POST-OPERATIVE LONG-TERM HEARING RESULTS IN PATIENTS WHO UNDERWENT OSSICULOPLASTIES

Kazuya Saito, Michio Isono, Mie Miyashita, Mitsuo Sato, Katumi Doi

Department of Otolaryngology, Kinki University School of Medicine, Osaka, Japan

Introduction

We empirically know that the hearing level of patients changes over time after surgery on their ears. To verify this empirical knowledge, we recently analyzed and investigated the following points: (1) When is the best post-operative hearing obtained? (2) How does post-operative hearing change? (3) Is there any difference in post-operative hearing among operative procedures? (4) What are possible factors for changes in post-operative hearing?

Materials and methods

The study involved 367 ears treated with ossiculoplasty in our hospital from April 2002 to April 2009. Gender and age distributions of the patients were 166 males and 201 females aged six to 79 years for 200 left and 197 right ears. A comparative study of operative procedures involved the following four types: tympano-stapedial interposition with incus (III-c; 127 ears); malleo-stapedial interposition with incus (III-i;120 ears); tympano-stapedial footplate interposition with incus (or cortex bone)(IV-c; 65 ears); and malleo-stapedial footplate interposition with incus (or cortex bone)(IV-i; 55 ears). The underlying disease was cholesteatoma (including congenital cholesteatoma) in 202 ears, chronic otitis media in 92 ears, traumatic ossicular dislocation in 16 ears, tympanosclerosis in 34 ears, ossicular anomaly in 21 ears and others in two ears.

Results

We analyzed the follow-up data for a period of three years after surgery. In cases of III-c procedures, the air conduction hearing level was highest at one year after surgery, although the difference was not statistically significant. After one year, the hearing level in III-c tended to gradually decrease over time. Cases of III-c procedures finally recorded a 2.7 dB elevation in air-conduction hearing threshold. The time course of air-bone gap levels was similar to the time course of air-conduction hearing level. The bone-conduction hearing level rose by 1.9 dB (Fig. 1A). Cases of III-I procedures followed a course similar to that followed by III-c cases. Cases of this procedure also had the highest haring level at one year after surgery, although the difference was not statistically significant. The air-conduction hearing threshold rose by only 1.5 dB, but the bone-conduction threshold rose significantly by 2.5 dB (Fig. 1B). IV-i cases also followed a course similar to cases of III-c and III-i, with the air-conduction threshold rose by 3.2 dB and the bone-conduction threshold by 1.9 dB (Fig. 1C). Unlike the cases having undergone other operative procedures, cases of IV-c recorded the highest air-conduction hearing immediately after surgery. In Cases of IV-c, the bone-conduction threshold rose significantly by 3.1 dB (Fig. 1D). There was no statistically significant difference in the outcome between any two of the four operative procedures.

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Fig. 1. The time course of bone hearing levels during the three-year period after each operative procedure for ears. A: III-c; B: III-I; C: IV-I; D: IV-c. Graphically, from left to right: the mean bone-conduction hearing; mean air conduction hearing and mean air-bone gap levels immediately before surgery, immediately one to six months) after surgery; and one, two and three years after surgery. The vertical axis indicates the hearing level.

Next, we compared six-year post-operative hearing data regardless of operative procedure between two groups divided by age at a cut-off level of age 45. The group aged 45 or younger showed no significant change in air-conduction threshold, bone-conduction threshold or air-bone gap levels even at six years after surgery (Fig. 2A). In the group aged 46 or older, however, significant elevation was recorded in the air-conduction threshold (elevation by eight dB) and in the bone-conduction threshold (elevation by 7.6 dB) during the period from immediately after surgery to six years after surgery. During this period, no significant change was noted in air-bone gap levels (Fig. 2B).

Discussion

As far as the outcome of hearing level after tympanoplasty is concerned, numerous reports comparing the short-term hearing data have been published.15 However, few reports are available with a detailed analysis of long-term course of hearing level.68 In these reports, the success rate often remained unchanged during the five- or six-year period, and the investigators reached the conclusion that the post-operative hearing data were stable.

However, post-operative hearing level was highest at one year after surgery and tended to decrease gradually after that point. Therefore, we cannot rule out that if the patients are followed for longer periods of time, significant changes in hearing level are revealed. When we analyzed changes in bone-conduction threshold, a significant elevation was noted following surgery with procedure III-i or IV-c. According to a past report, the post-operative bone-conduction threshold is usually improved compared to the pre-operative threshold.9 Also in our study, the bone-conduction threshold improved for a while after surgery, but it aggravated over

Post-operative long-term hearing results in patients who underwent ossiculoplasties time thereafter. To examine whether or not such a change would be associated with age, we analyzed the course of the bone-conduction threshold in relation to age. It was shown that bone-conduction threshold showed age-related changes. During this period, however, no significant change was noted in air-bone gap levels. This indicated that there was no deterioration of hearing associated with the operative manipulation involved in tympanoplasty, but rather that deterioration of air-conduction hearing occurred as the final output because of elevation in bone-conduction threshold. In other words, we may at least say that in elderly patients, age-related aggravation of bone conduction leads to deterioration of air-conduction hearing level over a long period of time after surgery.

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Fig. 2. The post-operative hearing results divided by age. A: under 45; B: over 46.

References

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2.Karasawa C, Isono M, Miyashita H, Nakayama K, Saito K, Kimura T, Murata K. Hearing Results of Tympanoplasty Type IV-c and type IV-i evaluated by new criteria. Otol Jpn 13(3):189–192, 2003

3.Ishinaga H, Sakaida H, Takeuchi K. Hearing results after tympanoplasty in our department. Otol Jpn 20(1):13–16, 2010

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5.Kubo T, et al. Hearing results of type III and IV tympanoplasty. Pract Otol Suppl 63: 61–66, 1993

6.Hoshikawa H, Fujiwara S, Furuta H, Mori N. Long-term analysis of middle ear cholesteatoma surgery followed more than 5 years. Otol Jpn 12(3):176–180, 2002

7.Furukawa M, et al. Long-term results of canal wall down tympanoplasty with canal reconstruction for middle ear cholesteatoma. Otol Jpn 15(2):133–138, 2005

8.Yamamoto E, Hirono Y, Okumura T. Long-term observations on ceramics implants. ORL 90(8):1262–1266, 1987

Sato H, Murai K, Hiraumi H, Kanda T. Evaluation of air-bone gap in ossiculoplasty. Otol jpn 12(5):575–580, 2002

Address for correspondence: Kazuya Saito, 37–2 Ohno Higashi, Osakasayama, Osaka, 589–8511, Japan. michiomail54@sakai.zaq.ne.jp

Cholesteatoma and Ear Surgery – An Update, pp. 325–327

Edited by Haruo Takahashi

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