published_or_final_version / Surgery / Master / Master of Surgery

Background: Endoscopic ear surgery has gained acceptance as a complementary tool to microscopic ear surgery, but perhaps not so much as an instrument for exclusive use.With this approach becoming popular, there is scarce data on cholesteatoma recidivism and hearing outcomes, when exclusively used. Objectives: Auditing outcomes of endoscopic ear surgery for the surgical management of cholesteatoma in the Groote Schuur hospital (above13 year age group) and the Red Cross War Memorial Children’s hospital (below 13 year age group) , with a secondary aim of comparing recidivism and hearing outcomes of 4 different surgical techniques for cholesteatoma resection, namely, exclusive endoscopic (EES), microscopic canal wall down (CWD), microscopic canal wall up (CWU) and combined endoscopic-microscopic techniques. Methods: A retrospective chart review was conducted at our two tertiary academic referral hospitals in Cape Town, namely, Red Cross War Memorial Children’s Hospital and Groote Schuur Hospital from January 2012 to December 2016. Results: A total of 128 cholesteatoma ear surgeries were done; 110 patients were above the age of 13 years and 18 patients were below the age of 13 years. Eight Red Cross patients underwent EES, 7 had CWU, 2 had CWD and 1 had a combined technique. Overall recidivism rate in this population was 33% (6/18), of which 2 were approached exclusively endoscopically, 2 underwent a microscopic CWU, 1 had a CWD and 1 had combined endoscopic-microscopic approach. The mean postoperative hearing in this group was 40dB compared to a preoperative mean of 50,3 decibels (dB). In the Groote Schuur group, 23 underwent an exclusive endoscopic approach; 42 had a CWU, 40 had a CWD and 5 had a combined endoscopic-microscopic approach. Overall recidivism rate for the above 13 year old group was 17% (19/110). Of those, 7 were from the endoscopic group, 8 from the CWU group, 1 from CWD group and 3 from the combined technique group. Mean postoperative hearing was 47,4dB compared to a preoperative hearing of 48,4dB. Conclusions: The CWD technique demonstrated superior outcomes in both the above and below 13 year age groups. In the above 13 year old group, the EES approach had the same recurrence rate as CWU. While paediatric cholesteatomas have much higher recidivism rates compared to adults, our below 13 year old group was too small to conclude any statistical significant differences between the different approaches, and therefore, further studies are required in this age group. Management of cholesteatoma requires a highly individualized approach that takes into account anatomic, clinical and social factors to determine the most appropriate surgical treatment paradigm

Robotic-assisted surgery is a rapid growing field, facing challenging tasks and demands from surgeons, in particular in minimally invasive and microsurgery. However many of the present robotic systems are not well integrated in the surgical workflow, too big or too expensive. Micron is an innovative fully handheld active micromanipulator that helps surgeons to improve position accuracy and precision in microsurgery by cancelling the normal hand tremor. This thesis proposes an improvement and development of Micron, considering as target the stapedotomy procedure, microsurgery performed at the middle ear that aims to restore the hearing impairments. Two tools, a handle and a brace were designed and prototyped and the control was adapted; at the end the entire system was assessed through some experiments. Promising results were obtained in terms of tremor cancellation but further research is needed in order to reach clear advantages.

Hintergrund: Für eine fortlaufende, standardisierte und systematische Erfassung von Komplikationen nach Ohroperationen existieren aktuell keine Vorgaben. Die Detektion, Dokumentation und Auswertung von komplikationsbehafteten postoperativen Verläufen dient dem Ausbau einer hohen Behandlungsqualität. Fragestellung: Das Ziel der vorliegenden Arbeit war die Etablierung einer fortlaufenden, standardisierten und systematischen Erfassung von unerwünschten Verläufen nach Ohroperationen. Aus diesen Verläufen sollten Parameter herauskristallisiert werden, die sich zur Charakterisierung und Beschreibung von Komplikationen und der Behandlungsqualität eignen. Dabei wurden Komplikationen nicht dichotom als vorhanden oder abwesend betrachtet, sondern auch deren zeitlicher Verlauf erfasst. Dieser prospektive Ansatz in der Erfassung von Verläufen findet sich in der aktuellen ohrchirurgischen Forschungslage nicht. Die Darstellung der Daten sollte in einer Weise erfolgen, dass zeitsparend und überblicksartig der tagesaktuelle Stand der vorhandenen Komplikationen, die Entwicklung der länger zurückliegenden Ereignisse sowie der Verlauf einer Komplikation verfolgt werden kann. Methode: Es erfolgte eine prospektive Erfassung aller Ohroperationen am HNO-Universitätsklinikum Dresden. Ohrspezifische Komplikationen wurden mittels Melderegister angezeigt. Eine Kontrolle der erfassten Daten erfolgte durch retrospektive Sichtung aller Verläufe (min. 6 bis max. 12 Monate postoperativ). Zur Detektion eines komplikationsbehafteten Verlaufes wurden Daten aus OP-Bericht, Anästhesieprotokoll und ärztlicher Verlaufsdokumentation erhoben. Neben einer qualitativ-deskriptiven Auswertung erfolgte die statistische Analyse des dynamischen Komplikationsverlaufes mittels Komplikationspersistenzfunktion (KPF) und anhand der medianen Persistenzzeit (MPZ). Ergebnisse Es konnten 525 Mittelohroperationen und 130 (24%) unterschiedliche Komplikationen analysiert werden. Am häufigsten trat ein postoperativer Knochenleitungsabfall (n=69 (13%)) auf. Das minimal erforderliche Nachbeobachtungs-intervall wurde durch den Eintritt in die Plateauphase (PP) der KPF bestimmt. Nach Eintritt in die PP kann die Wahrscheinlichkeit für Langzeitresiduen einer Komplikation anhand der Persistenzrate (PR) angegeben werden. Am Beispiel eines Knochenleitungsabfalles betragen diese Parameter 144 Tage (PP) mit einer PR von 27%. Die mediane Persistenzzeit eines KL-Abfalls betrug 79 Tage. Der zeitliche Aufwand für die Erfassung und Analyse der Daten lag im Durchschnitt bei 300-360min/Woche. Davon etwa 60±10min für einen komplikationsbehafteten und 10±4min für einen erwarteten Verlauf. Dies entspricht ca. 400h für die Auswertung eines Jahres bei 700 OPs/Jahr. Schlussfolgerung: Zur Routineerfassung von komplikationsbehafteten Verläufen sind standardisierte Prozesse und dynamische Analysen unerlässlich. Ermöglicht wird das durch den Kaplan-Meier-Schätzer als Komplikationspersistenzfunktion mit Hilfe der medianen Persistenzzeit (MPZ) und der Wahrscheinlichkeit für Langzeitresiduen einer Komplikation (=Persistenzrate (PR)). Das Pflegen eines Komplikationsregisters ist nur mit einem erheblichen Zeitaufwand und hohem Ressourcenverbauch in die klinische Routine integrierbar. Nichtsdestotrotz ist die Bedeutung und der Beitrag für die Qualitätsentwicklung und -beschreibung in der Ohrchirurgie enorm.:Abkürzungsverzeichnis IV 1. Einleitung 1 1.1 Qualität definieren 1 1.1.1 Deutsche Industrienorm DIN 2 1.1.2 Institute of Medicine (IOM) 2 1.1.3 Institut für Qualität und Transparenz im Gesundheitswesen (IQTIG) 3 1.1.4 Qualität als dynamischer Begriff in der Mittelohrchirurgie 3 1.1.4.1 Strukturqualität 4 1.1.4.2 Prozessqualität 4 1.1.4.3 Ergebnisqualität 4 1.1.5 Die Abwesenheit von Komplikationen als Ergebnisqualität 5 1.1.5.1 Unterscheidung zwischen Komplikation, Behandlungsmisserfolg und Fehler 5 1.1.5.2 Spezifische Komplikationen nach Mittelohroperationen 6 1.2 Mittelohrchirurgische Indikationen und Eingriffe 8 1.2.1 Sanierende Mittelohroperationen 8 1.2.1.1 Mastoidektomie 8 1.2.1.2 Radikaloperation 8 1.2.2.1 Myringoplastik 9 1.2.2.2 Ossikuloplastik 9 1.2.2.3. SAMEO-ATO 10 1.2.2 Tumorchirurgie des Felsenbeins 10 1.3 Frage- und Zielstellung der Arbeit 12 2. Methode 13 2.1 Studiendesign 13 2.2 Studienteilnehmer:innen 13 2.3 Zielgrößen 13 2.4 Datenquellen 14 2.4.1 HNO- Verlaufsdokumentation 14 2.4.2 Anästhesiologisches Protokoll 14 2.4.3 OP-Bericht und Arztbrief 14 2.4.4 Audiologische Daten 14 2.5 Klassifikation von Merkmalen 16 2.6 Statistische Methoden 16 2.6.1 Exkurs Kaplan-Meier-Schätzer (KM) 16 3. Ergebnisse 18 3.1 Erfassung der Komplikationen 18 3.2 Patient:innenkollektiv 19 3.3 Deskriptive Daten 20 3.3.1 Charakteristik der Fälle 20 3.3.2 Operationen 20 3.3.3 Komplikationen 22 3.3.3.1 Frühe Komplikationen 22 3.3.3.2 Späte Komplikationen 24 3.4 Struktur des inferenzstatistischen Ergebnisteils 25 3.5 Knochenleitungs-Abfälle 26 3.5.1 Charakteristik der Patientinnen mit KL-Abfall 26 3.5.2 Zeitliches Auftreten der KL-Abfälle 27 3.5.3 Zeitlicher Verlauf von KL-Abfällen 28 3.5.3.1 Stratifiziert nach frühen KL-Abfällen 30 3.5.3.2 Stratifiziert nach späten KL-Abfällen 31 3.5.3.3 Stratifiziert nach frühen und späten KL Abfällen32 3.5.3.4 Stratifiziert nach KL-Abfall und anderen Komplikationen 33 3.5.3.5 Stratifiziert nach Eingriffsart 34 3.6 Fazialisparesen 37 3.6.1 Charakteristik der Patient:innen mit Fazialisparese 37 3.6.2 Zeitlicher Verlauf von Fazialisparesen 38 3.7 Nachbeobachtungszeiten einzelner Komplikationen 39 3.7.1 Gehörgangsstenose 39 3.7.2 Wundheilungsstörungen (WHS) 40 3.7.3 Tinnitus 40 3.7.4 Schwindel (mit Reiz-/Ausfallnystagmen) 40 3.8 KPF nach intraoperativem Fräsen des Knochens 41 3.8.1 Alle Komplikationen 41 3.8.2 Stratifiziert nach Eingriffsart 42 3.8.3 Stratifiziert nach KL-Abfall 43 3.8.3.1 Frühe und späte KL-Abfälle 44 3.8.4 Fazialisparese 46 3.9 KPF nach Mastoidektomie, Radikalhöhlenanlage oder Gehörgangserweiterung 46 3.10 Zusammenfassung der medianen Persistenzzeiten und der Persistenzraten 47 3.11 Hörergebnisse 48 3.11.1 Hörergebnisse stratifiziert nach Eingriffsart 49 3.11.1.1 Tympanoplastik Typ 149 3.11.1.2 Tympanoplastik Typ 3 50 3.11.1.3 Cholesteatom OP 50 3.11.1.4 Stapesplastik 51 3.11.1.5 Sonstige Mittelohr-Operationen 51 3.11.2 Hörergebnisse stratifiziert nach KL-Abfall 52 3.11.2.1 Ohne KL-Abfall 52 3.11.2.2 Frühe KL-Abfälle 54 3.11.2.3 Späte KL-Abfälle 55 4. Diskussion 56 4.1 Studiendesign 57 4.2 Patient:innenkollektiv 57 4.3 Komplikationen nach Mittelohroperationen 57 4.3.1 Postoperativer Knochenleitungsabfall 59 4.3.2 Auswirkungen auf den zeitlichen Verlauf eines KL-Abfalls 60 4.3.3 Fazialisparese 62 4.4 Weitere registrierte Komplikationen 63 4.4.1 Gehörgangsstenose 63 4.4.2 Wundheilungsstörungen 64 4.4.3 Tinnitus 64 4.4.4 Schwindel 64 4.5 Hörergebnisse 66 4.5.1 Nach Tympanoplastik Typ 1 67 4.5.2 Nach Tympanoplastik Typ 3 68 4.5.3 Nach Cholesteatom Operation 68 4.5.4 Nach Stapesplastik 68 4.5.5 Nach sonstigen Mittelohroperationen 69 4.6 Hörergebnisse stratifiziert nach KL-Abfall 69 4.7 Schlussfolgerung 70 Zusammenfassung VI Summary VIII Tabellenverzeichnis X Abbildungsverzeichnis XI Literaturverzeichnis XII Danksagung XVII Ehrenwörtliche Erklärung XVIII

The chorda tympani nerve, also known as the taste nerve, runs uncovered through the middle ear cavity, a localization that exposes the nerve to pathological processes and surgical trauma in the middle ear. People operated on for otosclerosis tend to complain more about postoperative taste disturbances than those operated on for chronic otitis media. It has been suggested that this difference may be explained by gradual deterioration of chorda tympani nerve function caused by chronic otitis media infection and that further impairment caused by surgery is less noticeable in these patients. This thesis aimed to evaluate the function of the chorda tympani nerve, the effects of middle ear disease on taste and complications resulting from ear surgery for chronic otitis media or otosclerosis. This information will help to improve the ear surgeon’s ability to predict the prognosis of iatrogenic taste disturbances in patients with middle ear disease and after ear surgery. Taste was assessed using electrogustometry and the filter paper disc method before and after surgery for chronic otitis media or otosclerosis. Patients also completed questionnaires about symptoms and quality of life. The status of the chorda tympani nerve upon surgical opening of the ear and grading of the trauma to the nerve during the surgery were recorded. The ultrastructure of the chorda tympani nerve from healthy ears and from ears with chronic otitis media was examined. Electrogustometry and the filter paper disc method were evaluated. The results of electrogustometry and the filter paper disc method were highly reproducible, although their correlation was moderate. Patients with chronic otitis media, patients with a more traumatized nerve, female patients and younger patients were more likely to report postoperative taste disturbances. Most of the patients recovered their taste after 1 year. The quality of life study showed only minor changes after surgery. Electron microscopic observations of nerves from ears with chronic otitis media showed signs of structural degeneration, although signs of regeneration, such as sprouting were also observed. This results may explain the recovery of taste postoperatively and indicate that the nerve should be carefully handled during surgery.

Introdução: As particularidades da anatomia e a localização topográfica da orelha a tornam uma estrutura única no corpo humano, existindo diversas situações clínicas em que a sua reconstrução (total ou parcial) pode ser necessária. Devido à dificuldade técnica, as complicações pós-operatórias são freqüentes. Objetivos: Realizar análise epidemiológica dos pacientes submetidos à reconstrução de orelha devido a causas congênitas (microtia) e adquiridas (trauma, queimaduras e outras), com avaliação comparativa dos resultados, para definir qual grupo teria menores índices de complicações. Método: Realizada análise retrospectiva de 279 casos de reconstrução de orelha realizados de 1994 a 2004 na Disciplina de Cirurgia Plástica da Faculdade de Medicina da Universidade de São Paulo. Os pacientes foram separados em portadores de deformidades congênitas ou adquiridas e analisados comparativamente. Resultados: O sexo masculino foi mais prevalente tanto entre os pacientes portadores de deformidades congênitas (61,3%) quanto entre aqueles com deformidades adquiridas (68,75%). A média de idade no início dos procedimentos cirúrgicos foi de 14,3 anos nos pacientes com deformidades congênitas e 29,5 nas deformidades adquiridas. Trauma foi a principal causa de deformidade adquirida (55% dos casos adquiridos), seguido pelas queimaduras (29% dos casos adquiridos) e a única deformidade congênita observada no estudo foi a microtia. Em média, os pacientes dos grupos necessitaram de 4,2 cirurgias, mas aqueles com seqüelas de queimaduras foram submetidos a um número significativamente maior de procedimentos (5,9 - p < 0,01). As principais complicações foram a exposição de cartilagem (15,1% do total de casos), sem diferença entre os grupos, e a brida retroauricular (16,5% do total de casos), sendo esta última mais freqüente nos casos de microtia e seqüelas de queimaduras. Conclusões: Os casos de perda traumática mostraram menor índice de complicações quando comparados àqueles submetidos a reconstrução por microtia ou após queimadura. / Introduction: The distinctive anatomic features and topography render the ear unique in the human body. Total or partial reconstruction of the ear may be required in many clinical conditions, but because technical difficulties are common, the rate of postoperative complications increases. Objectives: To analyze the epidemiologic data of patients who underwent surgery for reconstruction of the ear due to congenital conditions (microtia) or acquired deformities (trauma, burns and others), and to compare the results in order to define which group had the lowest rate of complications. Methods: A retrospective analysis was conducted with 279 cases of ear reconstruction performed between 1994 and 2004 by the Discipline of Plastic Surgery of the University of São Paulo Medical School. The patients were initially separated in two groups, according to their condition (congenital or acquired), to compare their data. Results: Male was the prevailing gender in both groups of ear deformities: congenital (61.3%) and acquired conditions (68.7%). The patients with congenital deformities had a mean age of 14.3 years at the beginning of the treatment, whereas the patients with acquired deformities were 29.5 years old, in average. The major causes of acquired deformities were trauma (55% of the cases in this group) and burns (29%). The only cause of congenital deformity observed was microtia. Patients required an average of 4.2 surgical procedures. However, those with sequelae of burn injuries were submitted to a significantly higher number of procedures (5.9 - p < 0.01). Cartilage exposure (15.1% of the total) and postauricular bridles (16.5%) were the major complications observed in this study. The latter was more common among those cases with microtia and sequelae of burns. Conclusions: Patients with traumatic injuries had a better outcome after surgery than those with microtia or burn injuries, because of a lower rate of complications.

Introdução: As particularidades da anatomia e a localização topográfica da orelha a tornam uma estrutura única no corpo humano, existindo diversas situações clínicas em que a sua reconstrução (total ou parcial) pode ser necessária. Devido à dificuldade técnica, as complicações pós-operatórias são freqüentes. Objetivos: Realizar análise epidemiológica dos pacientes submetidos à reconstrução de orelha devido a causas congênitas (microtia) e adquiridas (trauma, queimaduras e outras), com avaliação comparativa dos resultados, para definir qual grupo teria menores índices de complicações. Método: Realizada análise retrospectiva de 279 casos de reconstrução de orelha realizados de 1994 a 2004 na Disciplina de Cirurgia Plástica da Faculdade de Medicina da Universidade de São Paulo. Os pacientes foram separados em portadores de deformidades congênitas ou adquiridas e analisados comparativamente. Resultados: O sexo masculino foi mais prevalente tanto entre os pacientes portadores de deformidades congênitas (61,3%) quanto entre aqueles com deformidades adquiridas (68,75%). A média de idade no início dos procedimentos cirúrgicos foi de 14,3 anos nos pacientes com deformidades congênitas e 29,5 nas deformidades adquiridas. Trauma foi a principal causa de deformidade adquirida (55% dos casos adquiridos), seguido pelas queimaduras (29% dos casos adquiridos) e a única deformidade congênita observada no estudo foi a microtia. Em média, os pacientes dos grupos necessitaram de 4,2 cirurgias, mas aqueles com seqüelas de queimaduras foram submetidos a um número significativamente maior de procedimentos (5,9 - p < 0,01). As principais complicações foram a exposição de cartilagem (15,1% do total de casos), sem diferença entre os grupos, e a brida retroauricular (16,5% do total de casos), sendo esta última mais freqüente nos casos de microtia e seqüelas de queimaduras. Conclusões: Os casos de perda traumática mostraram menor índice de complicações quando comparados àqueles submetidos a reconstrução por microtia ou após queimadura. / Introduction: The distinctive anatomic features and topography render the ear unique in the human body. Total or partial reconstruction of the ear may be required in many clinical conditions, but because technical difficulties are common, the rate of postoperative complications increases. Objectives: To analyze the epidemiologic data of patients who underwent surgery for reconstruction of the ear due to congenital conditions (microtia) or acquired deformities (trauma, burns and others), and to compare the results in order to define which group had the lowest rate of complications. Methods: A retrospective analysis was conducted with 279 cases of ear reconstruction performed between 1994 and 2004 by the Discipline of Plastic Surgery of the University of São Paulo Medical School. The patients were initially separated in two groups, according to their condition (congenital or acquired), to compare their data. Results: Male was the prevailing gender in both groups of ear deformities: congenital (61.3%) and acquired conditions (68.7%). The patients with congenital deformities had a mean age of 14.3 years at the beginning of the treatment, whereas the patients with acquired deformities were 29.5 years old, in average. The major causes of acquired deformities were trauma (55% of the cases in this group) and burns (29%). The only cause of congenital deformity observed was microtia. Patients required an average of 4.2 surgical procedures. However, those with sequelae of burn injuries were submitted to a significantly higher number of procedures (5.9 - p < 0.01). Cartilage exposure (15.1% of the total) and postauricular bridles (16.5%) were the major complications observed in this study. The latter was more common among those cases with microtia and sequelae of burns. Conclusions: Patients with traumatic injuries had a better outcome after surgery than those with microtia or burn injuries, because of a lower rate of complications.

Accessing the inner ear presents a significant challenge for the diagnosis and treatment of inner ear diseases. Many existing techniques to access the inner ear are invasive and can cause permanent damage to the cochlea. Recently, a novel microneedle has been fabricated to perforate the round window membrane (RWM) – a membrane sealing one of the two openings in the cochlea. These perforations enhance drug delivery into the inner ear, potentially improving the efficacy of therapeutics. Furthermore, they allow for the aspiration of perilymph samples, which is essential for diagnosing inner ear diseases. However, owing to limited knowledge about the mechanical properties of the RWM, certain technical aspects remain unexplored. Specifically, the interaction between the RWM and the microneedle during perforation is yet to be examined. This investigation is pivotal for the optimal design of microneedles — those robust enough to perforate RWMs yet delicate enough to minimize damage. In this thesis, we conduct a thorough examination of the guinea pig RWM, encompassing its geometry and its mechanical responses to pressures from the middle ear and inner ear. Additionally, we also formulate a comprehensive constitutive law for the guinea pig RWM. Our exploration begins with the creation of a U-Net model tailored to automatically segment the RWM. Despite the presence of other structures in the same image—such as bone, the basilar membrane, and ambient noise—the model proved invaluable for efficiently and automatically segmenting the RWM. To enhance accuracy, post-processing techniques like connected component analysis and majority voting were incorporated. Using this 3D model, we proceeded to study the RWM’s geometry. Recognizing the shrinkage observed in fixed RWMs, we integrated fresh RWM data to estimate the shrinkage ratio. Subsequently, we analyzed both the overall RWM thickness and that of the middle connective tissue layer—crucial metrics for future RWM modeling. Next, we proposed a method to evaluate the in-plane deformation of the RWM due to applied pressure. This involved using a bulge test system to pressurize and deform the RWM, combined with confocal microscopy to track stained nuclei or pre-introduced fluorescent beads on the RWM. We then utilized the coherent point drift (CPD) algorithm to measure the displacement of beads and nuclei. Results indicated that both markers could be successfully used to measure the RWM’s displacement. Further analysis revealed the in-plane Lagrangian strain of the RWM, with a significant observation being that the direction of maximum in-plane Lagrangian strain is perpendicular to the fiber direction. This underscores the crucial role of collagen fibers in determining the RWM’s mechanical properties. To conclude our study, we devised a constitutive law for the RWM, conceptualizing it as a combination of the ground substance and a family of dispersed fibers. This model was integrated into a FEBioStudio plugin, facilitating simulations of the RWM’s mechanical reactions to different pressures. Although our simulations closely aligned with experimental findings, some discrepancies were noted, likely stemming from an incomplete understanding of fiber dispersions. Nevertheless, our constitutive law reinforces the notion that fibers primarily govern the RWM’s mechanical characteristics.

Manual accuracy in microsurgery is reduced by tremor and limited access. A surgical approach through the middle ear also puts delicate structures at risk, while the surgeon is often working at an unergonomic position. At this point a micromanipulator could have a positive influence. A system was developed to measure “working accuracy”, time and precision during manipulation in the middle ear. 10 ENT- surgeons simulated a perforation of the stapedial footplate on a modified 3D print of a human skull in a mock OR. Each trial was repeated more than 200 times aiming manually and using a micro-manipulator. Data of over 4000 measurements was tested and graphically processed. Work strain was evaluated with a questionnaire. Accuracy for manual and micromanipulator perforation revealed a small difference. Learning curves showed a stronger decrease both in deviation and time when the micromanipulator was used. Also a lower work strain was apparent. The micromanipulator has the potential as an aiding device in ear surgery. / Die manuelle Genauigkeit in der Mikrochirurgie wird duch Tremor und limitierten Zugang eingeschränkt. Ein chirurgischer Eingriff am Mittelohr birgt außerdem ein Verletzungspotential für empfindliche anatomische Strukturen. Überdies ist die Sitzposition des Operateurs oft unergonomisch. Ein neuartiger Mikromanipulator kann auf diese Faktoren einen positiven Einfluss haben. Eine spezielle Software wurde entwickelt und Genauigkeit, Zeit und Präzision bei einem Eingriff am Mittelohr zu bestimmen. 10 Kopf- Hals- Chirurgen simulierten die Perforation der Steigbügelfußplatte an einem 3D Modell eines menschlichen Schädels in einem Demonstrations- OP. Jeder Versuch wurde mehr als 200 mal zunächst manuell und später mit Hilfe des Mikromanipulators wiederholt. Die Daten von mehr als 4000 Messversuchen wurden getestet und grafisch dargestellt. Die Arbeitsbelastung wure mittels eines Fragebogens evaluiert. Manuelle und mikromanipulatorgestütze Genauigkeit zeigten einen signifikanten, jedoch ,absolut betrachtet,sehr geringen Unterschied der Genauigkeit. Die Lernkurven zeigten einen steileren Verlauf sowohl im Hinblick auf Genauigkeit als auch Versuchszeit, wenn der Mikromanipulator zur Anwendung kam. Weiterhin war eine geringere Arbeitsbelastung zu erkennen. Der Mikromanipulator birgt Potential als kompaktes Hilfsmittel für die Ohrchirurgie.

INTRODUÇÃO: A ampliação dos critérios de indicação para cirurgia do implante coclear e os benefícios da preservação da audição residual no pósoperatório estimularam o desenvolvimento de técnicas cirúrgicas atraumáticas. Minimizar os traumas intracocleares durante a inserção do feixe de eletrodos do implante coclear é um passo fundamental para este intuito. O objetivo deste trabalho é avaliar se o trauma intracoclear é diferente quando o feixe de eletrodos do implante coclear é inserido através do quadrante anterossuperior ou anteroinferior da membrana da janela redonda. MÉTODOS: Vinte e cinco ossos temporais frescos de cadáveres humanos foram submetidos à timpanomastoidectomia padrão. Após exposição adequada da membrana da janela redonda, em metade dos ossos o feixe de eletrodos do implante coclear foi inserido via quadrante anterossuperior da membrana da janela redonda, e na outra metade via quadrante anteroinferior. Os ossos temporais foram desidratados e embebidos em epóxi, com o feixe de eletrodos in situ. As peças foram serialmente polidas, tingidas e visualizadas por meio de estereomicroscópio para avaliar o trauma intracoclear causado pela inserção do feixe de eletrodos. As imagens foram fotografadas. RESULTADOS: Em treze ossos temporais o feixe de eletrodos do implante coclear foi inserido via quadrante anterossuperior da membrana da janela redonda, e em doze ossos via quadrante anteroinferior. Obteve-se 372 superfícies. As análises histológicas revelaram diferentes graus de traumas às estruturas intracocleares. Os resultados mostraram que a inserção do feixe de eletrodos via quadrante anterossuperior ou anteroinferior acarretam a mesma frequência de trauma intracoclear. CONCLUSÕES: A presença de trauma intracoclear e a severidade dos traumas ocorridos no tocante à inserção do feixe de eletrodos de implante coclear pelo quadrante anterossuperior e anteroinferior da membrana da janela redonda não apresentou diferença estatisticamente significativa. Observou-se, porém, maior facilidade para exposição cirúrgica do quadrante anterossuperior em relação ao quadrante anteroinferior / INTRODUCTION: The expansion of the indication criteria for cochlear implant surgery and the benefits of preserving residual hearing postoperatively have stimulated the development of atraumatic surgeries. Minimizing the intracochlear traumas during the electrodes insertion is a critical step for this aim. The objective of this study is to assess whether there is a difference in intracochlear trauma when the cochlear implant electrode array is inserted through the anterior-superior or anterior-inferior quadrants of the round window membrane. METHODS: Twenty-five fresh human temporal bones were submitted to standard tympanomastoidectomy. After adequate exposure of the round window membrane, in half of the bones the cochlear implant electrode array was inserted via anterior-superior quadrant of round window membrane and in the other half via anterior-inferior quadrant. The temporal bones were dehydrated and embedded in epoxy with the electrodes array in situ. The specimens were serially polished, stained and viewed through a stereomicroscope to assess the intracochlear trauma caused by insertion of the electrode array. Resulting images were documented. RESULTS: In thirteen temporal bones the cochlear implant electrode array was inserted via anterior-superior quadrant of round window membrane and in twelve bones via anterior-inferior quadrant. Three hundred and seventy two surfaces were obtained. Histological examinations revealed varying degrees of damage to the intracohlear structures. The results showed that the insertion of the electrode array via anterior-superior or anterior-inferior quadrant lead to the same frequency of intracochlear trauma. CONCLUSIONS: The presence of intracochlear trauma and severity of traumas regarding the insertion of cochlear implant electrode array via anterior-superior and via anterior-inferior quadrant of the round window membrane showed no statistically significant difference. However, it was observed that surgical exposure of anterior-superior quadrant was easier than surgical exposure of anterior-inferior quadrant