|Year : 2013 | Volume
| Issue : 1 | Page : 23-26
Middle ear risk index as a prognostic factor in pediatric ossicular reconstruction
Khalid Almazrou, Munahi Alqahtani, Mohamed Alshehabi
Department ORL HNS, King Abdul-Aziz University Hospital, Riyadh, Kingdom of Saudi Arabia
|Date of Web Publication||6-Mar-2013|
King Abdul-Aziz University Hospital, Riyadh
Kingdom of Saudi Arabia
Source of Support: None, Conflict of Interest: None
Objectives: To study the hearing results in children following ossicular reconstruction and to determine if the middle ear risk index (MERI) is a useful tool for predicting the outcome of surgery. Design: A retrospective case series. Setting: A tertiary academic center. Patients: Forty-four children underwent ossicular reconstruction using autologous or alloplastic prostheses from January 1995 to January 2005. Materials and Methods: Patients' audiograms were evaluated preoperatively and postoperatively for pure-tone average (PTA) and air-bone gap (ABG). Each ear was scored using the MERI and a total index was calculated. Results: 23 boys and 21 girls were included in the study. The mean preoperative ABG was 38 dB, and the mean postoperative ABG was 25.3 dB. 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). The complications included perforation of tympanic membrane (13.6%), worsening of the conductive hearing loss (6.8%), retraction pockets (9.1%), recurrent or residual cholesteatoma (6.8%), high-frequency sensorineural hearing loss (4.45%), and prosthesis extrusion (2.3%). The mean follow-up period was 14 months. Conclusion: Children have poorer hearing outcome following ossicular reconstruction in comparison to the published adults' results. The MERI was not a reliable tool for predicting the hearing results of ossicular reconstruction in children.
Keywords: Cholesteatoma, Otitis media, Sensorineural hearing
|How to cite this article:|
Almazrou K, Alqahtani M, Alshehabi M. Middle ear risk index as a prognostic factor in pediatric ossicular reconstruction. Indian J Otol 2013;19:23-6
| Introduction|| |
Ossicular reconstruction is an operation performed to attempt to restore the continuity and the sound conduction capabilities of the ossicular chain. Multiple prosthetic materials and designs have been employed in reconstructing the ossicular chain. Autograft material is readily available at surgery (patient's own bone) and may be used to fashion prosthesis. 
Artificial reconstructive materials are alternatives but have their own concerns regarding audiological outcome and complication rates; most notably their extrusion rate. 
There are many variables that may influence the hearing results of ossicular reconstruction. The middle ear risk index (MERI) is one of the most reliable measuring tools to evaluate the results of ossicular reconstruction and to compare the outcome among different studies. 
The MERI encounters intrinsic and extrinsic factors that may influence the surgical intervention. The Intrinsic factors include Eustachian tube More Details function, severity of the disease, and status of the residual ossicular chain.
Extrinsic factors includes surgical technique, staging, design, and composition of the graft and the prosthesis. 
The reported results of ossicular reconstruction in children are few. Children have higher rate of eustachian tube dysfunction and recurrent upper respiratory tract infections. Ossiculoplasty is inherently more difficult in children also. As a result of this and as a result of a reticence on surgeons part to operate on this age group, there is lack of statistically significant data to support or definitively refute the efficacy of this important procedure in children.
The aim of this study is to report the hearing results of ossicular reconstruction in children and to determine if the MERI is useful in predicting the outcome of surgery in this population of patients.
| Materials and Methods|| |
A 10-year retrospective study was carried out at King Abdulaziz University Hospital, Riyadh, Saudi Arabia, from January 1995 to January 2005. The study was approved by and performed in accordance to the guidelines of the Institutional Committee of Research. All consecutive patients aged 18 year or less who underwent ossicular reconstruction with or without concomitant mastoidectomy procedures.
All preoperative and postoperative clinical and audiological data were recorded. The charts of 53 patients were reviewed. Nine charts were excluded because of incomplete or inadequate documentation or loss of follow-up. Data fields including age, sex, surgical procedure, MERI, and all the preoperative and postoperative audiograms were recorded for the remaining eligible 44 patients.
The bone and air conduction averages calculated as the mean of the thresholds at 0.5, 1, 2, and 4 kHz. This was in accordance with the guidelines delineated by the Committee on Hearing and Equilibrium of the American Academy of Otolaryngology-Head and Neck Surgery for the evaluation of results for treatment of conductive hearing loss. 
The average air-bone gap (ABG) was calculated using the difference between air conduction and the bone conduction averages at the same frequencies.
Hearing success was defined as a postoperative ABG of 20 dB or less. Each ear was fully scored using the Kartush scoring system, and an index total was calculated.  The subtotals for each category as well as the index total were compared with the postoperative ABG.
Data calculated for postoperative ABGs were then placed into groups as follows: Excellent results (0 10 dB ABG), good results (11-20 dB ABG), fair results (21-30 dB ABG), and poor results (ABG > 30 dB).
An increase of bone conduction threshold of more than 15 dB was considered as a postoperative sensorineural hearing loss (SNHL).
Our data were statistically analyzed using independent samples (unpaired, two-tailed student's) t-test, and Statistical Package for the Social Sciences (SPSS).
| Results|| |
The total numbers of patients was 44 (23 (52.27%) were boys and 21 (47.73%) were girls). Patients' ages ranged from 4 to 18 years (mean: 15.1). The mean follow-up period was 14 months (a range of 6-84 months).
The indications for surgery were chronic suppurative otitis media without cholesteatoma in 17 (38.64%) cases; cholesteatoma in 16 (36.36%) cases; tympanosclerosis in 9 cases (20.45%); and trauma in 2 (4.44%) cases.
Ten patients (22.73%) underwent canal wall up and six patients (13.66%) underwent canal wall down mastoidectomies in conjunction with the ossiculolasty. Twenty-two ears (50%) were reconstructed using autologus grafts. Alloplastic prosthesis was used in 21 (47.72%) cases.
The autologus grafts used were 16 sculpted incus (36.63%), 5 sculpted cortical bone (11.36%), and 1 sculpted malleus head (2.27%).
The alloplastic prostheses used were partial ossicular reconstruction prostheses (PORP) in 6 ears (13.66%) and total ossicular replacement prostheses (TORP) in 15 ears (34.10%).
Ossicular reconstruction was performed as a primary procedure in 36 (81.80%) patients, as a revision procedure in 4 (9.10%) patients, and as a staged procedure in 4 (9.10%) cases.
Tympanic membranes were intact in 8 (18.18%) patients and in 36 (81.82%) patients temporalis fascia grafts was used to reconstruct perforations.
The average postoperative ABG and the total MERI are shown in [Table 1].
|Table 1: Hearing results and average MERI for each group (a total of 44 ears)|
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The preoperative air conduction thresholds were between 15 and 53.75 dB (average, 47.18) and the postoperative air conduction thresholds were between 11.24 and 80 dB (average, 34.74).
The overall success rate (closure of the ABG to within 20 dB) was achieved in 17 cases (38.63%). The commonest complication was tympanic membrane perforation followed by retraction pockets and residual cholesteatoma, respectively [Table 2].
| Discussion|| |
In our series of pediatric patients, surgical success in terms of improved hearing was achieved in 38%. This result is similar to these reported by other authors. ,,
Kessler, et al. reported the use of PORPs and TORPs in children with success rates of 54%. Daniels et al. on the other hand used PORPs only in 62 of children and reported a success of closure to 20 dB or better in 66% of patients.
Most studies of ossicular reconstruction in the literature have focused on the hearing results in the adult patients. However, different definitions of success have been used, most of the studies considered postoperative ABG closure to 20 dB or less as surgical successes. The reported success rate ranged between 57% and 80% in several studies. 
There have been many reports discussing the prognostic factors and results of hearing outcome in ear surgery.  Belluci suggested four discrete stages of prognosis based on the status of the middle ear at presentation.  Black introduced the Surgical, Prosthetic, Infection, Tissues, and Eustachian tube (SPITE) system.  Wullstein proposed a five-part system to aid in determining the prognosis of hearing impairment based on residual ossicular remnants and how they may be reconstructed.  Austin subsequently developed a system that included the residual ossicular remnants.  Kartush has divided these into intrinsic factors: eustachian tube function, disease severity, and status of the residual ossicular chain and extrinsic factors which are within the surgeon's control. Extrinsic factors included, surgical technique, staging, design, and composition of the graft and prosthesis.  The MERI stratifies these factors into prognostic categories. The MERI has been revised in 2001.  Smoking is added as a middle ear risk and is given 2-risk points. Significant granulation tissue or effusions added 2-risk points. Furthermore, cholesteatoma risk value had been increased to 2-risk points  [Table 3].
Age criteria should not absolutely preclude ossicular reconstruction. A systematic approach with accurate data is required for pediatric patients whose parents are considering ossicular reconstruction surgery as an alternative to hearing aids.  Although hearing aids may provide a noninvasive method to manage the hearing loss in pediatric patients, the potentially negative psychological burden of externally worn hearing aids in the pediatric age group has been documented. ,
Several authors have suggested that the age can be a factor in predicting tympanoplasty success, but there is very little data on applying the same logic to ossiculoplasty in the pediatric population. Eustachian tube maturation has a major impact on the success rate in tympanoplasty. Some authors recommend avoiding tympanoplasty before the age of 7 years, while others recommend waiting until the child is over 12 years of age. A meta-analysis of these articles clearly indicates a great success rate with increased age in tympanoplasty; however, it is not entirely clear what age is the best. 
These findings are as yet not statistically applicable to osssiculoplasty in children, although logic would seem to indicate that they should be equally valid.
In this study, the MERI was found to be unreliable in predicting hearing results of ossicular reconstruction in children.
Despite the negative or insignificant statistical correlation, we think that future prospective investigations are required to determine the success and therefore wisdom of ossicular reconstruction in young children and the efficacy of the MERI score system in predicting the outcome. It may be that the perceived wisdom used to argue against tympanoplasty in the pediatric population does not correlate to outcomes of ossiculoplasty in terms of hearing outcomes.
| Conclusions|| |
Children have poorer hearing outcome following ossicular reconstruction in comparison to the published adults' results.
The MERI was not a reliable tool for predicting the hearing results of ossicular reconstruction in children.
Further prospective randomized controlled trials are required to further determine the efficacy of ossiculoplasty in children.
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[Table 1], [Table 2], [Table 3]