VARIATIONS OF PRE- AND POST-OPERATIVE HEARING LOSS DEPENDING ON THE SIZE OF TYMPANIC MEMBRANE PERFORATION

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1 Medical interventions VARIATIONS OF PRE- AND POST-OPERATIVE HEARING LOSS DEPENDING ON THE SIZE OF TYMPANIC MEMBRANE PERFORATION Bianca Niculescu 1, Doina Vesa 2, E. Tomescu 3 1. PhD Student, Dept of E.N.T., Iuliu Ha]ieganu U.M.Ph Cluj Napoca 2. Lecturer, Dept of O.R.L., Dun\rea de Jos University Gala]i 3. Professor PhD.,Dept of O.R.L., Iuliu Ha]ieganu U.M.Ph Cluj-Napoca Corresponding author: niculescu_bianca13@yahoo.com Abstract The aim: The present study aims at grouping the perforations of the tympanic membrane according to their precisely calculated sizes, in view of a subsequent establishment of hearing loss variation with such sizes; these data permit to appreciate the extent to which the initial size of the perforation influences the audiometric gain, after the successful closing of the perforation. Materials and method: The retrospective study included 148 patients whose unique pathology was perforation of the middle ear. The perforations were photographed and measured as ratio of tympanic membrane s area; the auditive losses were recorded on audiograms, both initially and after healing of the perforations. The difference between the auditive thresholds in aerial and bone conduction, and the air bone gap (ABG) were calculated prior to surgery, on each of the low, average and high frequencies. The patients selected for the study were divided into 4 groups, according to the perforations size, the obtained data being statistically analyzed. Results: The correlations between the 4 groups of dimensions of perforations and hearing loss showed the latter s dependence on frequencies. For perforations affecting less that 10% of the tympan, hearing loss and the post-operative audiological gain do not depend on the size of the perforation while, for the rest of perforations, both hearing loss and auditive recovery increase with the sizes of tympan defects. The highest audiometric gain was registered on low frequencies, whereas auditive recovery on high frequencies was not spectacular. Conclusions: Perforations of tympanic membrane should be measured with high precision and grouped according to their sizes, for subsequent establishment of the clinical and therapeutical measures to be taken, as well as for a correct estimation of the success of perforations closing. Keywords: perforation of tympanic membrane, ratio, myringoplasty, audiogramme INTRODUCTION Perforations of the tympanic membrane are quite frequent, being caused by infections, trauma or by iatrogenic manoeuvres. The size and localization of tympanic defects are variable, their correct evaluation being essential for a suc- cessful management of the pathology [1,2]. The positive diagnosis of the perforations is usually established by otoscopy, known as evidencing the lack of substance at the level of the tympanic membrane, as well as by tonal liminal audiogram, on which a transmisison hypoacusy or a mixed, predominantly transmission hypoacusy is recorded between 0 and 40 db, in cases in which perforation is the only disease of the middle ear [3,4]. A perforation is considered as successfully closed when the aspect of the tympanic membrane is normal, and the lower hearing is below 10 db, on audiograms recorded 3 months after spontaneous closing, under the mentor, of the perforations[5], or 6 months after myringoplasty[6]. A successful closing of the perforations may be obtained as a function of their characteristics in 3 ways, as follows: 1. spontaneous closing through restitutio ad integrum in cases of post-traumatic, recent, central, non-infected ruptures of a previously intact tympanic membrane, as well as in cases of correctly-treated acute otitis media with effusion.[4]. 2. closing under the epithelization mentor, in cases of recent membrane breakings and of old, simple, dry, post-otitis or post-traumatic perforations, which do not exceed 1/3 of the tympanic membrane [7]. 3. closing through myringoplasty, in the case of large perforations, exceeding 1/3 of tympan s surface, of the marginal or antero-superior perforations, of the perforations representing a stabilized sequel, with no effusions in the last 6 months 1 year, with functional tube, and in the case 236 volume 15 issue 3 July / September 2011 pp

2 VARIATIONS OF PRE- AND POST-OPERATIVE HEARING LOSS DEPENDING ON THE SIZE OF TYMPANIC MEMBRANE PERFORATION of perforations in patients whose profession requires an as high stereo-audition as possible (musicians, conductors, professors), with an auditive deficit of db [6]. The existing studies on such topics demonstrated that, the larger the perforations of the tympanic membrane, the more pronounced are the auditive losses they cause[8,9]. Debates are also recorded in the literature of the field on the extent of predictiveness of the perforation size as to the healing ratio of such a lesion. Some authors assert that a reversely proportional relation exists between the size of the perforation and its successful closing, while others have demonstrated that size is not a decisive factor in the process [10,11]. The objectives of the present study are: to classify perforations according to their precisely-stated sizes; to establish what type of hypoacusies cause such groups of perforations, considered as unique diseases of the middle ear, according to their size; to establish the extent to which the initial size of the perforations influences the auditive gain registered after their successful closing. MATERIALS AND METHOD A retrospective study was performed in the E.N.T. clinical section of the Sf. Apostol Andrei Urgency Hospital of Galaþi, on a group of 148 patients, in whom 156 perforations of the tympanic membranes were demonstrated by otoscopy and otomicroscopy. The inclusion criteria considered the following aspects: presence of no other lesion at the level of the tympanic membrane (e.g., tympanosclerosis plaques) apart from the perforation analysed, while the perforation should not display other diseases of the middle ear (e.g., interruptions/blockages of the ossicular chain) no difference exceeding 40 db should appear between the aerial and the bone curve (Air-Bone Gap =ABG) on the tonal liminal audiogram taken in the beginning of the consultation,; no lesions of the middle ear should be demonstrated in the intra-operatory stage; after healing of the perforation, the ABG should not exceed 10 db. Each perforation put into evidence was photographed with a MD SCOPE MS 101 videoscope, the images being stocked in the computer with the Universal Desktop Ruler v programme, the perforation area being calculated as percent value of the tympanic membrane area. The audiogrammes of the patients included in the study were made when they first came to the clinic, as well as 3-6 months after perforations healing, on the same ITERA II audiometer from GN OTOMETRICS. Statistical processing of data made use of a data basis of the authors, created with SPSS (Statistical Package for Social Sciences). Determination of the associations (correlations) among the various variables considered in the study (perforation size, perforation localization, hearing loss in decibels, on various frequencies) was performed as contingency tables with 2 inputs, which is a specific case of the associations between discrete variables, or by calculating the Pearson correlation coefficient, a case specific to continuous variables. For continuous data, the usual statistical indices were calculated, namely: arithmetic mean, standard deviation, standard error of the mean, etc. Testing of the significance of some association involved application of test 2 (in the case of frequency tables) and of test t (in the case of correlation coefficients). For discrete data, the absolute and relative frequencies, providing adequate data on the distribution of cases studied according to the categories of the respective variable, were calculated. RESULTS The measurements performed in the group under investigation demonstrated perforation sizes ranging between 0.8% and 72% of the tympanic area. The patients participating to the International Journal of Medical Dentistry 237

3 Bianca Niculescu, Doina Vesa, E. Tomescu study were divided into 4 groups, according to the perforation sizes, as follows: very small perforations, representing 0.85 % of the tympanic surface: 56; small perforations, representing 5-10 % of the tympanic surface: 36; average perforations, representing % of the tympanic surface: 38; large perforations, representing over 25 % of the tympanic surface (i.e., more than a quadrant of the tympanic membrane): 26; There were also calculated, prior to the surgery, the difference between the auditive thresholds in the air and bone conduction, the air bone gap (ABG), on each of the following frequencies: - low:, Hz; - mean: Hz; - high:, Hz. In a subsequent stage, the mean and standard deviation of pre-operative ABG was calculated on each frequency, for each group of perforations: I, II, III and IV (Table I). Table I value and standard deviation of the pre-operative Air Bone Gap ABG Mean Group I 16.96±7, ±7, ±8, ±7,40 10± ±2.56 Group II 16.66± ± ± ± ± ±3.64 Group III 21.84± ± ± ±8.48 Group IV 30±10 Mean 20.25± ± ± ± ± ± ± ± ± ± ± ± ±3.39 The highest hearing losses are registered over the and Hz frequencies, comparatively with the Hz frequency and the high and Hz frequencies. Statistically significant differences were recorded between the frequency values of Hz and Hz, for groups II and IV, when p < 0.05 (table II). A statistical comparison of the pre-operative ABG of the perforation groups demonstrated no significant differences between groups I-II, I-III, I-IV, II-III, III-IV (with p> 0.05 ), even if p< 0.05 for the ABG difference between groups II-IV, on a frequency of Hz (Table III). 238 Table II Statistical analysis (qui-square test) of the differences in hearing losses, on frequencies, among the perforation groups χ2 Group I Group II Group III Group IV Table III Statistical analysis (qui-square test) of the differences in hearing losses of the perforation groups on frequencies χ2 Group I II Group I III Group I IV Group II III Group II IV 3.81 Group III 1.28 IV In a subsequent stage, the mean value of postoperative ABG was calculated (Table IV) and compared with pre-operative ABG, statistically significant differences being obtained on all frequencies. Table IV value and standard deviation of postoperative ABG Post ABG GI 0.71± ±2, ± ± ± G II 0.83± ± ± G III 4.52± ± ± ± ± G IV 7.27± ± ± ± ± Hz ABG preop=20.25 ABGpostop=3.33 Hz ABGpreop=18.2 ABGpostop=2.74 Hz ABGpreop=17.75 ABGpostop=1.78 Hz ABGpreop=13.14 ABGpostop=0.93 Hz ABGpreop=11.5 ABGpostop=0.84 In the end, the mean values of the auditive gain were calculated and compared, for each volume 15 issue 3 July / September 2011 pp

4 VARIATIONS OF PRE- AND POST-OPERATIVE HEARING LOSS DEPENDING ON THE SIZE OF TYMPANIC MEMBRANE PERFORATION group of perforations, on each frequency (Table V). Table V auditive gain of the perforation groups on frequencies Auditive gain GI G II G III G IV The highest audiometric gain was registered at low frequencies, the auditive improvement at high frequencies being not spectacular. On the other hand, the lowest audiometric gain was recorded after closure of the small and very small perforations, below 10% of the tympanic membrane surface. The audiometric gain increased progressively for each group of size perforations, the maximum being attained after closing of the perforations larger than a quadrant (18.82 db). The differences between the gain of the various groups are quite small, being not statistically significant. DISCUSSION In the experimental group, the very small perforations were the most numerous, as they are generally not complicated and, consequently, not associated to other lesions of the middle ear. Perforations from group IV, with a surface larger than a quadrant of the tympanic membrane, were the fewest. Most of the initially-examined large perforations, either post-otitic or post-traumatic, were not accompanied by modifications of the elements from the middle ear (which would have induced additional hypoacusy), being therefore left aside. This explains the absence of the total (quasi-total) perforations in the present study. In other investigations, the perforations under analysis involved up to 100% of the tympanic membrane surface [8,9,12], which may assume other causes having provoked hearing losses (apart from perforations), once known that the mentioned studies made no rigorous selection of cases. More than that, no perforation International Journal of Medical Dentistry affects 100% of the tympan, as always a small rest of pars tensa will still remain under the timpano-malearic ligaments. As to the losses produced by perforations in sound transmission, the results obtained (Table I) show hat the highest hearing loss is recorded on low frequencies (19dB), while the losses are more reduced on mean frequencies (17dB), the values recorded on high frequencies being very low (11dB). Consequently, the hearing loss caused by perforations of the tympanic membrane depends on frequencies, which agrees with the literature studies [2,8,9,12]. The differences between the losses from extreme frequencies are not very large and, even if clinically significant, they are not statistically significant (Table II). In the case of perforations from groups III and IV, the higher the size of the tympanic defect, the more pronounced is the hearing loss, which means a higher ABG. Nevertheless, in the case of perforations from groups I and II, this rule is no longer valid, because hypoacusy does not advances with the size of the perforation. Statistically significant differences may be observed between the auditive losses caused by small and large perforations on high frequencies (Table III). These results support the conclusions of other studies, according to which the size of the tympanic membrane perforation is an important factor of hearing loss, the more pronounced losses being produced by large perforations [2,8,9,12]. However, in the present study, discussing perforations below 10% of the tympan surface, the perforation size does not influence hearing loss, any more. Classification according to size - of tympanic membrane perforations, as unique pathologies of the middle ear, along with observing the way in which the perforation size influences hearing loss, permitted a correct evaluation of the importance of perforation size in auditive recovery after its closing. Hearing improvement after closing of the perforation of the tympanic membrane has been demonstrated in several studies, [13,14] which approached the perforations of the tympanic membrane of various sizes in a global manner, 239

5 Bianca Niculescu, Doina Vesa, E. Tomescu when the post-surgery audiological gain was calculated. Having in view the large variety of the perforation sizes from linear to quasi-total ones it is mistaken to discuss hearing improvement in the case of closing of perforations, without mentioning their sizes. The thus obtained value of the auditive gain could not be applied to all perforations, regardless of their sizes. The impact of perforations sizes upon the successful closing of the perforations, as well as the audiological gain, is hardly discussed in literature. Analyses devoted to such topics were based on estimations of the initial sizes of the perforations, performed by different E.N.T. specialists [12,15] while, in the present study, images of all perforations and their precisely-measured sizes are included in the data base. The results of the present investigation show that, on the frequencies on which the highest losses had been registered prior to closing of the perforation, namely on low frequencies, the highest auditive recoveries were obtained. A comparison between the mean ABG values after closing of the perforations (Table IV) and the audiometric gain (Table V), on groups of sizes, shows that a mean of the two groups would evidence their progressive increase with the increase of perforation s size. However, the differences between the audiometric gains are low and, consequently, statistically insignificant. The audiometrically determined gain in air conduction hearing following successful closure of the tympanic membrane perforation exceeds 10% of tympan s area, being directlly proportional with the pre-operative perforation size. However, the size of the perforation is not astatistically significant factor for its good healing. In the case of small perforations, the auditive losses being lower, no considerable audiological gains should be expected, whereas the surgical interventions will mainly aim at protecting the middle ear cavity. CONCLUSIONS Perforations of the tympanic membrane should be precisely measured and grouped according to their sizes, for the establishment of the most suitable clinical and therapeutical measures, as well as for a correct estimation of their successful closing. The present study, devoted to tympan perforations, showed that hearing losses: depend on frequencies, higher losses being recorded on lower frequencies and lower ones on high frequencies, increase with the increase of perforation s size, in the case of perforations affecting more than 10% of the tympanic membrane surface. As to the influence of perforation s size upon its closing and upon the subsequent hearing improvement, the audiological gain is directly correlated with the initial size of the perforations only in the case of perforations exceeding 10%. That is why, the surgery for closing of the small perforations should not be applied exlcusively for improving hearing. References 1. Ibekwe T.S., Ijaduola G.T., Nwaorgu O.G. Tympanic membrane perforation among adults in West Africa Otol Neurotol 2007; 28: ; 2. Voss S.E., Rosowski J.J., Merchant S.N., Peake W.T. Non ossicular signal transmission in human middle ears: experimental assessment of the acoustic route with perforated tympanic membranes J. Acoust. Soc. Am.2007; 122: ; 3. Ataman T. Traumatismele urechii, Fiziopatologia traumatismelor urechii Bucure[ti, Editura Tehnic\, 2007, ; 4. Ataman T. Traumatismele urechii, Leziuni traumatice recenteale sistemului de transmisie miringo-osicular [i sechelelelor Bucure[ti, Editura Tehnic\, 2007, ; 5. Orji F.T.& AGU C.C Determinants of spontaneous healing in traumatic perforations of the tympanic membrane Clin.Otolaringol 2008; 33: ; 6. Ciuchi V. Patologia inflamatorie a urechii medii, Sechele postotitice Bucure[ti, Editura Medical\, 2004, ; 7. Tomescu E., Cosgarea M. Urgen]e [i manevre în practica O.R.L. Repararea perfora]iei membranei timpanice Cluj-Napoca, Editura Dacia, 1996, 62-66; 8. Voss S.E., RosowskiJ.J., Merchant S.N., Peake W.T. Middle-ear function with tympanic-membrane perforations. I. Measurements and mechanisms J. Acoust. Soc. Am.2001; 110: ; 240 volume 15 issue 3 July / September 2011 pp

6 VARIATIONS OF PRE- AND POST-OPERATIVE HEARING LOSS DEPENDING ON THE SIZE OF TYMPANIC MEMBRANE PERFORATION 9. Mehta R.P., Rosowski J.J., Voss S.E., O Neil E., Merchant S.N. Determinants of hearing loss in perforations of the tympanic membrane. Otol. Neurotol.2006; 27(February (2)): ; 10. Pignataro L, Berta LGD, Capaccio P, Zaghis A. Myringoplasty in children: anatomical and functional results. J Laryngol Otol 2001;115: ; 11. Gersdoff M, Gardin P, Decat M, Juantegui M. Myringoplasty: long-term results in adults and children. Am J Otol 1995;16: ; 12. Wasson J.D., Papadimitriou C.E., Pau H. Myringoplasty: impact of perforation size on closure and audiological improvement. The Journal of laryngology& Otology, 2009; 123: ; 13. Kotecha B., Fowler S., Topham J, Myringoplasty: a prospective audit study. Clin.Otolaryngol 1999; 24: ; 14. Bhat NA, De R Retrospective analysis of surgical outcome, symptom changes, and hearing improvement following myringoplasty. J Otolaryngol ; 29: ; 15. Lee P, Kelly G, Mills RP Myringoplasty: Does the size of the perforation matter? Clin Otolaryngol 2002; 27: International Journal of Medical Dentistry 241