Pre-operative Indicators of Ossicular Necrosis in Tubotympanic CSOM

Ossicular necrosis and erosion is commonly seen in CSOM with cholesteatoma but can also occur in tubotympanic CSOM. This usually comes as a surprise during surgery. Preoperative knowledge of ossicular necrosis helps the surgeon to be better prepared for the surgery and ossicular construction if required. Hence, this study is intended to identify the pre-operative indicators of ossicular necrosis. This cross sectional study was conducted in Father Muller Medical College in Mangalore. Sixty nine consecutive patients with tubotympanic CSOM underwent a detailed clinical examination with pure tone audiometry and subsequently tympanoplasty with or without cortical mastoidectomy. All clinical findings, pure-tone audiometry, and intraoperative otomicroscopic observations were recorded. Incidence of ossicular necrosis was 23 %. The incus was most frequently eroded followed by malleus and then stapes. On bivariate analysis patients age above 30 years (p = 0.05), duration of CSOM more than 10 years (p = 0.02), presence of granulation (p < 0.05), absence of tympanosclerosis (p = 0.01), moderately severe (45-60 dB) hearing loss (p = 0.01) and an air bone gap of more than 55.7 dB in the right ear and 63.95 dB in the left ear was found to be statistically significant (p < 0.05). On multivariate analysis only presence of middle ear granulation tissue was found to be the significant predicator [(p = 0.005), OR 14.37, 95 % CI 2.26-90.0]. The presence of granulation tissue and a wide air bone gap on pure tone audiometry were the best indicators of ossicular necrosis. Preoperative identification of these indicators can help the surgeon to be better prepared for the surgery.