REGENERATION OF MASTOID CAVITY USING POLYGLYCOLIC ACID SHEETS

Takayuki Kawashima,1,2 Yumi Ohta,1 Taro Hasegawa,1 Hironori Takebayashi,2 Takahiro Kitamura,2 Emi Maeda,2 Osamu Senba,2 Hidenori Inohara1

1Department of Otolaryngology – Head and Neck Surgery, Osaka University, Graduate School of Medicine, Osaka, Japan; 2Department of Otolaryngology – Head and Neck Surgery, Osaka Kouseinenkin Hospital, Osaka, Japan

Objective

It is very important to recover mastoid aeration after ear surgery, especially in case of cholesteatoma sometimes recurs. Gas exchange via the middle-ear mucosa functions actively in the normal middle ear and plays an essential role in the regulation of middle-ear pressure.18 Therefore, it is thought that regeneration of the middle-ear mucosa after removal of a nidus by ear surgery contributes to the aeration of the mastoid cavity after ear surgery. Polyglycolic acid (PGA), which is absorbed into the body, is often used in regenerative medicine as scaffold. It suppresses scar formation and regenerates the original tissue. The aim of this study was to regenerate the normal middle-ear mucosa and the pneumatic mastoid cavity after ear surgery in cases of cholesteatoma, using PGA sheets.

Materials and methods

Five patients with attic cholesteatoma underwent tympanoplasty with mastoidectomy. At the operation we stuck PGA sheets on attic and mastoid cavity, the mucosa of which was resected in order to remove choles-teatoma, and fixed them with fibrin glue (Fig. 1). Age at operation was from 23 to 67 years old (median 42 years). Four of the five patients underwent planned staged tympanoplasty. The remaining one had single-stage tympanoplasty. The observation period from the initial surgery was nine to 17 months (median 12 months). Four of the five patients had a poorly developed mastoid cavity. In these cases there was no aeration in the attic and mastoid cavity before operation. Degree of the pneumatization of attic and mastoid cavity was estimated by CT scan which was performed after initial operation from six months to one year.

Results

All patients had a well-pneumatized attic after the initial surgery. In two cases the mastoid cavity was fully pneumatized and also in two cases partially pneumatized (Table 1). In three cases that underwent a second-stage operation, PGA sheets used at the first-stage operation were absorbed and replaced by normal mucosa. The form of the tympanic membrane remained almost normal in all cases.

Table 1. results of

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Fig. 1. PGA sheets are fixed with fibrin glue (case 3).

Case presentation (Case 3)

The case involves a 23-year-old female patient. She had been diagnosed with cholesteatoma in her left ear and underwent surgery a few years ago, but purulent otorrhea persisted even after the operation. Therefore she consulted Osaka University hospital. At the first examination, attic retraction pocket, in which purulent otorrhea existed, was seen in her left ear. She was diagnosed with recurrent cholesteatoma. A CT scan before the operation revealed that no aeration could be seen in her attic and mastoid cavity (Fig. 2). Therefore, a planned staged tympanomastoidectomy using PGA sheets was performed. Six months after the first-stage operation, a CT scan was made. It was found that her mastoid cavity was fully pneumatized after the first-stage operation (Fig. 3). At the second-stage operation, performed 12 months after the first operation, the PGA sheets were absorbed and replaced by a normal mucosa (Fig. 4).

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Fig. 2. CT scan image before the first-stage operation. No aeration can be seen in the attic and mastoid cavity.

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Fig. 3. CT scan image after the first-stage operation. The mastoid cavity is fully pneumatized.

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Fig. 4. PGA sheets used at the first-stage operation are absorbed and replaced by normal mucosa.

Discussion

The middle-ear mucosa plays an essential role in the regulation of middle-ear pressure. Gas exchange according to concentration or pressure gradients via the mono-layered mucosa supplies adequate pressure in the middle ear. A defect of the normal middle-ear mucosa after removal of a nidus by ear surgery causes a loss of pressure regulation in the middle-ear cavity. Therefore, it is very important to regenerate the middle-ear mucosa after ear surgery, especially in recurring cases of cholesteatoma because of the negative pressure in the middle ear.

Recently, it is believed that wound healing due to scar tissue formation is faster than the regeneration of an original organ when a wound occurs in mammals. Therefore, the mucosa of the middle ear that has been resected in order to remove cholesteatoma is replaced by granulation tissue after the operation.

PGA has the following characteristics: 1) It is absorbed into the body; 2) It is used in regenerative medicine as scaffold; 3) It suppresses scar formation and regenerates the original tissue.

So it is possible that PGA sheets help the mucosa of the middle ear to regenerate, and suppress attic retraction by scar contraction. As a result of this study, the improvement of pneumatization after operation was observed in all cases. Also, the form of the tympanic membrane remained almost normal in all cases. This study demonstrated that PGA sheets were useful for regeneration of the mucosa in the middle ear cavity. This method may prevent the recurrence of cholesteatoma.

However, the problems of this study are: 1) The observation period is short; 2) This study does not include comparison with a control group; 3) It is still uncertain whether the regenerated mucosa has a gas exchange function or not. Therefore, further investigation is needed in future.

Conclusion

PGA sheets may be useful for regeneration of the mucosa in the middle-ear cavity.

References

1.Ikarashi F. The effect of respiratory mode on human middle ear pressure. Auris Nasus Larynx 25(4):349–354, 1998

2.Kanemaru S. Regeneration of mastoid air cells in clinical applications by in situ tissue engineering. Laryngoscope 115(2):253–258, 2005

3.Sade J, Luntz M, Levy D. Middle-ear gas composition and middle-ear aeration. Ann Otol Rhinol Laryngol 104:369–373, 1995

4.Takahashi H, Honjo I, Naito Y , Miura M, Tanabe M, Hasebe S, Toda H. Gas exchange function through the mastoid mucosa in ears after surgery. Laryngoscope 107:1117–1121, 1997

5.Yamamoto Y. Gas exchange function through the middle ear mucosa in piglets: comparative study of normal and inflamed ears. Acta Otolaryngol 119: 72–77, 1999

6.Doyle WJ, Seroky JT. Middle ear gas exchange in rhesus monkeys. Ann Otol Rhinol Laryngol 103:636–645, 1994

7.Magnuson B. On the origin of the high negative pressure in the middle ear space. Am J Otolaryngol 2(1):1–12, 1981

8.Hamada Y, Utahashi H, Aoki K. Physiological gas exchange in the middle ear cavity. Int J Pediatr Otorhinolaryngol 64(1):41–49, 2002

Address for correspondence: Takayuki Kawashima, 4–2-78 Fukushima, Fukushima-ku, Osaka, 553–0003, Japan. tkawa@mx2.canvas.ne.jp

Cholesteatoma and Ear Surgery – An Update, pp. 429–432

Edited by Haruo Takahashi

2013 © Kugler Publications, Amsterdam, The Netherlands