of patients across all age groups in both groups [Figure 1].
Among the study participants, a male preponderance of 54 males over that of 46 females with a male-to-female ratio of 1.2:1 was noticed. Out of the 54 males, 30 (55.5%) and 24 (44.4%) patients underwent autologous incus and autologous cartilage ossiculoplasty, respectively. Similarly, out of the 46 females, 22 (47.8%) underwent autologous incus ossiculoplasty and 24 (52.21%) underwent autologous cartilage ossiculoplasty.
Radiographic comparison of the groups revealed that Group I (autologous incus, n = 52) and Group II (autologous cartilage, n = 48) demonstrated sclerotic mastoids in 40 and 41 patients each, while diploic mastoids were seen in 12 and 7 patients, respectively. Hence, a majority of the participants (81%) had sclerotic mastoids whereas 19% had diploic mastoids and none had pneumatised mastoids among both the groups. [Figure 2] illustrates the erosion in the incus and cartilage of patients and their subsequent refashioning.
|Figure 2: Ossicular reconstruction. (a) Eroded incus with lenticular process. (b) Refashioning eroded incus. (c) Refashioning eroded cartilage. (d) Refashioned cartilage ready for grafting (e and f) Intraoperative photograph showing placement of refashioned incus and cartilage graft respectively|
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The baseline values were assessed preoperatively and were compared with the mean PTA at 6 months and the patients of Group I had a hearing gain of 6.02 decibels and Group II had 4.65 decibels. The difference in postoperative mean PTA observed in each of the two groups were found to be highly significant (P < 0.001). Therefore, it is inferred that substantial hearing gain was experienced by patients in both cohorts. The baseline air-bone gap values of both cohorts were assessed preoperatively and were compared with their respective mean ABG values at 6 months. The difference in the postoperative closure of the air-bone gap in each of the two groups was found to be statistically significant (P < 0.001), implying that the postoperative air-bone gap closure showed noteworthy improvement post ossicular reconstruction in both groups [Table 1].
|Table 1: Comparison of pure-tone audiograms (pure-tone average and air-bone gap) and middle ear risk index between the groups|
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However, on comparing the differences in mean PTA and mean air-bone gap preoperatively and postoperatively between the two groups, it was found that the difference was statistically significant for PTA (P = 0.0035) and insignificant for air-bone gap closure (P = 0.056). This implies that the postoperative hearing outcomes in terms of PTA were better for patients with an autologous incus graft (Group I) in comparison to patients with an autologous cartilage graft (Group II). However, improvement of the air-bone gap closure was almost equivalent across both groups [Table 1].
On assessing the MERI, it was found that 88.46% of patients in group I had a moderate risk index and compared to 62.5% in Group II. However, risk index of ≥7 was seen in 18 patients (37.5%) in Group II and 6 patients (11.54%) in Group I. The analysis had significance with a P = 0.002. On calculating the mean of the same between both the groups, the difference was found to be statistically significant (P < 0.001) as depicted in [Table 1].
With regard to the rate of graft uptake at 6 weeks postoperatively among the two groups, an equivalent response was observed. It was found that 47 (90.4%) patients from group I and 40 (87%) patients from Group II had successful outcomes [Figure 3].
This study found that 38 patients (73.07%) from Group I and 30 patients (62.5%) from group II had successful hearing outcomes based on postoperative ABG ≤20 dB. A multivariate analysis of various possible predictors of successful hearing outcomes was performed and age (P = 0.044) and MERI index (P = 0.021) were statistically significant predictors. This implies that the lower age group had a higher success rate in terms of air-bone gap. Similarly, lower MERI index values were associated with better hearing outcomes. In this study, 48 patients (48%) were found to have severe ossicular erosions intraoperatively necessitating cartilage reconstruction of the hearing mechanism. A multivariate analysis of possible predictors for severe ossicular erosion was performed using logistic multiple regression, which revealed gender (P = 0.046) to have a strong association with ossicular erosion, but the remaining parameters were found to be statistically insignificant. This indicates that the variables such as age, Law's view, preoperative PTA and pre-operative ABG cannot be considered as predictors of ossicular erosion [Table 2].
|Table 2: A multivariate analysis of possible predictors for severe ossicular erosion|
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In all the patients with severe ossicular erosions necessitating cartilage ossiculoplasty, the eroded incus was sent for histopathological examination. As illustrated by [Figure 4], of the 48 ossicles studied, 31 (64.5%) showed squamous epithelium and keratin flakes on the surface. The remaining 17 (35.42%) showed granulation tissue formation on the surface. None of the ossicles showed invasion of the squamous epithelium into the substance of the ossicle. Hence this study supports the use of incus as a viable graft for hearing reconstruction but the presence of microdeposits of squamous epithelium indicates the potential risk of residual cholesteatoma.
|Figure 4: Histopathological examination of eroded incus. (a) Squamous epithelium and keratin flakes on the surface. (b and c) Granulation tissue formation on the surface of the eroded incus|
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| Discussion|| |
The success of ossiculoplasty is contingent upon factors such as the middle ear milieu, pressure in the Eustachian tube, form of prosthesis/graft, surgical technique, erosion of ossicular chain, and presence of cholesteatoma.,, The current study proposed to investigate the reliability of preoperative predictors such as PTA, ABG, and MERI scores in anticipating hearing associated outcomes of ossiculoplasty.
The mean age of participants was 32.5 years in this study though ages ranging from 18 to 55 were noticed. The study was found to have a slight male predominance as indicated by a male-to-female sex ratio of 1.2:1. The analysis revealed that age could be a predictor of successful hearing postoperatively (P < 0.05).
In a randomized clinical trial by Naragund et al. to analyze the outcomes of ossiculoplasty in terms of PTA, successful hearing gain was seen in 58% of cases with autologous incus and in only 33% of cases with titanium prosthesis. Similarly, Woods et al. reported that post-operative mean ABG and mean PTA were significantly lower using incus reconstruction when compared to titanium prosthesis groups. These findings are in consonance with the results of the current study, where a significant improvement in hearing in terms of PTA (P < 0.001) and ABG (P < 0.001) in patients with autologous incus and cartilage ossiculoplasty. In addition, the former was found to have a slight edge over the latter as the difference in PTA was significantly better in patients having undergone autologous incus ossiculoplasty (P = 0.0035) in comparison to their control group counterparts who underwent middle ear reconstruction with autologous cartilage.
Almazrou et al. investigated the role of MERI as a prognostic factor in pediatric ossicular reconstruction in a 10-year retrospective study involving 44 children aged between 4 and 18 years. The mean MERI was 3.40 for excellent results (0–10 dB postoperative ABG), 4.42 for good results (11–20 dB postoperative ABG), 4.45 for fair results (21–30 dB postoperative ABG), and 4.06 for poor results (ABG >30 dB). They found that the MERI as a tool for anticipating the hearing outcomes of ossicular reconstruction showed poor reliability in children. Contrasting to which, in this study, MERI was shown to be a reliable tool for predicting the hearing outcomes of the ossicular reconstruction as patients with lower MERI index showed better success rate than patients with higher MERI index scores. The dissonance in findings between the two studies may be on account of the age groups of participants studied. In this study, MERI scores ranging between 1 and 3 were considered to be in the mild category, whereas scores between 4 and 6 and ≥7 were noted as moderate and severe, respectively. An observational prospective study by Bihani et al. showed that the lower the MERI index, higher was the chance of successful hearing outcome and vice versa. The MERI index was calculated for the patients on the basis of ossicular status, otorrhoea, perforation of the tympanic membrane, the omnipresence of middle ear granulation, and earlier instances of surgery. The present study also inferred the same result showing a lower MERI index to be a predictor of successful hearing outcome.
A study by Sousa et al. determined variables like the presence of cholesteatoma, status of middle ear mucosa, the presence of malleus handle, the presence of stapes superstructure, and surgical methods could influence hearing outcomes in terms of postoperative air-bone gap. However, in the current study, it was found that age and MERI index were significant predictors influencing hearing outcomes as compared to other intraoperative findings (P < 0.05).
Mahanty et al. did a nonrandomized prospective cohort study in 67 patients with different graft materials for ossiculoplasty to determine and compare the postoperative hearing outcome. They showed autologous incus has the lowest extrusion rates as compared to cartilage and titanium prosthesis. Similarly, the current study also showed the same results with the lowest extrusion rates (5 cases) for autologous incus as compared to cartilage.
In a study by Karja et al. on the role of chronic suppurative otitis media in the erosion of the ossicular chain, devoid of cholesteatoma, disruption in the ossicular chain was noticed in 59%–78% cases. The erosion in the vascular bone was attributed to the active granulation tissue by the authors. This phenomenon initiated by infection at first, is the fundamental mode of ossicular damage, in ear with or without cholesteatoma. Thomson et al. noted how bone erosion is more often accompanied by cholesteatoma than without but still carries the threat of occurrence even in the absence of cholesteatoma. Long process of the incus is the most frequently affected ossicle and cholesteatoma can give rise to fatal complications that are intracranial in nature such as meningitis, abscesses, lateral sinus thrombosis along with extracranial complications such as zygomatitis, facial nerve palsy, mastoiditis, and labyrinthine fistula. Recidivism postsurgery is a commonly observed risk associated with cholesteatoma. Mohanty et al. studied the appositeness of PTA as a predictor for incus erosion and proposed that incus necrosis was best anticipated by the manifestation of moderate to moderately severe hearing loss (45–70 dB HL). In contrast to all these studies, the concurrent study found that gender (P = 0.046) was a significant predictor for ossicular erosion among the variables studied. This discordance can stem from a smaller size of the population studied and differences in the study variables selected.
Dornhoffer et al. have previously reported the invasion of the incus by epithelial cells that manage to evade macroscopic examination following implantation of an autologous ossicular graft thereby putting the patient at the risk of recurrent cholesteatoma. Subotic and Femenic on performing a histologic analysis of the incus in 160 cases of chronic otitis media with cholesteatoma discovered that the procedure entails a high risk for malfunctioning of the transmissional apparatus or relapse of the inflammatory process. However, a study by Ng et al. deduced that autologous ossicles even after surface stripping under the operating microscope, can retain body and bulk, hence are safe to use for reconstruction after. Contrary to the previous findings, the results of the current study demonstrate the lack of squamous tissue invasion into the ossicular substance. Hence, an autologous incus graft carries a lot of potential as a graft of choice for ossicular reconstruction.
Lack of patients showing incus erosion hindered the assessment of hearing gain in such patients. Moreover, HRCT temporal bone was not assessed as only a few patients were included in this study had indication for HRCT temporal bone scan and hence its significance as a predictor of ossicular erosion could not be studied. Other limitations of this study were small sample size and briefly follow -up. Therefore, future randomized control trials with larger sample sizes and longer follow-up may help to conclusively pinpoint the preoperative predictors of ossicular necrosis. A multitude of studies have explored ossicular reconstruction for patients suffering from Otitis media, with the majority focused on the efficiency of incus or cartilage grafts in silos. The current study, however, has drawn a comparative analysis of postoperative outcomes of ossicular reconstruction with autologous incus graft and autologous cartilage graft in patients with chronic otitis media, which makes it the first of its kind.
| Conclusion|| |
Significant gain in hearing following ossiculoplasty with autologous incus and autologous cartilage was observed; however, the effectiveness of autologous incus in terms of pure tone audiometry outweighed that of cartilage. Although the invasion of incus by squamous epithelium was absent in all the case studies, microdeposits of epithelial cells can become a source for residual cholesteatoma. The study was also successful in determining age and MERI to be good predictors of successful hearing outcome.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2]