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ANL-1961; No. of Pages 5 Auris Nasus Larynx xxx (2015) xxx–xxx
Contents lists available at ScienceDirect
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Factors affecting postoperative outcome in otosclerosis patients: Predictive role of audiological and clinical features Mayuko Kishimoto a, Hiromi Ueda a,*, Yasue Uchida a, Michihiko Sone b a b
Department of Otorhinolaryngology, Aichi Medical University School of Medicine, Aichi, Japan Department of Otorhinolaryngology, Nagoya University School of Medicine, Nagoya, Japan
A R T I C L E I N F O
A B S T R A C T
Article history: Received 10 October 2014 Accepted 18 March 2015 Available online xxx
Objective: Factors affecting postoperative hearing results of patients with otosclerosis were analyzed. Methods: Included were 191 patients with otosclerosis in whom 234 primary stapes surgeries were performed from August 1991 to December 2011 by one surgeon in three tertiary hospitals. Evaluation of factors affecting postoperative hearing thresholds at individual frequencies were performed by logistic regression analysis. Results: Closure of the air-bone gap (ABG) after surgery was good at 2 kHz, but poor at 4 kHz and frequencies under 1 kHz. In addition, improvement at 8 kHz was worse than that at any other frequency. Multivariate logistic regression analysis by the stepwise method showed that under the mean preoperative ABG (odds ratio [OR] = 2.42), unilaterality (OR = 2.53) and male sex (OR = 2.65) were significantly better prognostic factors at 250 Hz. At 500 Hz, under mean preoperative ABG (OR = 2.56) was the significantly better factor. No significant factors were found at 1 kHz. Cochlear otosclerosis (OR = 3.57) was a significantly worse prognostic factor at 2 kHz. Under mean preoperative ABG (OR = 2.82) and younger age (OR = 1.03) were significantly better prognostic factors at 4 kHz. At 8 kHz, worse preoperative air conduction threshold (OR = 1.96) was a significantly better prognostic factor. Conclusion: Preoperative ABG, preoperative air conduction threshold, cochlear otosclerosis, male sex, laterality and age were significant prognostic factors for postoperative hearing outcome in otosclerosis patients. Especially, preoperative ABG was a significant prognostic factor at multiple frequencies. We suppose that patients with larger preoperative ABG have some other otosclerotic lesions outside the oval window niche. ß 2015 Elsevier Ireland Ltd. All rights reserved.
Keywords: Otosclerosis Postoperative air-bone gap Multivariate regression analysis Factor
1. Introduction The incidence of patients with clinical otosclerosis is considered to be smaller in Japan than that in Western countries [1]. However, the number of patients with otosclerosis has increased recently, and there has been a corresponding increase in the number of patients who have undergone stapes surgery [2]. As an operation for patients with otosclerosis, stapes surgery in which the stapes is removed partially (or totally) and an artificial prosthesis is used in the reconstruction of the ossicular chain has been the standard since first reported by Shea [3]. Since his report, the stapes surgery
* Corresponding author at: Department of Otorhinolaryngology, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi 480-1195, Japan. Tel.: +81 561 62 3311; fax: +81 561 63 3403. E-mail address: [email protected] (H. Ueda).
technique has been modified in various ways, for example, stapedectomy or stapedotomy, use of a laser or diamond drill, and with various prosthesis. Postoperative hearing results after stapes surgery are generally good, but cases with less than optimal results still exist [4]. We believe the ultimate goal for postoperative hearing outcome is that after surgery, all patients acquire closure of the postoperative air-bone gap (ABG) within 10 dB without postoperative bone conduction deterioration at all frequencies. Without doubt, the technique of the surgeon is the most important factor in postoperative hearing improvement. However, reports on other factors affecting postoperative hearing outcome are conflicting [4–7]. One group of authors [8] reported that ABG after surgery was good at 2 kHz and 4 kHz but was poor at 8 kHz and at frequencies below 1 kHz. They also pointed out the significant influence of the size of the fenestra of the stapes footplate and the preoperative ABG.
http://dx.doi.org/10.1016/j.anl.2015.03.001 0385-8146/ß 2015 Elsevier Ireland Ltd. All rights reserved.
Please cite this article in press as: Kishimoto M, et al. Factors affecting postoperative outcome in otosclerosis patients: Predictive role of audiological and clinical features. Auris Nasus Larynx (2015), http://dx.doi.org/10.1016/j.anl.2015.03.001
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ANL-1961; No. of Pages 5 M. Kishimoto et al. / Auris Nasus Larynx xxx (2015) xxx–xxx
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In this study, we retrospectively investigated the audiological and clinical features of patients with otosclerosis operated on by one surgeon and analyzed the factors affecting postoperative hearing results in the short term by multivariate logistic regression analysis. 2. Materials and methods From August 1991 through December 2011, 234 ears of 191 patients with otosclerosis underwent stapes surgery performed by a single surgeon at Nagoya University Hospital and Japanese Red Cross Nagoya Daiichi Hospital, Nagoya, Japan, or Aichi Medical University Hospital, Nagakute City, Japan. We excluded the patients who underwent stapes mobilization (4 ears) and who showed deterioration of greater than 10 dB in postoperative bone conduction (BC) thresholds at speech frequencies (2 ears). Of the patients, 80 (34.2%) were men and 154 (65.8%) were women. We recommended surgery for the patients with greater than 20 dB in preoperative ABG at speech frequencies. The surgical method was the same as described previously [9]. The surgeon (H.U.), the approach (transcanal), and the atticotomy with a chisel were the same for all patients. In our early surgical period up to 1999, the order of manipulation at surgery was as follows. First, a control hole was made in the stapes footplate to prevent the footplate from floating. Then the suprastructure of the stapes was removed. Next, a small fenestra of 0.8 mm was made using a Fisch’s manual microperforator (stapedotomy). Finally, a 0.6-mm-thick Schuknecht-type Teflon wire piston (GYRUS, USA) was inserted into the footplate opening and crimped onto the incus. Small pieces of connective tissue were placed around the piston and sealed with fibrin glue when either one half or all (stapedectomy) of the footplate was removed. In our later surgical period, from 1999 onwards, the reversal steps technique devised by Fisch [10] was mainly performed. First, a small fenestra of 0.8 mm was made, and a Teflon wire piston was inserted and crimped onto the incus. Then, the suprastructure of the stapes was removed. Following the introduction of this method, we could perform stapedotomy in many patients and prevent some complications such as a floating footplate [9]. However, in patients with a narrow oval niche, the stapes suprastructure was removed first. In some of the surgeries, a KTP laser or CO2 laser was used to cut the posterior crus and make a small fenestra. After 2007, a whole Teflon piston (GYRUS, USA) was mainly used instead of a wire piston. 2.1. Statistical analysis We used the univariate logistic and multivariate regression analysis (stepwise method) to predict which factors would affect the postoperative hearing results, which were evaluated at 3–12 months after surgery. We judged success when closure of the postoperative ABG was within 10 dB at 250 Hz, 500 Hz, 1 kHz, 2 kHz and 4 kHz, respectively, and when improvement of postoperative air conduction (AC) was above 10 dB at 8 kHz. We choose success (yes vs no) as the criterion variable. The predictive variables included in the logistic regression analysis were sex (male vs female), patient age, side (right vs left), laterality (bilateral vs unilateral), size of the fenestra (stapedotomy vs stapedectomy), order of removal of the stapes suprastructure (before prosthesis insertion vs after prosthesis insertion), prosthesis (wire piston vs piston), cochlear otosclerosis (otosclerotic foci identified beyond the oval window niche by computed tomography [CT] imaging, yes vs no), laser use (yes vs no), preoperative ABG (under mean value at 250 Hz, 500 Hz, 1 kHz, 2 kHz and 4 kHz, yes vs no) and preoperative AC thresholds (under mean value at 8 kHz, yes vs no). At first, we performed univariate analysis using these variables. From the
results of univariate analysis, we selected factors with a P value within 0.2 and performed multivariate logistic regression analysis by the stepwise method. A value of P < 0.05 was considered to indicate statistical significance. The analyses were performed with StatFlex version 6 statistical software (Artech Co., Osaka, Japan). 3. Results Demographic and clinical characteristics of the patients and the 234 ears are shown in Table 1. Stapedotomy (small hole in the stapes footplate) was performed in 151 ears (64.5%). Stapedectomy (half or complete removal of the stapes footplate) was performed in 83 ears (35.5%). Removal of the stapes suprastructure before prosthesis insertion was performed in 131 ears (56.0%), whereas that after prosthesis insertion was performed in 103 ears (44.0%). Cochlear otosclerosis in which otosclerotic foci were identified beyond the oval window niche by CT imaging was detected in 18 ears (7.7%). CO2 or KTP laser was used in only 15 ears (6.4%). Preoperative ABG (at 250 Hz, 500 Hz, 1 kHz, 2 kHz 4 kHz) and AC threshold at 8 kHz are shown in Table 2. Preoperative ABG and AC thresholds were maximum at 250 Hz and minimum at 2 kHz, as were their respective mean values. Fig. 1 shows the mean preoperative and postoperative air and bone conduction threshold for all surgical ears. Closure of the ABG after surgery was good at 2 kHz but poor at 4 kHz and at frequencies lower than 1 kHz.
Table 1 Demographic and clinical characteristics of the 234 ears. No. (%)
Characteristic Sex Male Female Age (years) Mean (range) Side Right Left Laterality Bilateral Unilateral Size of fenestra Stapedotomy Stapedectomy Removal of stapes suprastructure Before insertion After insertion Prosthesis Wire piston Piston Cochlear otosclerosis Yes No Laser use Yes No
80 (34.2) 154 (65.8) 45.4 (10–75) 134 (57.3) 100 (42.7) 167 (71.4) 67 (28.6) 151 (64.5) 83 (35.5) 131 (56.0) 103 (44.0) 184 (78.6) 50 (21.4) 18 (7.7) 216 (92.3) 15 (6.4) 219 (93.6)
Table 2 Preoperative ABG and AC threshold (8 kHz) in the 234 ears. Frequency
Minimum (dB)
Maximum (dB)
Mean (dB)
S.D. (dB)
250 Hz 500 Hz 1 kHz 2 kHz 4 kHz 8 kHz
25 15 10 5 5 10
85 75 70 55 65 Out of range
51.5 42.0 34.3 20.7 21.1 56.5
11.5 10.9 10.8 10.9 11.9 23.4
Abbreviations: ABG, air-bone gap; AC, air conduction; S.D., standard deviation. Mean and S.D. values at 8 kHz in 15 ears were excluded as being out of range.
Please cite this article in press as: Kishimoto M, et al. Factors affecting postoperative outcome in otosclerosis patients: Predictive role of audiological and clinical features. Auris Nasus Larynx (2015), http://dx.doi.org/10.1016/j.anl.2015.03.001
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Fig. 1. Mean preoperative and postoperative AC and BC thresholds for the 234 ears.
Especially, the lower the frequency went, the worse the closure of the ABG became under 1 kHz. In addition, improvement at 8 kHz was worse than that at any other frequency. The success rate after surgery at the individual frequencies is shown in Table 3. ABG closure to within 10 dB was best at 2 kHz (88.9%), and that at 4 kHz (81.6%) was next best. Under 1 kHz, the success rate worsened as the frequency decreased. Closure of the postoperative ABG to within 10 dB was worst at 250 Hz (38.0%). We generally do not examine the bone conduction threshold at 8 kHz. Therefore, we measured the number of ears in which the AC threshold improved to above 10 dB at 8 kHz after surgery. We Table 3 Success rate in the 234 ears. Frequency
250 Hz
500 Hz
1 kHz
2 kHz
4 kHz
8 kHz
Success rate, no. (%)
89 (38.0)
143 (61.1)
185 (78.7)
208 (88.9)
191 (81.6)
103 (47.0)
3
excluded 15 ears with out-of-range values for preoperative AC threshold at 8 kHz. Improvement above 10 dB at 8 kHz after surgery was recognized in 103 ears (47.0%). Results of univariate analysis of the factors affecting the closure of the postoperative ABG to within 10 dB using logistic regression analysis are shown in Table 4. At 250 Hz, preoperative ABG, laterality and sex were significant factors. Ears under the mean preoperative ABG showed a better success rate. Male ears had a better success rate than female ears, and unilaterally affected ears had a better success rate than bilaterally affected ears. At 500 Hz, under the mean preoperative ABG and unilaterally affected ears showed significantly better success rates. Significantly better success rates were shown at 1 kHz for ears in which a laser was used, at 2 kHz for ears without cochlear otosclerosis, and at 4 kHz for the factors of under the mean preoperative ABG and younger age. At 8 kHz, the significant factor was under the mean preoperative AC threshold. Ears with a worse preoperative AC had a better success rate. The results of multivariate logistic regression analysis by the stepwise method are shown in Table 5. At 250 Hz, under the mean preoperative ABG (odds ratio [OR] = 2.42), unilaterally affected ears (OR = 2.53) and male sex (OR = 2.65) were found to be significantly better prognostic factors. At 500 Hz, under the mean preoperative ABG (OR = 2.56) was the significantly better factor. No significant factors were found at 1 kHz. Cochlear otosclerosis (OR = 3.57) was a significantly worse prognostic factor at 2 kHz. Under the mean preoperative ABG (OR = 2.82) and younger age (OR = 1.03) were significantly better factors at 4 kHz, and at 8 kHz, under the mean preoperative AC threshold (OR = 1.96) was a significantly poorer prognostic factor. 4. Discussion
Closure of postoperative air-bone gap within 10 dB at 250 Hz, 500 Hz, 1 kHz, 2 kHz and 4 kHz. Improvement above 10 dB at 8 kHz after surgery.
Our results showed that closure of the ABG after surgery was good at 2 kHz but was poor at 4 kHz and at frequencies lower than
Table 4 Univariate logistic regression analysis of the 234 ears. Contrast
Factors
Sex Age Side Laterality Size of fenestra Removal of stapes suprastructure Prosthesis Cochlear otosclerosis Laser use Preoperative ABG Preoperative AC
P value
Male vs female Left vs right Unilateral vs bilateral Stapedotomy vs stapedectomy After vs before Piton vs wire piston Yes vs no Yes vs no
250 Hz
500 Hz
1 kHz
2 kHz
4 kHz
8 kHz
0.003 0.340 0.511 0.005 0.071 0.620 0.995 0.355 0.079 0.000 –
0.550 0.591 0.122 0.038 0.231 0.173 0.138 0.138 0.053 0.001 –
0.673 0.883 0.709 0.283 0.258 0.141 0.854 0.461 0.045 0.812 –
0.627 0.717 0.608 0.475 0.735 0.545 0.465 0.027 0.571 0.816 –
0.915 0.009 0.384 0.625 0.792 0.087 0.120 0.290 0.867 0.001 –
0.103 0.314 0.046 0.071 0.088 0.400 0.178 0.130 0.163 – 0.022
Abbreviations: ABG, air-bone gap; AC, air conduction. Underlined values indicate statistically significant. Table 5 Multivariate logistic regression analysis of the 234 ears. Factors
Contrast
P value (OR)
Sex Age Laterality Cochlear otosclerosis Preoperative ABG Preoperative AC
Male vs female
0.001 (2.65)
Unilateral vs bilateral Yes vs no
0.003 (2.53)
250 Hz
500 Hz
1 kHz
2 kHz
4 kHz
8 kHz
0.031 (1.03) 0.027 (3.57) 0.002 (2.42) –
0.001 (2.56) –
–
–
0.004 (2.82) –
– 0.016 (1.96)
Abbreviations: ABG, air-bone gap; AC, air conduction; OR, odds ratio.
Please cite this article in press as: Kishimoto M, et al. Factors affecting postoperative outcome in otosclerosis patients: Predictive role of audiological and clinical features. Auris Nasus Larynx (2015), http://dx.doi.org/10.1016/j.anl.2015.03.001
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1 kHz. In addition, improvement at 8 kHz was worse than that at any other frequency. These tendencies were recognized in a previous paper by one of the present authors [8] and in the reports of other researchers [11,12]. Somers et al. [11] and Persson et al. [12] tried to explain the reason for the poor improvement mainly by the size of fenestra in the stapes footplate. Ueda et al. [8] indicated a close relationship between both the preoperative and postoperative ABG at frequencies under 1 kHz and the size of the fenestra. In the present study, we investigated the causes of poor improvement of the postoperative hearing threshold at frequencies other than 2 kHz by using multivariate logistic analysis. We adopted the closure of the postoperative ABG at each frequency as the indicator of postoperative hearing outcome. Some authors [5,6] used the postoperative gain in AC as the indicator because deteriorated bone conduction after surgery might cause closure of the postoperative ABG even if the postoperative AC did not improve. We excluded the patients who showed deterioration of the postoperative bone conduction threshold of more than 10 dB at speech frequencies. In addition, measurement of the postoperative gain in AC is disadvantageous for the patients with a smaller preoperative ABG. In fact, several patients showed a preoperative ABG of below 0 dB at 2 kHz or 4 kHz. If deterioration of the postoperative bone conduction threshold does not occur, we believe that measurement of the closure of postoperative ABG is the best indicator of success. However, at 8 kHz we used the postoperative gain in AC instead because we usually do not measure the bone conduction threshold. The results of our multivariate logistic regression analysis clearly showed that preoperative ABGs at 250 and 500 Hz and at 4 kHz were significant prognostic factors for postoperative success rate at each frequency. At these frequencies, under the mean preoperative ABG showed significantly better success rates with relatively high ORs (above 2.0). This result was almost the same as those reported previously by one of our co-authors [8]. Bittermann et al. [7] showed that the chance of achieving a postoperative ABG of 10 dB or less at 4 frequencies (0.5, 1, 2 and 4 kHz) was 1.3 times higher in patients older than 40 years with a preoperative ABG of 30 dB or less compared with patients 40 years or younger with a preoperative ABG exceeding 30 dB. Their report agree with our result except for age. In addition, they and Marchese et al. [6] indicated that improvement of the postoperative AC threshold is higher in patients with larger preoperative ABG or AC threshold. This discrepancy may be due to the difference in the indicators of success rate. If we adopt postoperative AC threshold as an indicator of success rate, larger preoperative ABG and worse preoperative AC threshold may be good prognostic factors because of larger room for improvement. Our result at 8 kHz showed that a worse preoperative AC threshold was a significantly better prognostic factor, which supports the above-mentioned idea. Why does a larger preoperative ABG tends to result in a residual postoperative ABG? One explanation may be the thickness of the footplate. Hu¨ttenbrink [13] suggested that an increased thickness of the otosclerotic footplate causes a consequential decrease of sound transmission by the lateral contact of an angled piston used as the prostheses with the surrounding bone. However, we did not recognize such an extremely thick footplate in any of the present patients. The most reasonable explanation is the existence of an otosclerosis lesion at another site besides the oval window niche. Schuknecht and Barber [14] reported that more than 30% of temporal bone specimens with clinical otosclerosis have multiple otosclerotic foci such as an oval window and round window. Mansour et al. [15] indicated that 13% of patients with otosclerosis had round window involvement, and that patients with progressive round window involvement had a larger postoperative ABG. These findings suggest the postoperative residual ABG is due to the existence of these multiple otosclerosis lesions.
We adopted cochlear otosclerosis (i.e., otosclerotic foci identified beyond the oval window niche by CT imaging) as one of predictor variables. We used different CT imaging equipment at different facilities. The detection rate of fenestral otosclerosis was different depending on the CT imaging method and equipment used [16,17]. In addition, false-negative CT images may occur in some cases of fenestral otosclerosis in the sclerotic phase when there are no irregularities of the bone contour [18,19]. This is why we did not choose fenestral otosclerosis as one of predictor variables. There are many reports on the correlation of CT analysis and audiometry in the preoperative period [16,17,20]. These authors reported that patients with extensive otosclerosis show poorer preoperative AC and BC thresholds, but they did not perform evaluations with postoperative audiometry. Only Marx et al. [21] indicated that patients with extensive otosclerosis by CT imaging showed poorer postoperative (and preoperative) AC and BC thresholds and that ABG closure had a tendency to be better in extensive otosclerosis than in fenestral otosclerosis. Our results showed cochlear otosclerosis to be a significantly worse factor for ABG closure at 2 kHz. The reason for this discrepancy is unknown, but one reason may be that we choose more severe cases of cochlear otosclerosis. At 4 kHz, younger age resulted in a significantly better success rate although the OR was small. aWengen et al. [22] reported that the improvements of both the postoperative ABG and BC thresholds after total stapedectomy were significantly better in younger patients. However, there are some reports showing the opposite [7,18]. At 250 Hz, unilaterally affected ears, male sex and under the mean preoperative ABG were significantly better prognostic factors. The cause for this is unclear. In our previous report [23], both sex and age were not significant prognostic factors. In the present study, the average preoperative ABG of the unilaterally affected ears and the number of males were smaller, and that of the bilaterally affected ears and the number of females were greater, and this may be one of the reasons. Further accumulation of cases is needed. 5. Conclusions Preoperative ABG at 250 Hz, 500 Hz and 4 kHz, male sex and laterality at 250 Hz; cochlear otosclerosis at 2 kHz; age at 4 kHz; and preoperative AC threshold at 8 kHz were significant prognostic factors for postoperative hearing outcome in patients with otosclerosis. Especially, the preoperative ABG was a significant prognostic factor at multiple frequencies. We suppose that patients with larger preoperative ABG have some other otosclerotic lesions outside the oval window niche. Conflict of interest The authors declare no sources of financial support or conflicts of interest. References [1] Ohtani I, Baba Y, Suzuki T, Kano M, Deka RC. Why is otosclerosis of low prevalence in Japanese? Otol Neurotol 2003;24:377–81. [2] Yagi T. Incidence and characteristics of otosclerosis in the Japanese population. Auris Nasus Larynx 2002;29:257–60. [3] Shea Jr JJ. Fenestration of the oval window. Ann Otol Rhinol Laryngol 1958;67:932–51. [4] Laske RD, Ro¨o¨sli C, Chatzimichalis MV, Sim JH, Huber AM. The influence of prosthesis diameter in stapes surgery: a meta-analysis and systemic review of the literature. Otol Neurotol 2011;32:520–8. [5] Gerard JM, Serry P, Gersdorff MC. Outcome and lack of prognostic factors in stapes surgery. Otol Neurotol 2008;29:290–4. [6] Marchese MR, Conti G, Cianfrone F, Scorpecci A, Fetoni AR, Paludetti G. Predictive role of audiological and clinical features for functional results after stapedotomy. Audiol Neurotol 2009;14:279–85.
Please cite this article in press as: Kishimoto M, et al. Factors affecting postoperative outcome in otosclerosis patients: Predictive role of audiological and clinical features. Auris Nasus Larynx (2015), http://dx.doi.org/10.1016/j.anl.2015.03.001
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ANL-1961; No. of Pages 5 M. Kishimoto et al. / Auris Nasus Larynx xxx (2015) xxx–xxx [7] Bittermann AN, Maroeska MR, Tange RA, Vincent R, Dreschler WA, Grolman W. Primary stapes surgery in patients with otosclerosis: prediction of postoperative outcome. Arch Otolaryngol Head Neck Surg 2011;137:780–4. [8] Ueda H, Miyazawa T, Asahi K, Yanagita N. Factors affecting hearing results after stapes surgery. J Laryngol Otol 1999;113:417–21. [9] Ueda H, Kishimoto M, Uchida Y, Sone M. Factors affecting fenestration of the footplate in stapes surgery: effectiveness of Fisch’s reversal steps stapedotomy. Otol Neurotol 2013;34:1576–80. [10] Fisch U. Tympanoplasty, mastoidectomy and stapes surgery. New York: Thieme Medical Publishers; 1994. p. 214–27. [11] Somers T, Govaerts P, Marquet T, Offeciers E. Statistical analysis of otosclerosis surgery performed by Jean Marquet. Ann Otol Rhinol Laryngol 1994;103: 945–51. [12] Persson P, Harder H, Magnuson B. Hearing results in otosclerosis surgery after partial stapedectomy, total stapedectomy and stapedotomy. Acta Otolaryngol 1997;117:94–9. [13] Hu¨ttenbrink KB. Biomechanics of stapesplasty: a review. Otol Neurotol 2003;24:548–59. [14] Schuknecht HF, Barber W. Histologic variants in otosclerosis. Laryngoscope 1985;95:1307–17. [15] Mansour S, Nicolas K, Ahmad HH. Round window otosclerosis: radiologic classification and clinical correlations. Otol Neurotol 2011;32:384–92.
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[16] Naumann IC, Porcellini BP, Fisch U. Otosclerosis: incidence of positive findings on high-resolution computed tomography and their correlation to audiological test data. Ann Otol Rhinol Laryngol 2005;114:709–16. [17] Mori N, Toyama Y, Kimura N, Fujiwara S, Miyashita T, Ohsaki Y, et al. Detection of small fenestral otosclerotic lesions by high-resolution computed tomography using multiplanar reconstruction. Auris Nasus Larynx 2013;40:36–40. [18] Purohit B, Hermans R, Op de Beeck K. Imaging in otosclerosis: a pictorial review. Insights Imaging 2014;5:245–52. [19] Quensnel AM, Moonis G, Appel J, O’Malley JT, McKenna MJ, Curtin HD, et al. Correlation of computed tomography with histopathology in otosclerosis. Otol Neurotol 2013;34:22–8. [20] Kiyomizu K, Tono T, Yang D, Haruta A, Kodama T, Komune S. Correlation of CT analysis and audiometry in Japanese otosclerosis. Auris Nasus Larynx 2004;31:125–9. [21] Marx M, Lagleyre S, Escude´ B, Demeslay J, Elhadi T, Deguine O, et al. Correlations between CT scan findings and hearing thresholds in otosclerosis. Acta Otolaryngol 2011;131:351–7. [22] aWengen DF, Pfaltz CR, Uyar Y. The influence of age on the results of stapedectomy. Eur Arch Otorhinolaryngol 1992;249:1–4. [23] Ueda H, Miyazawa T, Yanagita N. [The influence of age and sex on the results of otosclerosis surgery]. Nihon Jibiinkoka Gakkai Kaiho 1998;101:185–91 [in Japanese].
Please cite this article in press as: Kishimoto M, et al. Factors affecting postoperative outcome in otosclerosis patients: Predictive role of audiological and clinical features. Auris Nasus Larynx (2015), http://dx.doi.org/10.1016/j.anl.2015.03.001
ANL-1961; No. of Pages 5 Auris Nasus Larynx xxx (2015) xxx–xxx
Contents lists available at ScienceDirect
Auris Nasus Larynx journal homepage: www.elsevier.com/locate/anl
Factors affecting postoperative outcome in otosclerosis patients: Predictive role of audiological and clinical features Mayuko Kishimoto a, Hiromi Ueda a,*, Yasue Uchida a, Michihiko Sone b a b
Department of Otorhinolaryngology, Aichi Medical University School of Medicine, Aichi, Japan Department of Otorhinolaryngology, Nagoya University School of Medicine, Nagoya, Japan
A R T I C L E I N F O
A B S T R A C T
Article history: Received 10 October 2014 Accepted 18 March 2015 Available online xxx
Objective: Factors affecting postoperative hearing results of patients with otosclerosis were analyzed. Methods: Included were 191 patients with otosclerosis in whom 234 primary stapes surgeries were performed from August 1991 to December 2011 by one surgeon in three tertiary hospitals. Evaluation of factors affecting postoperative hearing thresholds at individual frequencies were performed by logistic regression analysis. Results: Closure of the air-bone gap (ABG) after surgery was good at 2 kHz, but poor at 4 kHz and frequencies under 1 kHz. In addition, improvement at 8 kHz was worse than that at any other frequency. Multivariate logistic regression analysis by the stepwise method showed that under the mean preoperative ABG (odds ratio [OR] = 2.42), unilaterality (OR = 2.53) and male sex (OR = 2.65) were significantly better prognostic factors at 250 Hz. At 500 Hz, under mean preoperative ABG (OR = 2.56) was the significantly better factor. No significant factors were found at 1 kHz. Cochlear otosclerosis (OR = 3.57) was a significantly worse prognostic factor at 2 kHz. Under mean preoperative ABG (OR = 2.82) and younger age (OR = 1.03) were significantly better prognostic factors at 4 kHz. At 8 kHz, worse preoperative air conduction threshold (OR = 1.96) was a significantly better prognostic factor. Conclusion: Preoperative ABG, preoperative air conduction threshold, cochlear otosclerosis, male sex, laterality and age were significant prognostic factors for postoperative hearing outcome in otosclerosis patients. Especially, preoperative ABG was a significant prognostic factor at multiple frequencies. We suppose that patients with larger preoperative ABG have some other otosclerotic lesions outside the oval window niche. ß 2015 Elsevier Ireland Ltd. All rights reserved.
Keywords: Otosclerosis Postoperative air-bone gap Multivariate regression analysis Factor
1. Introduction The incidence of patients with clinical otosclerosis is considered to be smaller in Japan than that in Western countries [1]. However, the number of patients with otosclerosis has increased recently, and there has been a corresponding increase in the number of patients who have undergone stapes surgery [2]. As an operation for patients with otosclerosis, stapes surgery in which the stapes is removed partially (or totally) and an artificial prosthesis is used in the reconstruction of the ossicular chain has been the standard since first reported by Shea [3]. Since his report, the stapes surgery
* Corresponding author at: Department of Otorhinolaryngology, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi 480-1195, Japan. Tel.: +81 561 62 3311; fax: +81 561 63 3403. E-mail address: [email protected] (H. Ueda).
technique has been modified in various ways, for example, stapedectomy or stapedotomy, use of a laser or diamond drill, and with various prosthesis. Postoperative hearing results after stapes surgery are generally good, but cases with less than optimal results still exist [4]. We believe the ultimate goal for postoperative hearing outcome is that after surgery, all patients acquire closure of the postoperative air-bone gap (ABG) within 10 dB without postoperative bone conduction deterioration at all frequencies. Without doubt, the technique of the surgeon is the most important factor in postoperative hearing improvement. However, reports on other factors affecting postoperative hearing outcome are conflicting [4–7]. One group of authors [8] reported that ABG after surgery was good at 2 kHz and 4 kHz but was poor at 8 kHz and at frequencies below 1 kHz. They also pointed out the significant influence of the size of the fenestra of the stapes footplate and the preoperative ABG.
http://dx.doi.org/10.1016/j.anl.2015.03.001 0385-8146/ß 2015 Elsevier Ireland Ltd. All rights reserved.
Please cite this article in press as: Kishimoto M, et al. Factors affecting postoperative outcome in otosclerosis patients: Predictive role of audiological and clinical features. Auris Nasus Larynx (2015), http://dx.doi.org/10.1016/j.anl.2015.03.001
G Model
ANL-1961; No. of Pages 5 M. Kishimoto et al. / Auris Nasus Larynx xxx (2015) xxx–xxx
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In this study, we retrospectively investigated the audiological and clinical features of patients with otosclerosis operated on by one surgeon and analyzed the factors affecting postoperative hearing results in the short term by multivariate logistic regression analysis. 2. Materials and methods From August 1991 through December 2011, 234 ears of 191 patients with otosclerosis underwent stapes surgery performed by a single surgeon at Nagoya University Hospital and Japanese Red Cross Nagoya Daiichi Hospital, Nagoya, Japan, or Aichi Medical University Hospital, Nagakute City, Japan. We excluded the patients who underwent stapes mobilization (4 ears) and who showed deterioration of greater than 10 dB in postoperative bone conduction (BC) thresholds at speech frequencies (2 ears). Of the patients, 80 (34.2%) were men and 154 (65.8%) were women. We recommended surgery for the patients with greater than 20 dB in preoperative ABG at speech frequencies. The surgical method was the same as described previously [9]. The surgeon (H.U.), the approach (transcanal), and the atticotomy with a chisel were the same for all patients. In our early surgical period up to 1999, the order of manipulation at surgery was as follows. First, a control hole was made in the stapes footplate to prevent the footplate from floating. Then the suprastructure of the stapes was removed. Next, a small fenestra of 0.8 mm was made using a Fisch’s manual microperforator (stapedotomy). Finally, a 0.6-mm-thick Schuknecht-type Teflon wire piston (GYRUS, USA) was inserted into the footplate opening and crimped onto the incus. Small pieces of connective tissue were placed around the piston and sealed with fibrin glue when either one half or all (stapedectomy) of the footplate was removed. In our later surgical period, from 1999 onwards, the reversal steps technique devised by Fisch [10] was mainly performed. First, a small fenestra of 0.8 mm was made, and a Teflon wire piston was inserted and crimped onto the incus. Then, the suprastructure of the stapes was removed. Following the introduction of this method, we could perform stapedotomy in many patients and prevent some complications such as a floating footplate [9]. However, in patients with a narrow oval niche, the stapes suprastructure was removed first. In some of the surgeries, a KTP laser or CO2 laser was used to cut the posterior crus and make a small fenestra. After 2007, a whole Teflon piston (GYRUS, USA) was mainly used instead of a wire piston. 2.1. Statistical analysis We used the univariate logistic and multivariate regression analysis (stepwise method) to predict which factors would affect the postoperative hearing results, which were evaluated at 3–12 months after surgery. We judged success when closure of the postoperative ABG was within 10 dB at 250 Hz, 500 Hz, 1 kHz, 2 kHz and 4 kHz, respectively, and when improvement of postoperative air conduction (AC) was above 10 dB at 8 kHz. We choose success (yes vs no) as the criterion variable. The predictive variables included in the logistic regression analysis were sex (male vs female), patient age, side (right vs left), laterality (bilateral vs unilateral), size of the fenestra (stapedotomy vs stapedectomy), order of removal of the stapes suprastructure (before prosthesis insertion vs after prosthesis insertion), prosthesis (wire piston vs piston), cochlear otosclerosis (otosclerotic foci identified beyond the oval window niche by computed tomography [CT] imaging, yes vs no), laser use (yes vs no), preoperative ABG (under mean value at 250 Hz, 500 Hz, 1 kHz, 2 kHz and 4 kHz, yes vs no) and preoperative AC thresholds (under mean value at 8 kHz, yes vs no). At first, we performed univariate analysis using these variables. From the
results of univariate analysis, we selected factors with a P value within 0.2 and performed multivariate logistic regression analysis by the stepwise method. A value of P < 0.05 was considered to indicate statistical significance. The analyses were performed with StatFlex version 6 statistical software (Artech Co., Osaka, Japan). 3. Results Demographic and clinical characteristics of the patients and the 234 ears are shown in Table 1. Stapedotomy (small hole in the stapes footplate) was performed in 151 ears (64.5%). Stapedectomy (half or complete removal of the stapes footplate) was performed in 83 ears (35.5%). Removal of the stapes suprastructure before prosthesis insertion was performed in 131 ears (56.0%), whereas that after prosthesis insertion was performed in 103 ears (44.0%). Cochlear otosclerosis in which otosclerotic foci were identified beyond the oval window niche by CT imaging was detected in 18 ears (7.7%). CO2 or KTP laser was used in only 15 ears (6.4%). Preoperative ABG (at 250 Hz, 500 Hz, 1 kHz, 2 kHz 4 kHz) and AC threshold at 8 kHz are shown in Table 2. Preoperative ABG and AC thresholds were maximum at 250 Hz and minimum at 2 kHz, as were their respective mean values. Fig. 1 shows the mean preoperative and postoperative air and bone conduction threshold for all surgical ears. Closure of the ABG after surgery was good at 2 kHz but poor at 4 kHz and at frequencies lower than 1 kHz.
Table 1 Demographic and clinical characteristics of the 234 ears. No. (%)
Characteristic Sex Male Female Age (years) Mean (range) Side Right Left Laterality Bilateral Unilateral Size of fenestra Stapedotomy Stapedectomy Removal of stapes suprastructure Before insertion After insertion Prosthesis Wire piston Piston Cochlear otosclerosis Yes No Laser use Yes No
80 (34.2) 154 (65.8) 45.4 (10–75) 134 (57.3) 100 (42.7) 167 (71.4) 67 (28.6) 151 (64.5) 83 (35.5) 131 (56.0) 103 (44.0) 184 (78.6) 50 (21.4) 18 (7.7) 216 (92.3) 15 (6.4) 219 (93.6)
Table 2 Preoperative ABG and AC threshold (8 kHz) in the 234 ears. Frequency
Minimum (dB)
Maximum (dB)
Mean (dB)
S.D. (dB)
250 Hz 500 Hz 1 kHz 2 kHz 4 kHz 8 kHz
25 15 10 5 5 10
85 75 70 55 65 Out of range
51.5 42.0 34.3 20.7 21.1 56.5
11.5 10.9 10.8 10.9 11.9 23.4
Abbreviations: ABG, air-bone gap; AC, air conduction; S.D., standard deviation. Mean and S.D. values at 8 kHz in 15 ears were excluded as being out of range.
Please cite this article in press as: Kishimoto M, et al. Factors affecting postoperative outcome in otosclerosis patients: Predictive role of audiological and clinical features. Auris Nasus Larynx (2015), http://dx.doi.org/10.1016/j.anl.2015.03.001
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Fig. 1. Mean preoperative and postoperative AC and BC thresholds for the 234 ears.
Especially, the lower the frequency went, the worse the closure of the ABG became under 1 kHz. In addition, improvement at 8 kHz was worse than that at any other frequency. The success rate after surgery at the individual frequencies is shown in Table 3. ABG closure to within 10 dB was best at 2 kHz (88.9%), and that at 4 kHz (81.6%) was next best. Under 1 kHz, the success rate worsened as the frequency decreased. Closure of the postoperative ABG to within 10 dB was worst at 250 Hz (38.0%). We generally do not examine the bone conduction threshold at 8 kHz. Therefore, we measured the number of ears in which the AC threshold improved to above 10 dB at 8 kHz after surgery. We Table 3 Success rate in the 234 ears. Frequency
250 Hz
500 Hz
1 kHz
2 kHz
4 kHz
8 kHz
Success rate, no. (%)
89 (38.0)
143 (61.1)
185 (78.7)
208 (88.9)
191 (81.6)
103 (47.0)
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excluded 15 ears with out-of-range values for preoperative AC threshold at 8 kHz. Improvement above 10 dB at 8 kHz after surgery was recognized in 103 ears (47.0%). Results of univariate analysis of the factors affecting the closure of the postoperative ABG to within 10 dB using logistic regression analysis are shown in Table 4. At 250 Hz, preoperative ABG, laterality and sex were significant factors. Ears under the mean preoperative ABG showed a better success rate. Male ears had a better success rate than female ears, and unilaterally affected ears had a better success rate than bilaterally affected ears. At 500 Hz, under the mean preoperative ABG and unilaterally affected ears showed significantly better success rates. Significantly better success rates were shown at 1 kHz for ears in which a laser was used, at 2 kHz for ears without cochlear otosclerosis, and at 4 kHz for the factors of under the mean preoperative ABG and younger age. At 8 kHz, the significant factor was under the mean preoperative AC threshold. Ears with a worse preoperative AC had a better success rate. The results of multivariate logistic regression analysis by the stepwise method are shown in Table 5. At 250 Hz, under the mean preoperative ABG (odds ratio [OR] = 2.42), unilaterally affected ears (OR = 2.53) and male sex (OR = 2.65) were found to be significantly better prognostic factors. At 500 Hz, under the mean preoperative ABG (OR = 2.56) was the significantly better factor. No significant factors were found at 1 kHz. Cochlear otosclerosis (OR = 3.57) was a significantly worse prognostic factor at 2 kHz. Under the mean preoperative ABG (OR = 2.82) and younger age (OR = 1.03) were significantly better factors at 4 kHz, and at 8 kHz, under the mean preoperative AC threshold (OR = 1.96) was a significantly poorer prognostic factor. 4. Discussion
Closure of postoperative air-bone gap within 10 dB at 250 Hz, 500 Hz, 1 kHz, 2 kHz and 4 kHz. Improvement above 10 dB at 8 kHz after surgery.
Our results showed that closure of the ABG after surgery was good at 2 kHz but was poor at 4 kHz and at frequencies lower than
Table 4 Univariate logistic regression analysis of the 234 ears. Contrast
Factors
Sex Age Side Laterality Size of fenestra Removal of stapes suprastructure Prosthesis Cochlear otosclerosis Laser use Preoperative ABG Preoperative AC
P value
Male vs female Left vs right Unilateral vs bilateral Stapedotomy vs stapedectomy After vs before Piton vs wire piston Yes vs no Yes vs no
250 Hz
500 Hz
1 kHz
2 kHz
4 kHz
8 kHz
0.003 0.340 0.511 0.005 0.071 0.620 0.995 0.355 0.079 0.000 –
0.550 0.591 0.122 0.038 0.231 0.173 0.138 0.138 0.053 0.001 –
0.673 0.883 0.709 0.283 0.258 0.141 0.854 0.461 0.045 0.812 –
0.627 0.717 0.608 0.475 0.735 0.545 0.465 0.027 0.571 0.816 –
0.915 0.009 0.384 0.625 0.792 0.087 0.120 0.290 0.867 0.001 –
0.103 0.314 0.046 0.071 0.088 0.400 0.178 0.130 0.163 – 0.022
Abbreviations: ABG, air-bone gap; AC, air conduction. Underlined values indicate statistically significant. Table 5 Multivariate logistic regression analysis of the 234 ears. Factors
Contrast
P value (OR)
Sex Age Laterality Cochlear otosclerosis Preoperative ABG Preoperative AC
Male vs female
0.001 (2.65)
Unilateral vs bilateral Yes vs no
0.003 (2.53)
250 Hz
500 Hz
1 kHz
2 kHz
4 kHz
8 kHz
0.031 (1.03) 0.027 (3.57) 0.002 (2.42) –
0.001 (2.56) –
–
–
0.004 (2.82) –
– 0.016 (1.96)
Abbreviations: ABG, air-bone gap; AC, air conduction; OR, odds ratio.
Please cite this article in press as: Kishimoto M, et al. Factors affecting postoperative outcome in otosclerosis patients: Predictive role of audiological and clinical features. Auris Nasus Larynx (2015), http://dx.doi.org/10.1016/j.anl.2015.03.001
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1 kHz. In addition, improvement at 8 kHz was worse than that at any other frequency. These tendencies were recognized in a previous paper by one of the present authors [8] and in the reports of other researchers [11,12]. Somers et al. [11] and Persson et al. [12] tried to explain the reason for the poor improvement mainly by the size of fenestra in the stapes footplate. Ueda et al. [8] indicated a close relationship between both the preoperative and postoperative ABG at frequencies under 1 kHz and the size of the fenestra. In the present study, we investigated the causes of poor improvement of the postoperative hearing threshold at frequencies other than 2 kHz by using multivariate logistic analysis. We adopted the closure of the postoperative ABG at each frequency as the indicator of postoperative hearing outcome. Some authors [5,6] used the postoperative gain in AC as the indicator because deteriorated bone conduction after surgery might cause closure of the postoperative ABG even if the postoperative AC did not improve. We excluded the patients who showed deterioration of the postoperative bone conduction threshold of more than 10 dB at speech frequencies. In addition, measurement of the postoperative gain in AC is disadvantageous for the patients with a smaller preoperative ABG. In fact, several patients showed a preoperative ABG of below 0 dB at 2 kHz or 4 kHz. If deterioration of the postoperative bone conduction threshold does not occur, we believe that measurement of the closure of postoperative ABG is the best indicator of success. However, at 8 kHz we used the postoperative gain in AC instead because we usually do not measure the bone conduction threshold. The results of our multivariate logistic regression analysis clearly showed that preoperative ABGs at 250 and 500 Hz and at 4 kHz were significant prognostic factors for postoperative success rate at each frequency. At these frequencies, under the mean preoperative ABG showed significantly better success rates with relatively high ORs (above 2.0). This result was almost the same as those reported previously by one of our co-authors [8]. Bittermann et al. [7] showed that the chance of achieving a postoperative ABG of 10 dB or less at 4 frequencies (0.5, 1, 2 and 4 kHz) was 1.3 times higher in patients older than 40 years with a preoperative ABG of 30 dB or less compared with patients 40 years or younger with a preoperative ABG exceeding 30 dB. Their report agree with our result except for age. In addition, they and Marchese et al. [6] indicated that improvement of the postoperative AC threshold is higher in patients with larger preoperative ABG or AC threshold. This discrepancy may be due to the difference in the indicators of success rate. If we adopt postoperative AC threshold as an indicator of success rate, larger preoperative ABG and worse preoperative AC threshold may be good prognostic factors because of larger room for improvement. Our result at 8 kHz showed that a worse preoperative AC threshold was a significantly better prognostic factor, which supports the above-mentioned idea. Why does a larger preoperative ABG tends to result in a residual postoperative ABG? One explanation may be the thickness of the footplate. Hu¨ttenbrink [13] suggested that an increased thickness of the otosclerotic footplate causes a consequential decrease of sound transmission by the lateral contact of an angled piston used as the prostheses with the surrounding bone. However, we did not recognize such an extremely thick footplate in any of the present patients. The most reasonable explanation is the existence of an otosclerosis lesion at another site besides the oval window niche. Schuknecht and Barber [14] reported that more than 30% of temporal bone specimens with clinical otosclerosis have multiple otosclerotic foci such as an oval window and round window. Mansour et al. [15] indicated that 13% of patients with otosclerosis had round window involvement, and that patients with progressive round window involvement had a larger postoperative ABG. These findings suggest the postoperative residual ABG is due to the existence of these multiple otosclerosis lesions.
We adopted cochlear otosclerosis (i.e., otosclerotic foci identified beyond the oval window niche by CT imaging) as one of predictor variables. We used different CT imaging equipment at different facilities. The detection rate of fenestral otosclerosis was different depending on the CT imaging method and equipment used [16,17]. In addition, false-negative CT images may occur in some cases of fenestral otosclerosis in the sclerotic phase when there are no irregularities of the bone contour [18,19]. This is why we did not choose fenestral otosclerosis as one of predictor variables. There are many reports on the correlation of CT analysis and audiometry in the preoperative period [16,17,20]. These authors reported that patients with extensive otosclerosis show poorer preoperative AC and BC thresholds, but they did not perform evaluations with postoperative audiometry. Only Marx et al. [21] indicated that patients with extensive otosclerosis by CT imaging showed poorer postoperative (and preoperative) AC and BC thresholds and that ABG closure had a tendency to be better in extensive otosclerosis than in fenestral otosclerosis. Our results showed cochlear otosclerosis to be a significantly worse factor for ABG closure at 2 kHz. The reason for this discrepancy is unknown, but one reason may be that we choose more severe cases of cochlear otosclerosis. At 4 kHz, younger age resulted in a significantly better success rate although the OR was small. aWengen et al. [22] reported that the improvements of both the postoperative ABG and BC thresholds after total stapedectomy were significantly better in younger patients. However, there are some reports showing the opposite [7,18]. At 250 Hz, unilaterally affected ears, male sex and under the mean preoperative ABG were significantly better prognostic factors. The cause for this is unclear. In our previous report [23], both sex and age were not significant prognostic factors. In the present study, the average preoperative ABG of the unilaterally affected ears and the number of males were smaller, and that of the bilaterally affected ears and the number of females were greater, and this may be one of the reasons. Further accumulation of cases is needed. 5. Conclusions Preoperative ABG at 250 Hz, 500 Hz and 4 kHz, male sex and laterality at 250 Hz; cochlear otosclerosis at 2 kHz; age at 4 kHz; and preoperative AC threshold at 8 kHz were significant prognostic factors for postoperative hearing outcome in patients with otosclerosis. Especially, the preoperative ABG was a significant prognostic factor at multiple frequencies. We suppose that patients with larger preoperative ABG have some other otosclerotic lesions outside the oval window niche. Conflict of interest The authors declare no sources of financial support or conflicts of interest. References [1] Ohtani I, Baba Y, Suzuki T, Kano M, Deka RC. Why is otosclerosis of low prevalence in Japanese? Otol Neurotol 2003;24:377–81. [2] Yagi T. Incidence and characteristics of otosclerosis in the Japanese population. Auris Nasus Larynx 2002;29:257–60. [3] Shea Jr JJ. Fenestration of the oval window. Ann Otol Rhinol Laryngol 1958;67:932–51. [4] Laske RD, Ro¨o¨sli C, Chatzimichalis MV, Sim JH, Huber AM. The influence of prosthesis diameter in stapes surgery: a meta-analysis and systemic review of the literature. Otol Neurotol 2011;32:520–8. [5] Gerard JM, Serry P, Gersdorff MC. Outcome and lack of prognostic factors in stapes surgery. Otol Neurotol 2008;29:290–4. [6] Marchese MR, Conti G, Cianfrone F, Scorpecci A, Fetoni AR, Paludetti G. Predictive role of audiological and clinical features for functional results after stapedotomy. Audiol Neurotol 2009;14:279–85.
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