Prognostic Significance of MERI in Predicting the Postoperative Outcome of Surgery for Chronic Otitis Media

Background: Chronic otitis media (COM) is a long-term, irreversible inflammation of the middle ear lining that causes changes in the tympanic membrane. Chronic otitis media (COM) is a common middle ear disease and a serious health problem worldwide, especially in developing countries. The aim of this study was to investigate the role of the Middle Ear Risk Index (MERI) on the outcome of chronic otitis media and COM surgery to investigate implantation success and hearing improvement.

Methods: This was a prospective study conducted in the Department of Otolaryngology and Head Neck Surgery, BSMMU, Dhaka, Bangladesh January to June 2023. A total of 55 patients of COM were included in this study. Detailed ENT examination and preoperative pure tone audiometry were done in all patients. MERI score was calculated and patients were stratified based on the MERI score. All patients were evaluated at the end of 3 months postoperatively, for the status of graft uptake and improvement in hearing.

Results: Total 55 patients of COM were included in this study. The total numbers of males in our study were 23 (41.8%) and females were 32 (58.2%) which were almost comparable. Majority of the cases with mucosal disease underwent tympanoplasty (43.6%) and cortical mastoidectomy with tympanoplasty (38.2%) and cases with squamosal disease underwent combined approach tympanoplasty (5.4%), modified radical mastoidectomy (9.1%) and modified radical mastoidectomy with mastoid obliteration (3.6%). The difference in the proportion of the AB gap across the severity of MERI was statistically significant (p=0.011). The mean preoperative air conduction was 43.3±13.9 and the mean postoperative air conduction was 35.07±16.4 in the study population. The mean preoperative bone conduction was 15.04±10.5 and the mean postoperative bone conduction was 16.13±10.7. The mean preoperative AB gap was 28.28±11.2 and the mean postoperative AB gap was 18.65±11.6. The difference in the proportion of pre and postoperative AB gap was statistically significant (p<0.001). In our study 41 (74.5%) patients fell into the mild MERI category, 8 (14.6%) patients were categorized as moderate MERI group and only 6 (10.8%) patients were categorized as severe MERI group. Out of 41 mild MERI, 34 (82.9%) had successful graft uptake. In the moderate MERI group, the success rate was 75% (6 out of 8) and in the severe MERI group, it was 50% (3 out of 6). Among the people with mild MERI, the mean pre-op AB gap and post-op AB gap were 28.29 and 17.15 respectively. In moderate MERI group, the mean pre-op AB gap and post-op AB gap were 27.50 and 20.41 respectively and in severe MERI, the mean pre-op AB gap and post-op AB gap were 29.27 and 26.95 respectively. The MERI was found to be a remarkable predictor of the outcome of surgeries for COM. The patients with mild MERI scores had a significantly better prognosis than patients with severe MERI scores.

Conclusion: MERI is a very useful and honest predictor of the graft uptake and hearing benefit in patients undergoing surgeries for COM. It has an inverse relation with graft uptake and hearing benefit. Based on the MERI score, the likelihood of surgical success and hearing benefit could be explained to the patient of COM to give them realistic expectations.

Keywords: Meri, Com, Graft Uptake, Hearing Benefit