|Year : 2013 | Volume
| Issue : 4 | Page : 186-193
Hearing gain in different types of tympanoplasties
Sachin Gupta, Parmod Kalsotra
Department of Ear Nose Throat, Sri Maharaja Gulab Singh Hospital, Jammu, Jammu and Kashmir, India
|Date of Web Publication||7-Jan-2014|
Ward No. 6, Karan Nagar, Udhampur - 182 101, Jammu and Kashmir
Source of Support: None, Conflict of Interest: None
Aims: The aim of the present study was to find out the hearing improvement in different types of tympanoplasties. Settings and Design: Prospective, hospital-based. Subjects and Methods : A total of 50 patients were included who were 12 years old and above, of both sexes with conductive hearing loss due chronic otitis media with or without perforation. Results: The ratio of males (28) was more as compared with females (22). Maximum number of patients belonged to the age group of 10-20 years (34%), followed by 20-30 years (30%), whereas least number of cases was found in the age group of > 50 years. Hearing loss and otorrhea were present in majority of the cases (100% and 72%, respectively). A total of 18 of the cases had cholesteatomatous chronic suppurative otitis media, while 32 ears were observed to be noncholesteatomatous chronic suppurative otitis media. The average preoperative air conduction (AC) in the present study was found to be 46.6 dB ranging from 20 dB to 112.5 dB, while the average postoperative AC was found to be 39 dB with an average gain of 7.6 dB. The four frequency average preoperative and postoperative air-bone gap (ABG) were found to be 26.48 dB and 20.17 dB respectively, with the average gain of 6.3 dB. The average ABG closure within 0-30 dB was seen in 33 (82%) of the cases. Social hearing was achieved in 86% of the cases in type I, 46% in type II, and 40% in type III tympanoplasty. Conclusions: Tympanoplasty as a procedure when indicated without compromising for the disease, can be effectively used to improve hearing in chronic suppurative otitis media, and other types of conductive hearing losses.
Keywords: ABG closure, Air bone gap ABG, Hearing gain, Tympanoplasty
|How to cite this article:|
Gupta S, Kalsotra P. Hearing gain in different types of tympanoplasties. Indian J Otol 2013;19:186-93
| Introduction|| |
Chronic suppurative otitis media (CSOM) is a major cause of acquired hearing impairment especially in the developing world. Its social and economic implications are accordingly enormous.  Prevalence surveys which vary widely in definition and sampling methods show that the global burden of illness from CSOM involves 65-330 million individuals with draining ears 60% (39-200 million) of whom suffer from significant hearing impairment.
Tympanoplasty with or without mastoidectomy is indicated for chronic ear disease process such as tympanic membrane perforation resulting from previous middle ear infections, atelectasis of tympanic membrane, retraction pocket, cholesteatomas, tympanosclerosis, and chronic otitis media with effusion or mastoid granuloma.  Conductive hearing loss from ossicular chain abnormalities may occur from either discontinuity or fixation of ossicular chain. Ossiculoplasty is performed to repair or reconstruct the ossicular chain. Ossiculoplasty is required in 40%-90% of all tympanoplasties. 
The goal of tympanoplasty is to restore sound pressure transformation at the oval window by coupling an intact tympanic membrane with a mobile stapes footplate via an intact or reconstructed ossicular chain and to provide sound protection for the round window membrane by a closed, air containing, and mucosa-lined middle ear. 
Since the middle ear and the mastoid disease is being encountered more often and are being regularly operated upon, this study is intended to compare the hearing gain achieved in different types of tympanoplasties. Statistical methods are used to exclude the confounding factors and to determine the factors that have significant impact on successful outcomes. 
| Subjects and Methods|| |
The present study was a prospective study conducted in the department of E. N. T. and head and neck surgery, Sri Maharaja Gulab Singh Hospital, Government Medical College, Jammu for a period of 1 year commencing from November 2011 to October 2012. The study included 50 patients of both the sexes admitted in the department of ENT and head and neck surgery who were 12 years old and above, of both sexes with conductive hearing loss due chronic otitis media with or without perforation.
A thorough clinical work up of all the patients was done. Detailed history of the patients was taken and complete E. N. T. and head and neck examination was performed on all patients. The otoscopic examination was done and the findings were confirmed by examination under microscope.
The pure tone audiometry (PTA) test was performed within 7 days prior to the operation. The Audiometer (Elkon eda 3N3 multi) used in this study was manual. The technique followed was Carhart and Jerger's technique which is mostly used (technique of 5 up and 10 down method). The test was performed in acoustically treated room with no ambience noise. Standard head phones were used for air conduction (AC). Where ever the interaural air-bone gap (ABG) was 40 dB or more masking of AC using narrow band noise was applied. Patient was explained about the procedure before audiometry and adequate time was taken for testing. Speech discrimination scores were evaluated. Impedance audiometry was carried out wherever required.
Complete blood counts of the patient were done. Patents were investigated for blood urea, creatinine, electrolytes, liver function tests, and blood sugar. X-rays mastoid were done to see the pneumatization of mastoid bone, to rule out low lying dura and anteriorly placed sinus. High-resolution computed tomography of the temporal bones, wherever required, was done to determine the degree of mastoid pneumatisation, possible intracranial involvement, presence of labrynthine fistulae, tegmental defects, and Fallopian canal More Details anatomy.
Preparation of the patient
Patients were examined under the microscope and the findings of the otoscopic examination were confirmed. Otitis externa and acute exacerbation of chronic otitis media were controlled by appropriate drugs before surgery. A written, informed consent was taken from every patient.
All patients were operated under general anesthesia. Post-auricular approach was used in all cases. The operations were performed in single stage. The cases with cholesteatoma (18) were subjected to canal wall down mastoidectomy, while patients without cholesteatoma (32) underwent canal wall up mastoidectomy (cortical mastoidectomy). Disease processes leading to poor function of Eustachian tube More Details such as polyps, granulation tissue, infection, and purulent debris were removed at the time of operation. After clearing the disease from the middle ear and mastoid as necessary, the status of ossicular chain was assessed. Type of tympanoplasty procedure was planned according to the status of the middle ear and ossicular chain. Ossicular reconstruction was done with autologous incus. Temporalis fascia graft was used by underlay technique to cover the perforations of tympanic membrane.
The follow-up of the patients was done at weekly intervals for 4 weeks postoperatively. During follow-up period, ears with minimal discharge but healed middle ear were subjected to PTA after 1 month. Thereafter, the follow-up was done monthly for 2 months and PTA was conducted at the end of 2 nd and 3 rd months. All the cases were followed up postoperatively for a period of at least 3 months, and the incidence of discharge was noted. Discharge observed after an interval of 3 postoperative months has been taken as evidence of failure to heal.
The hearing results were compared in terms of average hearing gain, postoperative average ABG, and ABG closure.  The postoperative ABG closure was calculated by taking the difference between preoperative ABG and postoperative ABG at average frequencies of 500, 1000, 2000 and 4000 Hz. The audiometry results were reported according to American Academy of Otolaryngology-Head and Neck Surgery guidelines, except for thresholds at 3 kHz, which were substituted in all cases with thresholds at 4 kHz. 
The results reported are short-term hearing results only because the long-term success of any ossicular repair is largely dependent on factors outside the control of surgeon such as patient follow-up rates, Eustachian tube function, middle ear stability, and the condition of mucosa. The short-term results are, hence, a more accurate reflection of actual reconstructive procedures.
Data obtained were entered into a computer spread sheet and analyzed using the statistical package for social sciences computer software program version 15. The paired sample t test was used to compare differences in means in pre- and postoperative cases. Analysis of variance was used to compare the postoperative AC thresholds and postoperative ABGs of different tympanoplasties. P < 0.05 was considered statistically significant.
| Results|| |
The total number of patients enrolled during the study period was 50. Among these patients, 47 came for follow-up, while 3 patients were lost in the follow-up. Among the cases from adequate follow-up, seven (14%) cases were excluded from the study because of graft failure The detailed information regarding age, sex, clinical findings, preoperative AC threshold, pre-operative ABG findings, intraoperative middle ear and ossicular pathology, type of reconstruction and postoperative AC threshold, postoperative ABG findings were noted.
The age and gender distribution of the patients shows that the maximum number of patients belonged to the age group of 10-20 years (34%), followed by 20-30 years (30%), whereas least number of cases was found in the age group of > 50 years. The average age of the patients was 24 (±0.2) years (13-55 years). Number of male patients was 28, while the number of females was 22. Commonest presenting complaints were ear discharge and hearing loss seen in almost all the patients. Tinnitus was found in 16%, otalgia in 24%, and vertigo in 6% of the patients.
On the basis of underlying pathology, the ears operated on were divided into two groups. A total of 18 (36%) of the cases had cholesteatoma (CCSOM). A total of 32 (64%) ears were either chronically discharging but without cholesteatoma or they were dry ears with either perforations of the pars tensa or with intact but retracted tympanic membranes (NCCSOM). Modified Radical Mastoidectomy (MRM) with types III/IV tympanoplasty was done in cholesteatomatous cases, whereas noncholesteatomatous cases underwent cortical mastoidectomy with types I/II tympanoplasty.
Out of 50 patients, 16 (32%) patients underwent type I tympanoplasties, 16 (32%) type II, 12 (24%) patients required type III tympanoplasties, and 6 (12%) patients required type IV along with MRM. Type V tympanoplasty was not done in any of the cases.
Each case has been recorded graphically and is represented by a vertical line on the audiogram [Figure 1], [Figure 2], [Figure 3], [Figure 4]. A dotted line represents the bone conduction level and, therefore, the ultimate possible hearing improvement. An arrowed line represents the gain or loss in AC following surgery, the arrowed end showing the postoperative level, and the horizontal end the preoperative level. When no gain or loss has occurred, AC is represented by a small-shaded circle only.
|Figure 1: Hearing threshold of the patients in type I tympanoplasty (n = 14)|
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|Figure 2: Hearing threshold of the patients in type II tympanoplasty (n = 13)|
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|Figure 3: Hearing threshold of the patients in type III tympanoplasty (n = 10)|
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|Figure 4: Hearing threshold of the patients in the type IV tympanoplasty (n = 3)|
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The average preoperative and postoperative AC was calculated by taking the mean at frequencies 500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz. The average preoperative AC for type I, type II, type III, and type IV tympanoplasties was found to be 34.75 dB, 50.25 dB, 52 dB, and 76 dB. The postoperative AC levels at the end of 3 months were found to be 25.25 dB, 38.25 dB, 48.75 dB, and 92 dB with a gain of 9.8 dB, 12 dB, and 3.25 dB in type I, type II, and type III, respectively; while in type IV there was a loss of 8.16 dB. These differences were found to be statistically significant only in type I and type II tympanoplasties[Table 1],[Table 2] and [Table 3].
|Table 1: Statistical analysis of air conduction threshold in different tympanoplasties using paired t test|
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|Table 2: Statistical analysis of postoperative air conduction using analysis of variance|
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|Table 3: Statistical analysis of air conduction gain in different tympanoplasties using analysis of variance|
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Frequency-specific hearing gain
The frequency-wise hearing gain in different types of tympanoplasties was tabulated. [Table 4] shows that the mean hearing gain in type I tympanoplasty at 500 Hz, 1000 Hz, 2000 Hz, and 40000 Hz was 13.5 dB, 12.5 dB, 10 dB, and 13 dB with maximum hearing gain at 500 Hz.
|Table 4: Frequency-wise air conduction levels in different tympanoplasties|
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In type II tympanoplasty it varied from 17.5 dB at 1000 Hz-11 dB at 4000 Hz with maximum hearing gain at 1000 Hz and minimum at 4000 Hz.
Similarly, type III tympanoplasty showed variation in hearing gain from 22 dB at 500 Hz to 2 dB at 4000 Hz with maximum hearing gain at 500 Hz.
Type IV tympanoplasty depicted loss of hearing threshold at all frequencies with maximum hearing loss of 12 dB at 1000 Hz and minimum hearing loss of 6 dB at 500 Hz and 4000 Hz.
The hearing gain in different tympanoplasties was evaluated in terms of social adequacy  that is hearing gain was termed as:
- Socially adequate-Postoperative AC threshold was within 30 dB
- Not socially adequate-Postoperative AC threshold > 30 dB
- No improvement or worse.
The results of different tympanoplasties in terms of socially adequate hearing gain are shown in [Table 5]. In type I, 86% of the patients achieved socially adequate hearing, while in type II and type III it decreased considerably to 46% and 40%, respectively.
|Table 5: Socially acceptable hearing gain in different tympanoplasties (n=40)|
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Air bone gap
The four frequency average preoperative and postoperative ABG was found to be 26.48 dB and 20.17 dB, respectively, with the average gain of 6.3 dB. In type I, type II, type III, and type IV tympanoplasties, average postoperative ABG was found to be 11.25 dB, 20 dB, 26.5 dB, and 35.5 dB, respectively as compared with preoperative ABG of 19.75 dB, 26.25 dB, 31 dB, and 38 dB in these respective types. These differences were statistically significant only in type I tympanoplasty in the present study [Table 6] and [Table 7].
|Table 6: Statistical analysis of pre-and postoperative air-bone gap in different tympanoplasties using paired t test|
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|Table 7: Statistical analysis of postoperative air-bone gap using analysis of variance|
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Air bone gap closure
The ABG closure was divided into different categories like, 0-10 dB, 0-20 dB, 0-30 dB, and > 30 dB. It was noted that 33 (82%) of the cases fell in 0-30 dB, while 7 (18%) cases fell within > 30 dB. Among these, 9 (22.5%) cases fell within 0-10 dB, 22 (55%) up to 20 dB, and 33 (82%) up to 30 dB. The percentage of ABG closure in different tympanoplasties is shown in [Table 8]. The average ABG closures in type I, type II, type III, and type IV tympanoplasty were 7.5 dB, 6.25 dB, 4.5 dB, and 7 dB.
Type II tympanoplasty: With and without stapes suprastructure
The postoperative results in type II tympanoplasty in cases where stapes suprastructure (SS) was present were comparable to those in cases without stapes SS in [Table 9]. The average postoperative AC levels were 37 dB and 39.5 dB and the postoperative ABG was 19.5 dB and 21 dB, although, the preoperative AC levels were 47.5 dB and 54 dB in those with and without SS, respectively. The ABG closure varied being 8 dB in type II tympanoplasty with SS and 4 dB in those without SS.
|Table 9: Comparison of type II tympanoplasty with and without stapes supra-structure (n=13)|
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| Discussion|| |
Several series of tympanoplasties have been published showing the results of hearing. ,,,,, Some of the results have been excellent, but comparison between them is difficult. The criteria for operative intervention differ between each clinic and there are differences of calibration of audiometers. Different methods have been used by different authors to report the pure tone audiometric postoperative hearing results in tympanoplasty in the literature.
Post-operative results in major series have usually been assessed in terms of hearing gain exceeding 10 dB or 20 dB, , as diminution of the ABG within 10, 15, 20, or 30 dB , attainment of social hearing (0-30 dB); ,,, more rarely as the mean hearing gain,  postoperative hearing,  or ABG.  The Committee on Conservation of the American Academy of Ophthalmology and Otolaryngology  suggested stating the mean hearing gain in the range 500-2,000 cps. and a reduction of the ABG to 10 dB and less, 20 dB and less, and 30 dB and less, as well as any deterioration of conductive hearing. Elbrond and Elpern  calculated mean value audiogram for all frequencies. Threshold of intelligibility which included postoperative PTA and speech audiometry was used by Tos  to assess the hearing levels. The American Otosclerosis Study Group recommended that hearing improvement could be best estimated by observing the degree of closure of the ABG, and the best way of assessing the improvement in a series of cases is by the percentage closure of this ABG. 
The objectives of the present study were to compare the pre- and postoperative hearing results in terms of average hearing gain, average postoperative ABG, and the size of ABG closure in patients undergoing different types of tympanoplasties.
In the present study, the average of four frequencies 500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz were used for analysis of hearing gain and ABG. For calculation of the size of the postoperative PTA-ABG closure ABGs were divided into different bins of 0-10 dB, 0-20 dB, 0-30 dB, and > 30 dB. Hearing improvement results were also evaluated in terms of number of people attaining socially adequate hearing, that is, 0-30 dB postoperative hearing loss.
Hearing outcome in light of different variables
The mean hearing gain in different tympanoplasties in the present study was 7.6 dB. This was comparable to the results of Kolo and Ramalingam  who reported the overall mean preoperative pure tone average was 49.58 dB [standard deviation (SD 18.608)], while the overall mean postoperative pure tone average was 37.38 dB (SD 17.837). The difference between the overall mean pre- and postoperative pure tone average (hearing gain) was 12.19 dB (SD 12.924). Shetty  reported mean preoperative hearing threshold of 42.5 dB as compared with postoperative threshold of 20.41 dB with a hearing gain of 22.09 dB. Similarly, Vartiainen and Nuutinen  reported a mean hearing gain of 10.8 dB.
Analysis of results reveal that the hearing gain was better (9.5 dB and 12 dB) in type I and type II tympanoplasty which implies that better postoperative hearing gain could be achieved if the continuity of ossicles remained intact. Also, the hearing gain achieved was better in non-cholesteatomatous ears than that in chlesteatomatous ears.
Attainment of social hearing has been recommended by various authors ,,, as a parameter to measure success in tympanoplasty operations. The present study shows that socially acceptable hearing was achieved in most of the cases (86%) in type 1 tympanoplasty, while the percentage decreased with subsequent radical procedures [Table 10]. However, it is to be noted that in most of these cases, the preoperative bone conduction was so far reduced that social hearing could not be attained.
|Table 10: Comparison of the socially acceptable hearing results of different authors|
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Air bone gap
The ABG is a commonly used indicator to assess the results of middle ear surgeries. The postoperative ABG in different tympanoplasties show results similar to that in hearing gain with better closure of the gap in type I and type II tympanoplasties. However, the postoperative ABG is, by and large, dependent on patient's preoperative bone conduction. The patient's own statements concerning the bone conduction may be fairly uncertain, especially if the conduction is impaired, and may vary from one examination to another. Moreover, the bone conduction is more dependent than AC upon the adjustment of the audiograms and the patient's ability to cooperate. 
Air bone gap closure
It was noted that 33 (82%) of the study group cases fall in 0-30 dB ABG closure. While analysing the ABG closure in different tympanoplasties, it was found that ABG closure was seen best in type I (n = 14) with 13 (93%) of the cases within 0-30 dB closure. Type II cases had similar results with ABG closure within 0-30 dB in 12 (91%) of cases. Type III tympanoplasty (myringostapediopexy) had 7 (70%) of the cases within 0-30 dB, while in type IV (n = 3) it was in 1 (33%) case.
Not much of the literature is available pertaining to ABG closure in different tympanoplasties. Shrestha et al.,  and Cheang and Cho  reported ABG closure of 73.7% and 61% within 0-30 db in type III tympanoplasty, while Moustafa and Khalifa  observed hearing results of simple myringostapediopexy technique in 145 cases and showed that only 10% of these cases achieved PTA-ABG closure of less than 30 dB.
Vartiainen and Nuutinen  reported closure of postoperative ABG to within 20 dB in 51% of the cases (n = 277). Similarly, ABG closure to 0-15 dB was achieved by Tos  in 63% of the cases (n = 260).
Frequency-wise hearing gain
While analyzing the frequency-wise hearing gain in different tympanoplasties, it is observed that a gradual improvement occurs in hearing as the frequency becomes lower; this is easily explained, as tympanic perforations and other middle ear membrane injuries cause more intense hearing damage over low frequencies. This pattern is followed, more or less, in all types of tympanoplasties. While type I and type III tympanoplasty shows maximum average postoperative hearing gain seen at 500 Hz, type III shows maximum hearing gain at 1000 Hz. Type IV shows hearing loss at all frequencies with minimum loss at 500 Hz. Minimum hearing gain is seen in all types at 4000 Hz except type IV which shows maximum loss at 2000 Hz.
Similar results have been reported by Maroto et al.,  where he observed that higher was the frequency, lower was the hearing improvement with maximum improvement at 250 Hz. Choi et al.,  showed similar results with AC improvement at each frequency except 6,000 Hz. AC and ABG results in the open cavity mastoidectomy showed improvement only at the frequencies of 250 Hz, 500 Hz, and 2000 Hz. AC and ABG improved at low and mid frequencies but not in high frequencies above 3000 Hz when ossicular reconstruction was conducted.
In general, it may be said that the social hearing method is favorable in cases where the preoperative hearing has not been particularly poor. The postoperative ABG method affords a good supplement to the social hearing method and the hearing gain method, but out of the three methods, it is least suited as the sole criterion. It must pay regard to changes in the pre- and postoperative bone conduction.
Groups in which severe hearing impairments predominate present in an unfavorable light when assessed by the social hearing method, best by the relative hearing improvement method. The best orientation is afforded by the use of the social hearing method, the ABG method, and the hearing gain method simultaneously, stating also the condition prior to the operation.  The social hearing method gives mainly the patient's hearing ability, the hearing gain method the effectiveness of the surgeon and of the ossiculoplasty methods.
Vartiainen and Nuutinen  reported that cholesteatomatous ears showed poor-hearing results than other chronic ears. As might be expected, dry ears with sequelae to otitis media had the greatest improvement.
Although the findings of the present study corroborate that of other researchers who also reported good post-operative hearing levels, it does not investigate the possible effects of the type of surgery (canal wall up or canal wall down) and the status of middle ear at the time of surgery (wet or dry) on the postoperative hearing outcome. Vrabec et al., Chan, and Gersdorff et al., ,, are of the view that they are the important determinants of post-tympanoplasty hearing outcome, whereas Kiakujori et al., Murphy and Wallis Vartiainen and Nuutinen, and Baylan et al., ,,, have persistently emphasised that these variables do not in any way significantly influence the post-operative hearing outcome.
| Conclusions|| |
The development of tympanoplasty techniques was led by incidental and inspirational contributions from surgeons all over the world. The quest is still on to devise a way so as to give maximum postoperative hearing using minimal instrumentation. Different methods have been used by different authors to report the pure tone audiometric post-operative hearing results in middle ear surgery in the literature. Among these AC threshold gains, the postoperative ABG presented in 10 dB bins and ABG closure are commonly reported indicators of tympanoplasty outcome. The aim of the present study was to determine the hearing improvement in different types of tympanoplasties in terms of these variables.
Socially, adequate hearing has been obtained in a significant percentage of cases in types I, II, and III groups in which the results are comparable to those of other authors. The postoperative ABG is smaller in type I and ABG closure is better which worsens in subsequent types in accordance with the subsequent radical procedures. This can be attributed to the poorer preoperative bone conduction in these procedures. Moreover, in cases with advanced pathology, eradication of the disease was preferred to obtaining good hearing results while compromising the disease.
Many studies on tympanoplasty have found place in the literature with varying success rates. It is difficult to compare these studies because of different age groups and subgroups, the definition of success; as many studies did not look at hearing outcome, the technique used and the experience level of the surgeon. Therefore, the surgery of chronic middle ear disease is still a great challenge to otologists.
Though our case series is a small and follow-up is only for a short period, we tried to out lay the hearing loss pattern in CSOM cases and its improvement with tympanoplasty surgery. Hence, it is concluded that tympanoplasty as a procedure when indicated without compromising for the disease, can be effectively used to improve hearing in CSOM and other types of conductive hearing losses.
| References|| |
|1.||Ruby RR, Baliagh RH. Reconstructive middle ear surgery: Technique to improve hearing. Can Fam Physician 1992;38:2689-93. |
|2.||Sismanis A. Tympanoplasty Glassock-Shambough Surgery of the Ear. 5 th ed., Vol. 24. India: Elsevier; 2003. p. 462-83. |
|3.||Tos M. Indications for surgery and pre-operative management. Manual of Middle Ear surgery. New York: Thieme; 1993. p. 5. |
|4.||Merchant SN, Rosowski JJ. Auditory physiology. Glassock-Shambough Surgery of the Ear. 5 th ed. New Delhi: Elsevier; 2003. p. 64-78. |
|5.||Kim MB, Choi J, Lee JK, Park JY, Chu H, Cho YS, et al. Hearing outcomes according to the types of mastoidectomy: A comparison between canal wall up and canal wall down mastoidectomy. Clin Exp Otorhinolaryngol 2010;3:203-6. |
|6.||Lackany MA, Sarkis NN. Functional results after Myringoplasty and Type 1 tympanoplasty with the use of different graft materials. J Med Res Inst 2005;26:369-74. |
|7.||Shrestha BL, Bhusal CL, Bhattarai H. Comparison of pre and postoperative hearing results in canal wall down mastoidectomy with type 3 tympanoplasty. JNMA J Nepal Med Assoc 2008;47:224-7. |
|8.||Livingstone G, Millar H. Results of tympanoplasties, 1956-1959. J Laryngol Otol 1961;75:669-78. |
|9.||Wullstein H. Theory and practice of tympanoplasty. Laryngoscope 1956;81:1076-93. |
|10.||Berendes J, Link R, Zollner F. In: Zollner F, Hals-Nasen-Ohren-Heilkunde, editors. Vol. 2. Stuttgart: Thieme; 1966. p. 1327. |
|11.||Beales PH. Early experiences of the plastic surgery of the sound conducting apparatus with report of 57 consecutive cases. II. J Laryng Otol 1957;71:297-312. |
|12.||Schuknecht HF. Pathology of the ear. 2 nd ed. Philadelphia: Lea and Febiger; 1993. |
|13.||Proctor B. A statistical review of 177 tympanoplasties performed in 1957-1958. AMA Arch Otolaryngol 1960;71:469-77. |
|14.||Thorburn IB. Factors which influence the hearing result in the surgery of chronic otitis media. Laryng 1954;68:739. |
|15.||Portmann M. Tympanoplasty. Arch Otoaryngol 1963;78:2-19. |
|16.||Bandtlow O. Results of functional surgery of the ear. (A review of 4,460 operations). Arch Ital Otol Rinol Laringol 1959;70:122-31. |
|17.||Wullstein H. Results of tympanoplasty. AMA Arch Otolaryngol 1960;71:478-85. |
|18.||Pietrantoni L, Bocca E, Agazzi C, Zanotti G. Considerations on the current results of tympanoplasty. Arch Ital Otol Rinol Laringol 1959;70:132-46. |
|19.||Palva T, Pulkkinen K. Hearing after surgery in chronically discharging ears. I. Atticoantrotomy. Acta Otolaryngol 1960;51:175-85. |
|20.||Pfaltz CR, Luscher E, Voegeli R, Wey W. Reevaluation of results in tympanoplasty. A critical survey of 250 cases with particular regard to speech audiometry. Arch Otolaryngol 1962;75:405-14. |
|21.||Wullstein HL. Operations to improve the Gehores: principles and methods. Stuttgart: Thieme; 1968. |
|22.||Committee on hearing and equilibrium guidelines for the evaluation of results of treatment of conductive hearing loss. American Academy of Otolaryngology-Head Neck Surgery Foundation, Inc. Otolaryngol Head Neck Surg 1995;113:186-7. |
|23.||Elbrond O, Elpern BS. Reconstruction of ossicular chain in incus defects. An experimental study. Arch Otolaryngol 1965;82:603-8. |
|24.||Tos M. Assessment of the results of tympanoplasty. J Laryngol Otol 1972;86:487-500. |
|25.||Kolo ES, Ramalingam R. Hearing results post tympanoplasty: Our experience with adults at the KKR ENT Hospital. Indian J Otolaryngol Head Neck Surg 2012: 1-4. |
|26.||Shetty S. Pre-operative and post-operative assessment of hearing following tympanoplasty. Indian J Otolaryngol Head Neck Surg 2012;64:377-81. |
|27.||Vartiainen E, Nuutinen J. Long term Hearing results of one stage tympanoplasty for chronic otitis media. Eur Arch Otorhinolaryngol 1992;249:329-31. |
|28.||Chang I, Cho H. Tympanoplasty in Korea (Otorhinolaryngol). Arch Otorhinolaryngol 1977;217:237-40. |
|29.||Moustafa HM, Khalifa MA. Tympano-cartilago-stapediopexy: A method to improve hearing in open technique tympanoplasty. J Laryngol Otol 1990;104:942-4. |
|30.||Maroto D, Escalona Gutiérrez JJ, Conde Jiménez M, Casado Morente JC, Povedano Rodríguez V, Benítez-Parejo N. Functional results in myringoplasties. Acta Otorrinolaryngol Esp 2010;61:94-9. |
|31.||Choi HG, Lee DH, Chang KH, Yeo SW, Yoon SH, Jun BC. Frequency-specific hearing results after surgery for chronic ear diseases. Clin Exp Otorhinolaryngol 2011;4:126-30. |
|32.||Vrabec JT, Deskin RW, Grady JJ. Meta-analysis of pediatric tympanoplasty. Arch Otolaryngol Head Neck Surg 1999;125:530-4. |
|33.||Chan SC. Reconstructive middle-ear surgery for chronic otitis media. Ann Acad Med Singapore 1980;9:367-73. |
|34.||Gersdorff M, Garin P, Decat M, Juantegui M. Myringoplasty: Long-term results in adults and children. Am J Otol 1995;16:532-5. |
|35.||Kiakujori K, Esmaieli M, Faramarzi AS. The result of hearing in patients treated by surgery due to chronic otitis media. Casp J Intern Med 2010;1:138-40. |
|36.||Murphy TP, Wallis DL. Hearing results in patients after canal-wall-up and canal-wall-down mastoid surgery. Otolaryngol Head Neck Surg 1998;119:439-43. |
|37.||Baylan FR, Celikkanat S, Aslan A, Taibah A, Russo A, Sanna M. Mastoidectomy in non-cholesteatomatous chronic suppurative otitis media: Is it necessary? Otolaryngol Head Neck Surg 1997;117:592-5. |
[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9], [Table 10]