Rekonstruktion der Ossikelkette mit passiven Implantaten

[From reconstruction to function : Hands-on training in tympanoplasty using real-time feedback]

Hintergrund

In der Mittelohrchirurgie bedarf es ausgezeichneter feinmotorischer Fertigkeiten. Aufgrund des hohen Komplikationspotenzials im Mittelohr ist die Ausbildung dieser Fertigkeiten am Modell anzustreben.

Fragestellung

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?

Material und Methode

Vorliegende Publikationen und eigene Erfahrungen am Dresdener Tympanoplastikmodell (DTM) wurden analysiert und diskutiert.

Ergebnisse

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.

Schlussfolgerungen

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.

Identification of risk factors for residual cholesteatoma in children and adults: a retrospective study on 110 cases of revision surgery

Introduction

Residual disease after cholesteatoma removal is still a challenge for the otorhinolaryngologist. Scheduled “second-look” surgery and, more recently, radiological screenings are used to identify residual cholesteatoma as early as possible. However, these procedures are cost-intensive and are accompanied by discomfort and risks for the patient.

Objective

To identify anamnestic, clinical, and surgery-related risk factors for residual cholesteatoma.

Methods

The charts of 108 patients, including children as well as adults, having undergone a second-look or revision surgery after initial cholesteatoma removal at a tertiary referral hospital, were analyzed retrospectively.

Results

Gender, age, mastoid pneumatization, prior ventilation tube insertion, congenital cholesteatoma, erosion of ossicles, atticotomy, resection of chorda tympani, different reconstruction materials, and postoperative otorrhea did not emerge as statistically significant risk factors for residual disease. However, prior adenoid removal, cholesteatoma growth to the sinus tympani and to the antrum and mastoid, canal-wall-up 2 ways approach, and postoperative retraction and perforation were associated with a statistically higher rate of residual disease. A type A tympanogram as well as canal-wall-down plus reconstruction 2 ways approach for extended epitympanic and for extended epitympanic and mesotympanic cholesteatomas were associated with statistically lower rates of residual disease. A score including the postoperative retraction or perforation of the tympanic membrane, the quality of the postoperative tympanogram and the intraoperative extension of the cholesteatoma to the sinus tympani and/or the antrum was elaborated and proved to be suitable for predicting residual cholesteatoma with acceptable sensitivity and high specificity.

Conclusion

Cholesteatoma extension to the sinus tympani, antrum and mastoid makes a residual disease more likely. The canal-wall-down plus reconstruction 2 ways approach seems safe with similar rates of residual cholesteatoma and without the known disadvantages of canal-wall-down surgery. The described score can be useful for identifying patients who need a postoperative radiological control and a second-look surgery.

Experimental Simulation of Clinical Borderline Situations in Temporal Bone Specimens After Ossiculoplasty

OBJECTIVES

One reason for insufficient hearing improvement with a distinct air-bone gap after ossiculoplasty with implantation of partial or total ossicular replacement prostheses can be the dislocation or minimal shifting of the prosthesis. The aim of this study was the simulation of common clinical borderline situations with minimal shifting of the prosthesis in temporal bone specimens after ossiculoplasty. It was furthermore the goal to identify these specific situations through imaging by cone beam computed tomography (cbCT) and direct visual inspection using the operation microscope. Additionally, the functional status was evaluated using laser-Doppler vibrometry (LDV).

DESIGN

We used a total of four temporal bone specimens for this study. A reconstruction with a partial ossicular replacement prostheses was performed in three specimens and with a total ossicular replacement prostheses in one specimen, with good initial acoustic properties. Subsequently, one specific type of prosthesis failure was simulated in each specimen, respectively, by minimally shifting, tilting, or bending the prostheses from their initial positions. These changes were introduced step-by-step until a borderline situation just short of complete acoustic decoupling was reached. Each step was examined using both LDV and cbCT and observed through the operation microscope.

RESULTS

LDV was able to quantify the mechanic function of the ossicular chain after most of the manipulation steps by demonstrating the effect of any shifting of the prosthesis on the middle ear transfer function. However, in some situations, the middle ear transfer function was better with a visually more advanced failure of the prosthesis. In addition, cbCT showed most of the steps with excellent resolution and was able to delineate changes in soft tissue (e.g., cartilage covering).

CONCLUSION

cbCT seems to be a promising imaging technique for middle ear problems. As cbCT and LDV exhibited slightly different advantages and disadvantages regarding the demonstration of borderline situations, the combination of both techniques allowed for a more precise evaluation of middle ear reconstructions. Knowledge of the specific characteristics of these methods and their possible combination might help otologists and otosurgeons to refine indications for revision surgery and improve their personal patient counseling.

[Quality control following reconstructive middle ear surgery: from bench to bedside]

BACKGROUND

The ongoing improvement of imaging quality nowadays focuses increasingly more on immediate quality evaluation of surgical measures.

METHODS

Rotational tomography (RT) has been experimentally proven to be an alternative imaging technique to computed tomography (CT) in terms of quality and postoperative localization of middle ear implants in temporal bones. Based on these results imaging parameters were determined in the form of a surgical check list in order to systematically check individual but important surgical reconstructive steps.

RESULTS

The positive benefit of RT concerning immediate and significant postoperative quality control was confirmed by a patient study. The surgical check list was successfully implemented under clinical framework requirements. Among these standardized parameters the determined angulation of inserted middle ear implants was given outstanding significance due to the predictive value concerning functional outcome.

CONCLUSION

The RT procedure has been proven to be a reliable imaging tool for postoperative quality control following reconstructive middle ear surgery.