Homograft Tympanic Membrane Myringoplasty Edward C. Brandow, Jr, MD

\s=b\ During a six-year period, homograft tympanic membranes have been used successfully for myringoplasty or tympanoplasty in 85% of 175 cases. This percentage is not as high as might be expected with fascia, and the homografts have not been as dependable in the wet, draining ear. However, the results do show that the homograft is an acceptable grafting material. The eardrums are not suggested as substitutes for fascia, but

should be available for difficult cases. Their use is indicated in large or total defects to restore the natural anatomical conical shape of the eardrum, particularly in congenital atresia. The prime indication for their use is a missing malleus, and the malleus handle can be included within the transplant. The eardrum's rigid properties and the possibility of inclusion of ossicles make the homografts valuable in reconstruction of the old mastoid cavity.

(Arch Otolaryngol 102:473-477, 1976)

than six years

passed Moresince the homografthavetympanic

membrane for myringoplasty was introduced in the United States by Glasscock and House. Subsequently, many reports concerning this tech¬ nique have appeared in the American and European literature.1-7 Homografts have been an important topic Accepted for publication April 13, 1976. From the Albany Medical College, Albany, NY.

Reprint requests to 662 Madison Ave, Albany,

NY 12208

(Dr Brandow).

a number of panel discussions at major national and international meetings.

at

The purpose of this paper is to present a series of 176 cases of homograft tympanic membrane myringo¬ plasty, to discuss the general princi¬ ples of the technique, to give the advantage of these grafts, and to identify the present indications for their use. We all know that fascia works well in the repair of a perforation. Sheehy and Glasscock-'8 have reported a 96% success rate, and Hough,211 a few years ago, reported an even higher rate of 98%. Why then are we looking for a better material? The above results refer to healing the eardrum and sealing off the perforation. However, there are selected cases in which fascia may have some limitations and in which the homograft does have a definite advantage. In a large perforation or a total defect in the eardrum, the homograft will achieve a better anatomical recon¬ struction. The eardrum is not merely a membrane stretched across the bot¬ tom of the ear canal, but it has the shape of a cone, somewhat similar to the shape of a loudspeaker. Tonndorf and Khanna"' have shown that this conical shape of the tympanic mem¬ brane contributes physiologically to the effectiveness of sound transmis¬ sion. The position of the eardrum in rela-

tion to the

ear

canal forms

an

acute

angle anteriorly. Proper use and placement of the homograft avoids the problem of blunting of the ante¬ rior sulcus. Its conical shape helps the graft to adhere to the inward projec¬ tion of the malleus handle, and thus prevents the lateralization that occur

can

with fascia.

The most important indication for the use of the homograft eardrum is the case in which ossicles are missing and no malleus is present. The malleus handle can be included within the '

new transplant eardrum, giving bone that will provide the needed supporting structure for a later second-stage connection to the stapes a

or

to the oval window. As an alterna¬

tive, when there are no ossicles, an en bloc transplant of eardrum with

attached total ossicular chain can be used. Betow has recently reported 440 cases in which he used an attached total chain." At least some hearing improvement occurred in 90% of his patients, and many had a considerable

hearing gain.

The transplant is ideal for con¬ structing an eardrum in congenital atresia, in which case there has never been a tympanic membrane. Certain¬ ly, no other graft can approach the natural, physiological, and anatomical

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structure of

a new eardrum. How could fascia be expected to be as effec¬ tive a tympanic membrane? Reconstruction of the old mastoid

cavity is a difficult undertaking under the best conditions. The homograft eardrum has definite advantages, especially in attempting to rebuild the middle

ear

space. The stiffness of the

transplant eardrum tendency toward the

minimizes the inward sagging of the graft that may occur with fascia. In selected cases, the old cavity can be completely rehabilitated by reconstruction of the posterior bony canal wall. Various graft materials have been advocated for rebuilding the wall, but the prepared homograft bony posterior canal wall, as sug¬ gested by J. Pulec (oral communica¬ tion, 1973) and by Betow,7 has the distinct advantage of giving the best anatomical reconstruction. There is no question that the tech¬ nical aspects of the preparation and the molding of these transplants are time consuming, but this bone is well tolerated and takes well. A particular advantage is the possibility of includ¬ ing the attached tympanic membrane or the attached eardrum including the malleus handle. To consider a total transplant of bony wall, the eardrum, and the entire ossicular chain in one stage is technically quite difficult. Hearing restoration in these advanced problems usually requires a second-

stage procedure. The

use

of this

may prove to be

homograft eardrum particularly appli¬

cable in the concept of a modified type V tympanoplasty as advocated by Gacek" and Schuknecht et al.32 The prerequisite for a successful operation is adequate aeration of the hypotympanum and the area of the round window. The rigidity of the homograft should help this problem of ventilating the cavum minor. AVAILABILITY OF HOMOGRAFT DRUMS

Details

regarding donor selection,

procurement of the graft, and removal

of the eardrum from the temporal bone plug have been reported pre¬ viously. In some centers, pathologists may be reluctant to give permission for taking homograft specimens. However, passage of the Universal Donor Act has made graft material more readily available. Obtaining the graft and dissecting it from the bone

plug is still a time-consuming process,

and, for those otologists who are too busy to prepare their own material, ear banks have been established to facilitate distribution. Otological transplant material may be obtained from the Ear Bank Institute for Medical Research of Santa Clara County or from "Project Hear," both of which are located in California. A new eardrum bank, the Eastern Ear Bank, is being established at the Albany (NY) Medical College. Chiossone Lares offers an ear bank for the distribution of homografts through¬ out South and Central America.-7 Eardrums, ossicles, or eardrums with attached ossicles or an attached bony canal wall, can be ordered from one of these banks by the hospital, and the charge for the homograft material is covered by the patient's hospital in¬ surance. The transplant material is considered in the same category as blood for transfusions or as a pros¬ thesis used in ear surgery, such as the various tubes, wires, and pistons. In a resident training program, preparation of the eardrum grafts with dissection from the plug has been found to be an excellent teaching aid for the beginning resident in otology. It familiarizes the resident with the operating microscope and the delicate handling of tissue and middle ear instruments. PRESERVATIVE SOLUTION The method of preparation of the graft is important and has been the subject of considerable discussion. In Betow's original cases, fresh grafts did not take and were rejected. A preservative solution is needed to accomplish two main objectives: (1) to render the graft sterile to prevent

contamination and (2) to preserve the graft and reduce its antigenetic properties. A number of various preservative solutions have been tried: 70% alcohol, betapropylene, benzalkonium preparations, buffered formaldehyde solution, and Hank so¬ lution, which sterilizes, yet keeps the graft viable. All of these techniques are effective and have merit. The grafts used in this series have been preserved in Cialit, which is the solu¬ tion used by Betow, Marquet, and

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Plester. Freezing the grafts warrants a word of caution. It causes crystalli¬ zation of the tissue, which may weaken it. Cialit is a sodium salt of an organomercury compound that contains sulfur, and is very similar in chemical structure to thimerosal (Merthiolate). It is used as a 1:500,000 aqueous solu¬ tion, is a strong bacteriocidal solution, and assures sterility of the graft within 24 hours. In a more dilute form, Cialit is nonirritating to living tissue. In fact, it has been used in Europe for the preparation of injectable vaccines. In the present series, Cialit has proved to be an effective preservative solu¬ tion. No patient reacted immediately, and discharge occurred the day follow¬ ing the surgical procedure, which substantiates a lack of contamination or irritation from the preservative. Siefert" studied the biological prop¬ erties of tissue grafts and the effect produced by preservative solutions. He found that different types of tissue vary considerably. Collagenous homografts have a relatively mild immunological response when com¬ pared with other types of transplant material. Reaction on the part of the host to the graft is greatly reduced when the tissue is preserved and devi¬ talized. Siefert compared transplanta¬ tion of fresh collagen with preserved collagen and showed a substantial difference in the mesenchymal activi¬ ty and in the inflammatory response induced by the host recipient. He noted the effect of Cialit on collagen tissue and found that it altered and denatured the proteins and inacti¬ vated or destroyed tissue enzymes. He concluded that the immunological reaction of the host to the homograft is practically nonexistent, because the graft is rendered biologically inactive by its preparation in the preservative solution. Contrary to this and differing from Betow's initial experience, fresh ca¬ daver homograft eardrums have been used successfully. Recently, AntoliCandella-7' and Lang'-'1 have both reported successful transplantations of fresh cadaver eardrums. THE GRAFT

What

are we

transplanting? The

Fig

1.—Removal of canal-wall skin,

preserving vascular strip.

Fig 2 Deepithelialized eardrum overhang removed.

remnant with anterior canal-wall

—

only the mesodermal layer of the eardrum, which is the collagenous network of fibers, with its fibrocartilaginous annulus. It is primarily collagen, consisting of an acellular tissue that is almost completely avas¬ graft

middle

material consists of or

allar. Results of histological studies of the preserved homograft show amorphus collagen with very few cells and almost no vascular channels. Morri¬ son17' and Dawkins34 have verified the results of these studies of the homograft tympanic membrane with the electron microscope, and found that its structure is almost entirely colla¬

annulus or if the homograft is being used in an old cavity, a cuff of attached perios¬ teum may help secure the graft in place. No absorbable gelatin sponge (Gelfoam) is necessary in the middle ear for support, but once the graft is in place, the canal is packed with a gelatin sponge (Fig 1

through 4). If the patient has a large ear canal and if

proper visualization of the entire eardrum remnant is possible, the operation is

performed transmeatally through the ear speculum and, if possible, under local anes¬ thesia. However, if the patient is a child or if there is a small canal and any question about exposure, a postauricular incision is used.

RESULTS

gen.

TECHNIQUE The technique for using a homograft eardrum is similar to the conventional myringoplasty that was described by Plester11 '2 and by Glasscock and House17' and Glasscock and Sheehy,-'" substituting the homograft eardrum in place of fascia. Skin from the canal wall is removed, leaving the vascular strip or a strip of anterior canalwall skin, depending on the configurations of the canal and its anterior bulge. The graft is then placed laterally on the deepithelialized eardrum remnant, and the homograft is covered with the canal skin. It does not need complete coverage, but it is preferable to cover at least 75% of it to assure epithelialization. Care is taken to bring the canal skin across the graft to the anterior sulcus, but not up the anterior wall to avoid blunting. If the patient has no

During the past six years, 175 myringoplasties or tympanoplasties have been performed using a pre¬ served homograft tympanic mem¬

brane. In the first 29 cases, the homografts were not covered with canal skin, and they did not function well. There were only 18 patients whose homografts healed successfully, which is a discouraging success rate of 59%. Once the technique was modified and the graft was covered with canal skin, as suggested by Wehrs,-1 there were 123 successes out of 146 (84%). Including the original cases, 80% of the grafts healed primarily. Other authors who used the homograft tympanic membrane generally report about the same percentage of success,

have reported a success rate than 90%. higher These homograft myringoplasties were selected cases; primarily dry ears were chosen, and there was an attempt to eliminate any middle ear problem or Eustachian tube patholog¬ ical abnormalities that might contrib¬ ute to graft failure. Bellucci'"'7 would classify the cases as group 1, and all the patients would be expected to have a good prognosis for success. It has been generally agreed by most otologists that homograft eardrums do not do well in the wet or draining ear. The 84% success rate is not as high as might be expected with fascia, but it is an acceptable figure and does show that a homograft can give effec¬ tive eardrum repair. Once the graft has healed, it has not been prone to late breakdown. Only three of the 123 homografts later perforated. These eardrums are quite hardy and are resistant to infection. Two patients developed otitis media, one with rupture and discharge, but both did well with a course of anti¬ biotic therapy and have healed subse¬

and

some

quently. Marquet reports myringot-

omies in two cases without break¬ down.3 With respect to hearing improve¬ ment with an intact chain, hearing was found to close the air-bone gap in many cases, but was not noticeably

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Fig 3.—Homograft in place, lateral epithelium back over homograft.

higher than

to eardrum remnant. Elevated

with fascia. It is difficult

to compare the two techniques be¬ cause there are many factors that

differ with each ear. There were no cochlear losses, with the exception of one patient who developed a total loss. This patient with a total defect and an intact chain had no adverse reactions or any discharge following the opera¬ tion. The graft took beautifully, but she lost her hearing. A number of cases in the above series required staged secondary procedures with os¬ sicular repair. Three patients had a total chain and eardrum transplant, three had incus and malleus included, and four had the attached malleus handle included. This small series cannot give conclusive results, but the technique appears quite promising for hearing improvement in these most difficult reconstruction cases. What about the failures in this series? Fortunately, most have been small central defects or perforations in the homograft. Only a few cases have resulted in total breakdown or lack of acceptance of the graft. Most of the graft defects were easily repaired secondarily with earlobe fat. In three cases, there was failure of epithelium to cover the entire graft, even though it took well and sealed off the ear. This was also noted by F. Guilford (oral communication, 1971)

Fig 4—Canal-wall skin covering homograft vascular strip. It may be divided into two

placed adjacent to pieces to facilitate

placement. few of his homograft eardrum This problem, also, has been seen by J. L. Sheehy (oral communica¬ tion, 1974) with fascia in a few cases. In one patient, there was failure of the epithelium to grow over the short process of the transplanted malleus, which was included within the eardrum. in

a

cases.

FATE OF THE GRAFT

happens to the transplanted homograft eardrum? Is it eventually absorbed and replaced by fibrous What

tissue or does it remain intact within the healed layers of the eardrum? The potential for replacement by the host is well known to immunologists. Surgeons who are familiar with trans¬ plantations appreciate that homograft material, regardless of its na¬ ture, tends to be gradually replaced by a process of "creeping substitution" and eventually is rejected by the host. This rejection phenomenon is brought on by an awareness of the body to the foreign material that occurs as blood vessels invade the graft and it becomes vascularized. Eventually, an¬ tibodies are produced that attempt to destroy or replace the graft. In considering the fate of the homograft eardrum and other otological transplants, three important fac¬ tors differentiate them from other

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types of transplantation and minimize the immunological response. First, the

or structure of the graft is an acellular and avascular tissue. It can be compared with a "privileged" or "favored" tissue similar to the cornea or a heart valve. The collagen eardrum cannot be compared to other types of transplant material or even be consid¬ ered in the same category as an organ transplant. Second, as Cornish and Scott3* suggested, the middle ear is a "favored or privileged site" for trans¬ plantation to the anterior chamber of the eye. The tissue lining and blood supply of the ear are scanty when compared with other areas of the body. If this same transplant material were placed beneath a rich vascularized tissue, such as abdominal fat, it would probably be absorbed easily. Finally, as previously discussed, the graft has been rendered biologically inactive by the preparation technique. All of these factors combine to greatly reduce the antigen-antibody response of the host. Betow has attempted to show evidence of an antigenetic response in patients after this type of transplantation.7 He studied eosinophil and lymphocyte counts at various intervals following operation, but found no meaningful change. The histologie features of a homograft eardrum removed 18 months

nature

transplantation showed an amorphous structure, which repre¬ sented the old graft, surrounded by fibrous tissue. Interestingly, there were no foreign-body giant cells and no lymphocytic infiltration to suggest any evidence of a low-grade inflam¬ mation or any antigenetic reaction. If the homograft has been tolerated this well for 18 months, it has passed the period and the probability of graft rejection. Marquet- and Betow6 have likewise reported similar histological after

studies that showed almost a normal three-layer eardrum, with no evidence of replacement of the graft. Most defects that develop in homograft eardrums occur in the center of the graft. The breakdown does not occur at the periphery of the graft, where it is in contact with host tissue. If it were a rejection reaction, it most likely would have occurred at the pe¬ riphery and not in the center. The perforation probably results from insufficient vascularity reaching the center of the graft. A number of patients in this series are more than 6 years old, and the Marquet J: Myringoplasty by eardrum transplantation. Laryngoscope 78:1329-1336, 1.

1968. 2. Marquet J: Reconstructive

micro-surgery of the eardrum by means of tympanic membrane homograft: Preliminary report. Acta Otolaryngol a

62:459-464, 1966. 3. Marquet J: Homografts in myringoplasty.

Presented at the first International Congress of Oto-neurosurgery, Valencia, Spain, 1973. 4. Marquet J: Technique Inedit\l=e'\de Myringoplastie par Homogreffe de Tympano. Acta Otorhinolaryngol Belg 21:127-132, 1967. 5. Betow C: Homograft transplantation of tympanic membrane and ossicles. Presented at a meeting of the German Society of Ear, Nose, and Throat, September 1968. 6. Betow C: Transplantation von Trommelfell und Geh\l=o"\rknochelehenkettebei Tympanoplastik. Berlin, de Guyter & Co, 1970. 7. Betow C: Reconstruction of middle

ear

and

posterior osseous wall of auditory canal with homograft reconstruction of old radical cavities. Trans Am Acad Ophthalmol Otolaryngol 80:573\x=req-\ 576, 1975.

8. Betow C: Transplantation of tympanic membrane with total ossicular chain. Presented at the first International Congress of Oto-neurosurgery, Valencia, Spain, 1973. 9. Brandow EC: Homograft tympanic membrane in myringoplasty. Trans Am Acad Ophthalmol Otolaryngol 73:825-835, 1969. 10. Brandow EC: Homograft tympanic membrane transplant in myringoplasty. Acta Otorhinolaryngol Belg 24:38-44, 1970. 11. Plester D: Myringoplasty methods. Arch Otolaryngol 78:310-316, 1963. 12. Plester D: Tympanic membrane homografts in ear surgery. Acta Otorhinolaryngol Belg 24:34-37, 1970.

outline of the donor homograft with the fibrocartilaginous annulus can still be seen within the healed eardrum, which further substantiates the lack of absorption. If the graft is replaced by host tissue, it certainly maintains its identity. According to ophthalmologists, corneal transplants remain and are not absorbed or affected by host reaction. Thoracic surgeons have reported aortic heterografts, again preserved tissue, which is primarily collagen, that have per¬ sisted without absorption for as long as 15 years. Contrary to the hypothesis that homograft eardrums are impregnable, a few homografts that initially took well have shown almost complete disappearance of the graft and replacement with a false membrane. Plester (oral communication, 1973) has also noted absorption of the graft in a few of his patients. This absorption is the exception, however, and not the expected end result of the homograft eardrum.

that is required to obtain a homograft drum, the slightly lower take rate, and any other transplant problems justify the use of this graft material? Homograft eardrums are not suggested for simple patching of a perforation. They should be reserved for problem ears, ie, those that require major recon¬ struction. The advantages of the homograft eardrum in the large or total defect have been discussed. There is no question that the homograft is the graft of choice in congen¬ ital atresia. The most important indi¬ cation for its use is when there are no ossicles and when the malleus handle can be included within the eardrum transplant to offer a supporting struc¬ ture for later reconstruction. Finally, homografts are helpful in the recon¬ struction of the old mastoid cavity. The homograft eardrum is not sug¬ gested as a replacement for fascia in tympanoplasty, but the otologist should have these grafts readily avail¬ able to use in the reconstruction of difficult problems.

COMMENT

The

question is, do the added effort

References Smyth GD, Kerr AG: Tympanic membrane homografts. J Laryngol 83:1061-1066, 1969. 14. Mawson S: Tympano-ossicular homograft. Acta Otorhinolaryngol Belg 24:125-131, 1970. 15. Morrison AW: Experimental studies of homograft drums and ossicles in monkeys. Acta Otorhinolaryngol Belg 21:110-118, 1967. 16. Morrison AW: Homograft tympanoplasty and myringoplasty. Acta Otorhinolaryngol Belg 13.

24:45-52, 1970.

17. Perkins R: Human homograft otologic tissue transplantation buffered formaldehyde preparation. Trans Am Acad Ophthalmol Otolaryngol 74:278-282, 1970. 18. Smith MF, Proffitt SD, Shinn JB: An otologic tissue bank. Trans Am Acad Ophthalmol Otolaryngol 76:134-141, 1972. 19. Mackennon M: Homograft tympanic membrane in myringoplasty. Ann Otol Rhinol Laryngol 81:194-202, 1974. 20. Wehrs RE: Homograft tympanic membrane in tympanoplasty. Arch Otolaryngol 93:132-139, 1971. 21. Wehrs RE: The homograft tympanic membrane: A five-year study. Trans Am Acad Ophthalmol Otolaryngol 82:39-43, 1976. 22. Gristwood R: Homograft tympanic membrane. Presented at the third British Academic Congress, Edinburgh, 1973. 23. Lang R: Transplantation of fresh cadaver tympanic membranes in myringoplasty. Presented at the first International Congress of Otoneurosurgery, Valencia, Spain, 1973. 24. Antoli-Candella F: Homogreffes tympanoossiculaires. Acta Otorhinolaryngol Belg 24:111\x=req-\ 124, 1970. 25. Antoli-Candella F: Fresh cadaver drums in tympanoplasty. Presented at the first International Congress of Oto-neurosurgery, Valencia, Spain, 1973.

26. Lacher G, Jassaud P, Sanchez-Gil J: Les Homogreffes tympano ossiculaires. Rev Laryngol

Otol Rhinol 94:393-406, 1973. 27. Chiossone Lares E: Homograft tympanic membrane. Presented at the first International Congress of Oto-neurosurgery, Valencia, Spain, 1973. 28. Sheehy JL, Glasscock ME III: Tympanic membrane grafting with temporalis fascia. Arch Otolaryngol 86:391-402, 1967. 29. Hough JV: Tympanoplasty with the interior fascial graft technique and ossicular reconstruction. Laryngoscope 80:1385-1413, 1970. 30. Tonndorf J, Khanna SM: The role of the tympanic membrane in middle ear transmission. Ann Otol Rhinol Laryngol 79:743-753, 1970. 31. Gacek RR: Results of modified type V tympanoplasty. Laryngoscope 83:437-447, 1973. 32. Schuknecht HF, McGee TM, Oleksiuk S: Comments on tympanoplasty. Laryngoscope

70:1157-1168, 1960. 33. Siefert KE:

nous

homografts.

24:27-33, 1970.

Biological aspects of collageActa Otorhinolaryngol Belg

34. Dawkins RS: Experimental middle ear homografts. Presented at the Section of Otology, Royal Society of Medicine, London, 1970. 35. Glasscock ME, House WF: Homograft reconstruction of the middle ear: A preliminary report. Laryngoscope 78:1219-1225, 1968.

36. Bellucci RJ: Dual classification of tympa1973. 37. Bellucci R: Functional classification of at tympanoplasty. Presented Shambaugh's fifth International Workshop, Chicago, 1976. 38. Cornish CB, Scott PJ: Freeze dried sheep's heart valves in myringoplasty. Arch Otolaryngol 88:355-356, 1968.

noplasty. Laryngoscope 83:1754-1763,

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