Учебники / Middle Ear Mechanics in Research and Otology Huber 2006

oftheISJareabletoavoidpre-stressontheannularligament.Theseresults coincide with descriptions in literature where a multiplefold increase of incus and stapes inand excursions after artificial fixation of the incudomalleal joint were described [6]. According to our results alterations in sound transmission depending on IMJ-mobility have also been described previously [9].

Our experimental data demonstrate changes of middle ear function concerning dynamic and quasi-static behaviour after ossicular joint fixation, depending on localization, extent and order of fixation.

References

1.Hüttenbrink, K.B., The middle ear as a pressure receptor. In Hüttenbrink KB (ed.)

Middle ear mechanics in research and otosurgery. (UniMedia Dresden 1997) pp. 15–20

2.Cancura W., On the statics of malleus and incus and on the function of the malle- us-incus joint. Acta Otolaryngol (Stockh) 89 (1980) pp. 342–344

3.Murakami S., Gyo K., Goode R.L., E ect of middle ear pressure change on middle ear mechanics. Acta Otolarygol (Stockh) 117 (1997) pp. 390–395

4.Hüttenbrink K.B., Ossicle chain mechanics at static air pressures; II: Impaired joint function and reconstructed ossicle chain]. Laryng Rhinol Otol 67 (1988) pp. 100– 105

5.Marquet J., The incudo-malleal joint. J Laryngol Otol 95 (1981) p. 541

6.Eiber A., Kauf A., Computing displacements of middle ear ossicles due to static load. HNO 42 (1994) pp. 754–759

7.Pau H.W., Hüttenbrink K.B., Experimental studies in reconstructed middle ears – with special regard to static pressure on the footplate. Laryngo Rhino Otol

67 (1988) pp. 331–334

1088. Moser M., Fitness of civil aviation passengers to fly after ear surgery. Aviat Space Environ Med 61 (1990) pp. 735–737

9.Willi U.B., Ferrazzini M.A., Huber A.M., The incudo-malleolar joint and sound transmission losses. Hearing Research 174 (1–2) (2002) pp. 32–44

POSTOPERATIVE TYMPANOGRAM IN TYMPANOPLASTY WITH THIN SECTION CARTILAGE ISLAND

Chin-saeng Cho, MD, Jae-soo Lee, MD, Dong-sik Chang, MD, Myung-soo Choi, MD, Kyung-you Park, MD, Byoung-duk Lim, Phd*

Department of Otolaryngology-head and Neck Surgery, School of Medicine Eulji University, Dae-jeon, Korea

School of Mechanical Engineering, Yeungnam University, Gyungsan, Korea*

Keywords: Tympanoplasty, Tympanogram, Cartilage

Address: Chinsaeng Cho Dept. of ENT Seo-Gu Dunsan-dong 1306 Eul Ji University Hospital, Daejeon, Korea, Email: chinsaeng@hotmail.com

Background and objectives: The objectives of tympanoplasty are to remove the pathology and to reconstruct an acoustic transfer mechanism. The use of cartilage in the reconstruction of the tympanic membrane has been established especially in cases such as tubal dysfunction and adhesive processes. Cartilage o ers the advantage of higher mechanical stability in comparison with membranous transplants. However, it may alter the acoustic transfer characteristics, which may depend on the cartilage thickness.Therefore,theauthorshaveattemptedtodesignathinsectioncartilageisland with tragal cartilage for grafting material. The purpose of this study is to understand

the usefulness of the thin section cartilage island technique by comparing it with 109 conventional temporalis fascia technique using a tympanogram method.

Materialsandmethods:FromMarch2002toAugust2005,101casesoftympanoplasty type I using thin section cartilage island technique and 50 cases of tympanoplasty type I using temporalis fascia performed by one surgeon had been followed up for 6 months and reviewed. Static compliance, tympanometric width and tympanometric pattern were evaluated after 6 months with an impedance audiometer.

Results: In the thin section cartilage island technique group the percentage of cases with a static compliance within the normal compliance range (0.2~1.6ml) was 72% and 66% in the temporalis fascia group. The tympanometric width in the thin section cartilage island technique group was in 59% of the cases within the normal range (60~150mmH2O), whereas in the temporalis fascia group 54% of the cases were within

this range. In the thin section cartilage island technique group 67% showed a normal tympanometricpattern(Atype),whereasinthetemporalisfasciagroupthispercentage amounted to 62%.

Conclusion: The results of impedance audiometry show no statistical significance between thin section cartilage island and temporalis fascia. Therefore, it is suggested that the thin section cartilage island technique is suitable for a tympanoplasty.

1. Introduction

Thepurposesoftympanoplastyaretoremoveanirreversiblepathologyand to improve hearing. The middle ear can be protected from harmful environments by this procedure. Since Wullstein and Zollner established the tympanoplasty, temporalis fascia, vein, perichondrium or periosteum have been used as graft materials [1][2]. Recently, most surgeons have widely usedtemporalisfasciawithasuccessrateupto90%.Othermaterialswhich can be more stable and easier to take at the same operation field have been sought in cases of tubal dysfunction, total perforation or severe mucosal inflammation for achieving uptake rate [3][4]. Cartilage was used for many decades for this reason. It should be also considered because of its acoustic impedance in terms of mass and sti ness e ects associated with its thickness. There were some techniques using cartilage for graft material as palisade technique, thin section cartilage plate, and cartilage island technique [5][6][7][8]. Zahnert et al. reported that a cartilage thickness less than 0.5 mmisanacceptablecompromise[6].However,itwouldnotbeeasytosupport the meatal flap with a thin section cartilage plate, and the cartilage island was too thick to transfer the sound. This situation encouraged us to design a thin section cartilage island, which could be satisfactory in terms of size and thickness of the material and be large enough to cover the posterior tympanomeatal flap.

110 In the present study, we compared the postoperative tympanogram in casesofathinsectioncartilageislandwithtemporalisfasciatounderstand the usefulness of this technique in tympanoplasty.

2. Material and Methods

2.1 Patients

151earsof151patientswithchronicotitismediawereoperatedbythesame surgeon in Eulji Medical Center between March 2002 and August 2005.

Tympanoplasty type I using Thin Section Cartilage Island Technique had been performed in 101 ears and tympanoplasty with fascia in 50 ears. The median age at operation with Thin Section Cartilage Island Technique

Tympanometric measurements including static compliance, tympanometric width, and tympanometric pattern were done with a Middle-Ear Analyzer (Madsen Electronics ZODIAC 901) after 6 months postoperatively. For the statistical analysis, a χ2 test was carried out to compare the thin section cartilage island with fascia technique.

3. Results

3.1 Static compliance

The static compliance measurements in the fascia group (n=50) showed that 33 cases (66%) were in the normal range (0.2~1.6ml); 15 cases (30%) showed values of less than 0.2ml and 2 cases (4%) more than 1.6ml. The static compliance of thin section cartilage island graft (n=101) were as follows: 73 cases (72%) within the normal range of 0.2~1.6ml; 22 cases (22%) with less than 0.2ml and 6 cases (6%) with more than 1.6ml. Statistical analysis showed that there was no significant di erence between the two groups.

Table 1 Graft material and static compliance.

(P-value > 0.05)

112

3.2 Tympanometric width

The tympanometric width indicates the pressure di erence between two points on the tympanogram curve where the compliance is half the static compliance.

The results show that the fascia group (n=50) had 7 cases (14%) of normally ranged tympanometric width (60~150mmH2O); 27 cases of under ranged tympanometric width (< 60 mmH2O); and 16 cases (32%) of over ranged tympanometric width (> 150 mmH2O). The tympanometric width of the thin section cartilage island graft group (n=101) were as follows: 60 cases (59%) of 60~150 mmH2O (normal range); 18 cases (18%) of

< 60 mmH2O; and 23 cases (23%) of > 150 mmH2O. There was no significant di erence between the two groups.

Table 2 Graft material and tympanometric width.

(P-value > 0.05)

3.4 Tympanometric pattern

There were 31 A types (62%), 7 B types (14%), and 12 C types (24%) in the fascia group and 68 A types (67%), 11 B types (11%) and 22 C types (22%) in the Thin Section Cartilage Island Graft group. No significant di erence between the two groups was found.

Table 3 Graft material and tympanometric pattern.

(P-value > 0.05)

113

4. Discussion

It has been very common to use the perichondrium or fascia in tympanoplasty, in spite of its unacceptable results in cases of tubal dysfunction, adhesive process, tympanic fibrosis, or entire tympanic membrane defect [9]. Several authors preferred to use the cartilage of conchae or tragus in cases of middle ear pressure change [10][11][12]. However, the increased mass and sti ness of thick materials could influence the acoustic transfer properties.

Adkinetal.reportedthatairconductionthresholddepressionwas5~10dB incartilagegrafting.Therefore,theyuseditonlyinlimitedcases.According to other studiesthere wasnosignificantdi erence inhearingbetweengraft with fascia and cartilage [8][13][14][15]. We agree that mass and sti ness e ectofthickcartilagemayleadtohighfrequencyhearingloss.AsZahnert has suggested earlier, thin sections less than 0.5mm could be acceptable as a role of transformer [5].

The fascia has elastic fibers with irregular arrangement and unpredictable and irregular gaps between fibers which are filled with fibrous connective tissue. Therefore it often contracts and is being thickened. Such unstable properties make a surgeon look for other graft material such as tragal or conchal cartilage that is stable and easy to take at the operation field. The cartilage is very useful for its resistance to contraction and absorption in cases of tubal dysfunction, total perforation, or adhesive otitis media [14][16].

Thin section cartilage cannot reach a posterior meatal flap adequately foritslimitedsizeandfirmness.Inordertosolvethisproblem,theauthors have developed a thin section cartilage island technique using the section of cartilage attached to the perichondrium. Usually, the cartilage including perichondrium needs to be sectioned into less than 0.3~0.5mm for a proper sound conduction. While the conventional fascia has only fixed thickness, a variable thickness of graft material can be sliced according to the condition of middle ear and Eustachian tube. In this study, graft materials cartilage and fascia were compared by tympanograms which is an indirect method of assessing the sound conduction e ciency. There was no statistical significance between the two techniques observable in static compliance, tympanometric width, and tympanogram type, which are the major parameters of the tympanogram representing the mobility of tympanic membrane. This means that the thin section cartilage island

114could be similar to fascia in terms of the mobility. However, additional investigations maybe needed to determine whether this applies also to the sound transfer.

5. Conclusion

Theauthorshavecomparedtheconventionalfasciatechniquewiththethin section cartilage island by a tympanometric method. Static compliance, tympanometric width and type of tympanogram showed no statistically significant di erence between the two techniques. Therefore, this type of surgery could be performed in ordinary cases such as chronic otitis media.

Reference

1.Wullstein H., Theory and practice of tympanoplasty. Laryngoscope 66(1965) pp.1076–1093

2.Zollner F., The principles of plastic surgery of the sound-conducting apparatus. J Laryngol Otol. 69(1955) pp. 637–652

3.Glasscock M.E., House W.F., Homograft reconstruction of the ear. Laryngoscope 78(1968) pp. 1219-1225

4.Sheehy J.L., Glasscock M.E., Tympanic membrane grafting with temporalis fascia.

Arch Otolaryngol. 86(1967) pp. 391–402

5.Uzun C., Thomasen P.C., Andersen J., Tos M., A tympanometric comparison of tympanoplasty with cartilage palisades or fascia after surgery for tensa cholesteatoma in children. Laryngoscope 113(2003) pp. 1751–1757

6.Zahnert T., Hüttenbrink K.B., Murbe D., Bornitz M., Experimental investigations of the use of cartilage in tympanic membrane reconstruction. Am J Otol. 21(2000) pp. 322–328

7.Murbe D., Zahnert T., Bornitz M., Hüttenbrink K.B., Acoustic properties of di erent cartilage reconstruction techniques of the tympanic membrane. Laryngoscope 112(2002) pp. 1769–1776

8.Kirazli T., Bilgen C., Midilli R., Ogut F., Hearing results after primary cartilage tympanoplasty with island technique. Otolaryngolory-HNS. 132(2005) pp. 933– 937

9.Palva T., Surgical treatment of chronic middle ear disease. Acta Otolaryngol. 104(1987) pp. 279–284

14. Milewski C., Composite graft tympanoplasty in the treatment of ears with advanced middle ear pathology. Laryngoscope 103(1993) pp. 1352–1356

15. Amadee R.G., Mann W.J., Riechelmann H., Cartilage palisade tympanoplasty. Am J Otol. 10(1989) pp. 447–450

16. Elasfour A.A., Zaghloul H.S., Cartilage tympanoplasty: audiological and otological outcome. International Congress Series. 1240(2003) pp. 73–79

DO NON-PISTON COMPONENTS CONTRIBUTE TO SCALA VESTIBULI PRESSURE BEHIND THE FOOTPLATE IN GERBILS?

W.F. Decraemer1, O. de La Rochefoucauld2, W. Dong2, S.M. Khanna2, J.J.J. Dirckx1, E.S. Olson2

1 Univ. of Antwerp, Biomed. Physics, 177 Groenenborgerlaan, B 2020, Antwerp, Belgium

2 Columbia Univ., Dept. of OTO/HNS, 630 West 168th St., New York, NY 10032, USA

Keywords: 3-D stapes motion, scala vestibuli pressure

In recent papers we have shown that the mode of vibration of the ossicular chain in cat and human temporal bones is more complex than a simple rotation about a fixed axis andthatitalsochangeswithfrequency.Forthestapese.g.itwasshownthatrotationsof the footplate about its long and short axis are present besides the predominant pistonlike velocity component. As the footplate motion gives rise to the pressure wave set up in the cochlea, we investigated whether the non-piston components contribute to the pressure produced in the gerbil cochlea: 3-D vibration velocity of the stapes along

116with the scala vestibuli pressure were measured in the same animals. We found no correlation between non-piston components and scala vestibuli pressure.

1. Introduction

The motion of the stapes footplate produces the acoustical input into the cochlea. The mode of stapes vibration has been studied mainly in human temporal bones (for an overview: [1,2]) and in a few animal models (anesthetized cat [3], cat temporal bone: [4,5,6]). It is now quite well established that the motion is not purely piston-like but that at higher frequencies rotations about the long and short footplate axis are also present (“rocking”, “tilting”). Whether the non-piston motion components are functionally

important is still an open question. An argument in favor is the remarkable ability of the middle-ear to produce a gain between the sound pressure in the ear-canal and the acoustic pressure in the perilymph of the scala vestibuli (directly behind the footplate) that is a very smooth function of frequency,whilethefrequencyresponseofthepistoncomponentofthestapes exhibits some maxima and minima. This is especially prominent when we compare gain and motion curves not averaged over experiments of di erent individual preparations. Could it be that tilting of the footplate of the stapes fills in the gaps in the frequency response of the piston component resulting in a smoother pressure frequency response in the cochlea? Trying toanswerthisquestionwehavemeasuredinsuccessionscalavestibulipressure and 3-D vibration velocity of the stapes in the same animals (gerbil) and studied their correlation.

2. Material and Methods

Young adult Mongolian gerbils with healthy ears were used for this study. The animal preparation is described in detail in [7]. The external ear canal (EC) was cut to its bony end and a small plastic tube was cemented in place to hold the sound delivery tube. A probe tube microphone (B&K) measured the sound at about 1 mm from the superior edge of the pars tensa (EC pressure).

Scala vestibuli (SV) pressure directly behind the footplate (distance ~ 0.3mm) was measured with a miniature pressure sensor (Φ = 170 μm, [7,8]) inserted about 0.2 mm deep in a small, hand drilled hole in the cochlea (for a figure with the pressure location, see [9] Fig.1)

The stapes was exposed through a large opening of the bulla and its motion was measured from di erent viewing angles for single tone stimuli over a wide frequency range (200 Hz–1 kHz, step 200 Hz; 1 kHz–10 kHz,

step 250 Hz; 10 kHz–20 kHz, step 500 Hz; 20 kHz–40 kHz, step 500 Hz). 117 SPL for constant input to the driver was between 80 and 90 dB, in the linear range of the middle ear [8]. The procedure and equipment used are described in [10].

The rigid body global translation and rotation about the origin were calculated and transformed in the intrinsic reference system shown in Fig. 1(z-axistowardsreader);pistonmotionistranslationalongyandfootplate tilt about the long and short axes are rotations about x and z, respectively.