Academic literature on the topic 'Incudostapedial joint gap'

AbstractObjective:To determine the effectiveness of biocements in rebridging isolated incudostapedial erosion.Methods:A review of the use of biocements for isolated incudostapedial joint erosion was performed on publications from 1998 to 2012 available from Medline, Embase and Pubmed. Inclusion criteria were papers published in English, case series or comparative studies with more than 10 patients, isolated incudostapedial erosion through chronic ear disease, minimal air-bone gap less than 20 dB (or air-bone gap less than 10 dB) and follow up for at least one year.Results:In 108 patients, rebridging ossiculoplasty was performed using hydroxyapatite cement. Closure of air-bone gaps less than 20 dB and less than 10 dB was achieved in 80–94.4 per cent and 29–75 per cent, respectively. Glass ionomer cement was used in 318 patients. Closure of air-bone gaps less than 20 dB and less than 10 dB was achieved in 74–94 per cent and 40–76 per cent, respectively.Conclusion:Biocements can be successfully used to close isolated incudostapedial erosions. Larger comparative prospective studies documenting the length of eroded incus and types of reformation of the incudostapedial joint, with standardised reporting, are needed in the future.

AbstractObjectiveThis study aimed to evaluate the long-term results of ossiculoplasty using bone cement.MethodForty patients (24 females and 16 males; mean age: 34.1 ± 11.8 years; range, 9–54 years) with chronic otitis media with perforation but without cholesteatoma who had undergone incudostapedial rebridging ossiculoplasty using bone cement were evaluated retrospectively. Pre-operative and post-operative audiograms were evaluated. Bone conduction, air conduction and air–bone gaps were calculated according to international guidelines.ResultsThere was a mean reduction in pre-operative and post-operative air conduction (12.30 ± 11.98 dB), and this result was significant (p = 0.0001). There was a mean reduction in pre-operative and post-operative bone conduction (4.30 ± 6.69 dB), and this result was significant (p < 0.0001). The pre-operative air–bone gap was 27.65 dB and decreased to 19.65 dB during follow-up (p = 0.0001). No adverse reactions or complications were observed.ConclusionBone cement is reliable for the repair of incudostapedial-joint defects.

Temporal bone trauma can cause hearing loss and in case of prolonged conductive hearing loss, traumatic ossicular injury should be considered. Separation of the incudostapedial joint is the most common lesion, and stapediovestibular dislocation is relatively rare but can easily cause perilymphatic fistula. Here, we report a very rare case of external stapediovestibular dislocation after trauma, ending up with successful surgical outcome. A 27-year-old man with non-progressive hearing loss on the right side since childhood visited the clinic. Audiogram showed a conductive hearing loss with air-bone gap of 55 dB on the right side. Temporal bone CT revealed the disruption of ossicular chain. An exploratory tympanotomy identified multiple ossicular disruptions including external stapediovestibular dislocation with shiny fibrous membrane sealing the oval window. Ossicular chain reconstruction was performed using the total ossicular replacement prosthesis of titanium. A postoperative audiogram showed a recovery of air-bone gap less than 10 dB. To the best of our knowledge, this is the first case of external long-standing stapediovestibular dislocation, with oval window completely sealed with fibrous membrane, ending up with successful hearing recovery by surgery. This case would help dealing with such condition which can be encountered in the clinic.

A piezoelectric membrane transducer which offers an approach to treat sensorineural hearing loss is introduced. The sensor and the actuator element each consist of a titanium membrane with a single crystal piezo and are clamped into the same assembly housing. The transducer is placed into the incudostapedial joint gap (between incus and stapes ossicle) which offers a straightforward implantation after the drilling of an access through a mastoidectomy which is state of the art for otology surgeries. The sensor is measuring the force transmitted through the ossicular chain onto his membrane on the incus-side of the housing. An associated signal processing drives the actuator at the opposite side of the sensor to amplify the movement transmitted by the ossicular chain to the inner ear. The movement of the stapes footplate is related to the hearing perception. Therefore the proposed concept can be used as part of a fully implantable hearing aid. A finite elemente model (FEM) of a transducer is built and implemented in a existing FEM model of the middle ear. Both sensor and actuator performance span up a working range for the transducer which ranges from about 20 to 30 dB SPL up to 90 to over 120 dB SPL. In this study the range of the workspace is evaluated in dependency of the chosen piezoelectric material which can lead to significant changes of the results.

<p class="abstract"><strong>Background:</strong> Chronic suppurative otitis media can cause a wide range of pathologies in the middle ear that include irreversible mucosal changes, granulation tissue formation, cholesteatoma, tympanosclerosis, and destruction of ossicles. Knowledge regarding ossicular discontinuity before surgery enables the surgeon to be prepared for ossiculoplasty. Objective was to study the pre-operative clinical, audiological and microscopic findings in chronic otitis media mucosal type and correlate preoperative findings with intra-operative ossicular necrosis. </p><p class="abstract"><strong>Methods:</strong> Study design was observational, descriptive and cross sectional study. All patients were subjected to detailed clinical, otoscopic and microscopic examination to assess the size and site of perforation, presence or absence of ear discharge, granulation tissue, tympanosclerosis in the middle ear, exposure of incudostapedeal joint and condition of middle ear mucosa. Pure tone audiogram was also done. All patients underwent tympanoplasty±cortical mastoidectomy and the intraoperative findings of ossicular necrosis were noted. </p><p class="abstract"><strong>Results:</strong> Of the 105 patients, 18(17.1%) had ossicular necrosis. Bivariate analysis showed positive correlation for long standing disease (p=0.004), presence of discharging ear (p=0.014), polypoidal middle ear mucosa (p=0.000) granulations in middle ear (p=0.000) and also when incudostapedeal joint was exposed (p=0.005). Mean Air bone gap was higher with 35 dB in ossicular necrosis and 22.7 dB in intact ossicular chain was also statistically significant (p=0.0001).</p><p class="abstract"><strong>Conclusions:</strong> Ossicular necrosis was best indicated by the presence of polypoidal mucosa, granulation in the middle ear and higher air-bone gap on audiometry. However longer duration of disease, persistent active stage of disease and exposure of incudostapedeal joint were also found to be significant.</p>

Fragestellungen • Welchen Signalertrag kann ein Kraftsensor auf Basis eines Einkristallpiezo im Incudostapedialgelenk liefern? • Welchen Einfluss haben die anatomisch variierenden Randbedingungen des Mittelohres sowie Variationen der Positioniergenauigkeit? • Welche Leistungsparameter kann ein Wandler erreichen welcher das Sensorkonzept um ein stapesseitiges Aktorelement erweitert? • Welche prospektive medizinische Indikation lässt sich aus den Leistungsparametern abschätzen? Material und Methode Untersucht wurden sowohl Sensoren als auch Sensor-Aktor-Elemente, im Folgenden Wandler genannt, zum Einsatz im ISG des Mittelohres. Die Abmessungen betrugen jeweils 4.5x2.5x1 mm. Die Einkristallpiezos wurden dabei innenliegend auf je eine dünne ovale Biegeplatte aus Titan geklebt. Mit einer entsprechenden Durchführung der Anschlusskabel durch das Gehäuse ist eine hermetische Dichtung und damit die Biokompatibilität der Gesamtbaugruppe realisierbar. Durch die Bauform entspricht die Wirkungsweise von Sensor- und auch Aktor-element hauptsächlich einem Biegewandler. Der Sensor ist ein Kraftsensor. Der Aktor arbeitet abhängig von der Kettenvorspannung als eine Mischung aus Weg- und Kraftgeber. Die Elemente lagen jeweils als aufgebautes Testmuster vor. Sie konnten sowohl in einem physikalischen Modell des Mittelohrs als auch in Humanpräparaten untersucht werden. Als Eingangssignal kam jeweils ein Schallsignal über einen Geber im Gehörgang zum Einsatz, welches mit einem Mikrofon vor dem Trommelfell als Referenz gemessen wurde. Ein Maß für den Höreindruck der hypothetischen Patienten/Patientinnen stellt, wie bei Untersuchungen am Felsenbein üblich, die Bewegung der Steigbügelfußplatte dar. Diese kann im Felsenbein mit einem Laser Doppler Vibrometrie (LDV) und im Modell mit einem Mikrofon in einer Hohlkammer unter der Membran, auf welcher der künstliche Steigbügel sitzt, gemessen werden. Das dynamische Messsignal des Sensors wurde als elektrische Spannung aus dem Piezoelement nach einer Vorverstärkung von einer Messkarte im PC erfasst. Die Signalverarbeitung im kombinierten Sensor-/Aktorbetrieb erfolgte mit einem Field Programmable Gate Array (FPGA). Das Aktorelement wurde ebenfalls von diesem angesteuert. Durch einen Vergleich der Stapesfußplattenschwingung bei Aktoranregung und Anregung mit Schalldruck im Gehörgang konnte jeweils auf einen äquivalenten Schalldruck zurückgerechnet werden. Für den kombinierten Wandlerbetrieb wurde ein Least Mean Square (LMS) zur Rückkopplungsunterdrückung auf dem FPGA implementiert. Der Sensor wurde in zehn Felsenbeinen untersucht, der kombinierte Wandler kam in sechs Felsenbeinen (zwei ohne und vier mit mittels CO2-Laser erweitertem Gelenkspalt) zum Einsatz. Der Zugang erfolgte dabei über eine posteriore Tympanotomie mit Auftrennung des ISGs. Dies und die Insertion von Sensor oder Wandler erfolgte mit Standardinstrumentarium. Weitere fünf Felsenbeine wurden entlang der Normalenebene zur Stapeslängsachse auf Höhe des ISGs gespalten um Kraft-Weg-Messungen mit Kraftmesszelle und Lasertriangulationssensor durchführen zu können. Der laterale Schalleitungsapparat (Gehörgang, Trommelfell, Hammer-Amboß-Komplex) und der mediale Teil (Stapes, rundes und ovales Fenster, Innenohr) blieben hierbei intakt. Dadurch konnte die Vorspannung auf den Sensor nach Einbau und die amboss- und sensorseitige statische Steifigkeitsvariation der Kette bei Auslenkung untersucht werden. In einem Finite-Elemente-Methode (FEM) Modell des Mittelohrs und des Sensors konnten zur Validierung der Messergebnisse vergleichende Simulationen durchgeführt werden. Da das Simulationsmodell auf dynamische Felsenbeinmessungen gefittet ist sind sowohl quasistatische Untersuchungen als auch Aussagen über das Verhalten der Kette bei Vorspannung nur eingeschränkt möglich. Die Ergebnisse der Wandlermessungen wurden in ein Audiogramm eingetragen und mit Literaturdaten für typische Formen der Hörschädigung verglichen. Hiermit konnte eine erste Einschätzung über eine mögliche zukünftige medizinische Indikation getroffen werden. Ergebnisse und Schlussfolgerungen Das Sensorelement des Wandlers erzielte bei Schallanregung mit 1 Pa am Trommelfell Signalerträge von 0.1 mV bis 1 mV im audiologischen Frequenzbereich. Der Sensor nutzt einen Teil der natürlichen Übertragung im Gehörorgan (Gehörgang, Trommelfell, Hammer, Amboss). Die Übertragung des Signals erfolgt auf dem natürlichen Übertragungsweg. Dies kann einen positiven Einfluss auf Parameter wie das Klangbild oder das Richtungshören haben. Der Sensor zeigte sich robust gegenüber verschiedenen äußeren Einflussfaktoren. Kleine Variationen der Sensorposition oder zusätzliche Kontaktpunkte mit umliegenden Strukturen an Ambossfortsatz oder Hammergriff gehen mit einem Signalverlust von etwa 5 dB einher. Ein zusätzlicher Kontakt am Promontorium erzielt durch die verbesserte Lagerung des Sensors einen Signalgewinn von 5 dB. Die Leistung des Wandlers, insbesondere des Aktorelements, ist sehr stark von der Vorspannung in der Ossikelkette abhängig, welche bei der Wandlerinsertion hervorgerufen wird. Durch ein Aufweiten des Gelenkspalts versteift sich die Ossikelkette stapesseitig mehr als ambossseitig. Mit Hilfe künstlich erweiterter Gelenkspalte im Felsenbeinexperiment konnte das Verhalten zukünftiger miniaturisierter Wandlerelemente studiert werden. Der Dynamikbereich des Wandlers erstreckt sich experimentell zwischen einer sensorseitigen Hörschwelle mit breitbandig 30 dB Sound Pressure Level (SPL) und einem maximalen äquivalenten Aktorpegel von tieffrequent 70 dB SPL bis zu hochfrequent 120 dB SPL. Die Verstärkungsleistung innerhalb dieses Dynamikbereichs liegt hochfrequent bei 30 dB. Eine zukünftige medizinische Indikation des Wandlers kann im Bereich der Hochtonschwerhörigkeit und damit auch der klassischen Altersschwerhörigkeit liegen. Eine Behandlung von Patienten mit einer typischen Lärmschädigung ist ebenfalls denkbar. Der Sensor erscheint bereits für verschiedene Applikationen anwendbar während es für den kombinierten Wandler noch einige offene Fragen gibt, nichtsdestotrotz das Konzept bereits erfolgversprechend ist. Während die Leistungsfähigkeit des Wandlers prinzipbedingt durch die schwebende Lagerung nicht über den kompletten Frequenzbereich vollständig auf dem gleichen Niveau anderer implantierbarer Hörsysteme liegt, zeichnet sich das Konzept besonders durch einen vergleichsweise einfachen und prinzipiell reversiblen Eingriff aus.:I Einleitung II Inhalt und thematischer Zusammenhang der Publikationen III Publikation 1: Influence of the middle ear anatomy on the performance of a membrane sensor in the incudostapedial joint gap IV Publikation 2: Examination of a mechanical amplifier in the incudostapedial joint gap: FEM simulation and physical model V Publikation 3: Fully implantable hearing aid in the incudostapedial joint gap VI Ergebnisse und Diskussion VII Zusammenfassung VIII Summary
Background Implantable hearing systems have been a research topic for some time. Because of the im proving technology especially in terms of electronics miniaturisation and power supply fully implantable devices become the focus of attention. The performance parameters of existing components often meet the technical requirements but lack medical practicability. The insertion of the devices is often a very complex procedure and causes non-reversible changes in the patient’s anatomy. A new transducer system for sensor and actuator elements is introduced. It attempts to account for a reversible minimally invasive approach and feasible handling. The main idea is to insert a transducer into the Incudostapedial Joint (ISJ) gap. The design consists of a titanium housing with one or two titanium bending plates which are internally equipped with single crystal piezos for signal-acquisition or -generation. The attachment of the transducer is free floating in the joint gap without additional fixation points in the tympanic cavity. This concept enables a reduced sensitivity to body noise. The publications deal with the analysis of possible performance parameters of the transducers components in experiment and simulation. A further emphasis of the studies is how the humans highly variable anatomy affects the results. Questions • Which signal yields a force sensor based on a bending plate single crystal piezo in the ISJ? • How does the anatomical variation and the position accuracy influence the results? • What performance is to be expexted of a combined sensor/actuator transducer? • What is the prospective medical indication of the proposed transducer design? Material and methods A sensor and a transducer consisting of a sensor and an actuator element for application inside the ISJ gap were studied. Both could be prospective components of future Cochlea Implants (CIs) or Active Middle Ear Implants (AMEIs). The dimensions are 4.5x2.5x1 mm. The single crystal piezos are glued inside a thin oval titanium plate, with a proper lead of the wires out of the hermetically sealed housing ensuring biocompatibility of the whole assembly. The sensor- and actuator element mainly act in bending mode. The actuator works in a mix between force- and displacement actuator dependending on the ossicular chain pretension. The elements used were manually constructed prototypes. Measurements were performed with the elements inserted into a physical model of the middle ear as well as in human temporal bones. A sound generator’s signal in the auditory canal was the input into the system. The sound signal was measured in front of the tympanic membrane by a reference microphone. The movement of the stapes footplate was used as a measurement for the theoretical hearing sensation. It was measured either by Laser Doppler Vibrometry (LDV) for the temporal bone measurements or with a small microphone inside a cavity beyond the physical models plastics membrane equipped with the artificial stapes. The dynamic signal of the sensor in the form of an electrical voltage from the piezo element was preamplified and subsequently acquired by a data acquisition card. The signal conditioning and processing for the combined sensor- actuator-transducer was realised with an Field Programmable Gate Array (FPGA) card. With a comparison of the stapes footplate movement at actuator-excitation and sound-excitation a equivalent sound pressure could be calculated. For the combined transducer-operation a Least Mean Square (LMS) was established to suppress the feedback between sensor and actuator. The sensor was examined in ten temporal bones, the combined transducer was evaluated in six temporal bones (two unaltered and four with a joint gap extended by a CO2-laser). The access was untertaken in terms of a posterior tympanotomie with separation of the ISJ with needle or sickle knife. The insertion of sensor or transducer was done with standard instruments. Further five temporal bones were split normal to the stapes long axis at the level of the ISJ gap to measure force-displacement relations with load cell and laser triangulation sensor. The lateral sound conducting apparatus (auditory canal, tympanic membrane, malleus-incus-complex) remained intact as well as the medial part (stapes, inner ear with round and oval window). Therefore the pretension on the sensor element after insertion and the variation of the stiffness on both parts of the ossicular chain could be observed. In an Finite-Elemente-Method (FEM) model of the middle ear and the sensor the measurement results could be validated. Because the simulation model is fitted to dynamic temporal bone measurements the prediction of the systems behaviour is has some restrictions for quasistatic examinations and the analysis of the ossicular chain under pretension. The results of the transducer measurements are endorsed in an audiogram and compared with literature und typical forms of hearing impairment. This is sufficient for a first estimation of the prospective medical indication. Results and conclusion The transducer’s sensing element shows a signal yield from 0.1 mV to 1 mV for a sound pressure excitation of 1 Pa at the ear drum. The sound transmission occurs on the natural pathway. This could be beneficial to parameters like acoustic pattern and directional hearing could operate normally. The sensor is resilient against several factors. Small variations in the sensor position or additional contact points with the surrounding anatomy at long process of incus or malleus evoke a signal loss of up to 5 dB. An additional contact point with the promontory cause a signal gain of 5 dB due to the improved sensor fixation. The performance of the transducer and especially the actuator element depends strongly on the ossicular chain pretension which is induced during transducer insertion. The ossicular chain is stiffening much more on the stapes-side than on the incus-side during the stretch of the joint gap. By means of artificially widended joint gaps in temporal bone experiments the behavior of future miniaturised transducers could be studied. The experimental dynamic range of the presented transducer ranges from a sensor’s broadband hearing threshold level of 30 dB Sound Pressure Level (SPL) up to an actuator’s maximum an equivalent sound pressure level of 70 dB SPL low frequency respectively 120 dB SPL for high frequencies. The amplification performance of the transducer within this dynamic range is located at about 30 dB for high frequencies. A prospective medical indication of the transducers could be the treatment of high frequency hearing loss and therefore also presbyacusis. A treatment for patients with typical noise induced hearing loss seems to be equally feasible. At this stage in development, it seems feasible to implant the sensor-only concept in a number of applications, while the transducer concept faces some questions to resolve but is nevertheless promising. The transducers performance is not on the same level like other approaches in terms of technical characteristics for the whole frequency range but the concept stands out regarding feasible insertion and minimal invasivity.:I Einleitung II Inhalt und thematischer Zusammenhang der Publikationen III Publikation 1: Influence of the middle ear anatomy on the performance of a membrane sensor in the incudostapedial joint gap IV Publikation 2: Examination of a mechanical amplifier in the incudostapedial joint gap: FEM simulation and physical model V Publikation 3: Fully implantable hearing aid in the incudostapedial joint gap VI Ergebnisse und Diskussion VII Zusammenfassung VIII Summary