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Surgery of the middle ear requires a very high level of fine motor skills. Due to the increased potential for complications in middle ear operations, it is appropriate to acquire these skills beforehand by operating on a model.How satisfactory is the training on suitable models? Are the skills acquired from working on a model transferable to intraoperative situations? Will the type of model and its use for training influence ear surgery in the future?Available publications and own experiences with the Dresden tympanoplasty model (DTM) are analyzed and discussed.Although middle ear surgery makes very high demands on the surgeon and there is a significant risk for severe complications to the ear as a sense organ, there are currently very few options to train surgeons in advance. The DTM is a validated training model, which is capable of closing this gap. Due to the possibility of using a real-time feedback variation of the model, the understanding for reconstruction quality and intraoperative acoustic stress can be improved. The translation of the real-time feedback idea into actual middle ear surgery can improve reconstruction quality in the future.Training on suitable models is indispensable, especially when training as a surgeon to carry out middle ear operations. Adding another sense perception to the internal and external quality assessment of tympanoplasty by inclusion of the real-time feedback option, can optimize learning and operating processes.HINTERGRUND: In der Mittelohrchirurgie bedarf es ausgezeichneter feinmotorischer Fertigkeiten. Aufgrund des hohen Komplikationspotenzials im Mittelohr ist die Ausbildung dieser Fertigkeiten am Modell anzustreben.Wie gut ist die Ausbildungsmöglichkeit an geeigneten Modellen? Können die am Modell erlernten Fertigkeiten in die intraoperative Situation übertragen werden? Beeinflusst das Modell und die Ausbildung daran die zukünftige Ohrchirurgie?Vorliegende Publikationen und eigene Erfahrungen am Dresdener Tympanoplastikmodell (DTM) wurden analysiert und diskutiert.Obwohl die Mittelohrchirurgie hohe Anforderungen an den Ausführenden stellt und am Sinnesorgan Ohr schwerwiegende Komplikationen drohen, gibt es bisher nur wenige Trainingsmöglichkeiten dafür. Das DTM ist ein validiertes Übungsmodell, das diese Lücke schließen kann. Durch eine Real-Time-Feedback-Variante des Modells kann auch das Verständnis für Rekonstruktionsqualität und intraoperative akustische Noxen verbessert werden. Die Übertragung des Real-Time-Feedback-Gedankens in die reale Mittelohrchirurgie kann die Rekonstruktionsqualität zukünftig verbessern.Das Training an geeigneten Modellen ist speziell beim Erlernen der Mittelohrchirurgie anzustreben. Mit dem Real-Time-Feedback kann beim Lernen und Operieren eine weitere Sinneswahrnehmung in die eigene und fremde Qualitätskontrolle der Tympanoplastik sehr wirksam einbezogen werden.

Implantierbare Horgerate werden bei der Versorgung unterschiedlich bedingter Schwerhorigkeiten immer bedeutsamer. Das am haufigsten implantierte Mittelohrhorsystem ist die Vibrant Soundbridge (VSB, Fa. MED-EL, Innsbruck, Osterrreich). Es haben sich, nach Erweiterung der Indikation, verschiedene neue Ankopplungsmoglichkeiten ergeben. In der vorliegenden Arbeit wird das Anregungsverhalten der VSB anhand der Literatur, vorliegender Felsenbeinversuche und mittels Berechnungen im Finite-Elemente-Modell (FEM) eingehend beleuchtet. Daruber hinaus wird auf wichtige Begleitumstande der Ankopplung, Ubertragung und Messung eingegangen.

Hearing aids (HA) provide adequate support for many patients with hearing loss, but not all. Around one third of 10.000 patients provided with hearing aids in the Abbreviated Profile of Hearing Aid Benefit felt no actual benefit when using the hearing aid, although they demonstrated the necessary hearing improvement on speech audiometry. Epidemiological data show bad compliance, especially in older people. Only one in three hearing aid owners wears their device regularly. For this subpopulation of patients active middle ear implants (AMEIs) have been used since 1998. In the present review, the current indications for AMEIs are presented.A selective literature search in PubMed, as well as a guideline search at the Arbeitsgemeinschaft der Wissenschaftlichen Fachgesellschaften e. V. (German Association of Scientific Societies), was carried out.The present review shows that when there is an adequate indication the hearing capacity of patients can be thoroughly rehabilitated and thus their quality of life improved with the help of AMEIs. Although most commercially available systems have a satisfactory risk profile, increased extrusion rates, malfunctioning and facial paresis have been reported in older implant series. The advantages of AMEIs include increased hearing gain, reduced feedback, increased hearing quality, increased speech discrimination in the presence of background noise, and an absence of occlusion.The audiological indication for AMEIs in primary care is usually controversial, since the functional hearing gain and increase in speech discrimination may be small compared with modern conventional hearing aids. AMEIs thus play a main role in the secondary care of patients who do not have sufficient benefit or who have side effects after having a conventional hearing aid fitted.

Bei einer Tympanoplastik des Typs III durch Steigbugeluberhohung („partial ossicular replacement prosthesis“, PORP) oder in Columella-Technik („total ossicular replacement prosthesis“, TORP) muss die Prothesenlange mit den individuellen, intraoperativen anatomischen und physiologischen Gegebenheiten ubereinstimmen. Zur Bestimmung der notwendigen Sizer-Langen der Sizer-Disk wurde auf Datenbanken zuruckgegriffen. Die Messschablone fur die Knorpelgrosenbestimmung zur Abdeckung der Prothesenkopfplatten wurde von den Kopfplatten der Tubinger-Titan-Prothesen (TTP®) sowie der Dresdener-Titan-Prothese abgeleitet. Anschliesend wurden alle Funktionen in eine Kunststoffscheibe integriert. Ergebnis ist ein einfaches und preiswertes Multifunktionsinstrument (Tubinger Sizer-Disk, TSD) zum Einmalgebrauch, das eine exakte Distanzmessung fur jede Prothese bei TORP und PORP erlaubt. Fur die TTP®-Variac ermoglicht die TSD in einfacher Weise die intraoperative Herstellung der Prothese in der vom Operateur gewunschten Lange. Fur die PORP lasst die TSD eine Anpassung des Durchmessers des Prothesenfuses der TTP®, TTP®-Vario und TTP®-Variac zu und stellt eine Messschablone fur die Grosenbestimmung der Knorpelabdeckung des Titanprothesenkopfes zur Verfugung. Sizer und damit hergestellte Prothesen wurden in ersten Tympanoplastiken angewendet. Audiometrische Untersuchungen, die postoperativ nach 6 Wochen durchgefuhrt wurden, erzielten Ergebnisse, die denen einer bereits vorgestellten Studie mit TTP® und TTP®-Vario unter Verwendung des alten Instrumentariums entsprechen. Die neuen Instrumente fuhren zu einer Verbesserung der intraoperativen Praktikabilitat und Vereinfachung. Die audiologischen Ergebnisse bleiben erhalten.

Although the modern technique of otosclerosis surgery introduced by John Shea on 1st May 1956 has already been used throughout the world for almost fifty years it has not been possible to bring in line the differing opinions of surgeons concerning the optimum operation technique, the problems of the fenestration of the footplate, material and form of stapes replacement prosthetics and kind and place of their anchoring on the incus. Moreover, there is considerable disagreement among surgeons on a realistic evaluation of the findings of early and late results. During the last few decades otosclerosis surgery has become the hallmark of modern ear surgery and has been practiced in very highly specialized departments as well as in outpatient departments. The author, who has been very active in otosclerosis surgery since 1959-since 1979 with a modified personal technique-, wishes to prove that it is both meaningful and essential to modify the operation technique further, which is based on his own experiences and on more than 100 international publications. In this paper he presents his modified method, which has been tested on 1800 ears since 1979, as well as the results, achieved in this way.

Implantable hearing aids are not only gaining importance for the treatment of sensorineural hearing loss, but also for treatment of mixed hearing loss. The most frequently used active middle ear implant is the Vibrant Soundbridge (VSB) system (Fa. MED-EL, Innsbruck, Österrreich). Following widening of the spectrum of indications for the VBS, various new coupling systems have been established. Based on the literature, available petrosal bone investigations and finite element model (FEM) calculations, this article summarizes the current knowledge concerning mechanical excitation by the VSB. Important concomitant aspects related to coupling, transmission and measurement are also discussed.

Patients with air-bone gaps or combined hearing loss that cannot be corrected by tympanoplasty can be treated with bone conduction hearing aids. The disadvantages of conventional and percutaneous systems are, on one hand, the obvious external fixation components and on the other hand, the biological and psychosocial problems of open implants. This project was therefore set up to develop a semi-implantable, magnetically anchored transcutaneous bone conduction device, introduce it into clinical application and follow-up the results.The principle of this bone conduction device is the magnetic coupling of an external vibrator via implanted double magnets. After extensive laboratory tests, this method was introduced into the clinic in 2006. Following the initial pilot study, 184 implantations in 143 patients have been performed in Recklinghausen since 2008. Long-term evaluation of 20 congenital atresia patients treated with these devices was possible.Worldwide, more than 3000 of these devices have been implanted. The operative implantation technique is relatively simple. With the new "upside down technique", bone removal is no longer necessary. The 2.6-mm thin implants are hardly noticeable. The hearing improvement is similar to that of other bone conduction hearing aids.This semi-implantable transcutaneous bone conduction hearing device is another option for patients with air-bone gaps, combined hearing loss or single-sided deafness.

Active implantable hearing devices were primarily developed for sensorineural hearing loss. The vibrator coupling mechanisms were oriented towards normal middle ear anatomy and function. The aim of this project was to modify the only fully implantable hearing device with an implantable microphone for application in congenital auricular atresia, Carina™, and to introduce the modified device into the clinic. A special prosthesis was developed for the transducer and its individual coupling achieved by a special cramping system. The system was implanted in 5 patients with congenital auricular atresia. Audiological results were good; with patients' hearing gain exceeding 30 dB HL. Anatomic limits to the system's indications and technical drawbacks are also discussed.

By virtue of direct bone conduction, percutaneous bone-anchored hearing implants offer a high level of wearing comfort, as well as audiologically superior signal transmission due to less dampening. Over the years, titanium implants have been optimized and the surgical technique developed into a minimally invasive intervention without soft tissue reduction. This study aims to investigate the success rates of the various percutaneous implant systems.This retrospective study includes 191 patients who received a total of 283 percutaneous titanium implants for bone conduction hearing systems during the period from 01.01.1989 until 31.12.2013. Patient age ranged from 2 to 81 years (mean 36 years). The mean follow-up duration was 5.2 years.The overall osseointegration success rate was 92.6% and ranged from 90.5 to 100% for the various implant systems (p = 0.6). For children and adolescents, the success rate was 86.8%, compared to 95.2% in adults (p = 0.023). Classical soft tissue reduction was received by 185 patients, mainly via the dermatome technique. The linear incision technique was used in 3.8% of cases and the technique without soft tissue reduction in 3.7% of cases. Revision surgery for soft tissue problems was performed in 4.2% of cases.Success rates in adults were significantly higher than those in children and adolescents. Although success rates improved with the development of new systems, this did not reach statistical significance. Minimally invasive surgery without soft tissue reduction is considered state of the art.

The production of sweat in the temporal skin region may be a serious problem for patients with hearing aids, active middle ear implants or cochlear implants. We report on two patients suffering from a loss of function of their hearing aid and a reduction of the "wear comfort" of an active middle ear implant. The patients underwent intracutaneous botulinum toxin (BTX) treatment of the temporal skin region. In both patients a distinct improvement of their complaints occurred, enabling them to use their hearing aids and active middle ear implants continuously. BTX injections are suited to improve sweat-caused complaints in patients with hearing aids, active middle ear implants and cochlear implants.

In addition to hearing aids, stapesplasty represents the standard treatment of otosclerosis-induced hearing loss. In this procedure, the stapes superstructure is replaced by a prosthesis that is attached to the long process of the incus and communicates through a perforation in the footplate with the perilymphatic space of the inner ear. The removal of the stapes superstructure and perforation of the footplate are the critical steps of this surgical procedure. With the introduction of laser-assisted perforation techniques, the surgical safety of this method has been improved compared to conventional techniques. KTP, argon, as well as diode, Er:YAG and CO(2) lasers are used for stapedotomy. By using the CO(2) laser in conjunction with a scanner system, the number of laser applications required for the perforation of the footplate has been markedly reduced. In contrast to other systems, a more reproducible perforation diameter of the stapes footplate is achieved with a CO(2) laser equipped with a scanner. Complications such as uncontrolled leakage of perilymph, irradiation of inner ear structures or the occurrence of pressure waves with subsequent damage to the inner ear can be reduced by using a CO(2) laser. In this review, the surgical technique of CO(2) laser stapedotomy, including clinically established variants and paying particular attention to the one-shot technique, are described and discussed in comparison to other laser systems.

Even the most sophisticated prostheses for reconstruction of the ossicular chain do not work in the presence of Eustachian tube dysfunction. This review gives an update on the mechanisms of middle ear pressure regulation and middle ear ventilation, as well as methods for measuring the opening and closing function of the Eustachian tube. So far, in most tube function tests pressures are applied far beyond the physiological range in order to open the tube or force it to open. New methods like sonotubometry with perfect sequences (PSEQ) or the application of pressure in the nasopharynx with the Estève technique seem very promising. However, these measurements only provide snapshots of tube function. Presently, new tests are being developed for long-term measurements even in cases with perforated tympanic membranes. Attempts to improve impaired tube function have recently included laser surgery and balloon tuboplasty, yielding positive long-term results requiring verification in larger controlled studies. Eustachian tube dysfunction does not only mean blockage but can also include abnormal patencies of the Eustachian tube, for which new approaches are discussed here. In the case of suspected tube dysfunction, cartilage should be used to avoid early tympanic retraction or recurrent perforation; external ventilation using ventilation tubes should be considered.

Today the middle ear can be reconstructed in various ways: without any ossicular chain reconstruction, with reconstruction using autologous ossicles, with reconstruction using passive alloplastic implants or by using active implants. In recent decades, reconstruction with passive middle ear implants has increased for several reasons. It has been demonstrated that in the case of inflamed mucosa the resorption rate of autologous ossicles is around 15%. Modern alloplastic implants can be considered more resistant to inflammatory processes with high biocompatibility. Furthermore, modern alloplastic implants are low-weight with high rigidity. The greatest advantage lies in better coupling possibilities to the residual ossicular chain because of the introduction of coupling elements and also functional elements which are integrated into the prostheses. Due to the wide variety of passive implants this paper is intended to provide an overview of the best reconstruction solutions for the most typical ossicular chain defects using passive middle ear implants. Particular attention is paid to the use of alloplastic prosthesis compared to the use of autologous ossicles.

The saying "no surgery, no surgical complications" is certainly true for all specialties. Three categories of undesired events may occur following surgery: surgical sequelae, failure to cure and complications. A critical self-analysis of surgical complications often reveals that these arise in vexing fashion according to Murphy's law, i.e. "what can go wrong, will go wrong". Incomplete preoperative evaluation, insufficient exposure of the surgical field, failure to identify surgical landmarks and misjudgment of the patient's preoperative complaints may culminate in an undesired surgical outcome. Modern preoperative radiology, the possibilities of actual or even virtual temporal bone drilling in the laboratory and the surgeon's level of experience all ensure the relative rarity of relevant surgical complications in otology.

The incidence of middle to high-grade ear malformations in Germany is approximately 150 per year. For many years autologous rib cartilage has been used for ear reconstruction as a framework material. In spite of a good biocompatibility of autologous rib cartilage there are potential risks of framework deformity as well as donor site morbidity. The advantages of osseo-integrated implants have provided patients with predictable esthetic results, durability and improved retention of the ear prostheses. Porous polyethylene ear implants (Medpor®) have been used for over 20 years as a suitable framework material. The advantages of this promising technique are good biocompatibility, short hospitalization time and the possibility of a one-step reconstruction of total or subtotal ear defects. The reconstruction of ear malformations with porous polyethylene ear implants is possible even in patients over 6 years old. Moreover, polyethylene promotes revascularization due to its porous structure, resulting in a good incorporation at the implantation site. The use of porous polyethylene ear implants permits a more expedient, less invasive and reliable reconstruction in moderate or high-grade ear malformations with very convincing results.

Bone anchored hearing aids (BAHA) achieve optimal acoustic coupling by means of direct bone conduction via an osseointegrated percutaneous titanium implant. Currently this system has a record of over 30 years of clinical application and reliability. Patients with bilateral hearing loss with air-bone gaps will benefit from bilateral BAHA fitting. Likewise, unilateral conductive hearing loss with normal hearing on the other side can be treated with a BAHA. New developments in this field include the BAHA Intenso and also novel implant systems, such as the Epiplating system by Medicon, the alpha system by Otomag and the OBC system by Otorix. Due to the advantages of the BAHA system (possibility of preoperative testing, simple surgery without the risk of inner ear damage, MRI compatibility, etc.), the BAHA will keep its important role in hearing rehabilitation even in the era of other partially and totally implantable hearing devices.

Chronic tube dysfunction plays a major part in the development of chronic otitis media. Owing to the complex structure of the Eustachian tube, the development of successful therapeutic approaches to the treatment of tube function disorders is still difficult even today. The application of a gold tube wire (tube conductor) was reported in 1991, but no studies have yet been performed on the postoperative success rates achieved with tube conductors.In a retrospective study, the data relating to 125 patients who were operated on from 1996 to 1999 for treatment of different forms of chronic otitis media and also underwent transtympanic tube conductor implantation to improve tube ventilation disorder were evaluated. Data on pre- and postoperative tube function were available for 96 patients after a mean follow-up period of 18 months.All tube implantations were achieved without complications. Tube function normalized in 8 patients (8.3%), while the tube ventilation disorder remained unaffected in 88 patients (91.7%). A total of 23 (18.4%) tube conductors have so far been removed. The reasons for removal include persistent tube ventilation disorder, dislocation of the tube conductor in 7 patients (5.6%) and granulation around the tube wire in 7 cases (5.6%).The chronic tube ventilation disorder was improved by implantation of a tube conductor in only 8.3% of the patient population investigated. We are therefore of the opinion that this is not a suitable treatment for chronic tube ventilation disorders. The development of new, effective therapeutic approaches to the treatment of chronic tube ventilation disorders remains a priority.

In spite of modern technology conventional hearing aids are only helpful in a limited number of patients with sensorineural hearing loss. In particular, patients presenting with moderate to severe high frequency hearing loss but only mild hearing loss in the low frequencies suffer from problems associated with conventional hearing aids such as occlusion of the ear canal and feedback. The aim of the study was the evaluation of rehabilitation of patients with high frequency hearing loss with the active middle ear implant Vibrant Soundbridge.The Vibrant Soundbridge was surgically implanted into 30 patients, and the floating mass transducer was clipped onto the long process of the incus. Out of the 30 patients 9 presented with a ski slope audiogram of high frequency hearing loss of 25 dB within 1 octave in the frequency range 1000-8000 Hz. Main outcome measures were pure tone audiometry, speech audiometry in quiet and in noise.Residual hearing was preserved in all cases. Functional hearing gain was in proportion to the individual hearing losses and was remarkably high in the high frequencies up to 8000 Hz. Mean functional gain was 34 dB in the frequencies between 2000-8000 Hz. Speech recognition scores in quiet and in noise were significantly higher with the implant compared to the unaided situation.The middle ear implant Vibrant Soundbridge has been shown to be perform extremely well especially in the high frequencies. It offers a new solution for rehabilitation of high frequency hearing loss.

For type III tympanoplasty by partial ossicular replacement prosthesis (PORP) or total ossicular replacement prosthesis (TORP), the length of the prosthesis must match the individual intraoperative anatomical and physiological characteristics.Databanks were used to determine the necessary sizer length of the sizer disc. The measurement template for the size of the cartilage to overlay the prosthesis headplate was derived from the headplates of the Tübinger titanium prostheses (TTP) and the Dresdener titanium prostheses. Finally all functions were integrated into a synthetic plate.The result was a simple and reasonably priced disposable multifunctional instrument (Tübinger sizer disc TSD) which allowed an exact measurement for every prosthesis in TORP and PORP. For the TTP-Variac, the TSD enabled the simple intraoperative production of prostheses with the length desired by the surgeon. For PORP the TSD enabled an adaptation of the diameter of the prosthesis foot for TTP, TTP-Vario and TTP-Variac and provided a template for the size determination of the cartilage overlay of the titanium prosthesis head. The sizers and the resulting prostheses were used for initial tympanoplastic operations. Audiometric investigations carried out 6 weeks postoperatively gave results corresponding to those previously obtained in a study with TTP and TTP-Vario using the old instrumentation.The new instrumentation leads to an improvement of the intraoperative practicability and a simplification. The audiological results remain the same.

In order to further optimize the surgical technique with CO(2) laser in stapes surgery, a scanner system was used to obtain a footplate perforation of 0.5-0.6 mm with only one laser application ("one-shot" stapedotomy).A total of 255 patients with otosclerosis were submitted to primary CO(2) laser stapedotomy with a SurgiTouch scanner. This study discusses the surgical technique and clinical results.An adequately large perforation diameter could be achieved with a single shot in 68% of the patients treated. In 14% of the patients, a second laser application at the same site was necessary. In 18% the perforation had to be enlarged by several slightly overlapping laser applications without using the scanner. There was no evidence of laser dependent inner ear affections.CO(2) laser, combined with modern scanner systems, is well suited for application in stapes surgery.

Today, the reconstruction of the ossicular chain is standard in middle ear surgery. It is performed as a one step procedure in cases of non-inflamed middle ears, as well as in cases of chronic ear diseases. In contrast to the past, a large tympanic cavity is today regularly reconstructed, which contributes to a normally ventilated middle ear. Reconstruction of the ossicular chain is necessary to keep the tympanic membrane in its normal position.However, many modern prostheses are available with different designs and material properties. This article aims to give an overview of the acusto-mechanical and surgical aspects of ossicular chain reconstruction. After a description of normal middle ear vibration, the biomechanical background of the reconstructed middle ear (incus reconstruction, stapes reconstruction) is discussed.

We report the case of a 60 year old patient suffering from a displacement of her stapes piston after a rear-end collision with whiplash injury. Immediately after the accident she complained hearing loss and tinnitus. During the following days, the patient developed vertigo with lateropulsion. Diagnostic tympanoscopy showed a piston dislocation with migration into the vestibulum as a result of the blunt head trauma.

The reconstruction of the stapes superstructure is still a problem. Efforts for the fixation of implants on the footplate did not show satisfying results yet.In 6 guinea pigs a biovitro ceramic (Bioverit) was placed on the stapes footplate after removal of the superstructure. The exclusive bony fixation of the implants on the footplate should be achieved by the use of silicone foils. For control purposes replantation of autologous ossicles was done in one group of 3 animals and a sham operation was performed without any use of implants in the other group of 6 guinea pigs.After 21 weeks not only bony fixation of the implant with the footplate was observed, but furthermore with the wall of the middle ear. Bone formation was detected along the silicone foils. In the first control group of animals we found bony fixation of the replanted ossicles and even a bow-shaped reconstruction of the stapes superstructure in the second.The guinea pig was not an ideal model for questions of middle ear reconstructions due to its enormous potential for bone formation. In this animal model bony fixation of glass-ceramic with the stapes-footplate could be induced.

The application of cartilage in tympanoplasty has been generally accepted, because cartilage as a bradytrophic tissue allows stable and functionally reliable reconstruction of the eardrum even in difficult pathological conditions (such as subtotal defects, tympanosclerosis etc.). A special surgical technique using small cartilaginous chips for the reconstruction of the eardrum has been developed by J. Heermann, who introduced it as Palisade Cartilage Tympanoplasty (PCT). Although being increasingly applied in otosurgery, this technique has to date neither been evaluated regarding morphological and hearing results nor regarding its combination with titanium ossicular reconstruction prostheses.Therefore we reviewed 84 of 94 ears (92 patients, 58 female, 34 male) 12 to 36 months after PCT.A recurrent defect was seen in 2 ears (1 adhesive otitis, 1 subtotal defect). There were no extrusions of prostheses. Preoperatively an ear-bone-gap of 0-10 dB was seen in 2 ears, 11-30 dB in 48 and 31-59 dB in 34 ears. Postoperatively the corresponding numbers were 25, 50 and 9 ears.The low rate of recurrent tympanic membrane defects (2.4%) shows that palisade cartilage tympanoplasty is particularly appropriate for the management of difficult indications in middle ear surgery. Further, it could be demonstrated that the PCT can be combined safely with titanium ossicular reconstruction prostheses. Regarding postoperative hearing results the negative preselection of pathological conditions has to be considered.

A case of hyperacusis after tympanoplasty is presented. A 62-year-old woman experienced unilateral conductive hearing loss for about 60 years after antrotomy in infancy. Neurological or otoneurological symptoms were not evident. Tympanotomy showed a missing incus with discontinuity of the chain. Reconstruction was performed by interposition of a partial ossicular replacement prosthesis (PORP). The postoperative audiogram revealed minimal perceptive hearing loss in the high-frequency field in the operated ear. Several weeks after middle ear surgery, the patient complained of hyperacusis on the operated side, which persisted for more than 2 years. To alleviate the unpleasant sensations, an ear plug was used by the patient. In spite of the asymmetric hearing loss, no late onset auditory deprivation could be diagnosed. The pathophysiological causes of the hyperacusis have not yet been clarified. Possible reasons are discussed.

The sound transmission properties of three different commercially available middle ear implants and the prototype of a complete middle ear prosthesis (CoMEP) were evaluated with a special measurement system that permits standardized conditions. This system uses a mechanical middle ear model (MMM) which approximates the impedances of the tympanic membrane and inner ear. The implants were fitted under defined conditions into the MMM. Displacement of the artificial stapes footplate of the MMM was measured with an optical probe. The measurements of different middle ear prostheses showed that the mass of the implant was the most important factor for optimum high frequency transmission. The lightest implant (4 mg, titanium) showed the best results. The CoMEP revealed the highest sensitivity because of a slight enlargement of the diameter of the artificial tympanic membrane. These findings show that the CoMEP is able to restore sound transmission to a normal range. In a second experiment one of the implants was fitted into the MMM with different forces. The increase of stiffness produced a slightly better high frequency transmission at the expense of low frequency sensitivity. Hence, the fitting of the implant may not be too stiff because of its loss of mobility within a significant frequency range.

To determine the applicability of alloplastic materials as bone substitutes it is now standard procedure to test materials for possible toxic effects and to study their behavior in animal models and cell cultures. This is especially important with respect to middle ear implants that can be put at risk by recurrent infections and require additional testing in a bacterially contaminated environment.In the present study ionomeric cement (V-O CEM), bioactive glass ceramic and hydroxyapatite were subjected to contamination with S. aureus, E. coli, Pr. mirabilis, Ps. aeruginosa and Enterococci using agar diffusion and microbial suspension tests and examined for their antibacterial activity. A special feature of V-O CEM that had to be considered was that it could be implanted in two physical states (as a viscous substance and a fully hardened material).The agar diffusion test showed that an antibacterial effect of freshly mixed V-O CEM was demonstrable for up to 60 min. In the microbial suspension test growth of E. coli was found to be promoted after 48-h incubation by V-O CEM set for 1 h. S. aureus exhibited a depressed growth, while Pseudomonas cultures demonstrated cell death after 48 h. V-O CEM set for 24 h and 7 days, respectively, exerted a similar though less pronounced effect. Using the microbial suspension test, a comparison was also made of the antibacterial activities of 24-h V-O CEM, bioactive glass ceramic and hydroxyapatite against cultures of S. aureus, Pseudomonas and E. coli. The inhibitory effect of hydroxyapatite on the growth of S. aureus was found to persist beyond the 48-h incubation period. There was slight growth of E. coli in the presence of bioactive glass ceramic after 48 h, whereas hydroxyapatite produced inhibition of microbial growth. V-O CEM inhibited the growth of Pseudomonas, unlike bioactive glass ceramic and hydroxyapatite, which transiently promoted bacterial growth.Our findings showed that V-O CEM, bioactive glass ceramic and hydroxyapatite exhibited material-dependent bacterial colonization and thus resembled polymeric bone substitutes (susceptible to invasion by S. epidermidis) and metals (sensitive to S. aureus). In general, users of bone substitutes should conduct preclinical tests in order to obtain advance information on the properties of possible replacement material. Since there can be varying interactions between the materials studied and bacterial growth, material-specific effects on bacterial growth should be investigated. While it is recognized that in vitro studies are an inadequate simulation of the clinical situation, they still provide some insight into the likely behavior of a bone substitutes in human sites.

With the aid of a mechanical middle ear model (MMM) the sound transmission properties of different middle ear implants were investigated. Input of the MMM involved a broad-band signal from 100 to 5000 Hz that was supplied by a miniaturized loudspeaker. Displacement of an artificial stapes footplate was measured by a fiberoptic probe. The transfer functions of four different total ossicular replacement prostheses (TORPs) of different materials and shapes were compared. Three of the devices revealed similar transfer functions which corresponded to the typical curve of the normal middle ear. One of the prostheses demonstrated a high-frequency deterioration of approximately 5 dB. This effect was explained by a 3- to 6-times higher mass of the implant when compared to the others. Altogether, the weight of the prosthesis seems to have the most marked impact on sound transmission to the inner ear, whereas stiffness of the implant itself is less crucial as long as it can be regarded as a rigid body.

Special coupling devices made of pure gold or titanium have been developed to connect a new implantable hearing aid transducer (Tübingen implant) to the ossicular chain. They allow piezotransducer probe-tip connection to the long process of the incus or the stapedial head. Similar to the design of conventional PORPs (partial ossicular replacement prostheses), the coupling devices can be fixed at the ossicular chain, e.g., with the eye loop of stapedial piston prostheses or the bell element of golden wire PORPs. A crimp technique allows connection between coupling device and transducer probe tip [5]. The main disadvantage in connecting the long process of the incus or the stapes having is to drill a dorsal tympanotomy in the posterior wall of the ear canal during surgery. The short distance between tympanotomy and N. facialis contains serious surgical risks. To avoid the risk of facial paralysis, Fredrickson's alternative coupling technique for the body of the incus is investigated in this paper [2]. In this case, the transducer probe tip will be positioned to the incus body and placed on its surface with controlled elastic displacement of the ossicular chain. The simple direct attachment of the probe-tip end on the surface of the incus, however, will not guarantee a stable long-term connection. Thus, by creating a conical, 0.5-to 0.7-mm-deep hole in the incus, the probe tip will be fitted much better. With a novel surgical Erbium-YAG laser this can be done in a contactless procedure. In this paper, first results of microsurgical laser applications with human temporal bones will be shown.

Animal experiments with microbiologic examinations and studies in cell cultures have shown that ionomer cement is a biocompatible and biostable bone replacement material in the head and neck region. Clinical and functional results of its use in the human middle ear have proven to be satisfactory during a maximal period of 2.5 years observation. The present trial was continued in order to determine the long-term behavior of ionomer cement (Ionos partial and total ossicles) after reconstruction of the ossicular chain. The ossicular chain was reconstructed in 343 cases and included various losses of one or more of the ossicles (i.e., incus, incus and malleus, incus and stapes superstructure, and malleus, incus and stapes superstructure). Follow-up extended over a maximum period of 5.5 years. Patients were examined under a surgical microscope and a pure-tone audiogram was performed at regular intervals. Clinical and audiological results were obtained 3 months postoperatively in all reconstructive procedures performed (partial and total ossicular replacement prostheses). These were mainly stable but revision surgery was necessary in 9% of the cases. In 5% the prosthesis was displaced and in 3% the prosthesis had partially migrated through the eardrum. Complete rejection of the implants was observed in the course of infections in 1% of the cases. Ionomer cement as a bone replacement material was found to have all required criteria for its use in the middle ear (biocompatibility, biostability, stable audiologic results and easy workability). These findings show that ionomer cement can be recommended in all cases of ossicular reconstruction.

Ionomer-based cements are obtained by the reaction of an aluminum-fluoro-silicate glass with a polyalcenoic acid. During setting and hardening the cement bonds closely with adjacent hard tissue. The previous implantation of this material in the baboon tibia has held great promise as a possible use in bone replacement. In the present study the cement was tested concerning its biocompatibility and biostability in the middle ears of 64 rabbits. Viscid cement paste was inserted into the epitympanic space of each animal. A preformed cement strut was then placed to serve as a columella between the eardrum and stapes footplate. During a subsequent interval of 28 days up to 2 years middle ear specimens were evaluated under a surgical microscope, following which histologic sections were studied under light microscopic conditions. Findings demonstrated that after insertion of freshly mixed cement a firm adhesion to bone developed that proved to be biocompatible and biostable over time. After 28 days the preformed and fully hardened implants were overgrown by a delicate mucosa normally present in the middle ear. No evidence for any rejection of the implants could be found. The experience available to date indicates that ionomer cement is biocompatible and biostable, easy to handle and workable without splintering. With appropriate use it represents a useful implant material in surgery of the head and neck.