Malleus handle: determinant of success in ossiculoplasty

OBJECTIVE

The purpose of this study is to identify prognostic factors affecting outcome in ossicular chain reconstruction (OCR).

STUDY DESIGN AND SETTING

This study is a retrospective case series of electronic database at an academic institution.

MATERIALS AND METHODS

We reviewed 209 cases of chronic supportive otitis media performed from January 2000 through December 2007 and collected demographic, clinical, audiologic, and outcome information. Univariate analyses of group differences in terms of postoperative air-bone gap (ABG) changes were evaluated by analysis of variance. Multiple regression analyses were used to examine the relationship between postoperative ABG and the independent variables.

RESULTS

There were 105 cases of OCR the met the inclusion criteria (44 primary and 61 revision tympanoplasties), with an average follow-up of 19 months. The diagnoses were chronic suppurative otitis media without cholesteatoma in 36 cases and cholesteatoma in 69 cases. The mean preoperative ABG was 34 +/- 15 dB, and the mean postoperative ABG was 20 +/- 14 dB (P < 0.001). Of the independent variables analyzed, the type of procedure (ie, OCR performed during second-look tympanoplasty vs canal wall up vs canal wall down), preoperative ABG, and status of malleus handle were predictive of the success of OCR.

CONCLUSIONS

Favorable prognostic factors in OCR include smaller preoperative ABG and the presence of an intact malleus handle.

Results after revision stapedectomy with malleus grip prosthesis

Revision stapedectomy with a malleus grip prosthesis is a technically challenging otologic procedure. The prosthesis is usually longer and extends deeper into the vestibule than a conventional stapes prosthesis, creating the potential to affect the vestibular sense organs. The prosthesis also bypasses the ossicular joints, which are thought to play a role in protecting the inner ear from large changes in static pressure within the middle ear. The prosthesis is in close proximity to the tympanic membrane, thus increasing the risk for its extrusion. We reviewed our experience with revision stapedectomy with the Schuknecht Teflon-wire malleus grip prosthesis in 36 ears with a mean follow-up of 23 months. The air-bone gap was closed to within 10 dB in 16 ears (44%) and to within 20 dB in 26 ears (72%). The incidence of postoperative sensorineural hearing loss was 8% (3 ears). There were no dead ears. Extrusion of the prosthesis occurred in 1 case (3%). Nearly 50% of patients reported various degrees of vertigo or disequilibrium during the first 3 weeks after surgery. These vestibular symptoms resolved by 6 weeks in all but 1 case. We did not find evidence of damage to the inner ear due to the length of the prosthesis or due to the potential for direct transmission of changes in static pressures within the middle ear to the labyrinth. Our results are similar to those published in the literature for malleus attachment stapedectomy and conventional revision incus stapedectomy.

The use of malleus allografts in ossiculoplasty

OBJECTIVE

To assess the functional performance of remodeled malleus allografts in a malleus-footplate assembly in terms of hearing results and mid long-term stability.

STUDY DESIGN

A retrospective study of 60 consecutive patients who underwent a malleus allograft ossiculoplasty from 1993 until 2000. In all cases the incus and the stapedial arch were missing as the result of cholesteatoma (49), chronic otitis (5), incus necrosis resulting from stapes prosthesis (5), and congenital ossicular malformations (1). In all cases malleus allografts were remodeled to form a malleus-stapes assembly.

RESULTS

The audiometric results, using such an ossiculoplasty, revealed an overall median gain of 18.3 dB at 2 months, 22.3 dB at 6 months, and 25 dB 1 year postoperatively on Fletcher frequencies. An air-bone gap closure within 20 dB was achieved in 81% of all cases 1 year postoperatively. No cases of extrusion have been seen in our series.

CONCLUSION

Our findings suggest that malleus allografts are capable of generating good and stable functional results as malleus-stapes assembly.

Histopathology of ossicular implants

Ossicular and cortical bone grafts maintain their morphologic structure for long periods of time and show varying amounts of replacement of nonviable bone by new bone through a slow process of creeping substitution. Cartilage grafts develop chondromalacia, lose stiffness, and tend to be resorbed over time. Plastipore prostheses elicit foreign body giant cell responses with microscopic biodegradation of the implants. There is a great need for the study of well-documented human temporal bone cases with in situ ossicular implants.

[The hardness and osseous structure of preserved ear ossicles]

The mechanical rigidity (breaking strength) of normal human ossicles, preserved with cialit and formalin, was studied in a tension compression testing machine. The bony structure of the ossicles before and after crushing was examined via high-grade magnifying radiography. With this new technique, minute bony details of the ossicles, which up to now could be demonstrated only histologically--consequently destroying the object--can be visualised without inflicting any changes to the ossicle. The different preservation methods had no effect on the structure or the mechanical strength of the ossicles. The fracture lines were distributed at random, with no preferential direction. In further experiments, defects in the ossicles' surfaces, which were cut with diamond burrs, were investigated radiographically and with a scanning electron microscope. The compressed bone dust seals up the opened marrow spaces. This reduces bone resorption significantly, as could be demonstrated with removed ossicular transplants similarly prepared, with had been implanted several years ago. The high grade radiographic magnification revealed that several ossicles which were removed during typical middle ear operations, were covered with metallic powder, originating from the intra-operative contact of the burr with the metallic suction tube. The 10% nickel component of the alloy may cause problems in patients with known nickel allergy, considering the intensive contact with the vast surface of the disseminated metallic dust particles.

Homografts of the tympanic membrane with malleus; histological study in cat

The present experiments on cats were performed to explore the process of survival and take of transplanted homografts of tympanic membrane with malleus, the homografts being respectively preserved in 4% and 0.5% formalin (pH 7.0) solutions, and to explore the reaction of middle ear mucosa of the recipient. The present study also included gross and histopathological examinations of the eardrum and observation of fibers of the lamina propria of the transplanted tympanic membrane by means of polarizing microscopy and of vascularization by intravascular India ink injection. The experiments conducted using a total of 96 cats yielded results leading to the following conclusions. 1) After six months the transplanted tympanic membrane showed nearly normal histologic features, with a fibrous layer between the lining epithelial and thin mucosal layers. The middle ear mucosa also became thinner and was covered with ciliated epithelium at this stage. 2) As regards vascular distribution, most vessels entered from the peripheral regions to become distributed all over the eardrum with mutual anastomoses. 3) Fibrous tissues of the lamina propria of the pars tensa of the transplanted eardrum remained intact over the six month period. 4) The transplanted malleus was neither destroyed not absorbed, and proved to survive well with active vascularization. 5) The microscopic changes observed in the middle ear mucous membrane of the recipient showed non-specific reactions to Gelfoam. The grafts were not subjected to immunological rejection. Homograft thus offer the best grafting material, but seemed to show poor resistance to infection.

The homograft tympanic membrane after 12 years

The homograft tympanic membrane has been utilized in reconstructive middle ear surgery since 1968. Previous reports describing its preservation and use were published in 1971, 1972, 1976 and 1978. Throughout this time the same preservative of 70% ethyl alcohol and the same surgical technique of covering the transplant with canal skin or fascia has been employed. These transplants have been used to supplement, not replace, other grafting tissues, and to improve the graft-take rate and hearing results. The graft-take rate has averaged over 90% for the past 12 year and 98% for the past 5 years. The hearing results have been satisfactory in 69 to 95% of the cases depending on the associated ossicular reconstruction. Furthermore these results have been consistent and have not deteriorated with the passage of time.

Results of reconstructive mastoidectomy with homograft knee cartilage

The technique of reconstructing the posterior canal wall with homograft knee cartilage originally described in 1972 is reviewed and refinements are presented along with additional cases. The homograft knee cartilage is used in conjunction with the homograft tympanic membrane and ossicles to rebuild the middle ear and mastoid as near as possible to anatomical configuration and function. Anatomical follow-up of one year or more is reported on 63 ears. Satisfactory results were obtained in 36 of these ears or 57% of the total. Hearing results are reported overall and in relation to different types of reconstruction. One year or more follow-up demonstrates satisfactory hearing with an air-bone gap of 20 db or less in 77% of the postoperative ears.

Ossicular reconstruction in the absence of stapedial crura

The reconstruction of the ossicular chain when the stapes crura are absent presents a difficult problem in achieving satisfactory functional results in the treatment of chronic oitis media by tympanoplasty. When the malleus handle is present, the cases have been treated mostly by repositioning part of an incus or a piece of cartilage between the malleus handle and the mobile footplate. The problem becomes more difficult in tympanoplastic management of old radical cavities with no ossicules apart from the stapes footplate. Apart of repositioning a part of incus or a cartilage strut between the fascial graft and the footplate, the author has tried, in the management of these cases during the last 3 years, a new "umbrella type" of prosthesis made entirely of tragal cartilage. This prosthesis enables a good resting surface for the new tympanic membrane and the hearing improvement seems to be greater than that resulting from other types of ossicular reconstruction.

Homografts in chronic ear surgery

There has been a considerable expansion in the use of tympano-ossicular homografts in the past decade. The use of homograft tympanic membranes and homograft ossicles as well as combined tympano-ossicular homografts has been shown to be effective in reconstructive surgery for chronic otitis media. While homograft tympanic membranes are effective in the repair of perforations, temporalis fascia is at least as effective and more readily available. Therefore, the unique benefit of the tympano-malleal homograft (TMH) is that it is an effective way of replacing the malleus, the "building block" for reconstruction of the ossicular chain. The indications and techniques for the use of the TMH are presented and illustrated through representative cases. The inclusion of the TMH in the otologist's armamentarium offers another avenue for reconstruction of the chronically diseased ear.

[Implantation of ossicles (A histological study in animals) (author's transl)]

Autogenetic and allogenetic incuses as well as xenogenetic malleus were implanted into the middle-ear of rabbits after different procedures of conservation. The process of healing was studied by histological examination. The different conservation methods are leading to different antigenic qualities of the donor material. A different reorganization along the wurse of the donor vessels is resulting. Accordingly a different extent of osteoneogenesis of the intercellular substance is induced. The vascular tissue showed a revascularization in the case of autogenetic transplantation and in the case of implantation after cialit conservation of 1:5000. Whereas deep-freezing led to swelling, cialit conservation 1:500 to temporary fibrosis of the sides of vessels. Hyalinosis of the vessels was observed after lyophilization and gamma-sterilization of the xenogenetic malleus. The different effects on the healing process are discussed.

[The implantation of lyophilized and gamma-sterilized allogenetic incus and of lyophilized and gamma-sterilized xenogenetic malleus (calf) in rabbits and humans (author's transl)]

The histological reactions to the implantation of allogenetic and xenogenetic lyophilized and gamma-sterilized material into the middle ear of rabbits and men is described. In contrary to the behaviour of allogenetic material the xenogenetic shows a clear minor tendency of revitalisation. The reason is the antigen-antibody-reaction which takes place at the capillary network of the donor and leads to a hylinosis with following obliteration of the vascular rete. Therefore the angiogenetic osteogenesis cannot develop. The clinical usuability of such material is discussed.

Ossiculotympanic transplantation

Continued investigations into current tympanoplasty problems have been carried out in the Eye and Ear Clinic, Royal Victoria Hospital, Belfast. Retrospective studies have been helpful in identifying some of the main problems responsible for many of our unsatisfactory results, both in the irradication of disease and the restoration of aural function. Prospective studies into the behavior of grafting materials for tympanic reconstruction in the experimental animal have led us to an overwhelming preference for natural materials as opposed to plastics or stainless steel. Both homologous and autologous bone and cartilage appear to offer good prospects in ossicular replacement techniques. The most satisfactory material we have used for repair of tympanic membrane defects continues to be either autologous or homologous temporalis fascia. The long-term success of these materials in functional restoration is utterly dependent on continued aeration of the tubotympanic cleft.