Muller Journal of Medical Sciences and Research

ORIGINAL ARTICLE
Year
: 2021  |  Volume : 12  |  Issue : 1  |  Page : 6--12

The role of high-resolution computerized tomography as a diagnostic tool in the evaluation and planning of management of patients with chronic otitis media


Monali Mitra1, Priti Ashok Thakare2, Berton Craig Monteiro3, Dnyanesh B Amle4,  
1 Department of Otorhinolaryngology, Kasturba Medical College, Mangalore, Karnataka, India
2 Department of Otorhinolaryngology, Dr. Panjabrao Deshmukh Memorial Medical College, Amravati, India
3 Department of Radiodiagnosis, Father Muller Medical College, Mangalore, Karnataka, India
4 Department of Biochemistry, All India Institute of Medical Sciences, Nagpur, Maharashtra, India

Correspondence Address:
Dr. Berton Craig Monteiro
Department of Radiodiagnosis, Father Muller Medical College, Mangalore, Karnataka
India

Abstract

Context: Chronic otitis media (COM), a major cause of hearing impairment and its associated morbidity and mortality can be avoided with proper diagnosis and planned management. High-resolution computerized tomography (HRCT) is accessible and possesses role in the detection of COM. Aims: This study aims to evaluate the role of HRCT as a diagnostic tool in the evaluation and planning of management of patients with COM. Settings and Design: Prospective observational study. Subjects and Methods: The study included 100 subjects presenting with COM planned for detailed otorhinolaryngological and otoscopic examination, pure tone audiomentry, non-contrast HRCT of bilateral temporal bones and were exposed to initial medical management of symptoms and surgical management. Statistical Analysis Used: Data were expressed as percentage and mean ± standard deviation Kolmogorov–Smirnov analysis was performed for checking linearity of the data. Fischer's exact test or Chi-square test was used to analyze the significance of the difference between frequency distribution of the data. Results: For soft tissue attenuation, HRCT was 100% sensitive and specific for the presence of soft tissue mass. HRCT found to be 100% accurate in predicting cholesteatoma presence and was found to be sensitive in the range of 83.3%–100% and specific in range 87.04%–100%. For bony erosion, HRCT was found to be fairly accurate. These comparisons were found to be highly significant with P < 0.0001. Conclusions: HRCT of the temporal bone in subjects with COM can be a gold standard tool for diagnosis, surgical interventions, and follow-up.



How to cite this article:
Mitra M, Thakare PA, Monteiro BC, Amle DB. The role of high-resolution computerized tomography as a diagnostic tool in the evaluation and planning of management of patients with chronic otitis media.Muller J Med Sci Res 2021;12:6-12


How to cite this URL:
Mitra M, Thakare PA, Monteiro BC, Amle DB. The role of high-resolution computerized tomography as a diagnostic tool in the evaluation and planning of management of patients with chronic otitis media. Muller J Med Sci Res [serial online] 2021 [cited 2021 Dec 7 ];12:6-12
Available from: https://www.mjmsr.net/text.asp?2021/12/1/6/325479


Full Text



 Introduction



Chronic otitis media (COM) is an inflammation of the middle ear cleft resulting in long-term, or more often permanent changes in the tympanic membrane, including atelectasis, dimer formation, perforation, tympanosclerosis, retraction pocket development, or cholesteatoma without reference to the etiology or pathogenesis.[1],[2] The inflammation is usually accompanied with ear discharge and/or impairment in hearing.[3] The clinical presentation varies with the underlying severity of the infection, the host response, and the time course of its manifestations.

Especially in developing countries, COM is a major cause of acquired hearing impairment. The WHO data suggest 7.8% prevalence rate of COM in India.[4] A prior history of acute otitis media, parental history of COM, larger families, higher crowding index, and care in large day-care centers have been listed as risk factors for COM in.[1] Higher antibiotics have failed to reduce the COM incidences in case of chronic discharging ear. In such ears, the pathology is irreversible and time taking process resulting in intracranial complications. Therefore, it is advisable to recognize the disease at early stages and differentiate the major types of COM on clinical grounds namely the chronic mucosal disease and the COM with cholesteatoma; so as to adopt an appropriate surgical procedure and save the patient from hearing loss.[2] X-rays, computerized tomography (CT) scans, or magnetic resonance imaging scans are helpful diagnostic tools of COM, to rule out a cholesteatoma or any other associated complications. With the advent of helical scanning techniques, CT is widely accepted choice for imagining studies for the definitive preoperative bone imagining. Improvements in the high-resolution CT (HRCT) and advancements in radiological techniques have bettered the studies of temporal bone in patients with COM.[5]

In the present hospital setup, HRCT being easily available and its role in early detection of cases to prevent the complications of COM are of key interest. Thus, we aimed to evaluate the role of HRCT as a diagnostic tool in the evaluation and planning of management of patients with COM in our hospital.

 Subjects and Methods



This prospective observational study was conducted in the Department of Otorhinolaryngology, Jawaharlal Nehru Hospital and Research Institute Bhilai, Chhattisgarh, in the patients presenting with symptoms of COM with or without symptoms of any complications from June 2017 to May 2018. The study was approved by the Ethical Institute of the institute and written and informed consent was taken from the subjects or guardians before the scan and surgical management. The study subjects included all 100 cases aged above 16 years, diagnosed with COM, and who gave consent for the study. Subjects having a history of ear trauma, malignancy of middle ear, otitis externa, or previous histories of ear surgery were excluded from the study.

All the subjects were interviewed and investigated for their general examination, family history, chief complaints, past history, history of previous medications, and surgery if any. The selected patients were subjected to a detailed history and complete otorhinological examination followed by an otoscopic examination of the ear, the external auditory canal, status of tympanic membrane and middle ear mucosa. Pure tone audiometry (PTA) was done to document the severity of conductive hearing loss. The patients underwent X-ray mastoid Schuller's view before arriving at a provisional diagnosis of the type of COM in each case. All the cases were subjected to non-contrast HRCT scan of bilateral temporal bones using a 128 slice CT scanner – SCENARIA by HITACHI medical systems. Imaging was done in the axial plane under a slice thickness of 1 mm. Coronal, sagittal, and oblique multi-planar reconstruction of the axial images were done where required.

On HRCT temporal bone, the findings were classified based on the presence or absence of soft tissue attenuation with or without evidence of bony erosion. Soft tissue attenuation with bony erosion was taken to be suggestive of the presence of cholesteatoma. Other findings such as erosion of scutum or ossicles as well as erosion of lateral semicircular canal or facial nerve canal dehiscence were noted as evidence of complications of COM.

All the subjects were exposed to initial medical management of symptoms followed by appropriate surgical management. Patients with tubotympanic disease underwent tympanoplasty and patients with attico-antral disease with or without cholesteatoma underwent mastoidectomy either canal wall up or canal wall down types as required.

Data were expressed as percentage and mean ± standard deviation Kolmogorov–Smirnov analysis was performed for checking the linearity of the data. Fischer's exact test or Chi-square test was used to analyze the significance of the difference between frequency distribution of the data. P < 0.05 was considered statistically significant. SPSS © for windows™ version 20, IBM™ Corp., NY and Microsoft excel™ 2010, Microsoft® Inc. USA, was used to perform the statistical analysis.

 Results



[Table 1] indicates general characteristics and findings in the study subjects. The mean age of study population was found to be 47.65 ± 16.14 years and gender ration was found to be 0.63. While conductive hearing loss as detected by PTA was comparable (37% in right and 38% in left), 25% subjects were having complaints in both ears. The patients were subjected to PTA to quantify severity of hearing loss, and radiographic study of mastoid bone, findings of both are listed in [Table 1].{Table 1}

[Figure 1] and [Figure 2] depicate presenting complaints and examination findings in the study subjects respectively. While the most common presenting complaint was ear discharge (98%) most common examination finding was found to be Otorrhoea (83%). We were unable to visualize the tympanic membrane in 15% of patients. This was due to the presence of copious discharge, or polyp in the external auditory canal or sagging of the posterior meatal wall. Also, in 28% of patients, we were unable to visualize middle ear.{Figure 1}{Figure 2}

Provisional diagnosis of patients were arrived at by using various investigation techniques.Intra operative status of these subjects was confirmed by direct visualisation during surgery. [Table 2] denotes comparison of intra operative findings on HRCT and intra-operative findings and diagnostic efficacy of HRCT in comparison to intra-operative findings.{Table 2}

Sensitivity and specificity of HRCT for detection of soft tissue attenuation findings was found to be 100%. Remarkable diagnostic performance of HRCT was observed in comparison to intraoperative findings. For most of the parameters, HRCT showed 100% sensitivity and 100% specificity.

[Figure 3], [Figure 4], [Figure 5], [Figure 6] depicts HRCT findings for subjects at various stages of COM.{Figure 3}{Figure 4}{Figure 5}{Figure 6}

 Discussion



COM and related sequelae though known to cause economic morbidity and mortality are certainly avoidable. HRCT is noninvasive technique which can help to get the details of presence, location, and extent of disease also, it may prove useful in suspicion of congenital anomalies and in subject with a history of previous surgery leading to loss of surgical landmarks.[6] The importance of HRCT in the work up of patients with otitis media lies in the evaluation of status of ossicular chain, the tympanic and mastoid bony wall.[6]

Female preponderance in our study is in accordance to the study done by Vlastarakos et al.[7] Furthurmore, the age distribution is comparable to Mafee et al., in which the highest incidence of chronic suppurative otitis media was in third and fourth decades.[8] Symptomatology in our study which observed the most common presenting complaint to be ear discharge in 98% of patients, was similar to the findings of the study by Gyanu et al., where otorrhea was the presenting complaint in 100% cases and Yorgancilar et al.[9],[10] Other presenting complaints were decreased hearing in 91% of patients, tinnitus in 31%, fever in 16%, ear pain in 15%, giddiness in 12%, and facial weakness in 2% of patients. These symptoms of hearing loss, ear pain, giddiness, facial weakness, and fever are suggestive of complications of COM such as ossicular erosion, bony erosion over scutum, tegmen, lateral semicircular canal or even facial nerve canal dehiscence. HRCT thus becomes invaluable in early detection and treatment of complications.[9],[10]

The sagging of the posterior meatal wall as found in our study in 12% is considered as sign of mastoid is along with mastoid tenderness. Our findings of X-ray Mastoid Schuller's view correlated well with the appearance of the mastoid region on HRCT temporal bone as well as intra-operatively. Thus, X-ray Mastoid Schuller's view is adequate to identify the pneumatization status of the mastoid region accurately. This was in contrast to the study by Rai who found 44% well pneumatized mastoid appearance and 50% sclerotic mastoid appearance in their study.[2] On HRCT of the temporal bone, soft tissue attenuation was seen in 40% patients. However, we were unable to identify the type of soft tissue density on HRCT, i.e., unable to differentiate between cholesteatoma, granulation tissue, and polyps. This was higher to those found in the study by Gyanu et al., soft tissue without bony erosion is seen in 30% and slightly higher incidence with bony erosion in 66.6%.[9] Rai showed soft tissue attenuation with bony erosion in 64% cases.[2] However, were able to identify the location of soft tissue density on the HRCT temporal bone. Phillips et al. also showed a similar distribution of cholesteatoma on HRCT.[11]

HRCT was quite helpful in confirming the pathologies in patients presenting with features of complications. HRCT findings correlated well with the expected pathology in patients presenting with features of complications. The findings of ossicular erosion/absence intraoperatively differed slightly from that seen on HRCT temporal bone. Ossicular erosion was seen in 82% cases with cholesteatoma which is slightly less than that seen in the study by Gaurano and Joharjy who found it in 92% cases and similar to the studies by Swartz, and Mafee et al.[12],[13],[8] Absent ossicles were seen in 18% cases with cholesteatoma which is in contrast to studies done by Mozumder et al. who found absent malleus in 5% cases and absent incus in 43% cases.[14] Similar findings were found in a study by Albera et al.[15]

Those with bony erosion suggestive of cholesteatoma on HRCT were found to actually have cholesteatoma intraoperatively. So HRCT was 100% accurate in predicting cholesteatoma. Mafee et al. and O'Reilly et al. found HRCT to be highly sensitive and specific in identifying soft tissue mass whereas Jackler et al. and Garber et al.[16] found it to be less less sensitive and specific.[8],[17],[18],[19] O'Donoghue et al found bony erosion corresponding to cholesteatoma in 80% cases.[19],[20],[21]However, the HRCT was not able to differentiate between granulation tissue and polyps. In detecting ossicular erosion overall, HRCT was 100% sensitive and 87.04% specific with 7 cases of unidentified erosions. This is similar to studies by Mafee et al., Garber and Dort, Jackler et al., and Swartz, but contrasts with study by O'Reilly et al. where poor correlation was seen.[8],[16],[18],[13],[17]

HRCT was fairly accurate to detect bony erosions of temporal bone with sensitivity ranging from 87.04% to 100% and 100% specificity. For scutum erosion HRCT was 87.04% sensitive and 100% specific. This is in accordance to the study by Rocher P et al but contrasts with a study by Vlastarakos et al. where no correlation was found.[21],[22],[7] HRCT was also 100% sensitive and specific in identifying lateral semicircular canal erosion seen in 9 patients, which was similar to the findings of Mafee et al., Rocher P et al and Chee NW et al.[8],[22],[23] The incidence was the same as the 9% of LSCC fistula seen by SuatKeskin et al.[24]

In case of identifying facial canal dehiscence seen in 3 patients, HRCT was able to identify the site of erosion with 100% sensitivity and specificity which was in accordance with Mafee et al.[4] However, Garber and Dort also found HRCT to be 100% specific for the identification of facial canal dehiscence.[16] The incidence of lateral semicircular canal erosion and facial canal dehiscence found in this study were lower than that found in the study by Shah et al. who found it to be 22.9% each, respectively.[25]

Intraoperatively, we found 1 patient with anterior lying sigmoid sinus which was not detected on HRCT. The incidence of anterior lying sigmoid in this study is low compared to a study by Zelikovich who found it in 36.5% cases and similar to the findings by Tomura N et al., who found it in 1.6%.[26],[27]

Though the ultimate diagnosis of cholesteatoma can only be made at the time of surgery; prior radiological investigations may at times influence the decision and duration of surgical exploration in a positive way. Therefore, CT findings enable the surgeon to be informed of the risk factors and to be prepared for the possibility of upcoming complications.[28]

 Conclusions



HRCT is of useful diagnostic assistance as noninvasive and relatively inexpensive tool prior to actual surgical procedure. Further, it is also valuable and knows details of the extent of disease, the presence of anatomical variations and to predict potential complications. This HRCT should be recommended in all suspected cases of COM as a prior diagnostic procedure and to assist surgeon to determine the exact course of action.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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