|Year : 2014 | Volume
| Issue : 4 | Page : 183-188
Overlay versus underlay myringoplasty: A comparative study
Parmod Kalsotra, Rohan Gupta, Nitika Gupta, Sunil Kotwal, Anil Suri, Sonika Kanotra
Departments of ENT and Head and Neck Surgery, SMGS Hospital, Government Medical College, Jammu, Jammu and Kashmir, India
|Date of Web Publication||13-Dec-2014|
Source of Support: None, Conflict of Interest: None
Aims and Objectives: The objective of this study is to compare the outcome of overlay versus underlay myringoplasty procedure in the management of chronic inactive mucosal otitis media in terms of graft uptake, hearing improvement and complications. Materials and Methods: This study was conducted in the Department of Otorhinolaryngology and Head and Neck Surgery, S.M.G.S Hospital, Government Medical College, Jammu from June 1, 2012 to September 31, 2013 and clinical records of 77 patients who underwent myringoplasty by either overlay or underlay technique in this period were analyzed. A total of 72 patients with dry central tympanic membrane perforations of various sizes were included in this study. These patients were divided into two groups. In Group A, 37 patients were included in which tympanic membrane was repaired by using overlay technique of myringoplasty, whereas Group B comprised of 35 patients who underwent underlay myringoplasty. The results of two techniques were compared in terms of graft success rate that is, full uptake or failure to take up, medialization or lateralization of graft within 6 months of operation and improvement in hearing at the end of 6 months of follow-up. Results: In terms of graft uptake and postoperative AB gap improvement, Group B (underlay group) was slightly better with 91.43% uptake rate and mean postoperative AB gap of 11.11 dB than Group A (overlay group), which had 89.18% uptake rate and 11.72 dB as mean postoperative AB gap, though the difference was not statistically significant. There was only 1 case of graft medialization in Group B, while 3 cases had lateralization of graft in Group A. Conclusion: Both techniques of myringoplasty achieve satisfactory results, with the underlay technique being slightly better than the overlay technique. Therefore, underlay technique being technically simple should be preferred, but the ultimate decision about the technique to be employed depends on the surgeons preference and the site of perforation.
Keywords: Lateralization, Medialization, Myringoplasty, Overlay, Underlay
|How to cite this article:|
Kalsotra P, Gupta R, Gupta N, Kotwal S, Suri A, Kanotra S. Overlay versus underlay myringoplasty: A comparative study. Indian J Otol 2014;20:183-8
| Introduction|| |
Myringoplasty, an operation performed to repair or reconstruct the tympanic membrane  was introduced by Berthold  and was further developed by Wullstein  and Zollner.  It is also known as tympanoplasty type I, where peroperatively middle ear structures are exposed and are checked for functional integrity.  The otological surgeons have cultivated various effective techniques of myringoplasty over past 40 years in an attempt to achieve perfection by improving the result of the procedure.
Damage to the tympanic membrane is commonly the result of chronic ear disease; however, damage can also result from various forms of trauma, direct physical injury, burns, scalds, pressure effects, and head injuries. Iatrogenic trauma by inserting the ventillatory tube can also occur. Most of these perforations heal spontaneously such as those caused by trauma and acute supparative otitis media.  Long standing perforation leading to recurrent ear discharge needs myringoplasty.
There are a wide range of techniques of myringoplasty that are described in the literature and these include the underlay technique,  overlay technique,  "Gelfilm Sandwich" technique,  "Swinging Door" technique,  tipple "C" technique,  double breasting technique,  fascial pegging technique,  anterosuperior anchoring technique,  and laser assisted "spot welding" technique.  The two most common techniques for positioning the graft relative to the remnant of both the tympanic membrane and the tympanic annulus are the "underlay" and the "overlay" techniques. 
The former is widely used and is relatively simple to perform as the graft is placed entirely medial to the remaining drum (or annulus) and manubrium of malleus. This technique is ideal to repair small and easily visualized perforations, blunting and lateralization of the graft are avoided, the drum heals at the correct level relative to the annulus and the ossicles and it is quick and easy to perform. On the other hand, its disadvantages are that the middle ear space is reduced and adhesions may occur leading to medialization or atelectasis, there is increased failure because of a limited bed size for the graft supplying poor vascularity, exposure of the middle ear is relatively limited and it is not the ideal technique for perforations extending into the anterior annulus since placement of the graft is difficult.  In contrast, the overlay technique is more challenging and typically reserved for total perforations, anterior perforations, or failed underlay surgery.  In the overlay technique, the graft is placed lateral to the annulus and any remaining fibrous middle layer, after the squamous layer has been carefully removed from the tympanic membrane remnant and the ear canal. In this technique, there is an excellent visualization of the anterior metal recess, which is important in cases of anterior perforations reaching the anterior annulus. In addition, the healing rate is high because the drum is essentially replaced intact and the middle ear space is not reduced. The most serious disadvantages are blunting of the anterior metal recess and the lateralization of the graft; moreover, this technique is more laborious and has a longer healing time. 
The aim of this study is to analyze the difference in the success rate of the two above-mentioned myringoplasty techniques and to assess the advantages and disadvantages associated with each.
| Materials and Methods|| |
This study is an analysis of records of 77 patients who underwent ear surgery in the Department of Otorhinolaryngology and Head and Neck surgery, S.M.G.S Hospital, Government Medical College, Jammu from June 1, 2012 to May 31, 2013.
The patients having dry central perforation for at least 6 weeks were included in the study. All cases with cholesteatoma, tympanosclerosis, ossicular chain disorders and revision or combined procedures were excluded. Furthermore, patients aged <8 years, patients having focus of infection in the nose, sinuses, or throat and those having sensorineural hearing loss were excluded.
A thorough history and clinical examination of ear, nose and throat was carried out. Ears examination under microscope, tuning fork tests, radiological test (X-ray mastoid, Towne's view), laboratory investigation, and hearing function test (pure tone audiometry) were also performed.
Informed consent was obtained from the patients meeting the inclusion criteria.
In all patients, myringoplasty was performed under general anesthesia through a postauricular approach using temporalis fascia graft. Depending on the placement of the graft material, this study compares the underlay and overlay techniques of myringoplasty.
Bismuth iodine paraffin paste pack was placed in the external auditory canal for 2 weeks. The patients were advised to avoid straining, coughing, and forceful nose blowing postoperatively. All of them were called for follow-up at 2 weeks, 4 weeks, and then at monthly interval for first 6 months. At each visit otoscpoic ear examination and tuning fork tests were performed.
Postoperative pure tone audiometry was done 6 months after the operation and the functional outcome of both procedures was calculated by estimating the diminution (if any) in the amount of the air bone gap postoperatively at frequencies 0.5, 1, and 2 kHz.
A proforma was used to collect the data such as age, gender, perforation size and location, conductive loss present or absent, surgical approach, technique, postsurgical results, and complications.
Data analysis was carried out to find out statistical significance of the observed differences and associations. Comparison of proportions was done by Chi-square test and comparison of the mean was done by ANOVA, using Epi Info 18.104.22.168 statistical software. A value of P < 0.05 was considered significant.
| Results|| |
A total of 72 patients underwent myringoplasty from June 1, 2012 to September 31, 2013. Group A comprised of 37 cases (51.38%, 17 females, 20 males) whereas 35 cases (48.61%, 18 females, 17 males) were included in Group B.
In Group A, patients age ranged between 12 and 48 years with the mean age being 29.70 years (standard deviation [S.D] 11.16), while in Group B, it ranged between 11 and 45 years with a mean age being 28.14 years (S.D 10.83). On comparison of mean age of patients in the two groups by means of ANOVA the P value came out to be 0.66, which was statistically insignificant [Table 1].
The primary cause of disease in Group A was infection in 35 cases (94.6%) and trauma in 2 cases (5.40%), while in Group B infection was the cause in 32 patients (91.43%) and trauma in 3 patients (8.57%).
Left ear was involved in 23 patients (62.16%) while the right was involved in the remaining 14 patients (37.84%), in Group A whereas in Group B, 20 patients (57.14%) had their left ear involved and 15 patients (42.86%) had the involvement of the right ear.
In relation to the handle of malleus the perforation involved anteroinferior quadrant in 5 patients, anterosuperior quadrant in 1 patient, poster-inferior quadrant in 2 patients, anterior quadrant in 5 patients, posterior quadrant in 4 patients, inferior quadrant in 6 patients in Group A while in Group B it involved anteroinferior quadrant in 5 patients, anterosuperior quadrant in 1 patient, poster-inferior quadrant in 3 patients, posterosuperior quadrant in 1 patient, anterior quadrant in 4 patients, posterior quadrant in 6 patients, and inferior quadrant in 4 patients [Table 2].
|Table 2: Distribution of tympanic membrane perforation in Group A and Group B on the basis of their size and site|
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In Group A, the preoperative AB gap was <10 dB in 6 patients, between 11 and 20 dB in 11 patients, 21-30 dB in 12 patients and >30 dB in 8 patients with a mean AB gap 21.78 dB (S.D 10.27) whereas in group B it was <10 dB in 7 patients, between 11 and 20 dB in 12 patients, 21-30 dB in 10 patients and >30 dB in 6 patients with mean AB gap of 20.54 dB (S.D 9.80). Comparison of the mean preoperative AB gap in the two groups by means of ANOVA showed a statistically insignificant P = 0.61 [Graph 1].
The graft uptake rate was 89.18% (33 patients) of the 37 patients in Group A, out of the 5 patients with graft failure, there were 2 cases of large perforation and 1 case each of inferior quadrant, anteroinferior quadrant and subtotal perforation. It was 91.43% (32 patients) of the 35 patients in Group B, 2 patients out of the 3 with graft failure had anterior quadrant perforation while one had anteroinferior perforation. The results in terms of graft uptake were compared using Chi-square test, with a resultant P = 0.93, which was statistically insignificant [Table 3]. Lateralization of the graft was seen in 3 patients in Group A, while there was 1 case of graft medialization in Group B. In terms of complications group A showed more cases as compared to Group B but because of small sample size this could not be statistically tried [Table 4].
|Table 3: Comparison between Group A and Group B in terms of graft uptake and graft failure|
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|Table 4: Comparison between Group A and Group B in terms of medialization and lateralization|
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The hearing improved in 30 patients (81.08%) out of the 37 patients in Group A with the mean postoperative AB gap improving to 11.72 dB (S.D 6.93) and the postoperative AB Gap changing to <10 dB in 20 patients, between 11 and 20 dB in 11 patients and >20 dB in 6 patients while in Group B it improved in 30 patients (85.71%) out of the 35 patients with the postoperative AB gap changing to <10 dB in 17 patients, between 11 and 20 dB in 11 patients and >20 dB in 7 patients and the mean postoperative AB gap improving to 11.11 dB (S.D 6.41). Comparison by means of ANOVA of the mean postoperative AB gap between both the groups gave a P = 0.69 which was statistically insignificant [Graph 2], but the comparison between the pre- and post-operative AB gap in Group A had a P = 0.000003 and in Group B, the P = 0.00001, both of these values were statistically significant [Graph 3] and [Graph 4].
| Discussion|| |
Myringoplasty or tympanoplasty type 1 is the surgical procedure in which the reconstructive process is limited to repairing tympanic membrane perforation. The main objective of myringoplasty has traditionally been the closure of the tympanic membrane perforation to prevent chronic infections and to make the ear safe.  Consequently, the second objective is to improve the hearing loss which resulted due to perforation of the tympanic membrane. There is still no consensus about the optimal technique, which is often employed on the basis of the surgeon's preference and skills, and not on the type of the tympanic membrane perforation. 
All the patients included in our study were divided into two groups depending upon the technique utilized to repair the tympanic membrane perforation. When we compared Group A (overlay technique group) with Group B (underlay technique group), it was observed that there was no statistically significant difference between these two groups in terms of age wise distribution, gender wise distribution, duration of disease and cause of disease, due to matching at the time of selection.
In this study, the outcome in terms of graft uptake rate was slightly better in the underlay technique (91.43%) as compared to the overlay technique (89.18%), though the difference was statistically insignificant, P > 0.05, which was similar to those reported in literature by Crovetto De La Torre et al.  and Mishra et al. 
The results of this study were better than Ashfaq et al.  who reported a graft uptake rate of 73% with underlay technique in 105 cases and Khan and Khan  who reported 77.5% graft success rate in 94 cases using the same technique. These were also better than Fadl  who had 85.4% success with underlay technique series and 66.7% success in the overlay technique.
The results were comparable to Gupta  who had 86.6% success in his overlay technique series and Wang and Lin  who achieved an 82.1% and an 85% take rate with the overlay and the underlay techniques, respectively.
Glasscock  have reported a 91% success rate using the overlay technique and a 96% success rate with the underlay technique in a total of 273 ears. Sheehy and Anderson  have reported a 97% take rate in 472 overlay myringoplasty surgeries. The results achieved by Glasscock,  and Sheehy and Anderson  were better than those of the present study.
Rizer  reported a success rate of 95.6% in 554 overlay grafts and 88.8% in 158 underlay grafts with Brown et al.  having 74% success in underlay technique series and 100% success in overlay series, while the results of the present study were not consistent with both these studies, underlay being slightly better than overlay.
Patient selection may have had a role in the high success rate in the present study as patients presenting with mastoid or ossicular signs of pathology were excluded. It can also be attributed to short term follow-up of the patients involved in this study. Better results achieved with underlay technique may probably be due to less surgical manipulation and faster healing process. We observed a longer healing time in the overlay group due to the surgical manipulation involving the removal of the tympanic membrane remnant and the skin of the ear canal, which led to the development of granulation tissue.
The complication rate in the present study was quite low, there were 3 cases of graft lateralization in Group A and only 1 case of graft medialization in Group B, but due to small sample size the difference could not be statistically tried. These results were consistent with Sergi et al.  who reported no case of graft medialization in underlay group while 4 cases of graft lateralization in overlay Group, but were not in accordance with a study by Yigit et al.,  who reported the rate of complications with the underlay to be greater than overlay technique. In contrast to the study by Doyle et al.  blunting of the anterior angle in the overlay technique was not seen in the present study, which could be attributed to meticulous surgical technique to expose the anterior remnants.
In this study, both techniques were associated with significant improvement in hearing, with both achieving statistically significant results when the mean preoperative AB gap was compared to the mean postoperative AB gap for each group. However, the underlay technique appeared to achieve a slightly higher gain than the overlay technique, but statistical analysis showed an insignificant correlation with P > 0.05. Sergi et al.  also reported better results with underlay as compared to overlay technique, but with a statistically significant difference. Singh et al.  have reported a 93.3% success rate for each technique and a better hearing gain (92.8% vs. 57.1%) for patients treated with the underlay technique. Javid et al.  also reported postoperative mean reduction in air bone gap in underlay technique to be better (21 dB) than overlay technique.
| Conclusion|| |
Myringoplasty is a safe and effective technique to improve the quality of life of patients, avoiding continuous infections and allowing them contact with water. According to our results, overlay and underlay techniques of myringoplasty are equally effective in terms of graft success rate and hearing improvement, but in terms of complications underlay technique is superior to overlay technique. Underlay technique of myringoplasty is also relatively simple, technically easier to perform and takes less time as compared to overlay technique of myringoplasty. Therefore, underlay technique of myringoplasty should be widely used, but the overlay technique should be preferred in cases of anterior quadrant perforations.
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[Table 1], [Table 2], [Table 3], [Table 4]