ORIGINAL ARTICLE
Radiologic and Surgical Findings in Chronic Suppurative Otitis Media Aylin Gül, MD,* Mehmet Akdağ, MD,* Vefa Kiniş, MD,* Beyhan Yilmaz, MD,* Engin Şengül, MD,* Memik Teke, MD,† and Faruk Meriç, MD* Abstract: Our aim in this study was to evaluate the efficiency of preoperative temporal bone computed tomography (CT) in detecting pathologic conditions in patients with chronic suppurative otitis media (CSOM). The intraoperative findings and temporal bone CT results of 350 patients who were diagnosed with CSOM between September 1, 2010, and June 1, 2013, were compared. Comparison parameters were as follows: the presence of cholesteatoma, erosion of the outer ear bone canal, erosion of the middle ear chain, erosion of the dural plate, erosion of the lateral semicircular canal, erosion of the sigmoid sinus wall, and dehiscence of the facial canal. The contribution of CT was limited in showing the outer ear canal destruction, dural plate destruction, facial canal destruction, lateral semicircular canal destruction, and destruction of the sigmoid sinus wall. However, CTwas more sensitive in detecting cholesteatoma and erosion of the ossicular chain. These results indicate that preoperative CT of patients with CSOM serves as an important guide for otolaryngologists, although there are limitations in the evaluation of the CT results. Key Words: Chronic otitis media, computed tomography scan, surgery, temporal bone (J Craniofac Surg 2014;25: 2027–2029)
V
iewing the temporal bone is important for otolaryngologists, especially in determining the prevalence of pathologies that cannot be evaluated using otomicroscopic examination in patients with chronic suppurative otitis media (CSOM).1,2 The evaluation of preoperative anatomy is also important because it can help to anticipate possible complications. Thus, preoperative computed tomography (CT) plays a key role in the decision process before surgery. In addition, CT screening of the temporal bone can have legal value. Computed tomography has been used in the screening of the temporal bone and in many other fields since the 1980s. More recently, because CT is not competent in distinguishing between cholesteatoma, granulation texture, mucosal edema, and effusion, there have been concerns about the reliability of CT screening.3,4 Furthermore, CT has no guaranteed sensitivity for detecting erosive complications.5 No clear data on the value of CT screening before a From the *Department of Otorhinolaryngology, School of Medicine, and †Department of Radiology, Faculty of Medicine, Dicle University, Diyarbakir, Turkey. Received November 16, 2013. Accepted for publication April 7, 2014. Address correspondence and reprint requests to Aylin Gül, MD, Department of Otorhinolaryngology, School of Medicine, Dicle University, Diyarbakir 21280, Turkey; E-mail: [email protected] The authors report no conflicts of interest. Copyright © 2014 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000001017
CSOM surgery without complications exist5; however, there is unanimity in performing CT on cases with complications, suspicions of congenital anomalies, and revision surgery.3 Our aim in this study was to evaluate the efficiency of routine CT screenings before CSOM surgeries by retrospectively scanning the data of 350 patients who were diagnosed with CSOM and operated on and who underwent routine temporal bone tomography.
MATERIALS AND METHODS We retrospectively evaluated the intraoperative findings and preoperative temporal CT findings of 350 patients who were diagnosed with CSOM at the Dicle University Medical Faculty Otolaryngology Clinic between September 1, 2010, and June 1, 2013. The patients included in the study had consistent or intermittent otorrhea and hearing loss that lasted more than 3 months. Otomicroscopy revealed perforation of the eardrum, along with granulation in the middle ear, polyps filling the outer ear canal, seepage, and cholesteatoma or the suspicion of cholesteatoma in the patients. The patients who were diagnosed with CSOM because of these findings underwent canal wall down tympanomastoidectomy or canal wall up tympanomastoidectomy. Patients with chronic otitis media who had eardrum perforation but a dry middle ear and no exudate (nonsuppurative chronic otitis media) and patients who underwent tympanoplasty were excluded from this study. The patients’ intraoperative findings and CT scan results were compared on the basis of the following parameters: the presence of cholesteatoma, erosion of the outer ear canal, erosion of the middle ear ossicular chain, erosion of the dural plate, erosion of the lateral semicircular canal (LSSC), erosion of the sigmoid sinus wall, and dehiscence of the facial canal. A multiscan Philips Brilliance CT scanner (Philips Medical Systems, Cleveland, OH) was used for this study. The consecutive parts of the segments were 1 mm thick, and the evaluation was performed in the bone window, in the axial and coronal plane.
RESULTS Of the patients included in this study, 177 were male and 173 were female. The age range was from 7 to 71 years old, with a mean of 27 years. The preoperative CT scan results and intraoperative findings are shown in Table 1. Cholesteatoma was observed in 186 of the 350 patients during their surgical operations. The presence of cholesteatoma was predicted correctly in 114 of these cases with CT, and in 72 patients, cholesteatoma was not detected. Cholesteatoma was not observed in the intraoperative findings or tomography scan results of 146 patients. According to these data, CT detected cholesteatoma with a 61.3% sensitivity, 89% specificity, positive predictive value of 86.4%, and negative predictive value of 67%. Intraoperative ossicular chain destruction was observed in 238 patients and was detected with CT in 174 of them; it was not detected by CT in 64 patients. Ossicular chain destruction was not observed in the intraoperative findings or tomography scan results of 95 patients.
The Journal of Craniofacial Surgery • Volume 25, Number 6, November 2014
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
2027
The Journal of Craniofacial Surgery • Volume 25, Number 6, November 2014
Gül et al
TABLE 1. The Results of the Comparison of CT Scan Findings With Intraoperative Findings True-Positive EECD IOC FCD TE LSCE SSD C
6 174 5 5 3 4 114
(1.7%) (49.7%) (1.4%) (1.4%) (0.9%) (1.2%) (32.6%)
False-Positive
True-Negative
False-Negative
Sensitivity, %
Specificity, %
PPV
NPV
4 (1.2%) 17 (4.9%) 4 (1.2%) 11 (3.1%) 1 (0.3%) 2 (0.6%) 18 (5.1%)
335 (95.7%) 95 (27.1%) 316 (90.3%) 324 (92.6%) 342 (97.7%) 335 (95.7%) 146 (41.7%)
5 (1.4%) 64 (18.3%) 25 (7.1%) 10 (2.9%) 4 (1.1%) 9 (2.6%) 72 (20.6%)
54.5 73.1 16.7 33.3 42.9 30.8 61.3
98.8 84.8 98.8 96.7 99.7 99.4 89.0
60.0 91.1 55.6 31.3 75.0 66.7 86.4
98.5 59.7 92.7 97.0 98.8 97.4 67.0
C, cholesteatoma; EECD, external ear canal defect; FCD, facial canal dehiscence; IOC, intactness of ossicular chain; LSCE, lateral semicircular canal erosion; NPV, negative predictive value; PPV, positive predictive value; SSD, sigmoid sinus defect; TE, tegmen erosion.
Four patients with external ear bony canal defects reported on CTwere found to have no defects during surgery. The external ear bony canal defects of 5 patients could not be detected by CT. Of the 16 patients who were reported to have dural plate destruction based on CT results, 5 were found to have dural plate destruction in surgery; the results were false-positives in 11 patients (Fig. 1). Lateral semicircular canal destruction was reported in 4 patients using CT and was detected in 7 patients during their operations. Of the 4 patients who were found by CT to have destruction, 3 were found to have destruction during their operations. Computed tomography detected dehiscence of the facial nerve with a 16.7% sensitivity and 98.8% specificity. Facial canal dehiscence was observed in the tympanic segment of the facial canal in surgery (Fig. 2). Of the 13 patients found to have defects in the intraoperative sigmoid sinus wall, only 4 could be detected with CT. A defect was reported in 2 patients, but neither defect was observed surgically (Fig. 3).
DISCUSSION Computed tomography is the standard screening method for the temporal bone, but its role in the preoperative examination of CSOM patients remains unclear.6 It is important that CT screening be performed in both the axial and coronal planes to display pathologies of the temporal bone in detail.7,8 Controversy exists regarding the ability to determine whether a soft tissue density in the middle ear or mastoid cells is cholesteatoma, versus granulation tissue or a mucoid secretion, for example, using preoperative CT.4,9,10 Currently, erosion caused by the soft tissue on nearby bone structures is generally interpreted as indicating the presence of cholesteatoma.11 In our study, we also identified cholesteatoma on the basis of the destruction of the surrounding bone tissue, and CT identified cholesteatoma with a 61.3% sensitivity and 89% specificity. When the ossicular system is considered, the malleus and the incus can be easily evaluated with CT. However, the manubrium,
FIGURE 1. The same patient's dural plate images are shown. A, Soft tissue density in the attic region and the Prussak space and erosion of the scutum can be seen on the coronal CT image (hollow arrow). B, Intact wall (hollow arrow) of the scutum during the operation.
2028
the lenticular process, and the stapes, in which ossicular damage is more intense, are harder to view with CT.12 O'Reilly et al12 reported that they could show that the ossicular chain was intact in 50% of their cases using CT. Mafee et al13 succeeded in defining the condition of the ossicular chain in 89% of their cases. Tatlipinar et al5 correctly determined the condition of the ossicular chain at a rate of 85.1%. In our study, the ossicular chain was found to be intact in 45% of the cases, and the condition of the ossicular chain was predicted correctly in 60% of the cases. Because different ossicular system elements are viewed in different screening planes, it is hard to comment about them. Radiologic interpretation could be more robust if radiologists were well informed of their patients' clinical features. In addition, results would be improved if the otolaryngologist and the radiologist cooperated in interpreting CT images. The risk for destruction or complication of the dural plate, the facial canal, the LSSC, and the sigmoid sinus is always present. Thus, prior knowledge of the conditions of these areas is important in decreasing the risks. The dural plate is best observed in the coronal plane and as a thin bone plaque covering the epitympanum and the mastoid.5 Jackler et al11 reported that they detected dural plate destruction in 4 patients and received false-positive results in 8 patients. O'Donoghue et al14 noted that destruction was detected with CT in 2 patients without any false-positives. O'Reilly et al12 reported that they detected destruction in 5 of 11 cases, with 6 falsepositives. Mafee et al13 also reported no false-positive cases. In our study, there were 11 false-positives, and 5 patients were correctly predicted to have dural plate destruction. Coronal and axial cross sections are necessary to evaluate the tympanic (horizontal) and mastoid (vertical) segments of the facial canal.9,11 The tympanic segment of the facial canal can be better evaluated in the coronal plane, and dehiscence is generally observed in this segment.11 Varying results regarding cross sections have been reported in the literature. O’Reilly et al12 observed dehiscence in 4 of the 9 patients determined to have dehiscence using CT. In comparison, the ratio was 4 of 5 patients for Freng et al15 and 3
FIGURE 2. The same patient's facial nerve images are shown. A, Intact lateral wall (hollow arrow) of the facial nerve canal can be seen on the axial CT image. B, Dehiscence (hollow arrows) of the tympanic portion of the facial nerve canal during the operation.
© 2014 Mutaz B. Habal, MD
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
The Journal of Craniofacial Surgery • Volume 25, Number 6, November 2014
Radiologic and Surgical Findings in CSOM
5. Computed tomography cannot distinguish between cholesteatoma, granulation, mucosal edema, and effusion but instead interprets them all as soft tissue density. 6. Preoperative temporal bone CT is beneficial as a preparation for possible medicolegal problems.
Data acquired by CT before surgery can contribute to safer operations for CSOM patients. FIGURE 3. The same patient's sigmoid sinus images are shown. Lateral wall dehiscence (hollow arrow) of the sigmoid sinus can be seen on the axial CT image and during the operation.
of 9 patients for O’Donoghue et al.14 Mafee et al13 did not detect dehiscence during surgery in any of the 6 patients determined to have dehiscence using CT. In our study, dehiscence was observed in 5 of the 9 patients who were found to have dehiscence with CT. In all of these cases, the dehiscence was in the tympanic segment, and cholesteatoma was present. Walshe et al6 reported that, although they did not detect sigmoid sinus wall destruction using CT, it was observed in 1 case in their study of 20 cases. In our study, CT detected sigmoid sinus wall destruction with a 31% sensitivity and 99% specificity. Lateral semicircular canal destruction can cause sensorineural hearing loss and vestibular dysfunction and can be evaluated in both the coronal and axial sections. However, the bone canal is more likely to be accidentally interpreted as having destruction in the coronal section, especially when there is soft tissue nearby. For this reason, axial cross sections are more suitable for interpretation.11 In their series of 42 patients, Jackler et al11 detected LSSC destruction in only 4 of 8 patients reported to have it based on CT. O'Reilly et al12 reported a false-positive rate of 3.5% and related the false-positives to the neighboring soft tissue of the lateral canal in coronal cross sections. In our study, intraoperative destruction was not observed in 1 of 4 patients reported to have LSSC destruction based on CT. We believe that it is necessary to routinely evaluate most CSOM patients with temporal bone CT because CT is important in the mastoid surgery decision process and for collecting information on special anatomic structures. In this study, we analyzed data from our clinic retrospectively and reached some conclusions on the necessity of preoperative CT scans for CSOM patients: 1. Computed tomography can affect the decision about the type of operation and can help prevent complications by providing the surgeon with information about possible problems due to anatomic differences. 2. In all cases, cross sections should be in both the coronal and axial planes for more accurate evaluations of anatomic structures. 3. The presence of bone destruction on CT can be evaluated as indicating cholesteatoma. 4. Computed tomography can provide detailed information about the outer ear canal, the ossicular chain, the facial canal, the lateral SSC, the position of the sigmoid sinus, and the dural plate, but misinterpretations are possible.
ACKNOWLEDGMENT The authors thank Dicle University DUBAP for sponsoring the English editing of this manuscript.
REFERENCES 1. Banerjee A, Flood LM, Yates P, et al. Computed tomography in supurative ear disease: does it influence management? J Laryngol Otol 2003;114:454–458 2. Watts S, Flood LM, Klifford K. A systematic approach to interpretation of computed tomography scans prior to surgery of midle ear cholesteatoma. J Laryngol Otol 2000;114:248–253 3. Leighton SEJ, Robson AK Anslow P. The role of CT imaging in the management of chronic suppurative otitis media. Clin Otolaringol 1993;18:23–29 4. Yates PD, Flood LM, Banerjee A, et al. CT scanning of middle ear cholesteatoma: what does the surgeon want to know? Br J Radiol 2002;75:847–852 5. Tatlipinar A, Tuncel A, Ay Öğredik E, et al. The role of computed tomography scanning in chronic otitis media. Eur Arch Otorhinolaryngol 2012;269:33–38 6. Walshe P, McConn Walsh R, Brennan P, et al. The role of computerized tomography in the preoperative assessment of chronic suppurative otitis media. Clin Otolaryngol Allied Sci 2002;27:95–97 7. Zonneveld F. The value of non-reconstructive multiplanar CT for the evaluation of the petrous bone. Neuroradiology 1983;25:1–10 8. Chakeres D, Spiegel P. A systematic technique for comprehensive evaluation of the temporal bone by computed tomography. Radiology 1983;146:97–106 9. Blaney SP, Tierney P, Oyarazabal M, et al. CT scanning in “second look” combined approach tympanoplasty. Rev Laryngol Otol Rhinol (Bord) 2000;121:79–81 10. Alzoubi FQ, Odat HA, Al-Balas HA, et al. The role of preoperative CT scan in patients with chronic otitis media. Eur Arch Otorhinolaryngol 2009;266:807–809 11. Jackler RK, Dillon WP, Schindler RA. Computed tomography in suppurative ear disease: a correlation of surgical and radiographic findings. Laryngoscope 1984;94:746–752 12. O’Reilly BJ, Cheverton I, Wylie C, et al. The value of CT scaning in chronic suppurative otitis media. J Laryngol Otol 1991;105:990–994 13. Mafee MF, Levin BC, Applebaum EL, et al. Cholesteatoma of middle ear and mastoid. A comparison of the CT scan and operative findings. Otolaryngol Clin North Am 1988;2:265–293 14. O’Donoghue GM, Bates GJ, Anslow P, et al. The predictive value of high resolution computed tomography in chronic suppurative otitis ear disease. Clin Otolaryngol 1987;12:89–96 15. Freng A, Larsen P, Nordhus T. Cholesteatomas of the temporal bone. Preoperative CT versus preoparetive findings. Scand Audiol Suppl 1988;30:185–188
© 2014 Mutaz B. Habal, MD
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
2029
Radiologic and Surgical Findings in Chronic Suppurative Otitis Media Aylin Gül, MD,* Mehmet Akdağ, MD,* Vefa Kiniş, MD,* Beyhan Yilmaz, MD,* Engin Şengül, MD,* Memik Teke, MD,† and Faruk Meriç, MD* Abstract: Our aim in this study was to evaluate the efficiency of preoperative temporal bone computed tomography (CT) in detecting pathologic conditions in patients with chronic suppurative otitis media (CSOM). The intraoperative findings and temporal bone CT results of 350 patients who were diagnosed with CSOM between September 1, 2010, and June 1, 2013, were compared. Comparison parameters were as follows: the presence of cholesteatoma, erosion of the outer ear bone canal, erosion of the middle ear chain, erosion of the dural plate, erosion of the lateral semicircular canal, erosion of the sigmoid sinus wall, and dehiscence of the facial canal. The contribution of CT was limited in showing the outer ear canal destruction, dural plate destruction, facial canal destruction, lateral semicircular canal destruction, and destruction of the sigmoid sinus wall. However, CTwas more sensitive in detecting cholesteatoma and erosion of the ossicular chain. These results indicate that preoperative CT of patients with CSOM serves as an important guide for otolaryngologists, although there are limitations in the evaluation of the CT results. Key Words: Chronic otitis media, computed tomography scan, surgery, temporal bone (J Craniofac Surg 2014;25: 2027–2029)
V
iewing the temporal bone is important for otolaryngologists, especially in determining the prevalence of pathologies that cannot be evaluated using otomicroscopic examination in patients with chronic suppurative otitis media (CSOM).1,2 The evaluation of preoperative anatomy is also important because it can help to anticipate possible complications. Thus, preoperative computed tomography (CT) plays a key role in the decision process before surgery. In addition, CT screening of the temporal bone can have legal value. Computed tomography has been used in the screening of the temporal bone and in many other fields since the 1980s. More recently, because CT is not competent in distinguishing between cholesteatoma, granulation texture, mucosal edema, and effusion, there have been concerns about the reliability of CT screening.3,4 Furthermore, CT has no guaranteed sensitivity for detecting erosive complications.5 No clear data on the value of CT screening before a From the *Department of Otorhinolaryngology, School of Medicine, and †Department of Radiology, Faculty of Medicine, Dicle University, Diyarbakir, Turkey. Received November 16, 2013. Accepted for publication April 7, 2014. Address correspondence and reprint requests to Aylin Gül, MD, Department of Otorhinolaryngology, School of Medicine, Dicle University, Diyarbakir 21280, Turkey; E-mail: [email protected] The authors report no conflicts of interest. Copyright © 2014 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000001017
CSOM surgery without complications exist5; however, there is unanimity in performing CT on cases with complications, suspicions of congenital anomalies, and revision surgery.3 Our aim in this study was to evaluate the efficiency of routine CT screenings before CSOM surgeries by retrospectively scanning the data of 350 patients who were diagnosed with CSOM and operated on and who underwent routine temporal bone tomography.
MATERIALS AND METHODS We retrospectively evaluated the intraoperative findings and preoperative temporal CT findings of 350 patients who were diagnosed with CSOM at the Dicle University Medical Faculty Otolaryngology Clinic between September 1, 2010, and June 1, 2013. The patients included in the study had consistent or intermittent otorrhea and hearing loss that lasted more than 3 months. Otomicroscopy revealed perforation of the eardrum, along with granulation in the middle ear, polyps filling the outer ear canal, seepage, and cholesteatoma or the suspicion of cholesteatoma in the patients. The patients who were diagnosed with CSOM because of these findings underwent canal wall down tympanomastoidectomy or canal wall up tympanomastoidectomy. Patients with chronic otitis media who had eardrum perforation but a dry middle ear and no exudate (nonsuppurative chronic otitis media) and patients who underwent tympanoplasty were excluded from this study. The patients’ intraoperative findings and CT scan results were compared on the basis of the following parameters: the presence of cholesteatoma, erosion of the outer ear canal, erosion of the middle ear ossicular chain, erosion of the dural plate, erosion of the lateral semicircular canal (LSSC), erosion of the sigmoid sinus wall, and dehiscence of the facial canal. A multiscan Philips Brilliance CT scanner (Philips Medical Systems, Cleveland, OH) was used for this study. The consecutive parts of the segments were 1 mm thick, and the evaluation was performed in the bone window, in the axial and coronal plane.
RESULTS Of the patients included in this study, 177 were male and 173 were female. The age range was from 7 to 71 years old, with a mean of 27 years. The preoperative CT scan results and intraoperative findings are shown in Table 1. Cholesteatoma was observed in 186 of the 350 patients during their surgical operations. The presence of cholesteatoma was predicted correctly in 114 of these cases with CT, and in 72 patients, cholesteatoma was not detected. Cholesteatoma was not observed in the intraoperative findings or tomography scan results of 146 patients. According to these data, CT detected cholesteatoma with a 61.3% sensitivity, 89% specificity, positive predictive value of 86.4%, and negative predictive value of 67%. Intraoperative ossicular chain destruction was observed in 238 patients and was detected with CT in 174 of them; it was not detected by CT in 64 patients. Ossicular chain destruction was not observed in the intraoperative findings or tomography scan results of 95 patients.
The Journal of Craniofacial Surgery • Volume 25, Number 6, November 2014
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
2027
The Journal of Craniofacial Surgery • Volume 25, Number 6, November 2014
Gül et al
TABLE 1. The Results of the Comparison of CT Scan Findings With Intraoperative Findings True-Positive EECD IOC FCD TE LSCE SSD C
6 174 5 5 3 4 114
(1.7%) (49.7%) (1.4%) (1.4%) (0.9%) (1.2%) (32.6%)
False-Positive
True-Negative
False-Negative
Sensitivity, %
Specificity, %
PPV
NPV
4 (1.2%) 17 (4.9%) 4 (1.2%) 11 (3.1%) 1 (0.3%) 2 (0.6%) 18 (5.1%)
335 (95.7%) 95 (27.1%) 316 (90.3%) 324 (92.6%) 342 (97.7%) 335 (95.7%) 146 (41.7%)
5 (1.4%) 64 (18.3%) 25 (7.1%) 10 (2.9%) 4 (1.1%) 9 (2.6%) 72 (20.6%)
54.5 73.1 16.7 33.3 42.9 30.8 61.3
98.8 84.8 98.8 96.7 99.7 99.4 89.0
60.0 91.1 55.6 31.3 75.0 66.7 86.4
98.5 59.7 92.7 97.0 98.8 97.4 67.0
C, cholesteatoma; EECD, external ear canal defect; FCD, facial canal dehiscence; IOC, intactness of ossicular chain; LSCE, lateral semicircular canal erosion; NPV, negative predictive value; PPV, positive predictive value; SSD, sigmoid sinus defect; TE, tegmen erosion.
Four patients with external ear bony canal defects reported on CTwere found to have no defects during surgery. The external ear bony canal defects of 5 patients could not be detected by CT. Of the 16 patients who were reported to have dural plate destruction based on CT results, 5 were found to have dural plate destruction in surgery; the results were false-positives in 11 patients (Fig. 1). Lateral semicircular canal destruction was reported in 4 patients using CT and was detected in 7 patients during their operations. Of the 4 patients who were found by CT to have destruction, 3 were found to have destruction during their operations. Computed tomography detected dehiscence of the facial nerve with a 16.7% sensitivity and 98.8% specificity. Facial canal dehiscence was observed in the tympanic segment of the facial canal in surgery (Fig. 2). Of the 13 patients found to have defects in the intraoperative sigmoid sinus wall, only 4 could be detected with CT. A defect was reported in 2 patients, but neither defect was observed surgically (Fig. 3).
DISCUSSION Computed tomography is the standard screening method for the temporal bone, but its role in the preoperative examination of CSOM patients remains unclear.6 It is important that CT screening be performed in both the axial and coronal planes to display pathologies of the temporal bone in detail.7,8 Controversy exists regarding the ability to determine whether a soft tissue density in the middle ear or mastoid cells is cholesteatoma, versus granulation tissue or a mucoid secretion, for example, using preoperative CT.4,9,10 Currently, erosion caused by the soft tissue on nearby bone structures is generally interpreted as indicating the presence of cholesteatoma.11 In our study, we also identified cholesteatoma on the basis of the destruction of the surrounding bone tissue, and CT identified cholesteatoma with a 61.3% sensitivity and 89% specificity. When the ossicular system is considered, the malleus and the incus can be easily evaluated with CT. However, the manubrium,
FIGURE 1. The same patient's dural plate images are shown. A, Soft tissue density in the attic region and the Prussak space and erosion of the scutum can be seen on the coronal CT image (hollow arrow). B, Intact wall (hollow arrow) of the scutum during the operation.
2028
the lenticular process, and the stapes, in which ossicular damage is more intense, are harder to view with CT.12 O'Reilly et al12 reported that they could show that the ossicular chain was intact in 50% of their cases using CT. Mafee et al13 succeeded in defining the condition of the ossicular chain in 89% of their cases. Tatlipinar et al5 correctly determined the condition of the ossicular chain at a rate of 85.1%. In our study, the ossicular chain was found to be intact in 45% of the cases, and the condition of the ossicular chain was predicted correctly in 60% of the cases. Because different ossicular system elements are viewed in different screening planes, it is hard to comment about them. Radiologic interpretation could be more robust if radiologists were well informed of their patients' clinical features. In addition, results would be improved if the otolaryngologist and the radiologist cooperated in interpreting CT images. The risk for destruction or complication of the dural plate, the facial canal, the LSSC, and the sigmoid sinus is always present. Thus, prior knowledge of the conditions of these areas is important in decreasing the risks. The dural plate is best observed in the coronal plane and as a thin bone plaque covering the epitympanum and the mastoid.5 Jackler et al11 reported that they detected dural plate destruction in 4 patients and received false-positive results in 8 patients. O'Donoghue et al14 noted that destruction was detected with CT in 2 patients without any false-positives. O'Reilly et al12 reported that they detected destruction in 5 of 11 cases, with 6 falsepositives. Mafee et al13 also reported no false-positive cases. In our study, there were 11 false-positives, and 5 patients were correctly predicted to have dural plate destruction. Coronal and axial cross sections are necessary to evaluate the tympanic (horizontal) and mastoid (vertical) segments of the facial canal.9,11 The tympanic segment of the facial canal can be better evaluated in the coronal plane, and dehiscence is generally observed in this segment.11 Varying results regarding cross sections have been reported in the literature. O’Reilly et al12 observed dehiscence in 4 of the 9 patients determined to have dehiscence using CT. In comparison, the ratio was 4 of 5 patients for Freng et al15 and 3
FIGURE 2. The same patient's facial nerve images are shown. A, Intact lateral wall (hollow arrow) of the facial nerve canal can be seen on the axial CT image. B, Dehiscence (hollow arrows) of the tympanic portion of the facial nerve canal during the operation.
© 2014 Mutaz B. Habal, MD
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
The Journal of Craniofacial Surgery • Volume 25, Number 6, November 2014
Radiologic and Surgical Findings in CSOM
5. Computed tomography cannot distinguish between cholesteatoma, granulation, mucosal edema, and effusion but instead interprets them all as soft tissue density. 6. Preoperative temporal bone CT is beneficial as a preparation for possible medicolegal problems.
Data acquired by CT before surgery can contribute to safer operations for CSOM patients. FIGURE 3. The same patient's sigmoid sinus images are shown. Lateral wall dehiscence (hollow arrow) of the sigmoid sinus can be seen on the axial CT image and during the operation.
of 9 patients for O’Donoghue et al.14 Mafee et al13 did not detect dehiscence during surgery in any of the 6 patients determined to have dehiscence using CT. In our study, dehiscence was observed in 5 of the 9 patients who were found to have dehiscence with CT. In all of these cases, the dehiscence was in the tympanic segment, and cholesteatoma was present. Walshe et al6 reported that, although they did not detect sigmoid sinus wall destruction using CT, it was observed in 1 case in their study of 20 cases. In our study, CT detected sigmoid sinus wall destruction with a 31% sensitivity and 99% specificity. Lateral semicircular canal destruction can cause sensorineural hearing loss and vestibular dysfunction and can be evaluated in both the coronal and axial sections. However, the bone canal is more likely to be accidentally interpreted as having destruction in the coronal section, especially when there is soft tissue nearby. For this reason, axial cross sections are more suitable for interpretation.11 In their series of 42 patients, Jackler et al11 detected LSSC destruction in only 4 of 8 patients reported to have it based on CT. O'Reilly et al12 reported a false-positive rate of 3.5% and related the false-positives to the neighboring soft tissue of the lateral canal in coronal cross sections. In our study, intraoperative destruction was not observed in 1 of 4 patients reported to have LSSC destruction based on CT. We believe that it is necessary to routinely evaluate most CSOM patients with temporal bone CT because CT is important in the mastoid surgery decision process and for collecting information on special anatomic structures. In this study, we analyzed data from our clinic retrospectively and reached some conclusions on the necessity of preoperative CT scans for CSOM patients: 1. Computed tomography can affect the decision about the type of operation and can help prevent complications by providing the surgeon with information about possible problems due to anatomic differences. 2. In all cases, cross sections should be in both the coronal and axial planes for more accurate evaluations of anatomic structures. 3. The presence of bone destruction on CT can be evaluated as indicating cholesteatoma. 4. Computed tomography can provide detailed information about the outer ear canal, the ossicular chain, the facial canal, the lateral SSC, the position of the sigmoid sinus, and the dural plate, but misinterpretations are possible.
ACKNOWLEDGMENT The authors thank Dicle University DUBAP for sponsoring the English editing of this manuscript.
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© 2014 Mutaz B. Habal, MD
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
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