TYPE-IV TYMPANOPLASTY FOR PATIENTS WITH SEVERED TENSOR TYMPANI TENDON DURING CHOLESTEATOMA SURGERY

Takehisa Saito, Takechiyo Yamada, Norihiko Narita, Hideyuki Yamamoto, Masafumi Sakashita, Seita Kubo, Dai Suzuki, Kazuhiro Ogi, Masafumi Kanno, Shigeharu Fujieda

Department of Otolaryngology, Head and Neck Surgery, Faculty of Medicine, University of Fukui, Fukui, Japan

Introduction

The tensor tympani tendon (TTT) lies between cochleariform process and neck of the malleus. The tensor tympani muscle is connected to the tendon directly.1 The function of the TTT is to maintain the proper position of the malleus handle and to control excessive lateral movement of the eardrum by retracting and relaxing the malleus handle and eardrum.2 The TTT sometimes disappears due to cholesteatoma invasion, and is frequently severed to eradicate cholesteatoma in the tympanic cavity to make the anterior part of the eardrum mobile and to aid inspection of the protympanum.2 If the TTT is severed during cholesteatoma surgery, the eardrum becomes unstable. Generally speaking, in type-IV tympanoplasty, a columella inserted between the footplate of the stapes and the eardrum has a tendency to become unstable. These factors may lead to poor post-operative hearing result, especially in staged tympanoplasty, because the tympanomeatal (TM) flap is repeatedly elevated. Post-operative hearing result of type-IV tympanoplasty for middle-ear cholesteatoma performed in our hospital between 1996 and 2005 was poor (success rate; 52%). During this period, the TTT was frequently severed and the TM flap was repeatedly elevated. Therefore, we performed type-IV ossicular reconstruction without elevation of the TM flap during secondary surgery to improve post-operative hearing results.

Methods

Type IV ossicular reconstruction was performed between 2006 and 2011 without TM flap elevation during secondary surgery in cases with severed TTT during primary surgery. The surgical procedure was as follows: 1) The TM flap was not elevated; 2) Transmastoid approach alone was used; 3) Residual cholesteatoma was eradicated by endoscopy; 4) Ossicular reconstruction was performed using a columella such as autologous ossicle, cortical bone, and TORP (Apaceram®). The distance between the footplate and the malleus handle or eardrum was precisely measured; 5) If possible, ossicular reconstruction of type IV with interposition was selected because then stability of the columella is certain. The postoperative hearing result was considered ‘successful’ when at least one of the following criteria was satisfied: 1) Post-operative hearing level within 30 dB; 2) Post-operative air-bone gap within 15 dB. 3. Hearing gain over 15 dB.

Results

Post-operative hearing results of type IV with TM flap elevation performed during one-stage and two-stage tympanoplasty between 1996 and 2005 are shown in Table 1. During this period, the TTT was frequently severed. When the TTT was preserved, the success rate was 100%, although ossicular reconstruction was performed during the second stage. On the other hand, when the TTT was severed, the success rate decreased to 53%. In addition, the success rates were similar, even if the TM flap was elevated once or twice. These findings indicate that whether the TTT is severed or preserved is an important factor. During this period, the incidence of staged tympanoplasty in type IV tympanoplasty for cholesteatoma was 72%.

Hearing results after type-IV reconstruction in one-stage surgery alone performed between 2006 and 2011 are shown in Table 2. During surgery, the TM flap was elevated in all cases. The success rate was poor in both severed tendon and preserved tendon groups. These results indicate that post-operative hearing result of type IV in one-stage surgery was poor.

According to preservation or severance of the TTT during primary surgery and elevation or no elevation of the TM flap during secondary surgery, all patients who underwent staged tympanoplasty and re-operation between 2006 and 2011 were divided into four groups. Group 1: severed TTT and with TM flap elevation; Group 2: severed TTT without TM flap elevation; Group 3: preserved TTT with TM flap elevation; Group 4: preserved TTT without TM flap elevation.

Table 3 shows the hearing results after type IV reconstruction (in staged surgery and re-operation) with TM flap elevation during secondary surgery. When the TTT was severed (group 1), the success rate was only 20%. On the other hand, if the TTT was preserved, the success rate was 100% (group 3). There was a significant difference between the two groups (p < 0.05).

Table 4 shows hearing results after type-IV and type-V reconstruction (in staged surgery and re-operation) without TM flap elevation during secondary surgery. Type V or stapedectomy with columella was performed in two patients with fixed footplate. In these two groups, the success rates were better: 73% in group 2 and 86% in group 4, respectively.

Table 5 shows the summary of this study. If the TTT was severed, the success rate became better, when the TM flap was not elevated during secondary surgery. In addition, if the TTT was preserved, the success rate was better, even if the TM flap was elevated.

Table 1. Post-operative hearing results of type IV (IV c + IV i) with tympanomeatal flap elevation during one-stage and two-stage tympanoplasty (1996–2005, n = 61).

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Table 2. Hearing results after type IV (one-stage) tympanoplasty with tympanomeatal (TM) flap elevation (2006–2011, n = 8).

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Table 3. Hearing results after type IV (staged surgery and re-operation) with tympanomeatal (TM) flap elevation (2006–2011, n = 9).

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Table 4. Hearing results after type IV& V (staged surgery and re-operation) without tympanomeatal (TM) flap elevation (2006–2011, n = 18).

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Table 5. Post-operative hearing results of type IV& V tympanoplasty during second-stage surgery and re-operation (2006–2011, n = 27).

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Discussion

The crucial factors that affect the results of tympanoplasty on hearing are presence of the handle of the malleus, the TTT, and the superstructure of the stapes. The handle of the malleus stabilizes the columella and the TTT also stabilizes the columella.3 However, in type-IV tympanoplasty for cholesteatoma, the TTT is frequently severed and the superstructure of the stapes is already absent. In such conditions, it was recommended, in the second stage of tympanoplasty, that reconstruction of the ossicular chain might be performed through the mastoid without disturbing the skin of the external auditory canal and the position of the new tympanic membrane.3 Therefore, in patients with severed TTT, if the TM flap is elevated again during secondary surgery, the position of the eardrum becomes more unstable, or so-called lateralization will occur. In addition, if type-IV tympanoplasty is performed during secondary surgery, instability of the columella becomes more serious. From the present study, it was revealed that post-operative hearing results became better if the TM flap was not elevated and ossicular reconstruction was performed by transmastoid approach alone. If the TTT is severed during primary surgery and the TM flap is not elevated during secondary surgery, lateral movement of the eardrum is minimal. In such cases, when type IV and V tympanoplasty is performed, the columella becomes stable. By these procedures, better hearing results can be expected.

Conclusion

It was concluded that post-operative hearing results was better if the TTT was preserved. When the TTT was severed, hearing result was better in staged surgery and re-operation groups than that in one-stage surgery group. If the TTT is severed during primary surgery, it will be better to perform tympanoplasty type IV and V with columella without TM flap elevation during secondary surgery to obtain better hearing results.

References

1.Chen T, Gan RZ. Experimental measurement and modeling analysis on mechanical properties of tensor tympani tendon. Med Eng Phys 30:358–366, 2008

2.Bauer M, Vona I, Gerlinger I. Reconstruction of the tensor tympani tendon. J Laryngol Otol 120:240–243, 2006

3.Sanna M. Sunose H, et al. (eds.). Middle Ear and Mastoid Microsurgery, pp187–204. Stuttgart/New York: Georg Thieme Verlag KG, 2012


Address for correspondence: Takehisa Saito, MD, Department of Otolaryngology, Head and Neck Surgery, Faculty of Medicine, University of Fukui, Matsuoka-Shimoaizuki 23–3, Eiheiji-cho, Yoshida-gun, Fukui 910–1193, Japan. takehisa@u-fukui.ac.jp

Cholesteatoma and Ear Surgery – An Update, pp. 257–260

Edited by Haruo Takahashi

2013 © Kugler Publications, Amsterdam, The Netherlands