Abstract
To evaluate predictive value of high resolution computed tomography in atticoantral disease. We conducted a prospective observational study in 49 patients suffering from atticoantral disease at tertiary referral institute. Preoperatively, all the patients underwent unenhanced high resolution computed tomography (HRCT) of temporal bone parallel to orbitomeatal line by using multislice scanner. We evaluated presence of soft tissue attenuation, ossicular erosion, facial canal erosion, dural exposure, erosion of semicircular canal, labyrinthine fistula, erosion of scutum and tegmen tympani in CT scan. HRCT is recommended in atticoantral disease with complications. This study demonstrates the predictive value of HRCT of temporal bone as a diagnostic modality in atticoantral disease. HRCT shows 100% sensitivity (Sn) of soft tissue density detected in middle ear, aditus and attic. Specificity (Sp) was more for eustechian tube area and sinus tympani. Ossicular erosions of malleus (Sn = 90.9%, Sp = 75%), incus (Sn = 93.2%, Sp = 80%), stapes (Sn = 78.8%, Sp = 68.8%) were detected. Erosion of scutum (Sn = 94.1%, Sp = 80%), tegmen (Sn = 66.7%, Sp = 100%), sinus plate (Sn = 100%, Sp = 97.9%), facial nerve canal (Sn = 75%, Sp = 100%), semicircular canal fistula (Sn = 80%, Sp = 97.7%) and cochlear promontory fistula (Sn = 50%, Sp = 97.9%) were evaluated. HRCT temporal bone helps to evaluate disease extent and involvement of surrounding structures. Hence it helps in deciding surgical approach and also prevents impending complications.
Electronic supplementary material
The online version of this article (10.1007/s12070-018-1465-6) contains supplementary material, which is available to authorized users.
Keywords: Atticoantral disease, Middle ear cleft, High resolution computed tomography
Introduction
The use of high resolution computed tomography (HRCT) of temporal bone is controversial in atticoantral disease (AAD) which doesn’t have intracranial complications [1]. AAD is described as unsafe type of chronic otitis media (COM) due to it’s association with cholesteatoma which has a property of bone erosion and intraoperative complications [2]. Chronic otitis media (COM) is defined as permanent abnormality of pars tensa or flaccida. COM is broadly classified as mucosal disease which presents as permanent perforation of pars tensa with normal middle ear mucosa and squamous disease which shows retraction of pars flaccida or posterosuperior region of pars tensa [3]. The British literature classifies COM as tubotympanic or atticoantral disease on the basis of embryology of middle ear cleft. Atticoantral disease (AAD) presents as perforation of pars flaccida or postero-superior quadrant of pars tensa. The pathology of the disease is irreversible and it results in progressive hearing loss and sometimes endanger life of the patients with it’s complications if not diagnosed early and treated accordingly. High resolution computed tomoghraphy (HRCT) of temporal bone helps in deciding approach of surgery and also to diagnose expected intra and post-operative complications. We conducted the study aiming to evaluate the predictive value of HRCT of temporal bone as a diagnostic modality for atticoantral disease.
Materials and Methods
We did a prospective observational study in a tertiary referral institute between July 2012 and January 2014. Patients aged between 05 and 65 years suffering from atticoantral type of COM with no previous history of ear surgeries or systemic illnesses were included in the study. All patients were clinically evaluated after taking complete history with otomicroscopy. Pure tone audiometry was done. Pre-operative the HRCT imaging of temporal bone was done in all the cases.
Imaging Protocol
Non-contrast enhanced HRCT of temporal bone was performed parallel to the orbito-meatal line by spiral technique using multislice scanner. Contiguous axial and coronal thin slices of both temporal bones were reconstructed using high resolution matrix and bone algorithm. Soft tissue windowing and sagittal reformatting were done wherever required. Intravenous contrast was given in patients with suspected intracranial complications.
We analysed CT images for presence of soft tissue attenuation in middle ear clefts, ossicular erosion, facial nerve canal erosion, dural exposure, erosion of semicircular canal, labyrinthine fistula, erosion of lateral wall of attic (scutum) and erosion of tegmen tympni. All patients underwent mastoidectomies under general anaesthesia by postaural approach. We did canal wall up mastoidectomies in 10 patients, canal wall down mastoidectomies in 39 patients including including 3 radical mastoidectomies and one subtotal petrosectomy. Systemic antibiotics were given postoperatively and patients were discharged on either the second or the third postoperative day. We evaluated each patient intraoperatively and correlated with preoperative CT images. We analysed the statistical significance of the data obtained during the study using statistical tools like sensitivity, specificity and predictive value.
Results
We conducted the study in 49 patients with atticoantral disease. All the patients complained of otorrthoea. The next common clinical feature was decreased hearing (n = 31, 62%). Patients presented with otalgia (n = 15, 30%), vertigo (n = 6, 12%), tinnitus (n = 5, 10%), fever with chills and rigors (n = 5, 10%), headache (n = 4, 8%) swelling behind the ear (n = 3, 6%) and facial weakness (n = 2, 4%) [Graph 1 in ESM]. We didn’t find any patient with intracranial complications like meningitis, subdural abscess, brain abscess or otitic hydrocephalus.
All the patients were evaluated by otoscopy and otomicroscopy. We observed that most patients presented with retraction of parts flacida with scutam erosion (n = 20, 41%). Few patients presented with marginal perforation (n = 11, 23%), postero-superior retraction pocket (n = 10, 20%) and polyp (n = 8, 16%) [Graph 2 in ESM].
We found that HRCT has 100% sensitivity to detect soft tissue density in middle ear, aditus, attic and protympanum though it’s not specific for cholesteatoma. We assessed positive predictive value of HRCT to diagnose soft tissue density in middle ear (PPV = 87.8%), aditus (PPV = 87.8%) attic (PPV = 85.7%) and protympanum (PPV = 83.3%). We found that HRCT has 97.6% specificity and sensitivity to detect soft tissue density in antrum (Fig. 1). It has 79.2% sensitivity and specificity to detect soft tissue density in difficult area like sinus tympani (Fig. 2). Whereas it has better specificity (82.4%) and sensitivity (82.4%) for anterior epitympanum to deect soft tissue density [Table 1; Graph 3 in ESM].
Fig. 1.
Erosion of mastoid cortex
Fig. 2.
Soft tissue density in sinus tympani
Table 1.
Extent of soft tissue density in various sites of middle ear cleft
| Extent of soft tissue density | HRCT | IO | Sensitivity | Specificity | PPV | NPV |
|---|---|---|---|---|---|---|
| Middle ear | 49 | 43 | 100 | 0 | 87.8 | 0 |
| Aditus | 49 | 43 | 100 | 0 | 87.8 | 0 |
| Attic | 49 | 42 | 100 | 0 | 85.7 | 0 |
| Antrum | 45 | 40 | 97.6 | 97.6 | 88.9 | 75.0 |
| Sinus tympani | 22 | 19 | 79.2 | 79.2 | 88.4 | 81.5 |
| Anterior epitympanum | 21 | 14 | 82.4 | 82.4 | 66.7 | 89.3 |
| Eustechian tube area | 6 | 5 | 100 | 100 | 83.3 | 100 |
HRCT high resolution computed tomography, IO intra op, PPV positive predictive value, NPV negative predictive value
Identifying the scutum and ossicular erosions preoperatively helps the surgeons for prior decision of ossiculoplasty. Erosion of scutum is found in acquired cholesteatoma but absent in congenital type [2]. We found that the sensitivity and specificity of scutum erosion in HRCT was 94.1 and 80% respectively. Malleus, incus and stapes were found to be eroded in 69.4, 85.7 and 63.3% respectively in HRCT and 67.3, 89.8 and 67.3% respectively intraoperatively [Table 2; Graph 4 in ESM].
Table 2.
Erosions of scutum and ossicles
| Scutum/ossicles | HRCT | IO | Sensitivity | Specificity | PPV | NPV |
|---|---|---|---|---|---|---|
| Scutum | 35 | 34 | 94.1 | 80 | 91.4 | 85.7 |
| Malleus | 34 | 33 | 90.9 | 75 | 88.2 | 80 |
| Incus | 42 | 44 | 93.2 | 80 | 97.6 | 57.1 |
| Stapes | 31 | 33 | 78.8 | 68.8 | 83.9 | 61.1 |
HRCT high resolution computed tomography, IO intra op, PPV positive predictive value, NPV negative predictive value
As mentioned before, we didn’t find any intracranial complications in any patient. There were intra-temporal complications as erosion of tegmen tympani, sinus plate, facial nerve canal, semicircular canal and cochlear fistula. We found that HRCT has 66.7% sensitivity and 100% specificity to detect erosion of tegmen tympani, whereas sensitivity and specificity to detect erosion of sinus plate were 100 and 97.9% respectively. On the other hand, it has 75% sensitivity and 100% specificity to detect erosion of facial nerve canal (Fig. 3). The specificity to detect cochlear fistula and SCC erosion (Fig. 4) was 97.9%. [Table 3; Graph 5 in ESM].
Fig. 3.
Erosion of facial nerve canal
Fig. 4.
Erosion of semicircular canal
Table 3.
Intratemporal complications
| Complications, erosion | HRCT | IO | Sensitivity | Specificity | PPV | NPV |
|---|---|---|---|---|---|---|
| Tegmen tympani | 4 | 6 | 66.7 | 100 | 100 | 95.6 |
| Sinus plate | 3 | 2 | 100 | 97.9 | 66.7 | 100 |
| Facial nerve canal | 6 | 8 | 75 | 100 | 100 | 95.3 |
| SCC | 5 | 5 | 80 | 97.9 | 80 | 97.7 |
| Cohlear fistula | 2 | 2 | 50 | 97.9 | 50 | 97.9 |
HRCT high resolution computed tomography, IO intra op, PPV positive predictive value, NPV negative predictive value
Discussion
CT scan in atticoantral type COM is indicated in any intratemporal or intracranial complications, suspected associated congenital anomalies, lack of anatomical landmarks due to prior surgery. Studies have shown that coordination with preoperative CT images of temporal bone with intraoperative findings provide useful information about surgical approach and may prevent inadvertent intraoperative complications.
Atticoantral disease is usually diagnosed by its typical oto-endoscopic or oto-microscopic features like erosion of attic, retraction of posterosuperior region of pars tensa, aural polyp, granulations and sometimes visible cholesteatoma flakes. CT image helps to determine the extent of disease in various locations of middle ear clefts. In CT scan, cholesteatoma is described as non-dependent soft tissue attenuation in areas of middle ear clefts, though it cannot differentiate fluid and mucousal disease with cholesteatoma. Extent of cholesteatoma in different areas of middle ear like epitympanum including anterior epitympanic sinus, mesotympanum including sinus tympani, antrum is important factor for the audiological and anatomical success of the surgery. We found that detection of soft tissue density by CT image in attic and aditus had sensitivity of 100%. These finding was similar to the study conducted by Sirigiri et al. [4]. Another study conducted by Bathla et al. showed high sensitivity and specificity of HRCT for detection of disease extent in epitympanum (100, 94%) and mesotympanum (98, 98%) [3].
The sensitivity of detection of disease of HRCT in antrum was 97.6% which was similar to observations by Ranga Reddy Sirigiri et al. In our study the sensitivity and specificity to detect cholesteatoma in the protympanum were 100 and 97.7% respectively. The specificity was found to be higher than results found by Sirigiri et al. (84%) [4]. Studies show that though CT scan does not differentiate cholesteatoma from fluid and mucosal disease, it helps in decision making of surgical approach.
One of the reasons of recurrent cholesteatoma is incomplete disease removal. The sites where disease can be missed are sinus tympani, facial recess, anterior epitympanic recess. We found that the sensitivity and specificity of HRCT to detect disease in hidden area like sinus tympani were 79.2 and 88% respectively comparable to the findings observed by Walshe et al. [5].
In hypotympanum, sensitivity of HRCT was 100% which correlates well with observations by Sirigiri et al. [4] but specificity was not measurable because all cases showed soft tissue density in hypotympanum.
Scutum erosion was seen in 71.4% cases of cholesteatoma which was less than that observed by Gaurano et al. [6]. This study demonstrates that HRCT is 94.1% sensitive and 80% specific in detecting scutum erosion which is comparable to the study by Keskin et al. [7].
Study showed that HRCT had better predictive value for erosion of malleus and incus than for stapes. Malleus head and incus body are better seen on axial section, while handle of malleus and long process of incus are better seen in coronal section. We found that HRCT was 90.9% sensitive and 75% specific to diagnose malleus erosion. This was consistent with studies conducted by Sirigiri. Study conducted by Karki et al. described the sensitivity and specificity to detect malleus erosion were 100 and 95.23% respectively [8].
Erosion of long process of incus is commonly encountered intraoperative finding during mastoid surgeries due to it’s precarious blood supply. HRCT detects erosion of incus correctly in 85.7% cases which was comparable to the study by which was similar to study by Jackler et al. [11]. Study conducted by Karki et al. [8] showed that sensitivity and specificity of incus erosion were 100 and 80.48% respectively.
Cholesteatoma that involves posterior mesotympanum eroding stapes suprastructure by its enzymatic action, becomes factor determining the type of tympanoplasty in post modified radical mastoidectomy. It is challenging to identify erosion of stapes due to its smaller structure and presence of soft tissue around it. HRCT was 78% sensitive and 88% specific in detecting erosion of stapes and this was similar to the study conducted by O’Donoghue et al. [9]. However this was contradictory to study conducted by Chee et al. [10] who found excellent correlation of erosion of stapes in HRCT. This discrepancy may be attributed to differential observations by radiologists. Karki et al. [8] showed 96% sensitivity and 71.4% specificity in detection of erosion of stapes.
Preoperative knowledge of dural exposure with tegmen erosion alert the surgeon to avoid complication during surgery. We found that HRCT was 66.7% sensitive to detect erosion of tegmen tympani. This findings was similar to Jackler, O'Reilly et al., and Gerami et al. [11, 12].
The common site for facial nerve dehiscence seen in tympanic tympanic segment [2]. Dehiscence of facial nerve canal puts it at higher risk of injury during surgery. Therefore prior knowledge of dehiscence is important to avoid facial nerve paralysis. The present study demonstrates 75% sensitivity and 100% specificity in detecting dehiscence of facial nerve canal. Similar result was found by Alzoubi et al. [13] and Sirgiri et al. [4]. According to Karki et al. [8] the sensitivity and specificity of dehiscence of facial canal was 100 and 75%.
We found that HRCT was 100% sensitive and specific in detecting cochlear promontory fistula which was similar to results showed by Alzoubi [13].
HRCT was 100% sensitive and 97% specific with 1 false positive case detecting sigmoid sinus plate erosion. The findings were comparable with Vlastarakos et al., Sirigiri et al. [4].
Fistula of lateral semicircular canal is the commonest intratemporal complication of COM [2]. It is advisable to be more cautious during dissecting the disease from semicircular canal. We found that there was 97.7% specificity and 80% sensitivity in detecting lateral semicircular canal dehiscence. Our study was similar to Prata et al., and Sirigiri and Alzoubi et al. [4, 14]. Karki et al. [8] showed 100 specificity but 53.84% sensitivity for lateral semicircular dehiscence.
Conclusion
Improvements in radiological techniques has enhanced the knowledge of inter-relationship of tympanomastoid compartments with adjacent neuro-vascular structures. HRCT in atticoantral disease without intracranial complication is debatable. The present study demonstrates the predictive value of HRCT of temporal bone in terms of disease involvement, ossicular erosion, scutum erosion etc. The study therefore recommends that HRCT temporal bone can be advised not only in cases of intracranial complications but also in all other cases of COM to detect the extent of disease and presence of anatomical variations.
Electronic Supplementary Material
Below is the link to the electronic supplementary material.
Compliance with Ethical Standards
Conflict of interest
The authors declare that they have no conflict of interest.
Ethical Approval
All procedures involving human participants were in accordance with the ethical standards of the institution.
Informed Consent
Informed consent was obtained from all individual participants included in the study.
References
- 1.Bathla M, Doshi H, Kansara A. Is routine use of high resolution computerized tomography of temporal bone in patients of atticoantral chronic suppurative otitis media without intracranial complications justified? Indian J Otolaryngol Head Neck Surg. 2018;70(1):79–86. doi: 10.1007/s12070-017-1103-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Gulya AJ, Minor LB, Poe DS, editors. Glasscock-Shambaugh surgery of the ear. 6. Raleigh: People’s Medical Publishing House; 2010. [Google Scholar]
- 3.Gleeson M, Browning GB, Clarke R, editors. Scott–Brown’s otolaryngology, head and neck surgery. 7. London: Hodder Arnold; 2008. [Google Scholar]
- 4.Sirigiri RR, Dwarakanath K. Correlative study of HRCT in attico-antral disease. Indian J Otolaryngol Head Neck Surg. 2011;63(2):155–158. doi: 10.1007/s12070-011-0162-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Walshe P, McConn Walsh R, Brennan P, Walsh M. The role of computerized tomography in the preoperative assessment of chronic suppurative otitis media. Clin Otolaryngol Allied Sci. 2002;27(2):95–97. doi: 10.1046/j.1365-2273.2002.00538.x. [DOI] [PubMed] [Google Scholar]
- 6.Gaurano JL, Joharjy IA. Middle ear cholesteatoma: characteristic CT findings in 64 patients. Ann Saudi Med. 2004;24(6):442–447. doi: 10.5144/0256-4947.2004.442. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Keskin S, Cetin H, Gurkan TH. The correlation of temporal bone CT with surgery findings in evaluation of chronic inflammatory diseases of middle ear. Eur J Gen Med. 2011;8(1):24–30. doi: 10.29333/ejgm/82692. [DOI] [Google Scholar]
- 8.Karki S, Pokharel M, Suwal S, Poudel R. Correlation between preoperative high resolution computed tomography (CT) findings with surgical findings in chronic otitis media (COM) squamosal type. Kathmandu Univ Med J. 2017;15(57):84–87. [PubMed] [Google Scholar]
- 9.O’Donoghue GM. Cholesteatoma: diagnosis and staging by CT scan. J Otolaryngol. 1987;12:157–160. [PubMed] [Google Scholar]
- 10.Chee NW, Tan TY. The value of preoperative high resolution CT scans in cholesteatoma surgery. Singap Med J. 2001;42(4):155–159. [PubMed] [Google Scholar]
- 11.Jackler RK, Dilon WP, Schindler RA. Computed tomography in suppurative ear disease: a correlation of surgical and radiographic findings. Laryngoscope. 1984;94(6):746–752. doi: 10.1288/00005537-198406000-00004. [DOI] [PubMed] [Google Scholar]
- 12.Gerami H, Naghavi E. Comparision of preoperative computed tomography scan imaging of temporal bone with intra-operative finding in patient undergoing mastoidectomy. Saudi Med J. 2009;30(1):104–108. [PubMed] [Google Scholar]
- 13.Alzoubi FQ, Odat HA, Al-balas HA, Saeed SR. The role of preoperative CT scan in patients with chronic otitis media. Eur Arch Otorhinolaryngol. 2009;266(6):807–809. doi: 10.1007/s00405-008-0814-6. [DOI] [PubMed] [Google Scholar]
- 14.Prata AAS, Antunes ML, et al. Comparative study between radiological and surgical findings of chronic otitis media. Int Arch Otolaryngol. 2011;15(1):72–78. [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.