Ulrich Vorwerk

Artificial Petrous Bone Produced by Stereolithography for Microsurgical Dissecting Exercises

Training in microsurgery of the middle ear requires dissecting to be carried out on petrous bone. Human petrous bone structures are not available in adequate quantity to permit extensive practicing. Using synthetic resins, true reproductions of petrous bone can be obtained by means of a stereolithographic method, yielding structures of the petrous part which are highly similar to human bone. Digital data sets are obtained from spiral CT scans, and transferred to CAD systems such that, using stereolithography, petrous bone facsimiles are produced on the parametric model. Any number of such models of an original can be produced. Thus, identical structures can be made available for a wide range of uses. Exercises conducted on artificial petrous bone so produced are equivalent to those carried out on human structures, in terms of material properties and visualisation of anatomic details.

Präparierübungen am künstlichen Felsenbein Herstellung von Felsenbeinfaksimiles durch Stereolithographie

ZusammenfassungDas Erlernen der Mikrochirurgie des Mittelohrs setzt Präparationen am Felsenbein voraus. Für umfangreiche Präparationsübungen stehen nicht ausreichend humane Felsenbeinstrukturen zur Verfügung. Durch die Herstellung naturgetreuer Felsenbeine aus Kunstharzen im Stereolithographieverfahren können menschlichem Knochen sehr ähnliche Strukturen der Felsenbeinpyramide nachgebildet werden. Durch die Aufnahme digitaler Datensätze aus Scans von Spiral-CT-Untersuchungen und Überführung in CAD-Systeme können an dem geschaffenen parametrischen Modell mit Hilfe der Stereolithographie Felsenbeinfaksimiles vergegenständlicht werden. Es ist die Erstellung beliebig vieler solcher Modelle eines Originals realisierbar. Damit ist eine Bereitstellung von identischen Strukturen für verschiedenste Untersuchungen am Felsenbein gegeben. Präparationen an den hergestellten künstlichen Felsenbeinen entsprechen sowohl in den Materialeigenschaften und in der anatomischen Detaildarstellung denen an humanen Strukturen. Präparierübungen können somit in identischer Weise durchgeführt werden.SummaryLearning microsurgery of the middle ear requires preparations of temporal bones. Ethical and moral restrictions in obtaining specimens make training and research with temporal bone preparations increasingly more difficult. Due to the complex structure of the temporal bone with its communicating cavities, the manufacture of facsimiles up to now has been impossible. Rapid prototyping techniques must be able to produce identical objects from an original one. By using CT scans of temporal bones from anatomic preparations and patients we have been able to reconstruct 3D pictures on a CAD workstation. We are now able to incorporate data in a stereolithographic system to create an anatomic facsimile of the temporal bone. It is possible to produce a considerable number of these facsimiles from the same real object. With this method we can produce models of human structure for medical teaching, training and research. Our artificial preparations of temporal bones correspond to both the material characteristics and anatomic details of human structures, allowing various surgical exercises to be carried out.

Histologische Untersuchungen des Trommelfelldefektrandes bei der chronischen Otitis media mesotympanalis

ZusammenfassungIn einer Studie wurden die während einer Tympanoplastik entnommenen Trommelfelldefektränder von 111 Patienten mit einer chronischen Otitis media mesotympanalis histologisch untersucht. Die Aufarbeitung der Präparate erfolgte durch Paraffineinbettung und Hämatoxylin-Eosin-Färbung. Bei 67 Patienten (60%) endete die Trommelfellepidermis direkt an der Kante des Perforationsrandes; 27 Präparate (24%) zeigten eine Epithelialisierung der Trommelfellrückfläche, ohne den Resektionsrand zu erreichen. Bei 17 Patienten (16%) war der gesamte Resektionsrand vollständig epithelialisiert. Diese Patienten wiesen fast alle eine nicht nachweisbar durchgängige Tuba auditiva auf. Die Größe der Trommelfellperforation hatte keinen Einfluß auf die Epithelausbreitung. Es besteht jedoch ein Zusammenhang zwischen der Migrationstendenz des Epithels und dem Auftreten permanenter Trommelfellrezidivperforationen nach Tympanoplastik. Von 17 Patienten, deren resezierter Trommelfellrand in den mikroskopischen Präparaten vollständig mit Plattenepithel bewachsen war, wiesen 4 (23%) einen dauerhaften Rezidivdefekt auf. Die Zahl der postoperativen Rezidive war bei den Patienten, welche keine oder nur geringe Epithelmigration in Richtung der Trommelfellinnenfläche aufwiesen, signifikant kleiner.SummaryIn the present study we investigated resected tympanic membranes taken during tympanoplasty. Tissue from 111 patients with chronic otitis media was analyzed after being embedded in paraffin and stained with hematoxylin and eosin. In 67 patients (60%) the tympanic membrane epidermis did not extend beyond the margin of the perforation rim, so that no epithelial migration was observed on the inner side of the tympanic membrane. In 27 specimens (24%) we found an epithelial migration on the inner side of the tympanic membrane, but this did not extend to the margins of the excised tissue. In 17 tissue specimens (16%) epithelial migration extended to the margins of the resected tissue. Clinically, these patients were found to have non-functioning Eustachian tubes. The size of the tympanic membrane perforation was not found to impact on epithelial migration. However, there was a correlation between the extent of the epithelial migration seen in the specimens and the occurrence of a permanent tympanic membrane perforation after tympanoplasty. Of 17 patients with these findings, 4 (23%) had consistent reperforations. The tympanic membrane rims of these patients were completely covered with squamous epithelium. Patients with no or only little epithelial migration to the inner side of the tympanic membrane were found to have a significantly lower postoperative rate of recurrent infection and drum reperforation.

Observation of Eardrum Movements during Quasi-Static Pressure Changes by High-Speed Digital Imaging

Under specific quasi-static pressure conditions during the Valsalva manoeuvre, high-speed digital video pictures of eardrum displacements were recorded using an endoscope and a Kodak Image Ektapro 1000 Motion Analyzer. A new type of data interface enabled the complete videoclip to be saved and processed digitally, and, with special mathematical algorithms, it is possible to generate three-dimensional computer animations of eardrum movements under quasi-static pressure. The present study describes patterns of eardrum movements under static pressure changes (Valsalva manoeuvre). These patterns were consistent with the results of finite-element simulations of highly similar eardrum displacements reported by other workers.

[Otitis media with effusion : frequency, diagnosis, and therapy in early childhood].

BACKGROUND Otitis media with effusion (OME) as the most common cause of hearing loss in childhood plays an important role in the follow-up after failed newborn hearing screening (NHS). The introduction of the NHS allows OME to be diagnosed and treated in the first months of life. MATERIAL AND METHODS In 715 children referred to the Department of Phoniatrics and Pedaudiology of the Ear, Nose, Throat University Hospital of Magdeburg during the period 2006-2010, the prevalence and therapy process of OME during follow-up could be determined. RESULTS OME was diagnosed in 16 % of the patients. Spontaneous resolution was observed in 37 % of the cases, while 46 % of the children were treated surgically. A substantially increased risk for persistent OME was observed in children with craniofacial dysmorphia or cleft palate. CONCLUSION Using NHS, OME can be diagnosed and treated early, thus, preventing potential problems in the linguistic, social and intellectual development of children.

High-Speed Digital Videoimaging of Fast Eardrum Motions During Valsalva Maneuver

Digital high-speed camera systems are used to record high-frequency videoclips. After adapting this technology to the analysis of eardrum motions, fast motions of the eardrum can be recorded using an endoscope. Under specific static pressure conditions during the Valsalva maneuver, recordings of eardrum motions were made. The use of a Kodak Image Ektapro 1000 Motion Analyzer allowed only conventional videosignal processing and storage. A new type of data interface made it possible to save and process the complete videoclip digitally. Using an image-processing workstation and special mathematical algorithms, three-dimensional computer animations of fast eardrum motions under static pressure can be generated. In the present study, several animations of fast eardrum movements are described. High-speed digital videoimaging is an adequate method to describe fast eardrum displacements under static pressure (Valsalva maneuver). It is possible to create visible time-shift images of separate eardrum parts during the fast Valsalva maneuver.

Population-based cross-sectional study to assess newborn hearing screening program in central Germany

OBJECTIVES Early diagnosis of congenital hearing loss is fundamental to minimize the negative consequences on the speech development. To lower the age at diagnosis and at intervention in hearing impaired children, not only universal newborn hearing screening (NHS) but also tracking is considered essential. The aim of the study was to evaluate the first six years after implementation of the population based newborn hearing screening program in Saxony-Anhalt, one German Federal State. METHODS The cross-sectional cohort study consisted of three cohort samples. Overall 102,301 infants born between January 2010 and December 2015 were included. NHS protocol was developed as dual target group protocol with two sub-protocols. The screening technique included Transient Evoked Otoacoustic Emissions (TEOAE) and Automated Auditory Brainstem Response (AABR) test. Newborns were assigned to the sub-protocols according to their audiological risk factors. Additionally, to evaluate the quality of NHS and tracking (false-negative screening) we were analysing data from a cohort of hearing impaired children diagnosed up to the age of three years. We calculated quality indicators and compared them with international guidelines. RESULTS 101,102 (98.8%) infants were screened. The prevalence of bilateral neonatal hearing loss was 2.32 per 1000 newborns. The median age was two days at first screening, three month at diagnostic testing, and four month at intervention onset. 2.6% infants were lost to follow-up. 56.3% had a final diagnosis of bilateral sensorineural hearing loss. The sensitivity of 0.85 (KI 95%: 0.76–0.91) and a specificity of 0.84 (KI 95%: 0.84–0.85) was calculated for the NHS program. CONCLUSIONS The analysis of benchmarks and outcomes of NHS demonstrated that the program reaches its main goal to identify the hearing impaired newborns in a timely manner.

Musikalische Fähigkeiten bei Kindern mit auditiver Verarbeitungs- und Wahrnehmungsstörung

Objective Difficulties in solving musical tasks are observed in clinical practice in children with an auditory processing disorder (APD). There is a paucity of research on musical ability in children with an APD. Material and Methods To assess musical skills we had 15 children aged 6-11 years with the diagnosis of APD perform a test, and compared them to a control group of 15 children. Results APD children did significantly worse in pitch discrimination, reproduction of rhythm and singing. Correlations between language-based and musical skills in the APD-group were observed. Conclusions Greater attention should be paid to musical skills in APD diagnostics. The positive impact of musical training on language development and cognitive abilities in general has been demonstrated in numerous studies. Musical training should be the focus of further discussion for therapeutic methods of APD in the presence of musical deficits.

Follicular dendritic cell sarcoma of the tonsil.

Follicular dendritic cell sarcoma (FDCS) is a rare neoplasm that occurs extranodally and nodally. The following case report describes a 24-year-old male patient who suffered from FDCS of the tonsil. He presented at the ENT Department of the University Hospital Magdeburg with throat pain that had lasted for 3 months. There were neither B symptoms nor abnormal fatigue. An extended tonsillectomy was performed. The morphological and immunohistochemical findings confirmed the diagnosis of FDCS. FDCS should be considered as an important differential diagnosis in spindle cell tumors of the tonsil.

Resonant Frequency Pattern in Multifrequency Tympanograms: Results in Normally-Hearing Subjects: Patrón de resonancia frecuencial en timpanogramas de multifrecuencia: Resultados en normoyentes

This paper presents experimental data on the evaluation of middle ear resonances by multifrequency tympanometry. Multifrequency tympanograms (MFTs) of 18 normally-hearing subjects were recorded with a frequency resolution of 15 Hz. The fine structure found in the MFT patterns was compared with findings in literature. A first approach for the evaluation of this fine structure was made explaining the great variability of the main ossicular resonance frequencies described in previous publications. The consequence of the present investigation is that the concept of the main ossicular resonance has to be revised critically.