|Year : 2017 | Volume
| Issue : 2 | Page : 104-107
Effect of mastoid pneumatization on myringoplasty success: A radiological study
Hazem Saeed Amer1, Mohammad Waheed El-Anwar1, Mohammad Abdelhady1, Ghada Abdulmonaem2, Khaled Mohammad Elgerby2
1 Department of Otorhinolaryngology, Head and Neck Surgery, Faculty of Medicine, Zagazig University, Zagazig, Egypt
2 Department of Radiodiagnosis, Faculty of Medicine, Zagazig University, Zagazig, Egypt
|Date of Web Publication||14-Jun-2017|
Mohammad Waheed El-Anwar
Department of Otorhinolaryngology, Head and Neck Surgery, Faculty of Medicine, Zagazig University, Zagazig
Source of Support: None, Conflict of Interest: None
Objectives: The objective of the study was to evaluate the effect of mastoid pneumatization on myringoplasty success. Patients and Methods: Forty-two adult patients with dry central tympanic membrane perforation scheduled for myringoplasty were included in the study. Computed tomography (CT) scans of the temporal bone coronal and axial cuts were done 1–2 days before surgery. The patients were evaluated on the basis of postoperative graft taking. Results: Success rate was 85.7% while failure rate was 14.3%. The mean longitudinal diameter of the mastoid was found to be 2.35 cm in succeeded cases and 1.43 cm in failed cases with near significant difference (P = 0.0636). The mean transverse diameter was 1.44 cm in succeeded cases and 0.83 cm in failed cases with a significant difference (P = 0.0476). The mean depth of the mastoid was 0.4 in both succeeded and failed cases. The mean total mastoid volume was 2.832 ml in succeeded cases and 1.13 ml in failed cases with nonsignificant difference (P = 0.1218). The mean mastoid surface area was 516.9 cm2 in succeeded cases and 448.5 cm2 in failed cases with a significant difference (P = 0.0087). Conclusions: Success rate of myringoplasty is higher in patients with chronic suppurative otitis media (CSOM) having large mastoid system than those having small one. Preoperative CT scans in patients with CSOM undergoing myringoplasty are advisable.
Keywords: Computed tomography, mastoid, myringoplasty, pneumatization
|How to cite this article:|
Amer HS, El-Anwar MW, Abdelhady M, Abdulmonaem G, Elgerby KM. Effect of mastoid pneumatization on myringoplasty success: A radiological study. Indian J Otol 2017;23:104-7
|How to cite this URL:|
Amer HS, El-Anwar MW, Abdelhady M, Abdulmonaem G, Elgerby KM. Effect of mastoid pneumatization on myringoplasty success: A radiological study. Indian J Otol [serial online] 2017 [cited 2020 Jan 24];23:104-7. Available from: http://www.indianjotol.org/text.asp?2017/23/2/104/208019
| Introduction|| |
The goals of tympanic membrane (TM) repair in tubotympanic chronic suppurative otitis media (CSOM) are to close the perforation, remove the disease, and improve hearing of the patient.
Tympanoplasty is an established procedure for TM perforation repair. However, the overall success of myringoplasty varies greatly. To some degree, this reflects patient selection and surgical expertise. Even in the best hands, however, there remains a percentage of failure, either immediate or delayed.
Various factors have been implicated to affect the results of myringoplasty; ventilation of middle ear is an essential predictor of the functional results following middle ear reconstruction. It is a complex and dynamic process depending on a number of factors including the functional status of the Eustachian tube More Details, the degree of pneumatization of mastoid air cells, and the condition of middle ear mucosa. The role of mastoid pneumatization in the middle ear aeration is not exactly known. However, it forms an air reservoir and acts as a surge tank to minimize pressure fluctuation.
A major advance in imaging of the ear structures has occurred with the development of the high-resolution thin-section computed tomography (CT). The bony portions of the temporal bone are depicted with approximately the same resolutions with polytomography, but CT has added a whole new dimension for evaluation of the ear by allowing visualization of the soft tissue components within and adjacent to the temporal bone.
The current study aimed at detecting the value of CT imaging in the assessment of size of mastoid air cells (mastoid pneumatization) and to correlate it with operative results (myringoplasty success rate).
| Patients and Methods|| |
This prospective study was conducted at the Otorhinolaryngology and Radiodiagnosis Departments, University Hospitals, over a period from January 2015 to August 2016.
This study was approved by the Institutional Review Board of our institute, and informed consent was signed by all enrolled patients after explanation of the research purpose.
Forty-two adult patients with dry central TM perforation caused by tubotympanic CSOM and apparently healthy middle ear mucosa at least for 3 months scheduled for myringoplasty were included in the current study. All included patients should have normal eustachian tube function and hearing level corresponds to the size and site of the TM perforation (no suspicion of ossicular chain defect or other pathology).
Patients with active ear discharge, atticoantral CSOM, revision cases, patients who underwent any type of mastoidectomy, those with suspected ossicular pathology having more than 40 dB air-bone gap, and those with sensorineural hearing loss were excluded from the study.
All patients were subjected to preoperative full history taking, clinical examination, laboratory testing, and pure tone audiometry.
CT scans of the temporal bone coronal and axial cuts were done for all cases 1–2 days before surgery. CT scan cuts were evaluated by all authors to estimate the degree of ventilation of mastoid antrum and mastoid air cells.
Myringoplasty was done using underlay technique under general anesthesia in all cases. Postauricular approach was used, and the conchal perichondrium graft was harvested for all cases.
The patients in this study were evaluated on the basis of postoperative graft taking. Successful closure of perforation was defined as an intact TM 1 month postoperatively.
Computed tomography image acquisition and analysis
All temporal bone CT scans were performed using a 128 multidetector CT scanner (Brilliance 16 Power 2.3.0, Phillips, the Netherlands) with the following parameters: angled gantry parallel to orbitomeatal line, tube voltage 120 kV, tube current 330 mA, 750 ms gantry rotation time, 16 mm × 0.75 mm collimation, 1024 × 1024 imaging array, and 0.75 mm slice thickness with no interslice gap and with a convolution filter for edge enhancement and noise reduction. The images were postprocessed on a workstation using dedicated software (Voxar 3D Barco v. 6.3, United Kingdom), in which a semiautomatic algorithm defines an Hounsfield unit threshold between adjacent structures selected by the user.
The parameters of the measurements were selected by two radiologists who performed the volume measurements in all patients. Both readers were blinded to the previous measurements.
Measurements were reported at the malleus-incus level (ice cream cone appearance), in which the following locations were marked to guide the volume measurement: anterior wall of the internal auditory meatus, lower limit of the intrapetrous internal carotid artery, medial limit of the petrous apex (next to the petro-occipital fissure), superior limit of the petrous apex, cochlea, and semicircular canals. CT Studies in which the anatomy required to perform the measurements were not adequately demonstrated were excluded from the study.
The measurements of the linear dimensions of the mastoid air cells. The width, height, and anteroposterior length of each side and the total width of both mastoids were calculated [Figure 1] and [Figure 2].
|Figure 1: Axial computed tomography of the surface area of the right (a) and left (b) mastoid air cells at the malleus-incus level (ice cream) measuring the oblique line drawn from the most lateral point of the mastoid bone air cells parallel to the longitudinal axis of petrous bone corresponding the maximum length of the mastoid pneumatization and maximum length of the line perpendicular to the transverse oblique line (a) on the same computed tomography image|
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|Figure 2: Axial computed tomography of the surface area of the right (a) and left (b) mastoid air cells at the malleus-incus level of other patients|
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For each image, the perimeter (cm) and area of all air cells (cm 2) were highlighted, measured, and summed across images. These sums were multiplied by 0.25 cm (section interval) to yield mastoid surface area (cm 2) and volume (ml), respectively.
This procedure is essentially identical to that used previously to measure mastoid surface area and volume in adult patients.
The area of each mastoid air cells in each ear was measured in every axial CT image [Figure 1] and [Figure 2] and multiplied by the slice thickness. The sum of all measurements was equal to the volume of the mastoid bone.
Statistical comparisons and descriptive statistics were performed using the SPSS statistical software package (version 18.0; SPSS, Inc., Chicago, IL, USA). P< 0.05 was considered statistically significant.
| Results|| |
Forty-two patients had large-sized central dry TM perforation (using Saliba classification for TM perforation) for whom myringoplasty was performed (42 ears) were included in this study. They were19 males (45.2%) and 23 females (54.8%) and their ages ranged from 10 to 56 years (mean 25.7 years).
Three months postoperatively, successful closure of TM perforation was detected in 36 ears (success rate was 85.7%) whereas residual perforation was detected in 6 ears (failure rate was 14.3%). No operated ear showed otitis media with effusion or TM atelectasis.
Successful closure of TM perforation was defined in 17 males and 19 females, whereas residual perforation was detected in 2 males and 4 females. The differences as regards sex of succeeded and failed cases were found to be statistically nonsignificant (P = 0.5271). It was found that the mean age was 27.3 years in succeeded cases and 25.7 years in failed cases. The differences as regards age of patients were also found to statistically nonsignificant (P = 0.7367) [Table 1].
The mean longitudinal diameter of the mastoid was found to be 2.35 cm in succeeded cases and 1.43 cm in failed cases with near significant difference (P = 0.0636). The mean transverse diameter was1.44 cm in succeeded cases and 0.833 cm in failed cases with a significant difference (P = 0.0476). The mean depth of the mastoid was 0.4 in both succeeded and failed cases. The mean total mastoid volume was 2.832 ml in succeeded cases and 1.13 ml in failed cases with nonsignificant difference (P = 0.1218) [Table 2].
|Table 2: Statistical differences in measured dimensions of the mastoid in succeeded and failed ears|
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On the other hand, the mean mastoid surface area was 516.9 cm 2 in succeeded cases and 448.5 cm 2 in failed cases with a significant difference (P = 0.0087) [Table 2].
| Discussion|| |
Myringoplasty is a reconstructive operation for the TM perforation performed to prevent recurrent ear discharge and to improve hearing impairment caused by TM perforation., It is now an established procedure for TM perforation repair, but improving the results of this procedure is the goal of most related recent studies.,
Outcome of myringoplasty can be affected by various factors. Mastoid factors include the extent of mastoid pneumatization and the presence of inflammatory disease in the mastoid. It has been documented in many previous studies , that clinical ear disease is associated with small air cell systems. However, the effect of mastoid pneumatization on myringoplasty success is a controversial otologic question that has remained unresolved over the decades.
In the current study, myringoplasty was performed in 42 ears with a success rate of 85.7% and failure rate of 14.3%. The differences between succeeded and failed cases as regards the age and sex of cases were found to be statistically nonsignificant.
Previously, many researchers studied this relation between success rate in myringoplasty and mastoid pneumatization by combining myringoplasty with cortical mastoidectomy. However, in the current study, the authors tried to investigate this relation on a preoperative radiological basis. Thus, in the preoperative CT scans, mastoid dimensions, surface area, and mastoid volume were calculated for each case, and their effect on myringoplasty success rate was studied.
Significant differences were detected in the mean longitudinal diameter and mean mastoid surface area between succeeded and failed cases, while the difference in the transverse diameter between the two groups was found be near significant (P = 0.0636).
A lot of controversy exists around the role of mastoidectomy during repair of TM perforation in cases of tubotympanic type of CSOM. There are differing opinions regarding combining mastoidectomy with tympanoplasty in these patients.
Holmquist and Bergström first suggested that mastoidectomy improves the chance of successful tympanoplasty for patients in such patients. They found that creation of an aerated mastoid enhances success rate in such patients those with small mastoid air cell system. Several authors support the theory formulated by Holmquist and Bergström although this theory was opposed by studies of Balyan et al. and Jackson et al.
The results of our study support the concept of doing cortical mastoidectomy with myringoplasty but in patients with small mastoid system as it was noticed that the success rate of myringoplasty is higher in patients with large CT mastoid system than those having narrow one [Table 2].
This study also reflects the importance of doing preoperative CT scan of temporal bone in patient with safe CSOM undergoing myringoplasty to estimate the state of mastoid pneumatization rate adding this factor to the variables affecting success and formal consent.
It is concluded from this study that success rate after myringoplasty in patients with large mastoid systems is higher than success rate in those with small mastoid system. This could be attributed to the buffering effect of the larger volume of mastoid air on pneumatization within the middle ear space and more mucosal surface area, with its secretory/absorption functions. Thus, preoperative CT scan in patients with CSOM undergoing myringoplasty is useful.
Larger sample studies comparing results of myringoplasty alone and myringoplasty with cortical mastoidectomy in patients with small mastoid systems on the preoperative CT are required.
| Conclusions|| |
Success rate of myringoplasty is higher in patients with CSOM having large mastoid system than those having small one. Preoperative CT scans in patients with CSOM undergoing myringoplasty are advisable. Further future studies in patients have CSOM with small mastoid systems are still needed to confirm the role of combining mastoidectomy with myringoplasty in such patients.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]