CORRELATION BETWEEN HIGH RESOLUTION COMPUTED TOMOGRAPHY OF TEMPORAL BONE WITH INTRAOPERATIVE FINDINGS IN SAFE AND UNSAFE CHRONIC OTITIS MEDIA

Abstract

INTRODUCTION: “Chronic otitis media (COM) is defined as the chronic inflammation of the middle ear and mastoid cavity, which presents with recurrent ear discharge or otorrhoea through tympanic membrane perforation‖.1 This usually begins as childhood disease like Acute otitis media or other forms of otitis media.2 Chronic otitis media is of two types, SAFE type also called as Tubo tympanic disease ( TTD) and UNSAFE type also called as Attico antral disease (AAD), as the name suggests Unsafe type of Chronic otitis media is associated with both intracranial and extracranial complications if left untreated.3 Conventional radiography does not permit a detailed study of middle ear and mastoid. High resolution computed tomography (HRCT) has completely replaced conventional multidirectional tomography in evaluation of the temporal bone. HRCT has high resolution, multiplanar reconstructions and 3D reconstructions which provide global information of middle ear structures. This gives surgeon better information and plays a major role in preoperative and post-operative evaluation of the patients with Unsafe type of Chronic Otitis Media(AAD). India has the second highest prevalence of Chronic otitis media in the world. Therefore we are performing this study in our institute in kolar region . No well designed study has been done to exclusively document the Chronic otitis media and their complications in our institute. Our study can contribute to plan an effective surgical and management strategy in patients with Chronic otitis media( in both safe and unsafe type). OBJECTIVES OF THE STUDY: 1) To observe and document the findings of HRCT temporal bone in Tubo tympanic and Attico antral type of chronic otitis media XII 2) To document the extent of involvement of middle ear, mastoid segment and any intracranial complications occurring due to Chronic otitis media 3) To compare the HRCT Temporal bone findings in Tubo tympanic and Attico antral type of Chronic otitis media to the intra operative findings such as ossicular chain erosion, facial canal dehiscence, scutum erosion, tegmen tympani erosions, mastoid involvement MATERIALS AND METHODS: This is a Crossectional analytical study was conducted in 51 patients with Chronic otitis media who presented to the Department of Otorhinolaryngology in R.L Jalappa Hospital & Research Centre attached to Sri Devaraj Urs Medical College, Tamaka, Kolar from December 2019 to September 2021. STUDY PERIOD: DECEMBER 2019 TO SEPTEMBER 2021 Data was entered into Microsoft excel data sheet and was analyzed using SPSS 22 version software. Categorical data was represented in the form of Frequencies and proportions. Continuous data was represented as mean and standard deviation. RESULTS: This study was a crossectional analytical study that was conducted at our institute on 51 patients with Chronic otitis media, 21 patients were having Unsafe type of COM and 30 patients were with Safe type of COM. Our study showed female preponderance and maximum patients with COM are in the age group of 21 to 30 years. Incus is the most commonly eroded ossicle in our study followed by malleus and stapes. In our study Strong surgico radiological XII I correlation was found in identification of Facial recess involvement , mastoid, aditus and antrum involvement and also in cholesteatoma involving mesotympanum and hypotympanum . In few cases where there are posterior semicircular canal fistulas and cholesteatoma involving the epitympanum and sinus tympani HRCT showed 100% sensitivity and specificity in our current study .In our study there is reliable correlation of HRCT with intra operative findings in the diagnosis of Malleus erosions, Tympanic membrane perforations , tegmen and sigmoid sinus plate erosions, tympanic segment of facial canal dehiscence and in the identification of lateral semicircular canal dehiscence. There is moderate correlation in diagnosis of Incus erosions and Labrynthine segment of facial canal dehiscence in our study. In case of identification of stapes erosion and Eustachian tube involvement in unsafe type of COM the correlation of HRCT with intraoperative findings showed fair agreement CONCLUSION: 1) HRCT of temporal bone plays a promising role in pre-operative assessment of Chronic otitis media as it depicts the extent of the disease and integrity of most of the structures of middle ear cleft . 2) Each section of the HRCT scan should be studied carefully, not to miss minute details like small labrynthine fistulas without any symptoms. It alerts the surgeon to make a plan prior to the surgery in view of any impending complications. 3) HRCT also gives a preoperative overview about ossicular chain status which helps for prior documentation and patient counseling regarding the hearing status post operatively. HRCT temporal bone guides as a blueprint for the surgeon intraoperatively. XI V 4) There are few pitfalls in HRCT Temporal bone which include identification of stapes erosion, dehiscence in mastoid segment of FN and discrepancies in postoperative cases of Tympanomastoidectomies due to destruction of the bony landmarks. HRCT scan sometimes may overestimate the disease extent and cannot differentiate between cholesteatoma and granulation tissue. Inspite of these limitations HRCT scan is a valuable and useful investigative tool prior to COM surgeries. 5) HRCT temporal bone is an useful investigation to evaluate patients planned for surgical treatment of COM and should be mandatorily done. However the surgeon should also be aware that it can sometimes miss minor bony erosions and unlike MRI, it cannot differentiate fluid from soft tissue.